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How to prove that pork meat has parasites

How to prove that pork meat has parasites



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I suspect that the pork sold at a certain shop is infected with the parasite pork tapeworm (Taenia solium).

Is there a way I can prove this without special equipment? Would it work to leave the raw meat in the fridge (at 4 degrees Celcius, or higher?) for a week or so and the worms will come out of their eggs and grow big enough for the eye?


Short answer
T. solium infection can be identified in pork meat by visual inspection.

Background
The stage of the life cycle of the tape worm T. solium in pigs is characterized by cysticerci, which is the larval stage consisting of a protoscolex (head) of the tapeworm. Humans are the definitive host, which means they are the species in which the parasite completes its life cycle, reaches adulthood and is able to produce eggs.

The larvae are observable in pork meat, and cysticercosis is generally identified during slaughter when cysts can be seen in muscle or organs (Fig. 1).


Fig. 1. T. solium cysticerci. (A): as seen in infected pork. (B): excised into a Petri dish. The white dot in each cyst corresponds to the scolex. Source: Garcia et al. (2011)

It is not until these cysticerci are ingested by humans that the tape worm starts to develop fully into a meters-long tape worm, as it enters the next and final stage of its life cycle (Fig. 2).


Fig. 2. Taenia life cycle. Source: CDC

Hence, leaving the meat in the fridge will not induce growth, as a human is needed to induce outgrowth of the protoscolex into the mature tape worm.

Reference
Garcia et al., Lancet (2011): 362 (9383): 547-56


FACTS ON PIGS and PORK Why We Should not Consume Pork

The pig or swine is a very popular food item with most Christians. Yet, they are unaware that the Eternal ( יהוה ) they profess to believe in had condemned the eating of swine’s flesh. The condemnation was based on some very sound biological, principles. Here are some facts on pork that prove it to be a very unhealthy food to eat.

  • A pig is a real garbage gut. It will eat anything including urine, excrement, dirt, decaying animal flesh, maggots, or decaying vegetables. They will even eat the cancerous growths off other pigs or animals.
  • The meat and fat (on those ‘nice’ strips of bacon) of a pig absorbs toxins like a sponge. Their meat can be 30 times more toxic than beef or venison.
  • When eating beef or venison, it takes 8-9 hours to digest the meat, so what little toxins are in the meat are slowly put into our system and can be filtered by the liver. But when pork is eaten, it takes only 4 hours to digest the meat. We thus get a much higher level of toxins within a shorter time.
  • Unlike other mammals, a pig does not sweat or perspire. Perspiration is a means by which toxins are removed from the body. Since a pig does not sweat, the toxins remain within its body and in the meat.
  • Pigs and swine are so poisonous that you can hardly kill them with strychnine or other poisons.
  • Farmers will often pen up pigs within a rattlesnake nest because the pigs will eat the snakes, and if bitten they will not be harmed by the venom.
  • When a pig is butchered, worms and insects take to its flesh sooner and faster than to other animals’ flesh. In a few days, the swine flesh is full of worms.
  • Swine and pigs have over a dozen parasites within them such as tapeworms, flukes, worms, and trichinae. There is no safe temperature at which pork can be cooked to ensure that all these parasites, their cysts, and eggs will be killed.
  • Pig meat has twice as much fat as beef:
    -a 3oz T-bone steak contains 8.5 grams of fat.
    -a 3oz pork chop contains 18 grams of fat.
    -a 3oz beef rib has 11.1 grams of fat.
    -a 3oz pork spare rib has 23.2 grams of fat.
  • Cows have a complex digestive system, having four stomachs. It thus takes over 24 hours to digest their vegetarian diet causing its food to be purified of toxins. In contrast, the swine’s one stomach takes only about 4 hours to digest its foul diet, turning its toxic food into flesh.
  • The swine carries about 30 diseases that can be easily passed to humans.
  • The trichinae worm of the swine is microscopically small, and once ingested can lodge itself in our intestines, muscles, spinal cord or the brain. This results in the disease trichinosis. The symptoms are sometimes lacking, but when present they are mistaken for other diseases, such as typhoid, arthritis, rheumatism, gastritis, MS, meningitis, gall bladder trouble, or acute alcoholism.
  • The pig is so poisonous and filthy, that nature had to prepare him a sewer line or canal running down each leg with an outlet to the bottom of the foot. Out of this hole oozes pus and filth his body cannot pass into its system fast enough.
    Some of this pus gets into the meat of the pig (anyone for pig’s trotters?)

There are other reasons grounded in biological facts that could be listed to show why pigs and swine should not be eaten. But a true Christian should only need one reason why not to eat this type of food and that is because the Eternal (יהוה) prohibited it. Those who say that Yeshua the Messiah abolished the law condemning pork are motivated by their stomach, not Scripture. The problems with pork are biological, and Messiah never changed the laws of biology.
From the “Covenant Messenger” (2007) – CM credits source as International News for your Health.
In the original:
The Eternal ( יהוה) appears as ‘ God ’ Yeshua appears as ‘Jesus’ Messiah appears as ‘Christ’
the Scriptures appears as the Bible.

Unless otherwise noted, all Scriptures are from The Scriptures,
Copyright by Institute for Scripture Research.
Used by permission.


Yes, The Scientific Evidence Says That Eating Pork Does Cause Cancer

What we eat is literally killing us.


“For behold, the Lord will come in fire, and his chariots like the whirlwind,
to render his anger in fury, and his rebuke with flames of fire.
16 For by fire will the Lord enter into judgment, and by his sword, with all flesh
and those slain by the Lord shall be many.
17 “Those who sanctify and purify themselves to go into the gardens, following one in the midst, eating pig’s flesh and the abomination and mice, shall come to an end together , declares the Lord . – Isaiah 66


And the Lord spoke to Moses and Aaron, saying to them, 2 “Speak to the people of Israel, saying, These are the living things that you may eat among all the animals that are on the earth. 3 Whatever parts the hoof and is cloven-footed and chews the cud, among the animals, you may eat… 7 And the pig , because it parts the hoof and is cloven-footed but does not chew the cud, is unclean to you . 8 You shall not eat any of their flesh, and you shall not touch their carcasses they are unclean to you. -Leviticus 11

“And if you faithfully obey the voice of the Lord your God, being careful to do all his commandments that I command you today, the Lord your God will set you high above all the nations of the earth. 2 And all these blessings shall come upon you and overtake you, if you obey the voice of the Lord your God… 58 “If you are not careful to do all the words of this law that are written in this book, that you may fear this glorious and awesome name, the Lord your God, 59 then the Lord will bring on you and your offspring extraordinary afflictions, afflictions severe and lasting, and sicknesses grievous and lasting. 60 And he will bring upon you again all the diseases of Egypt, of which you were afraid, and they shall cling to you. 61 Every sickness also and every affliction that is not recorded in the book of this law, the Lord will bring upon you, until you are destroyed.

A stunning new report from the World Health Organization has concluded that there is clear scientific evidence that eating processed meat causes cancer. In particular, the WHO specifically mentioned processed pork products such as bacon, sausages and hot dogs. Of course for those of us that have been investigating these things for a long time, this doesn’t exactly come as a shock. The alternative health community has been talking about the evidence that pork causes cancer for decades. But for the WHO to come out and say these things publicly is a really big deal.

News of this new report made headlines all over the globe on Monday. The following comes from a story in USA Today…

Eating hot dogs, ham and other processed meat can cause colorectal cancer, and eating red meat “probably” can cause cancer, the World Health Organization’s cancer agency reported Monday.

Kurt Straif of the International Agency for Cancer Research said the risk of developing colorectal cancer from eating processed meat remains small but rises with the amount consumed. Consuming red meat was linked to colorectal, pancreatic and prostate cancer, but the link was not as strong, the IARC report said.

“In view of the large number of people who consume processed meat, the global impact on cancer incidence is of public health importance,” Straif said.

And the numbers that the WHO is talking about are quite striking.

For example, the WHO says that adding just one hot dog to your diet per day significantly increases your risk of colorectal cancer…

According to studies cited in the WHO report, for every 50 grams of processed meat someone eats per day — the equivalent of a little more than a single hot dog — your risk of colorectal cancer goes up by 18%.

In case you still aren’t getting the picture, Cancer Research UK has put together a pretty little graphic to help you figure it out…

Once again, none of this is really “new”.

Over the past few years, some of the most prominent organizations in the medical world have been talking about this link…

Eating too much red meat has already been linked to heart disease, various types of cancer, and early death, but has never officially been classified as a cancer-causing food. In 2014, the WHO’s International Agency for Research on Cancer (IARC) – the same organization arm that classified the herbicide glyphosate as probably carcinogenic –cited studies linking red and processed meats to colorectal, esophageal, lung, and pancreatic cancer, saying that determining the connection was a “high priority.”

According to the World Cancer Research Fund, “There is strong evidence that eating a lot of these foods [red and processed meat] increases your risk of bowel cancer.” Experts estimate that half of all cases of the disease could be prevented by adopting a healthier lifestyle.

Additionally, according to Harvard Medical School, cutting out or reducing red meat consumption can help prolong your life by up to 20%. The study, published in the Archives of Internal Medicine, found unequivocally that people who ate the most red meat (especially processed red meats) died younger, and most often from cardiovascular diseases and cancer.

And the evidence that pork is particularly bad for us is absolutely overwhelming. The following is an extended excerpt from one of my previous articles…

Americans have a love affair with pork. We consume massive amounts of bacon, ham, sausage, pepperoni, etc.

But is that actually healthy for us?

Most people have never stopped to consider this, but they should. The following is an excerpt from a paper entitled “The Adverse Influence Of Pork Consumption On Health” by Professor Hans-Heinrich Reckeweg…

The fact that pork causes stress and gives rise to poisoning is known. It is obvious that this does not only apply to preparations of fresh pork such as cold cuts, knuckles, feet, ribs and cutlets, etc., but also to cured meats (ham, bacon, etc.) and to smoked meats prepared for sausages.

Consumption of freshly killed pork products causes acute responses, such as inflammations of the appendix and gall bladder, biliary colics, acute intestinal catarrh, gastroenteritis with typhoid and paratyphoid symptoms, as well as acute eczema, carbuncles, sudoriparous abscesses, and others. These symptoms can be observed after consuming sausage meats (including salami which contains pieces of bacon in the form of fat).

And here are some more reasons why you should think twice about eating pork…

A pig is a real garbage gut. It will eat anything including urine, excrement, dirt, decaying animal flesh, maggots, or decaying vegetables. They will even eat the cancerous growths off other pigs or animals.

The meat and fat of a pig absorbs toxins like a sponge. Their meat can be 30 times more toxic than beef or venison.

When eating beef or venison, it takes 8 to 9 hours to digest the meat so what little toxins are in the meat are slowly put into our system and can be filtered by the liver. But when pork is eaten, it takes only 4 hours to digest the meat. We thus get a much higher level of toxins within a shorter time.

Unlike other mammals, a pig does not sweat or perspire. Perspiration is a means by whic h toxins are removed from the body. Since a pig does not sweat, the toxins remain within its body and in the meat.

Pigs and swine are so poisonous that you can hardly kill them with strychnine or other poisons. Farmers will often pen up pigs within a rattlesnake nest because the pigs will eat the snakes, and if bitten they will not be harmed by the venom.

When a pig is butchered, worms and insects take to its flesh sooner and faster than to other animal’s flesh. In a few days the swine flesh is full of worms.

Swine and pigs have over a dozen parasites within them, such as tapeworms, flukes, worms, and trichinae. There is no safe temperature at which pork can be cooked to ensure that all these parasites, their cysts, and eggs will be killed.

Pig meat has twice as much fat as beef. A three-ounce T-bone steak contains 8.5 grams of fat a three-ounce pork chop contains 18 grams of fat. A three-ounce beef rib has 11.1 grams of fat a three-ounce pork spare rib has 23.2 grams of fat.

Cows have a complex digestive system, having four stomachs. It thus takes over 24 hours to digest their vegetarian diet causing its food to be purified of toxins. In contrast, the swine’s one stomach takes only about four hours to digest its foul diet, turning its toxic food into flesh.

The swine carries about 30 diseases which can be easily passed to humans. This is why God commanded that we are not even to touch their carcass. (Leviticus 11:8).

The trichinae worm of the swine is microscopically small, and once ingested can lodge itself in our intestines, muscles, spinal cord or the brain. This results in the disease trichinosis. The symptoms are sometimes lacking, but when present they are mistaken for other diseases, such as typhoid, arthritis, rheumatism, gastritis, MS, meningitis, gall bladder trouble, or acute alcoholism.

Sadly, a significant number of readers will respond very negatively to this article.

Because they absolutely love pork and they do not want to give it up.

And of course the meat industry moved very rapidly to cast doubt on today’s WHO report…

But the meat industry was quick to dismiss the warning claiming it had been ‘rigged’ and was not based on proper evidence.

Dr Betsy Booren, Vice President of Scientific Affairs at the North American Meat Institute said: ‘They tortured the data to ensure a specific outcome.

‘Followers of the Mediterranean diet eat double the recommended amount of processed meats.

‘People in countries where the Mediterranean diet is followed, like Spain, Italy and France, have some of the longest lifespans in the world and excellent health.

Hopefully some people will be persuaded by this article, but I don’t expect that most people will.

Most people end up believing exactly what they want to believe, and that includes the truth about the food that they are shoving into their faces.

Unfortunately, in the United States today we can’t even rely on the big food corporations to label their products accurately. Just check out what a different new study recently discovered…

Some dogs were labeled pork-free — important for certain religions — but were found to contain pork after all. Others listed only one type of meat but included several or didn’t contain all the ingredients listed.

Even grosser: 2 percent of all samples were found to have traces of human DNA in them. Veggie dogs were the worst off, accounting for 67 percent of the hygiene issues and two-thirds of the human DNA found.

The good news: As bad as some brands were found to be, there are some trustworthy options out there. The report lists the soy chorizo and meatless corn dogs at Trader Joe’s as safe picks for vegetarians, and Taveritte’s, Whole Foods’ 365 brand, Aidell’s, Hebrew National, Ball Park, Oscar Mayer, and Johnsonville for meat eaters.

And just because your hot dog is labeled “vegetarian” does not mean that there isn’t any meat in it. The following is an excerpt from a recent Natural News article…

The fact that human DNA is being found in hot dogs might mean Bob fell into the meat grinder again. More likely, however, it just means that people working on these food lines aren’t wearing beard nets or gloves. It’s interesting that most of the problems were found in veggie dogs, which are positioned as being healthier than meat-based hot dogs. Apparently, veggie dogs aren’t 100% vegetarian because they also contain some human parts.

According to the Clear Food report, 10% of vegetarian hot dogs contained meat. Sadly, Clear Food refuses to name which brands were contaminated!

It is 2015, and yet with all of our technological advances we can’t even trust that our food is not severely contaminated?

I wish that I had better news for you. As Americans, we have a love affair with meat. Personally, I don’t eat pork, but I do really enjoy beef, turkey, chicken, etc. Most of us are accustomed to having meat several times per day, and the vast majority of us never really stop to think of the health impact that this may be having on us and our families.

Do you think that this new WHO report will cause people to stop and reflect on the garbage that they are shoveling down their throats on a daily basis?


Analysis:

These messages and also videos shared online since many years warn people that when Coca Cola (Coke) is poured onto raw Pork, it causes Worms to come crawling out of the meat. They caution people to be wary of consuming pork, that it can make them really sick when the parasites inside are ingested along with the meat. Let us learn if the said claim is really a fact or not.

Source

These messages warning people that coke brings out the worms hidden inside raw pork have been shared online for more than a decade and were also shared through emails initially. They said that when coke is added to raw, uncooked pork, after 5 or 10 minutes, tiny worms will surface from the meat.

The claims in the messages seem to be referring to Trichinosis or trichiniasis, a parasitic disease caused by eating raw or undercooked pork in this case, when larvae of a species of roundworm Trichinella spiralis (commonly called the trichina worm) infects the victim. However, the parasite referred to as the “pork worm” also occurs in carnivorous and omnivorous animals like rodents, horse, bears, wild boar, fox, dog, wolf, seal, walrus and others. This concern of Trichinosis arises mostly when you eat raw, undercooked meats, or low quality pork for that matter.

Pork and Coke Videos

Some people posted videos online (like the one in this article) claiming to show that they have found worms in raw pork after soaking it in Coke. There is no credible evidence to prove the claim in question is a fact. The claims in the videos are hoaxes, misinterpretations or ‘deliberate findings’ perhaps using poor quality pork. Soaking pork or for that matter any meat in coke for hours together may even bring out their chemical (or residual) constituents that may be shown as worms. There are also many other videos showing no such thing happens.

Cooking pork meat to safe temperatures kills most of the worms, if any. CDC suggests safe cooking temperatures for various meats. You can use a food thermometer to measure the internal temperature of cooked meat. Moreover, over the years, the prevalence of Trichinosis has declined considerably in domestic pigs, also because many countries have meat inspection programs in place.

Consumption of pork is forbidden in some religions. The pork meat from domestic pig is consumed worldwide because it is very high in thiamin (vitamin B1) and has good protein content. Nonetheless, it should also be noted that pork meat is high in cholesterol and saturated fat.

Conclusion

Soaking raw, uncooked pork meat in coke does not cause worms to surface, the claim, as such, is an urban legend that has been around for more than a decade now. But of course, one has to choose healthy, hygienic quality pork and also make sure to cook it well.


The meat allergy: Researcher IDs biological changes triggered by tick bites

A University of Virginia School of Medicine scientist has identified key immunological changes in people who abruptly develop an allergic reaction to mammalian meat, such as beef. His work also provides an important framework for other scientists to probe this strange, recently discovered allergy caused by tick bites.

The findings by UVA's Loren Erickson, PhD, and his team offer important insights into why otherwise healthy people can enjoy meat all their lives until a hot slab of ground beef or a festive Fourth of July hot dog suddenly become potentially life-threatening. Symptoms of the meat allergy can range from mild hives to nausea and vomiting to severe anaphylaxis, which can result in death.

"We don't know what it is about the tick bite that causes the meat allergy. And, in particular, we haven't really understood the source of immune cells that produce the antibodies that cause the allergic reactions," Erickson explained. "There's no way to prevent or cure this food allergy, so we need to first understand the underlying mechanism that triggers the allergy so we can devise a new therapy."

Understanding the Meat Allergy

People who develop the allergy in response to the bite of the Lone Star tick often have to give up eating mammalian meat, including beef and pork, entirely. Even food that does not appear to contain meat can contain meat-based ingredients that trigger the allergy. That means people living with the meat allergy must be hyper-vigilant. (For one person's experience with the meat allergy, visit UVA's Making of Medicine blog.)

The allergy was first discovered by UVA's Thomas Platts-Mills, MD, an allergist who determined that people were suffering reactions to a sugar called alpha-gal found in mammalian meat. Exactly what is happening inside the body, though, has remained poorly understood. Erickson's work, along with that of others at UVA, is changing that.

Erickson's team in UVA's Department of Microbiology, Immunology and Cancer Biology has found that people with the meat allergy have a distinctive form of immune cells known as B cells, and they have them in great numbers. These white blood cells produce antibodies that release chemicals that cause the allergic reaction to meat.

In addition, Erickson, a member of UVA's Carter Immunology Center, has developed a mouse model of the meat allergy so that scientists can study the mysterious allergy more effectively.

"This is the first clinically relevant model that I know of, so now we can go and ask a lot of these important questions," he said. "We can actually use this model to identify underlying causes of the meat allergy that may inform human studies. So it's sort of a back-and-forth of experiments that you can do in animal models that you can't do in humans. But you can identify potential mechanisms that could lead to new therapeutic strategies so that we can go back to human subjects and test some of those hypotheses."


Timeline

Italy, Austria-Hungary, Spain, Germany, Romania, Greece, and Denmark prohibited the importation of American pork alleging the presence of trichinae.

U.S. Department of State issued inquiries to the pork industry about meat safety.

Microscopic survey of pork products for trichinae was made in Atlanta, Boston, Chicago, Montreal, and Washington, D.C.

Bureau of Animal Industry&rsquos Meat Inspection Division began microscopic examination for the detection of trichinae in pork to be exported to countries requiring such inspection.

Charles W. Stiles found no evidence in Germany that cases of trichinosis originated from American pork, but he determined that microscopic inspection was inadequate.

Microscopic inspection of pork was discontinued.

B. H. Ransom discovered that trichinae in pork could be destroyed by refrigeration of 5° F for 20 days.

The destruction of trichinae by refrigeration of infected pork was reported by U.S. Department of Agriculture (USDA) as a control measure for trichinosis.

Ransom and Benjamin Schwartz established definitely that a temperature of 137 °F was ample for the destruction of trichinae.

1920-21

Schwartz demonstrated that the vitality of trichinae could be destroyed by massive doses of x-rays.

Schwartz devised a method for preparing trichinae antigen free from muscle tissue and tested it on pigs experimentally infected with trichinae.

Schwartz initiated an investigation to determine the current frequency of Trichinella spiralis infection in swine in the United States.

The Beltsville Parasitology Laboratory began a new project to investigate the effectiveness of the current meat inspection procedures designed to detect and inactivate larvae of Trichinella spiralis in pork products.

A new antigen containing the metabolic products of live trichina larvae was prepared and tested on hogs by the intracutaneous method.

Investigations of trichinae in hogs confirmed that more garbage-fed hogs were infected and harbored heavier infections than grain-fed hogs.

L. A. Spindler, in cooperation with O. G. Hankins of the Animal Husbandry Division's Meats Laboratory, showed that dehydration of pork containing viable trichinae to a 3 percent moisture level at temperatures of 102 to 120 °F would kill all the parasites.

Spindler reported that rapid dehydration of trichinous pork lowered the thermal death point of the parasites.

1953-1954

States passed laws against feeding raw garbage to swine, in an effort to control the viral disease vesicular exanthema. As a result of these measures, trichinae infection decreased dramatically. http://www.aphis.usda.gov/vs/trichinae/docs/fact_sheet.htm

1968-1969

John S. Andrews with D. E. Zinter and N. E. Schultz tested a pooled-sample digestion technique developed in 1967 by W. J. Zimmermann of Iowa State University designed to facilitate the examination for trichinae of all hogs slaughtered in modern abattoirs with high-speed slaughtering capability. This procedure is now the world standard for recovering larvae from muscle of all animals, and the mandatory method for meat inspection in countries where inspection is required (e.g., European Union).

K. D. Murrell and Gerhard A. Schad, University of Pennsylvania, in an epidemiological study, provided evidence that swine trichinosis was more prevalent in the swine of the northeastern United States than previously thought, especially in production systems that feed food waste.

J. Ralph Lichtenfels and Murrell, using the scanning electron microscope, examined the three &rdquospecies&rdquo of Trichinella spiralis that were reported to be distinguishable on morphological grounds. Their results demonstrated this approach was not reliable.

Murrell and Schad investigated the role of syvatic animals as reservoir hosts of Trichinella spiralis, and found a relatively high prevalence in wildlife in the U.S. Middle Atlantic region, especially in black bears in Pennsylvania. Importantly, isolates of Trichinella were found to include both Trichinella spiralis, and another genotype that, unlike Trichinella spiralis, had very low infectivity in pigs.

1982-1985

Anthony Kotula, Beltsville Agricultural Research Center (BARC) Meat Science Laboratory, Murrell and H. R. Gamble, Animal Parasitology Institute, developed new thermal death curves for Trichinella spiralis trichinae in pork which became the standard for USDA recommendations on cooking and freezing for the de-vitalization of pork for home consumption and for commercial pork processing.

1985-1987

Gamble and Murrell develop a serological method (ELISA) for detecting anti-Trichinella antibody in pigs using a highly specific secretory/excretory product (ES) from the muscle larval stage. This overcame the non-specificity and low sensitivity problems plaguing all existing serological tests a U.S. patent was issued for this antigen. It remains the international gold standard for immunodiagnosis and was the basis for several commercial tests that are widely used. Gamble later developed a molecular procedure to produce recombinant diagnostic antigens, and a monoclonal antibody for specific diagnostic tests.

Murrell and H. P. Marti of the Animal Parasitology Institute, discovered that the most important immune protective mechanism in pigs against Trichinella spiralis is antibody-mediated and attacks the newborn larvae migrating in the blood stream. Murrell, Marti and Gamble were eventually awarded a U.S. patent for a vaccine based on the antigens of the newborn larvae.

Murrell and R. J. Brake of the U.S. Department of Energy Sandia National Laboratory determined the gamma irradiation dosage for killing Trichinella spiralis muscle larvae. This was the data needed by both the USDA Food Safety and Inspection Service and the U.S. Food and Drug Administration to issue the first approvals for irradiation of red meat for controlling pathogens.

1986-1987

Schad, David A. Leiby of the University of Pennsylvania, and Murrell demonstrated in both natural and experimental on-farm conditions the important role of rats in transmitting Trichinella spiralis to farm pigs. John B. Dame, F. Stringfellow, and Murrell, using new molecular tools showed that Trichinella spiralis was interchanged between wildlife and farm pigs and rats surrounding infected farms, underscoring the role reservoir hosts play in the epidemiology of trichinellosis. In experimental studies carried out in Illinois, R. Hanbury, P. Dobey, and Murrell demonstrated that on-farm cannibalism is also a major mode of transmission, even when rats are controlled.

Dame and Murrell identified genetic markers which distinguished genotypes of Trichinella that varied in their infectivity to pigs. One isolate from bears was later determined to be a new species by the International Trichinella Reference Center in Rome, and was named Trichinella murrelli. This species, although poorly infective for pigs, is considered to be the most common species in wild animals in North America and responsible for most human cases derived from game meat.

1987-1990

Gamble and colleagues at Texas A&M University worked with USDA&rsquos Food Safety and Inspection Service to validate the safety of commercial methods for the production of dry cured hams.

1988 to present

Gamble, and later Hill, worked with USDA&rsquos Agricultural Marketing Service in establishing and maintaining training and quality assurance programs for carcass testing used to support U.S. exports of horsemeat (1988-2004) and pork (1996 to present).

Dante Zarlenga (API) and Gamble published the first sequencing data on diagnostic antigens for Trichinella spiralis. This work was subsequently taken up by many other researchers.

1990 to present

Researchers including Gamble and Hill supported national surveys for Trichinella (under the APHIS National Animal Health Monitoring Surveys) to document the decline and absence in Trichinella infection in conventionally raised pigs in the U.S. This information has been important in assuring the safety of U.S. pork when establishing trade agreements.

Murrell and Lichtenfels, with collaborators Edoardo Pozio and Giuseppe La Rosa of the International Trichinella Reference Center in Rome, made a substantial advancement in the control of trichinellosis by applying biochemical and biological methods to completely revise the systematics of the genus Trichinella. This clarified many puzzling observations on the biology of Trichinella and greatly enhanced understanding of the disease&rsquos epidemiology, especially the identification of those few species (particularly Trichinella spiralis) which are the greatest risk for infection of pigs.

Zarlenga and colleagues introduced a multiplex PCR method that unequivocally differentiated the genotypes of Trichinella, particularly the encapsulated and unencapsultaed types. This method is the basic tool now in use world wide to distinguish Trichinella species.

1999-2000

Gamble, working with colleagues in the International Commission on Trichinellosis, developed the first in a series of guidelines on control of trichinellosis, establishing a consensus of international experts. Additional guidelines were subsequently developed and serve as references for international authorities such as the Codex Alimentarius and the World Organization for Animal Health.

Gamble and Christian Kapel of Denmark conducted a series of comparative studies in pigs on infectivity and antibody responses to Trichinella spiralis and several sylvatic species of Trichinella. The results showed that sylvatic species from North America have very low infectivity, and therefore, have a low risk for spillover to pigs with outdoor exposure.

Gamble and David G. Pyburn of USDA's Animal and Plant Health Inspection Service developed in collaboration with the U.S. pork producers a certification program to farms that achieve a designation as Trichinella-free.

Zarlenga, Benjamin Rosenthal, Eric P. Hoberg, Pozio, and La Rosa published a ground-breaking paper on the evolution and biogeography of the genus Trichinella.

Dolores E. Hill and colleagues determined the viability and infectivity of Trichinella spiralis in frozen horse muscle. Infected horse meat has been the infection source for a number of trichinellosis outbreaks, particularly in Europe one outbreak in Paris was attributed to exported horse meat from the U.S. infected with Trichinella murrelli.

Rosenthal, Zarlenga, and colleagues published a study on the genetics of Trichinella spiralis that explains the role of humans in dispersing Trichinella spiralis throughout the world.

Hill and collaborators conducted an international ring trial to evaluate the specificity and sensitivity of the ELISA-ES antigen diagnostic test for pig infections. The results demonstrated that the test was very robust, accurate, and reproducible.

Hill and colleagues found that Trichinella spiralis does not survive in an independent sylvatic cycle, which has important implications for assessing the risk of Trichinella spiralis infecting pigs raised in extensive systems.

Zarlenga, in an international collaboration, published a draft genome of Trichinella spiralis, an important advance in understanding the biology of this parasite.


Trichinosis parasite gets DNA decoded

Scientists have decoded the DNA of the parasitic worm that causes trichinosis, a disease linked to eating raw or undercooked pork or carnivorous wild game animals, such as bear and walrus.

After analyzing the genome, investigators at Washington University School of Medicine in St. Louis and their collaborators report they have identified unique features of the parasite, Trichinella spiralis, which provide potential targets for new drugs to fight the illness. The research is published online Feb. 20 in Nature Genetics.

While trichinosis is no longer a problem in the United States -- fewer than a dozen cases are reported annually -- an estimated 11 million people worldwide are infected. Current treatments are effective only if the disease is diagnosed early.

"It takes less than two weeks for the larvae to travel from the intestine to muscle, where they live," says lead author Makedonka Mitreva, PhD, research assistant professor of genetics at Washington University's Genome Center. "Once the worms invade the muscle, drugs are less effective. While the disease is rarely deadly, patients often live for months or years with chronic muscle pain and fatigue until the worms eventually die."

Today, trichinosis occurs most often in areas of Asia and Eastern Europe where pigs are sometimes fed raw meat, and meat inspections are lax.

The new research also has implications far beyond a single parasitic disease, the researchers say. T. spiralis is just one of many thousands of parasitic roundworms called nematodes that, according to the World Health Organization, infect 2 billion people worldwide, severely sickening 300 million. Other species of parasitic nematodes cause diseases in pets and livestock and billions of dollars of crop losses annually.

Among nematodes, T. spiralis diverged early, some 600-700 million years before the crown species, C. elegans, a model organism used in research laboratories. To date, the genomes of 10 nematodes, including five parasitic worms, have been decoded. The latest addition of the T. spiralis genome now allows scientists to compare species that span the phylum.

"T. spiralis occupies a strategic position in the evolutionary tree of nematodes, which helps fill in important knowledge gaps," explains senior author Richard K. Wilson, PhD, director of Washington University's Genome Center and professor of genetics. "By comparing nematode genomes, we have identified key molecular features that distinguish parasitic nematodes, raising the prospect that a single targeted drug may be effective against multiple species."

Over all, the genome of T. spiralis is smaller than that of C. elegans. It has 15,808 genes, compared to C. elegans' 20,000.

Moreover, about 45 percent of T. spiralis genes appear to be novel. These genes have not been found in other organisms and are not listed in public gene databases. The researchers say the worm's early evolutionary split or its distinctive lifestyle -- it can't survive outside the body -- may account for this extensive collection of enigmatic genes.

The researchers also found 274 families of proteins that are conserved among all nematodes and that do not exist in other organisms, including humans. Furthermore, they identified 64 protein families that are exclusive to parasitic nematodes.

"This provides opportunities for scientists to dig deeper into the distinctive features of parasitic nematodes that can be targeted with new drugs," Mitreva says. "If those drugs target molecular features unique to parasitic worms, it is more likely the side effects of those drugs will be minimal in humans."

The research is supported by the National Human Genome Research Institute and the National Institute of Allergy and Infectious Diseases, both of the National Institutes of Health.

Collaborators include scientists at Washington State University, the U.S. Department of Agriculture, Cornell University and Divergence, Inc.

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Materials provided by Washington University School of Medicine. Note: Content may be edited for style and length.


Trichinella species, the smallest nematode parasite of humans, has an unusual lifecycle, and are one of the most widespread and clinically important parasites in the world. [2] The small adult worms mature in the small intestine of a definitive host, such as a pig. Each adult female produces batches of live larvae, which bore through the intestinal wall, enters the blood (to feed on it) and lymphatic system, and are carried to striated muscle. Once in the muscle, they encyst, or become enclosed in a capsule. Humans can become infected by eating infected pork, horsemeat, or wild carnivores such as fox, cat, hyena or bear. [2]

Morphology Edit

Males of T. spiralis measure between 1.4 and 1.6 mm long, and are more flat anteriorly than posteriorly. The anus can be found in the terminal end, and they have a large copulatory pseudobursa on each side. [2] The females of T. spiralis are about twice the size of the males, and have an anus found terminally. The vulva is located near the esophagus. The single uterus of the female is filled with developing eggs in the posterior portion, while the anterior portion contains the fully developed juveniles. [2]

Trichinella spiralis can live the majority of its adult life in the intestines of humans. To begin its lifecycle, T. spiralis adults invade the intestinal wall of a pig, and produce larvae that invade the pig's muscles. The larval forms are encapsulated as a small cystic structure within a muscle cell of the infected host. When another animal (perhaps a human) eats the infected meat, the larvae are released from the nurse cells in the meat (due to stomach pH), and migrate to the intestine, where they burrow into the intestinal mucosa, mature, and reproduce. [3] Juveniles within nurse cells have an anaerobic or facultative anaerobic metabolism, but when they become activated, they adopt the aerobic metabolism characteristics of the adult. [2]

Female Trichinella worms live for about six weeks, and in that time can produce up to 1,500 larvae when a spent female dies, she passes out of the host. The larvae gain access to the circulation and migrate around the body of the host, in search of a muscle cell in which to encyst. [3] The migration and encystment of larvae can cause fever and pain, brought on by the host inflammatory response. In some cases, accidental migration to specific organ tissues can cause myocarditis and encephalitis that can result in death.

Nurse cell formation Edit

This nematode is a multicellular parasite that lives within a single muscle cell, which it extensively modifies according to its own requirements. [4]

Nurse cell formation in skeletal muscle tissue is mediated by the hypoxic environment surrounding the new vessel formation. [5] The hypoxic environment stimulates muscle cells in the surrounding tissue to upregulate and secrete angiogenic cytokines, such as vascular endothelial growth factor (VEGF). This allows the migrating T. spiralis larva to enter the myocyte and induce the transformation into the nurse cell. VEGF expression is detected surrounding the nurse cell immediately after nurse cell formation, and the continued secretion of VEGF can maintain the constant state of hypoxia. [6] [7]

The first symptoms may appear between 12 hours and two days after ingestion of infected meat. The migration of adult worms in the intestinal epithelium can cause traumatic damage to the host tissue, and the waste products they excrete can provoke an immunological reaction. [2] The resulting inflammation can cause symptoms such as nausea, vomiting, sweating, and diarrhea. Five to seven days after the appearance of these symptoms, facial edema and fever may occur. Ten days following ingestion, intense muscular pain, difficulty breathing, weakening of pulse and blood pressure, heart damage, and various nervous disorders may occur, eventually leading to death due to heart failure, respiratory complications, or kidney malfunction, all due to larval migration. [2]

In pigs, infection is usually subclinical, but large worm burdens can be fatal in some cases. [8]

Muscle biopsy may be used for trichinosis detection. Several immunodiagnostic tests are also available. Typically, patients are treated with either mebendazole or albendazole, but efficacy of such products is uncertain. Symptoms can be relieved by use of analgesics and corticosteroids. [2]

In pigs, ELISA testing is possible as a method of diagnosis. Anthelmintics can treat and prevent Trichinella infections. [8]

Trichinosis (trichinellosis) is a disease caused by tissue-dwelling roundworms of the species Trichinella spiralis. In the United States, the national trichinellosis surveillance system has documented a steady decline in the reported incidence of this disease. During 1947 to 1951, a median of 393 human cases was reported annually, including 57 trichinellosis-related deaths. During 1997–2001, the incidence in the US decreased to a median of 12 cases annually, with no reported deaths. The decrease was largely due to improved compliance with standards and regulations by commercial pork producers. [9]

In the United States, Congress passed the Federal Swine Health Protection Act, restricting the use of uncooked garbage as feed stock for pigs, and creating a voluntary Trichinae Herd Certification Program. [9] The Trichinae Herd Certification Program is a voluntary pre-slaughter pork safety program that provides documentation of swine management practices to minimize Trichinella exposure. The goal of the program is to establish a system under which pork production facilities that follow good production practices might be certified as Trichinella-safe. [10] In addition to the reduction in Trichinella prevalence in commercial pork, processing methods also have contributed to the dramatic decline in human trichinellosis associated with pork products. [ citation needed ] Through the U.S. Code of Federal Regulations, the USDA has created guidelines for specific cooking temperatures and times, freezing temperatures and times, and curing methods for processed pork products to reduce the risk of human infection from Trichinella contaminated meat. [9] Pork products meeting these guidelines are designated certified pork. [ citation needed ]

It was reported in 2005 that the prevalence of human infections from Trichinella spiralis was low in the United States, despite nonexistent meat inspection with respect to trichinella. This was due to strict enforcement of the regulations applying to large meat production facilities: most cases have been from raw or undercooked meat from game animals. [11]

Also reported in 2005, the rate of infection from Trichinella spiralis was significantly higher in people living in parts of Europe, Asia, and Southeast Asia than in the United States. However, EU nations employ several strategies for detecting meat infected with Trichinella spiralis. If tests are consistently negative, then a trichinella-free designation is applied to a given meat supply. Rare outbreaks still occur despite this rigorous system: France, Italy, and Poland have reported outbreaks due to eating raw horsemeat. At that time, the parasite was considered endemic in Japan and China, while Korea had recently reported its first human cases of trichinosis. [11]

In most abattoirs, the diaphragms of pigs are routinely sampled to detect Trichinella infections. [8]

Post-slaughter human exposure is also preventable by educating consumers on simple steps that can be taken to kill any larvae that can potentially be in meat bought at the local supermarket. Freezing meat in an average household freezer for 20 days before consumption will kill some species of Trichinella. Cooking pork products to a minimum internal temperature of 160 °F (72 °C) will kill most species, and is the best way to ensure the meat is safe to eat. [12]

It was reported in 2009 that political and economic changes had caused an increase in the prevalence and incidence rates of this parasite in many former eastern European countries due to weakened veterinary control on susceptible animals. [13] This complicated the meat trade industry within European Union countries, and exportation of pork outside the EU. [13] As a result, the European Union and some associated countries implemented a Trichinella monitoring program for pigs, horses, wild boar, and other wildlife species while the European Commission implemented a new regulation to control Trichinella in meat in order to improve food safety for European consumers [13]

Illegal pork importation from places with low safety standards allows the spread of the parasite from endemic to nonendemic countries. [13] Illegal importation and new food practices and dishes including raw meat have resulted in human trichinosis outbreaks in many European countries, including Denmark, Germany, Italy, Spain, and the United Kingdom. [13]

The economic cost of detecting trichinosis can be another cost burden. In 1998, a rough global cost estimate was $3.00 per pig to detect the parasite. [13] At the same time, in the 15 countries comprising the European Union in 1998, about 190 million pigs were killed in slaughterhouses annually, leading to an estimated economic impact of testing of about $570 million per year. [13] However, depending on the size of the specific slaughterhouse, the actual costs could be more than an order of magnitude smaller (i.e. less than .30 per pig). [13]

The Trichinella spiralis draft genome became available in March, 2011. [14] The genome size was 58.55 Mbp with an estimated 16,549 genes. [15] The T. spiralis genome is the only known nematode genome to be subject to DNA methylation, [16] an epigenetic mechanism that was not previously thought to exist in nematodes.


Hazards and Diseases

Prevalence in Pigs

Trichinella prevalence in pigs varies from country to country, and regionally within countries. The lowest prevalence rates in domestic swine are found in countries where meat inspection programs have been in place for many years (including, in particular, countries of the European Union (EU)). In some instances, countries with long-standing inspection programs consider themselves free from Trichinella in domestic swine. In countries of eastern Europe, higher prevalence rates of Trichinella have been reported in pigs and this is supported by higher numbers of cases of human trichinellosis. Increased prevalence of Trichinella infection in pigs in some of the Balkan countries is the result of changes from large government run farms to small holdings where pigs are raised outdoors. In the US, no formal inspection programs have been used to control Trichinella in pigs. However, changes in the pork industry which focus on confinement housing and other measures of biosecurity have essentially eliminated this infection from the domestic pork supply.

Only sporadic information is available on the prevalence of trichinellosis in South America, Africa, and Asia, but these limited reports suggest high infection rates occur in pigs in some countries. For example, in rural areas of China where pigs are raised outdoors in uncontrolled environments, pig infection rates can be 50% or higher.


Contents

The great majority of trichinosis infections have either minor or no symptoms and no complications. [9] The two main phases for the infection are enteral (affecting the intestines) and parenteral (outside the intestines). The symptoms vary depending on the phase, species of Trichinella, quantity of encysted larvae ingested, age, sex, and host immunity. [10]

Enteral phase Edit

A large burden of adult worms in the intestines promotes symptoms such as nausea, heartburn, dyspepsia, and diarrhea from two to seven days after infection, while small worm burdens generally are asymptomatic. Eosinophilia presents early and increases rapidly. [11]

Parenteral phase Edit

The severity of symptoms caused by larval migration from the intestines depends on the number of larvae produced. As the larvae migrate through tissue and vessels, the body's inflammatory response results in edema, muscle pain, fever, and weakness. A classic sign of trichinosis is periorbital edema, swelling around the eyes, which may be caused by vasculitis. Splinter hemorrhage in the nails is also a common symptom. [12]

They may very rarely cause enough damage to produce serious neurological deficits (such as ataxia or respiratory paralysis) from worms entering the central nervous system (CNS), which is compromised by trichinosis in 10–24% of reported cases of cerebral venous sinus thrombosis, a very rare form of stroke (three or four cases per million annual incidence in adults). [13] Trichinosis can be fatal depending on the severity of the infection death can occur 4–6 weeks after the infection, [14] and is usually caused by myocarditis, encephalitis, or pneumonia. [15]

The classical agent is T. spiralis (found worldwide in many carnivorous and omnivorous animals, both domestic and sylvatic (wild), but seven primarily sylvatic species of Trichinella also are now recognized:

Species and characteristics Edit

    is most adapted to swine, most pathogenic in humans, and is cosmopolitan in distribution. [citation needed] is the second-most common species to infect humans it is distributed throughout Europe, Asia, and northern and western Africa, usually in wild carnivores, crocodiles, birds, wild boar, and domesticated pigs. [citation needed]
  • T. murrelli also infects humans, especially from black bear meat it is distributed among wild carnivores in North America. [citation needed] , which has a high resistance to freezing, is found in the Arctic and subarctic regions reservoir hosts include polar bears, Arctic foxes, walruses, and other wild game. [citation needed]
  • T. nelsoni, found in East African predators and scavengers, has been documented to cause a few human cases.
  • T. papuae infects both mammals and reptiles, including crocodiles, humans, and wild and domestic pigs this species, found in Papua New Guinea and Thailand, is also nonencapsulated. [16]
  • T. pseudospiralis infects birds and mammals, and has demonstrated infection in humans [17] it is a nonencapsulated species.
  • T. zimbabwensis can infect mammals, and possibly humans this nonencapsulated species was detected in crocodiles in Africa. [1]

Taxonomy Edit

  • Kingdom: Animalia
  • Phylum: Nematoda
  • Class: Adenophorea
  • Order: Trichurida
  • Family: Trichinellidae
  • Genus: Trichinella

Lifecycle Edit

The typical lifecycle for T. spiralis involves humans, pigs, and rodents. A pig becomes infected when it eats infectious cysts in raw meat, often porcine carrion or a rat (sylvatic cycle). A human becomes infected by consuming raw or undercooked infected pork (domestic cycle). In the stomach, the cysts from infected undercooked meat are acted on by pepsin and hydrochloric acid, which help release the larvae from the cysts into the stomach. [10] The larvae then migrate to the small intestine, and burrow into the intestinal mucosa, where they molt four times before becoming adults. [10]

Thirty to 34 hours after the cysts were originally ingested, the adults mate, and within five days produce larvae. [10] Adult worms can only reproduce for a limited time, because the immune system eventually expels them from the small intestine. [10] The larvae then use their piercing mouthpart, called the "stylet", to pass through the intestinal mucosa and enter the lymphatic vessels, and then enter the bloodstream. [18]

The larvae travel by capillaries to various organs, such as the retina, myocardium, or lymph nodes however, only larvae that migrate to skeletal muscle cells survive and encyst. [14] The larval host cell becomes a nurse cell, in which the larva will be encapsulated, potentially for the life of the host, waiting for the host to be eaten. The development of a capillary network around the nurse cell completes encystation of the larva. Trichinosis is not soil-transmitted, as the parasite does not lay eggs, nor can it survive long outside a host. [5] [19]

Diagnosis of trichinosis is confirmed by a combination of exposure history, clinical diagnosis, and laboratory testing. [ citation needed ]

Exposure history Edit

An epidemiological investigation can be done to determine a patient's exposure to raw infected meat. Often, an infection arises from home-preparation of contaminated meat, in which case microscopy of the meat may be used to determine the infection. Exposure determination does not have to be directly from a laboratory-confirmed infected animal. Indirect exposure criteria include the consumption of products from a laboratory-confirmed infected animal, or sharing of a common exposure with a laboratory-confirmed infected human. [14]

Clinical diagnosis Edit

Clinical presentation of the common trichinosis symptoms may also suggest infection. These symptoms include eye puffiness, splinter hemorrhage, nonspecific gastroenteritis, and muscle pain. [14] The case definition for trichinosis at the European Center for Disease Control states, "at least three of the following six: fever, muscle soreness and pain, gastrointestinal symptoms, facial edema, eosinophilia, and subconjunctival, subungual, and retinal hemorrhages." [14]

Laboratory testing Edit

Blood tests and microscopy can be used to aid in the diagnosis of trichinosis. Blood tests include a complete blood count for eosinophilia, creatine phosphokinase activity, and various immunoassays such as ELISA for larval antigens. [14]

Legislation Edit

Laws and rules for food producers may improve food safety for consumers, such as the rules established by the European Commission for inspections, rodent control, and improved hygiene. [14] A similar protocol exists in the United States, in the USDA guidelines for farms and slaughterhouse responsibilities in inspecting pork. [20]

Education and training Edit

Public education about the dangers of consuming raw and undercooked meat, especially pork, may reduce infection rates. Hunters are also an at-risk population due to their contact and consumption of wild game, including bear. As such, many states, such as New York, require the completion of a course in such matters before a hunting license can be obtained. [21]

Meat testing Edit

Testing methods are available for both individual carcasses and monitoring of the herds. [22] Artificial digestion method is usually used for the testing of individual carcasses, while the testing for specific antibodies is usually used for herd monitoring. [22]

Food preparation Edit

Larvae may be killed by the heating or irradiation of raw meat. Freezing is normally only effective for T. spiralis, since other species, such as T. nativa, are freeze-resistant and can survive long-term freezing. [14]

  • All meat (including pork) can be safely prepared by cooking to an internal temperature of 165 °F (74 °C) or higher for 15 seconds or more.
  • Wild game: Wild game meat must be cooked thoroughly (see meat preparation above) Freezing wild game does not kill all trichinosis larval worms, because the worm species that typically infests wild game can resist freezing. : Freezing cuts of pork less than 6 inches thick for 20 days at 5 °F (−15 °C) or three days at −4 °F (−20 °C) kills T. spiralis larval worms but this will not kill other trichinosis larval worm species, such as T. nativa, if they have infested the pork food supply (which is unlikely, due to geography).

Pork can be safely cooked to a slightly lower temperature, provided that the internal meat temperature is at least as hot for at least as long as listed in the USDA table below. [23] Nonetheless, allowing a margin of error for variation in internal temperature within a particular cut of pork, which may have bones that affect temperature uniformity, is prudent. In addition, kitchen thermometers have measurement error that must be considered. Pork may be cooked for significantly longer and at a higher uniform internal temperature than listed below to be safe. [ citation needed ]

Internal Temperature Internal Temperature Minimum Time
(°F) (°C) (minutes)
120 49 1260
122 50.0 570
124 51.1 270
126 52.2 120
128 53.4 60
130 54.5 30
132 55.6 15
134 56.7 6
136 57.8 3
138 58.9 2
140 60.0 1
142 61.1 1
144 62.2 Instant

Unsafe and unreliable methods of cooking meat include the use of microwave ovens, curing, drying, and smoking, as these methods are difficult to standardize and control. [14]

Pig farming Edit

Incidence of infection can be reduced by: [ citation needed ]

  • Keeping pigs in clean pens, with floors that can be washed (such as concrete)
  • Not allowing hogs to eat carcasses of other animals, including rats, which may be infected with Trichinella
  • Cleaning meat grinders thoroughly when preparing ground meats
  • Control and destruction of meat containing trichinae, e.g., removal and proper disposal of porcine diaphragms prior to public sale of meat

The US Centers for Disease Control and Prevention make the following recommendation: "Curing (salting), drying, smoking, or microwaving meat does not consistently kill infective worms." [24] However, under controlled commercial food processing conditions, some of these methods are considered effective by the USDA. [25]

The USDA Animal and Plant Health Inspection Service (APHIS) is responsible for the regulations concerning the importation of swine from foreign countries. The Foreign Origin Meat and Meat Products, Swine section covers swine meat (cooked, cured and dried, and fresh). APHIS developed the National Trichinae Certification Program this is a voluntary "preharvest" program for U.S. swine producers "that will provide documentation of swine management practices" to reduce the incidence of Trichinella in swine. [26] The CDC reports 0.013% of U.S. swine are infected with Trichinella. [26]

As with most diseases, early treatment is better and decreases the risk of developing disease. If larvae do encyst in skeletal muscle cells, they can remain infectious for months to years. [14]

Primary treatment Edit

Early administration of anthelmintics, such as mebendazole or albendazole, decreases the likelihood of larval encystation, particularly if given within three days of infection. [12] However, most cases are diagnosed after this time. [14]

In humans, mebendazole (200–400 mg three times a day for three days) or albendazole (400 mg twice a day for 8–14 days) is given to treat trichinosis. [27] These drugs prevent newly hatched larvae from developing, but should not be given to pregnant women or children under two years of age. [10]

Secondary treatment Edit

After infection, steroids, such as prednisone, may be used to relieve muscle pain associated with larval migration. [ citation needed ]

Vaccine research Edit

Researchers trying to develop a vaccine for Trichinella have tried to using either "larval extracts, excretory–secretory antigen, DNA, or recombinant antigen protein." [28] Currently, no marketable vaccines are available for trichinosis, but experimental mouse studies have suggested a possibility. In one study, microwaved Trichinella larvae were used to immunize mice, which were subsequently infected. Depending on the dosage and frequency of immunization, results ranged from a decreased larval count to complete protection from trichinosis. [29]

Another study [30] used extracts and excretory–secretory products from first-stage larvae to produce an oral vaccine. [31] To prevent gastric acids from dissolving the antigens before reaching the small intestine, scientists encapsulated the antigens in microcapsules. This vaccine significantly increased CD4+ cell levels, and increased antigen-specific serum IgGq and IgA, resulting in a statistically significant reduction in the average number of adult worms in the small intestines of mice. The significance of this approach is that, if the white blood cells in the small intestine have been exposed to Trichinella antigens (through vaccination), when an individual does get infected, the immune system will respond to expel the worms from the small intestine fast enough to prevent the female worms from releasing their larvae. A DNA vaccine tested on mice "induced a muscle larvae burden reduction in BALB/c mice by 29% in response to T. spiralis infection". [28]

About 11 million humans are infected with Trichinella T. spiralis is the species responsible for most of these infections. [32] Infection was once very common, but this disease is now rare in the developed world, but two known outbreaks occurred in 2015. In the first outbreak, around 40 people were infected in Liguria, Italy, during a New Year's Eve celebration. [33] [34] The second outbreak in France was associated with pork sausages from Corsica, which were eaten raw. [35] The incidence of trichinosis in the U.S. has decreased dramatically in the past century from an average of 400 cases per year mid-20th century down to an annual average of 20 cases per year (2008–10). [8] The number of cases has decreased because of legislation prohibiting the feeding of raw meat garbage to hogs, increased commercial and home freezing of pork, and the public awareness of the danger of eating raw or undercooked pork products. [36]

China reports around 10,000 cases every year, so is the country with the highest number of cases. [14] In China, between 1964 and 1998, over 20,000 people became infected with trichinosis, and more than 200 people died. [28]

Trichinosis is common in developing countries where meat fed to pigs is raw or undercooked, but infections also arise in developed countries in Europe where raw or undercooked pork, wild boar and horse meat may be consumed as delicacies. [14]

In the developing world, most infections are associated with undercooked pork. For example, in Thailand, between 200 and 600 cases are reported annually around the Thai New Year. This is mostly attributable to a particular delicacy, larb, which calls for undercooked pork as part of the recipe. [ citation needed ]

In parts of Eastern Europe, the World Health Organization reports, some swine herds have trichinosis infection rates above 50%, with correspondingly large numbers of human infections. [37]

United States Edit

Historically, pork products were thought to have the most risk of infecting humans with T. spiralis. However, a trichinosis surveillance conducted between 1997 and 2001 showed a higher percentage of cases caused by consumption of wild game (the sylvatic transmission cycle). This is thought to be due to the Federal Swine Health Protection Act (Public Law 96-468) that was passed by Congress in 1980. Prior to this act, swine were fed garbage that could potentially be infected by T. spiralis. This act was put in place to prevent trichinella-contaminated food from being given to swine. Additionally, other requirements were put in place, such as rodent control, limiting commercial swine contact with wildlife, maintaining good hygiene, and removing dead pigs from pens immediately. [38]

Between 2002 and 2007, 11 trichinosis cases were reported to the CDC each year on average in the United States, and 2008–10 averaged 20 cases per year [8] these were mostly the result of consuming undercooked game (sylvatic transmission) or home-reared pigs (domestic transmission).

Religious groups Edit

The kashrut and halal dietary laws of Judaism and Islam prohibit eating pork. In the 19th century, when the association between trichinosis and undercooked pork was first established, this association was suggested to be the reason for the prohibition, reminiscent of the earlier opinion of medieval Jewish philosopher Maimonides that food forbidden by Jewish law was "unwholesome". This theory was controversial, and eventually fell out of favor. [39]

Reemergence Edit

The disappearance of the pathogen from domestic pigs has led to a relaxation of legislation and control efforts by veterinary public health systems. Trichinosis has lately been thought of as a re-emerging zoonosis, supplemented by the increased distribution of meat products, political changes, a changing climate, and increasing sylvatic transmission. [40]

Major sociopolitical changes can produce conditions that favor the resurgence of Trichinella infections in swine and, consequently, in humans. For instance, "the overthrow of the social and political structures in the 1990s" in Romania led to an increase in the incidence rate of trichinosis. [41]

As early as 1835, trichinosis was known to have been caused by a parasite, but the mechanism of infection was unclear at the time. A decade later, American scientist Joseph Leidy pinpointed undercooked meat as the primary vector for the parasite, and two decades afterwards, this hypothesis was fully accepted by the scientific community. [42]

Parasite Edit

The circumstances surrounding the first observation and identification of T. spiralis are controversial, due to a lack of records. In 1835, James Paget, a first-year medical student, first observed the larval form of T. spiralis, while witnessing an autopsy at St. Bartholomew’s Hospital in London. Paget took special interest in the presentation of muscle with white flecks, described as a "sandy diaphragm". Although Paget is most likely the first person to have noticed and recorded these findings, the parasite was named and published in a report by his professor, Richard Owen, who is now credited for the discovery of the T. spiralis larval form. [18] [43]

Lifecycle Edit

A series of experiments conducted between 1850 and 1870 by the German researchers Rudolf Virchow, Rudolf Leuckart, and Friedrich Albert von Zenker, which involved feeding infected meat to a dog and performing the subsequent necropsy, led to the discovery of the lifecycle of Trichinella. Through these experiments, Virchow was able to describe the development and infectivity of T. spiralis. [44]

The International Commission on Trichinellosis (ICT) was formed in Budapest in 1958. Its mission is to exchange information on the epidemiology, biology, pathophysiology, immunology, and clinical aspects of trichinosis in humans and animals. Prevention is a primary goal. Since the creation of the ICT, its members (more than 110 from 46 countries) have regularly gathered and worked together during meetings held every four years: the International Conference on Trichinellosis. [ citation needed ]


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