|Larval form coiled in a spiral.|
This parasite has an interesting life cycle. It begins with an uninfected animal eating an infected animal. This can happen amongst domestic animals such as pigs or amongst wild animals living in various environments. Epidemiologist W. C. Campbell constructed four life cycles based on the involved hosts of this parasite. The first was the domestic cycle, which involved pigs and is the most important cycle that involved accidental human infection. The other three may be due to other species of Trichinella and may also involve accidental human infection, but is far less common than the first cycle. These three cycles are known as sylvatic cycles and involve different animals for different climatic regions. To keep things simple, we will only talk about the domestic cycle today.
|Cross section of muscle tissue containing nurse cells.|
|Nurse cells that formed in a pig's diaphragm.|
Within pigs, this parasite is transmitted by pigs eating infected meat scraps from other animals or from their common practice of cannibalism. (Trust me, I grew up on a pig farm...YES Wilbur will eat his babies if their mother accidentally lays on them, suffocating one while nursing three. They are stupid, dirty creatures, and they deserve to be eaten. Plus, bacon is delicious!)
After becoming infected, a person may start having symptoms in as little as 12 hours or as much as 2 days. As the worms move through the body, they damage parts of the intestine and cause immune responses that result in inflammation. Such responses can manifest as nausea, vomiting, sweating, and diarrhea. 5-7 days later, some people experience fevers or facial swelling (a.k.a. "facial edema"). After 10 days, people will experience intense muscular pain, difficulty breathing, low blood pressure, and possible nervous disorders. The disease can cause severe damage to the heart, respiratory issues, or kidney malfunction that can eventually lead to death.
|An artist's depiction of a |
larva in a nurse cell.
In pigs, the symptoms are often undetectable unless the parasite load is so much that it can cause fatality (uncommon).
Diagnosis, Prevention, and Treatment
|For a muscle biopsy, you have to make |
an incision in the skin to reveal the
underlying muscle, then a hollow
needle is used to extract a small
amount of muscle tissue for
Pigs are diagnosed following ELISA testing.
To prevent the transmission of this disease, the US has a national surveillance system that tracks reported cases and inspects sources of possible contamination. The pork industry has also made changes in order to reduce pig exposure to this disease and to recognize warning signs of infection in order to treat pigs before being slaughtered for their meat. Laws have also reduced risk of human infection by regulating pork processing procedures, such as providing guidelines for specific cooking and freezing temperatures and times as well as for curing procedures.
|I like this picture of the medicine because|
it looks like a worm was drawn on one
side of this pill! :p
To treat trichinosis, humans and pigs are both prescribed antihelminthic drugs such as mebendazole or albendazole. In humans, this is not always affective. Humans also receive corticosteroids and painkillers to cope with the pain of the infection as it is being treated.
Moral of the Story
|Mmmm...Teriyaki pork loin! |
Is it cooked all the way through?...
|Because I can't NOT post a picture of a parasite colored in rainbow...|