FAMILY MEDICINE® COLUMN
By John C. Wolf, D.O.
Associate Professor of Family Medicine®
Ohio University College of Osteopathic Medicine

COOKING, FREEZING PREVENTS RARELY SERIOUS TOXOPLASMOSIS

Question: I have heard about catching "toxo" from skinning and eating wild game. I recently read an article that makes me afraid to hunt deer this season. This is unfortunate because my family enjoys venison meat and jerky. How great is the risk from "toxo" and what should I do to protect my family and myself?

The illness commonly called "toxo" is more properly referred to as toxoplasmosis. It is caused by the parasite Toxoplasma gondii that is the most common parasitic infection in the world. A large percentage of the human population of the United States is infested with this parasite. Estimates range from 3 to 30 percent, with southern parts of the country generally having a higher incidence. Before I address specific information for hunters, I want to explain more about the basic condition. The organism T. gondii can infect most animals and birds. The parasite exists in these animals in either an actively reproducing form or in a quiescent cystic form. This is true for humans as well.

We humans usually acquire an infestation by ingesting a cystic form. This can happen when you eat meat from an infested animal, such as a deer. You can also become infested by eating food that's been contaminated by contact with the feces from one of these animals. Less commonly, you can become infested by breathing the dust from the dried feces of an infested animal. House cats which have had contact with outdoor animals -- birds, mice, moles, etc. -- are frequently the offending party that brings T. gondii into the house.

For most individuals, there are no symptoms from infestation with this parasite. The condition is only detected when a blood test that is specific for it is done. A few individuals may develop fatigue, sore throat, swollen lymph nodes and a fever -- a condition that appears much like infectious mononucleosis. Only in very rare instances does initial infestation produce a severe illness in those with a normal immune system. When severe symptoms do develop, treatment with anti-parasitic drugs is usually effective. One exception to the generally benign nature of this disorder, involves unborn children. If a woman is infested during the first three months of pregnancy, her fetus may develop birth defects or have specific medical problems later in childhood.

Now to address the hunter's risk of toxoplasmosis -- the frequency of this parasite in deer varies from location to location, but it is generally fairly high. Therefore, you should assume that any wild game you take, including deer, have this disease. Since the real risk of acquiring the parasite comes from eating the meat that contains dormant cysts, no special precautions are necessary when skinning or processing the animal. Gloves, on the other hand, provide an extra measure of safety. I always wear them. Cooking meat until it is no longer pink in the center kills toxoplasmosis cysts. No more rare venison steaks for me! Freezing also kills them. Therefore, if you like your meat less than well done, you should freeze the venison until it is solid before cooking it. You should also first freeze meat that you plan to make into jerky.

Toxoplasmosis is a preventable risk for hunters. Keep in mind that the greatest health risks for deer hunters involve prevention of falls, heart attacks and infection from cuts and scratches. There is also the remote risk of gunshot wound. Go hunting, but be careful.

Family Medicine® is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.