Racoons and Roundworms

I wrote this piece for the Brandon Sun in 1999, and have been asked from time to time to repeat it.




Racoons may be cute and cuddly but they could be carrying a deadly roundworm inside of themselves. The large common roundworm, (baylisascaris procyonis) lives in the intestines of many of these animals.



Studies in the United States have shown that from 70% to 80% of the racoons checked were infected with this roundworm. The eggs form these roundworms are found in the feces of the racoon. It takes about thirty days for the eggs to develop into larvae. The young raccoon has probably become infected at an early age through their mothers body, or from the local environment of the den. The roundworm also uses intermediate hosts in their life cycle. Some of the common carriers include mice, squirrels, rabbits and birds; however, any mammal or bird can be a host carrier. When the racoon eat these infected hosts, they can also become infected by this secondary pathway.



The adult worms, about 6 - 8 inches long and 3/8 inch thick, are tan in colour, cylindrical and tapered at both ends. Infected animals are normal in appearance and show no signs of infection until a short period of time has passed.



When the eggs hatch inside the host animal the larvae penetrate the intestines and migrate through the liver and lungs. From the lungs, they migrate to other parts of the body, especially to the head, neck and brain. This will cause liver and lung damage and the cause of central nervous system disease because of the damage caused to the brain and the spinal cord.



After a period of time, the animals may have a tilted head or slight stumbling when they walk as the nervous system is affected. As the disease progresses, the animal may circle, roll, keep falling over and lie on its sides and paddle with its feet. The animal eventually will lie down and stay lying down, become comatose and finally death.



Most animals develop nervous abnormalities within one to three weeks of ingestions of the eggs. The length of time it takes of the death of the animal to occur depends on the amount of eggs ingested.



The disease is diagnosed with a microscopic examination at autopsy. The larvae or lesions are usually found in the brain, eyes and other tissues.



It will cause death in humans. Documented cases of severe organ damage, eye disease and debilitating central nervous system disease have occurred. It is difficult to diagnose in a living animal. A person or animal that shows signs of eye or central nervous system disease and has a history of association with a pet or wild racoons or a suspected contaminated area could have been in direct contact to this roundworm. An article from the Department of Paediatrics SUNY Health Science Centre at Syracuse reported that a thirteen month old child did survive his infection. The disease, however, cannot be cured and the child continues to have severe neurological complications.

There are no drugs known to kill the migrating larvae or the adult. There is little which can be done to reverse the damage caused by the larvae. Treatment is mainly supportive and designed to decrease inflammatory reactions.



The racoon can contaminate an area very rapidly. The animal will shed about 19850 eggs per gram of feces, but it is known for the count to be as high as 100.000 eggs per gram of feces. An average amount of feces is about 100 grams.



The roundworm eggs are some of the most resistant parasite eggs known. They can survive formaldehyde or hydrochloric acid solutions. Freezing detergents, disinfectants and dyeing do not affect them and they can survive for years even in adverse conditions. Heat seems to be the only thing that will kill these eggs. Autoclaving, flaming the area with gas or a propane torch will do the trick. Large areas of contamination such as soil, concrete, etc. are best decontaminated by torching. Contaminated star, hay, etc. should be carefully removed and burned. Special protection, such as disposable gloves and masks should be worn to prevent self infection. This is important in dry and dusty areas where dry feces may be stirred up and inhaled.



If there are any animals living with the proximity of where a racoon has been then these animals should be considered as possible victims of roundworm. These animals need to be watched carefully to see if they will develop any of the symptoms for the roundworm infection. If a human has been in contact with racoo9ns or their feces, they should consult with their doctor. It is not a well known disease and the doctor may not be aware of it. An expert in parasitic disease should be consulted for clinical problems and the symptoms investigated.



There is no real effective treatment so prevention is paramount to this disease.





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