Is Raccoon Roundworm a Threat to Pest Professionals?

As most of you know, there are several different types of parasites we as pest management professionals must be cautious and aware of while out on our jobs. These include ectoparasites such as fleas, ticks, mosquitoes and lice. However, there are also some endoparasites (e.g., roundworms and hookworms) that are of importance as well. These include the Ascarid roundworms such as the common dog and cat roundworms (Toxocara canis and T. cati). A related Ascarid roundworm that has been getting attention during the past couple of years is the raccoon roundworm, Baylisascaris procyonis. But is this parasite a health risk in practical terms to on-the-job pest professionals (including wildlife damage professionals)? Let’s take a look.

THE RACCOON ROUNDWORM. The raccoon roundworm is actually a fairly common parasite of raccoons and other wild animals in many parts of the United States, although it seems to be absent from most areas of the Southeast. The larvae of the roundworm are microscopic, but after maturing throughout 10 to 12 weeks, the adults can reach lengths of 5 to 9 inches. The adult female roundworm lays eggs that can be passed in the feces of raccoons (or some other host). Infected raccoons can shed millions of eggs per day. New eggs require about 30 days to embryonate. The eggs can then survive for as many as 12 years depending on environmental conditions. Even more incredible is the fact that the eggs are not vulnerable to any common household disinfectants — including bleach.

When raccoon roundworm eggs are ingested accidentally by humans, the results can range from asymptomatic to the more severe cases, where large numbers of the larvae literally migrate through different areas of the body including the lungs, through the retina in the eyes and even into the brain. This condition is appropriately called visceral and ocular larvae migrans (V/OLM). In the most serious cases, a disease of the central nervous system — known as eosinophilic meningitis — develops which is usually fatal.

People become infected with B. procyonis by accidentally ingesting infective eggs from contaminated soil, water, fomites or via contaminated hands. Young children are more vulnerable because they tend to put many things in their mouths, or suck on dirty fingers and hands. One child, for example, died of raccoon roundworm infection after chewing on a piece of infected bark brought into the house with firewood. The severity of the disease depends on the number of eggs ingested and to where the larvae migrate. Fortunately for pest professionals, the most severe cases of V/OLM are quite uncommon.

Only five deaths associated with raccoon roundworm have been recorded in the United States since 1981, but just how many people have been infected with raccoon roundworm at asymptomatic levels (i.e., without realizing it) is, of course, not known. But parasitologists estimate about 10,000 people become infected with animal roundworms each year in the United States and most recover without treatment. Moreover, the great majority of these cases involve dog and cat roundworms and not the raccoon roundworm. So why the concern now? Well, as most pest professionals know, raccoon populations are exploding in many urban and suburban communities across the United States. Part of this explosion is due to the loss of natural raccoon habitats due to land development. But this carnivore adapts very quickly to the lifestyles of urbanites.

Other factors include mild winters and a public that tends to be “raccoon friendly.” In fact, many people deliberately leave food out in their backyards hoping to catch a glimpse of “Rocky Raccoon and family” coming in to feed at night. Residential areas located near parks and wooded areas containing creeks and streams are particularly vulnerable to large raccoon populations. For example, some urbanites are amazed to learn that as many as 25 to 45 raccoons are foraging around their neighborhoods of only two acres while they and their neighbors are asleep. A recent life-threatening case of raccoon roundworm in a child in a California community illustrates the threat posed by heavy populations. Officials there estimate 1,200 to 2,000 raccoons occupy an area covering only one square mile. The raccoon roundworm infection rate of the raccoons in this California community was determined to be 100%. Because the eggs are not susceptible to the typical commercial disinfectants and cleaners and because they can survive in the environment for long periods, there is considerable need for caution and education in communities with heavy raccoon populations that also contain heavy B. procyonis infection rates.

AVOIDANCE AND AWARENESS. In general, avoidance and awareness are the keys to preventing infections of B. procyonis for both pest professionals and homeowners alike. And, as pest professionals in your community, you can provide a valuable service by educating your clients as to the potential health hazards associated with raccoons. The following are but a few recommendations. Additional information can be obtained from health officials in your area.

• Homeowners should be informed of the importance of not encouraging raccoons to feed and remain around their homes. And baby raccoons should never, ever, be kept as pets for children.
  
  
• Raccoons have favorite spots they like to use as latrines in residential areas. These include wood piles, sandboxes, underneath decks and crawlspaces, and in garages. Educate your clients about the importance of pest-proofing their homes and out buildings, as well as keeping sandboxes covered and elevating woodpiles off the ground or covering them.
  
  
• Raccoons in chimneys are an obvious concern. Feces will accumulate during the spring and summer, the time when fireplaces are not being used, and pose potential risks later. Chimney caps are a must in raccoon areas. Once raccoons have infested chimneys and fireplaces, raccoon roundworm eggs can be destroyed by having the homeowners build a strong fire after the raccoons and feces have been removed.
  
  
• Pest professionals inspecting attics, crawlspaces and other areas that are prone to raccoon activity should protect themselves by wearing coveralls, gloves, respirators and avoiding as best as possible any animal feces in these areas (thus the importance of a good, bright flashlight).
  
  
• For all practical purposes, the only method of killing the eggs is via fire. Pest professionals who deal with raccoon removal programs flame their traps and other contaminated equipment using portable propane torches.

A THREAT OR NOT? So, is raccoon roundworm a disease threat to the average pest professional? Most adults are not likely to accidentally ingest or inhale large numbers of the eggs. Thus, the risk to pest professionals appears to be very small. But what are the chances through pest management and wildlife trapping work of accidentally ingesting or inhaling a few eggs from time to time, here and there? Well, that’s the whole point. For me, asymptomatic or not, I do not want ANY roundworms living inside me! I bet you don’t either. Take precautions. Always use good biohazard safety practices while inspecting and working in the urban jungle.

Dr. Robert Corrigan, a contributing editor to PCT magazine, is president of RMC Pest Management Consulting, 5114 Turner Road, Richmond IN 47374. He can be reached at 765/939-2829.