Key Points:
- Raccoon roundworms are parasites that are common in raccoons. Eggs from the parasites are in raccoon feces (poop), and become infectious 2-4 weeks after the feces are deposited.
- People and pets can become infected by ingesting raccoon feces or by ingesting items contaminated by them such as soil or dirt.
- Most infections are in children and others who are more likely to put dirt or animal waste in their mouth.
- While human infections are rare, severe disease can occur if the young (larval) forms of the worm travel to the spinal cord, brain, and eyes.
- Infection in pets is very rare and the risk of a person getting the parasite from a pet is very low.
- The best way to avoid infection with this parasite is to avoid touching raccoon feces, and to not attract raccoons to your property.
About Raccoon Roundworm (Baylisascaris procyonis)
Baylisascaris procyonis is an intestinal parasite or roundworm commonly found in raccoons. It does not cause illness in raccoons but parasite eggs are passed in raccoon feces (poop). These parasite eggs can infect people if the person ingest soil, water or material contaminated with raccoon feces. Many other animals such as dogs, cats, rabbits, rodents, birds and non-human primates can also become infected if they ingest raccoon feces, or if they eat an infected animal. Note that most other animal species do not shed or release eggs of this parasite in their feces after they get infected.
Raccoons are common in many areas in Los Angeles County. It is important to not attract raccoons to your property. Raccoons are attracted to outdoor food and water sources. They also may be attracted places where they can make a den (to sleep) or to form a latrine (a place to poop). Raccoons usually like to poop on hard and elevated surfaces, such as rooftops and woodpiles, but they can poop elsewhere.
Follow these tips to make your property less inviting to raccoons:
- Do not feed raccoons or keep them as pets.
- Do not feed wildlife and avoid leaving open sources of food outdoors for community cats.
- Feed household pets indoors, close pet doors at night, and never leave pet food or water sources outdoors especially overnight.
- Pick up and discard any sources of food outside such as fruit that has fallen from trees.
- Keep all trash in tightly closed containers.
- Close off access to basements, attics, and crawl spaces and clear brush and trees away from your property and roof line to discourage raccoons from sleeping or defecating nearby.
- Cover all sandboxes when not in use, as raccoons may defecate in sandboxes.
- Be aware that raccoons and other wildlife may also be attracted to fishponds and bird feeders.
What should I do if I have a raccoon latrine on my property?
Raccoon feces should be removed promptly when found. Raccoon feces that are still fresh are not infective for raccoon roundworm (it takes 2-4 weeks for the parasite eggs to become infective). Therefore if feces are removed promptly, any concern about raccoon roundworm is greatly decreased.
- Take care to avoid contaminating hands and clothes. Wear disposable gloves, rubber boots that can be scrubbed or cover your shoes with disposable booties that can be thrown away. Wear a well-fitting N95-rated respirator.
- If the feces are dry, avoid creating fecal dust. Spray a small amount of water or place damp paper towels over the feces.
- Pick up the raccoon feces using a shovel or inverted plastic bag. Double bag them, seal tightly and then discard in a closed outdoor trash bin.
- Clean off any remaining visible feces from the location or tools with detergent and water.
- Decontaminate hard smooth surfaces (including shovels) by applying boiling water or by using a steam cleaner. Note that most chemicals do not kill raccoon roundworm eggs, but high heat kills them instantly.
- Remove and discard gloves. Wash clothing in high heat and detergent. Wash hands with soap and water.
- Some latrines may be in places that are difficult or unsafe to clean. In those cases, hiring a private company to remove the latrine and clean the area may be necessary.
Raccoon Roundworm in People
How does it spread?
People become infected by consuming raccoon feces or material contaminated with raccoon feces. Most infections are in children and others with a condition called pica, who are more likely to put dirt or animal waste in their mouth. Baylisascaris infection cannot be transmitted person to person. Hunters, trappers, taxidermists, and wildlife handlers may also be at increased risk if they have contact with raccoons or raccoon habitats.
Fewer than 25 cases of Baylisascaris disease in people have been documented in the United States. However, it is possible that some cases are incorrectly diagnosed as other illnesses or go undiagnosed so the actual number of cases of disease may be higher. Cases that are diagnosed tend to be severe. Baylisascaris cases have been reported in California, Illinois, Louisiana, Massachusetts, Michigan, Minnesota, Missouri, New York, Oregon, Washington and Pennsylvania. As of 2018, there were 23 published human neurological cases in the US; six of the infected persons died.
What are common symptoms of raccoon roundworm in people?
In people, the eggs will not develop into roundworms in the intestine like in raccoons. Instead, the eggs will develop into larvae that may travel through the body. While human infections are rare, severe disease can occur if the larvae go to the spinal cord, brain, or eyes. Symptoms usually start 1-4 weeks after ingesting the parasite eggs and can include nausea, tiredness, loss of coordination, lack of attention to people and surroundings, loss of muscle control, blindness, coma, and death.
How can I avoid getting raccoon roundworm?
The best way to avoid getting sick is to stay away from raccoon feces and keep children away from areas where raccoons and raccoon feces may be present. Do not feed raccoons or keep them as pets. Avoid attracting raccoons to your home or property to minimize the risk of them setting up a den or a latrine (places where raccoons defecate or poop) nearby. Washing your hands with soap and water after being outside and before eating helps to prevent accidental ingestion of the parasite eggs.
What if I think someone in my family has raccoon roundworm?
If you think you or someone else may have ingested raccoon feces, seek immediate medical attention. Early treatment can reduce the severity of infection. If you do not have a doctor, call the Public Health InfoLine at 833-540-0473. Open every day from 8am-8pm.
Raccoon Roundworm in Pets
How does it spread in animals?
Raccoon roundworms mature into adult roundworms, and produce parasite eggs in the intestines of raccoons and occasionally in dogs. These parasites do not mature to adult worms in cats, so infected cats do not have eggs from the parasite in their feces. Adult worms can lay millions of eggs, especially in raccoons, which are then shed or released in the animal’s feces. The eggs are not immediately infectious when they are passed in the feces. It takes 2-4 weeks for the eggs to become infectious in the environment (in dirt, soil). That means fresh feces do not transmit the parasite. The parasite spreads when another animal eats the feces containing infectious parasite eggs.
Can pets spread the parasite to people?
When cats get infected with raccoon roundworm, they do not shed the parasite eggs in their feces and therefore cannot spread this parasite to people. When dogs get infected, they sometimes can pass parasite eggs in their feces, so there is some risk that a dog’s stool might transmit it to people. But there are fewer eggs of this parasite in dog feces than in raccoon feces. It is not necessary to get rid of your pet if they are exposed to raccoon feces. Talk to your veterinarian about maintaining your pets on a deworming treatment plan to prevent and treat any roundworm infections. Promptly remove pet feces from your property and wash your hands after removing feces or touching your pet. The risk of Baylisascaris infection from pets is extremely low, and taking these precautions will decrease the risk even further.
What are common symptoms of raccoon roundworm in pets?
Symptoms in other animals other than raccoons vary depending on where the parasite has migrated within the body. When the young larval worms migrate throughout the body into organs or to the spinal cord or brain or eyes, it can cause incoordination, circling, tremors, blindness and death.
How to prevent and treat infection in pets?
Preventing interactions between pets and wildlife including raccoons helps to prevent the spread of many diseases including Baylisascaris. Monitor pets when outdoors and do not allow pets to access areas where raccoons may have defecated.
Feed pets indoors to avoid attracting wildlife to your home and never leave food or water outside especially overnight. Open source feeding outdoors is not recommended for community cats.
Pets should be seen at least annually for a check up with a veterinarian where a fecal (poop) test can be done to check for a variety of types of intestinal worm infections. Note that fecal tests are not an effective method for detecting raccoon roundworm in cats. For dogs, a fecal test can sometimes detect this parasite. However, a negative fecal test result in a dog does not completely rule out the presence of raccoon roundworm. Therefore it is recommended that you ask a veterinarian about using a monthly intestinal worm control product for your pet that is effective against roundworms.
Resources & News
LA County Resources
- Raccoon Roundworm: Information for the Public
- Frequently Asked Questions about Raccoon Roundworm (Baylisascaris)-English
- Frequently Asked Questions about Raccoon Roundworm (Baylisascaris)- Spanish
- Low-cost veterinary services in LA County
- LA County DPH Animal Disease Surveillance Report 2015
- Pg 60: Two clusters of brain infections of Baylisascaris in animals, 2010-2011
- Special Studies Report
- Case of Baylisascaris in a person in 2000
- LAC DPH policy on feeding free-roaming cats
External Resources
News
- Raccoon Roundworm in Los Angeles County (September 17, 2024)
- Public Health Investigating a Rare Disease Spread from Animals to Humans (September 17, 2024)