Zoonoses-The Hidden Danger

Silver Sands Veterinary Center                    06May2016                       Donald H. DeForge, VMD

Zoonoses

One Hidden Danger

Toxocariasis and Your Pet

From the Center for Disease Control

Toxocariasis FAQs

What is Toxocariasis?

Toxocariasis is an infection transmitted from animals to humans (zoonosis) caused by the parasitic roundworms commonly found in the intestine of dogs (Toxocara canis) and cats (T. cati).

Who is at risk for Toxocariasis?

Anyone can become infected with Toxocara. Young children and owners of dogs or cats have a higher chance of becoming infected.

Approximately 13.9% of the U.S. population has antibodies to Toxocara. This suggests that tens of millions of Americans may have been exposed to the Toxocara parasite.

How can I get Toxocariasis?

Dogs and cats that are infected with Toxocara can shed Toxocara eggs in their feces. You or your children can become infected by accidentally swallowing dirt that has been contaminated with dog or cat feces that contain infectiousToxocara eggs. Although it is rare, people can also become infected from eating undercooked meat containing Toxocara larvae.

What are the clinical manifestations of Toxocariasis?

Many people who are infected with Toxocara do not have symptoms and do not ever get sick. Some people may get sick from the infection, and may develop:

• Ocular toxocariasis: Ocular toxocariasis occurs when Toxocara larvae migrate to the eye. Symptoms and signs of ocular toxocariasis include vision loss, eye inflammation or damage to the retina. Typically, only one eye is affected Ocular Larva Migrans

• 
• Ocular Toxocariasis

How serious is infection with Toxocara?

In most cases, Toxocara infections are not serious, and many people, especially adults infected by a small number of larvae (immature worms), may not notice any symptoms. 

The most severe cases are rare, but are more likely to occur in young children, who often play in dirt, or eat dirt (pica) contaminated by dog or cat feces.

How is Toxocariasis spread?

The most common Toxocara parasite of concern to humans is T. canis, which puppies usually contract from the mother before birth or from her milk. The larvae mature rapidly in the puppy's intestine; when the pup is 3 or 4 weeks old, they begin to produce large numbers of eggs that contaminate the environment through the animal's feces. Over a 2 to 4 week time period, infective larvae develop in the eggs. Toxocariasis is not spread by person-to-person contact like a cold or the flu.

What should I do if I think I have Toxocariasis?

See your health care provider to discuss the possibility of infection and, if necessary, to be examined. Your provider may take a sample of your blood for testing.

What is the treatment for Toxocariasis?

Visceral toxocariasis is treated with antiparasitic drugs. Treatment of ocular toxocariasis is more difficult and usually consists of measures to prevent progressive damage to the eye.

How do I prevent Toxocariasis?

• Take your pets to the veterinarian to prevent infection with Toxocara. Your veterinarian can recommend a testing and treatment plan for deworming.
• Wash your hands with soap and water after playing with your pets or other animals, after outdoor activities, and before handling food.
• Teach children the importance of washing hands to prevent infection.
• Do not allow children to play in areas that are soiled with pet or other animal feces.
• Clean your pet's living area at least once a week. Feces should be either buried or bagged and disposed of in the trash. Wash your hands after handling pet waste.
• Teach children that it is dangerous to eat dirt or soil.

Supplemental Material:

• Visceral larva migrans:
  • Occurs mostly in preschool children.
  • The larvae invade multiple tissues and clinical features include fever, anorexia, abdominal pain, weight loss, cough, wheezing, pleural effusion, hepatosplenomegaly, urticaria, subacute meningitis/encephalitis, seizures, monoarthritis, cutaneous vasculitis, myocarditis and hypereosinophilia.
  • Death (from severe cardiac, pulmonary or neurological involvement) may occur but is rare.

Comments from the Companion Animal Parasite Council--

• Prevent the transmission of intestinal ascarids from pets to people.  
• Avoid environmental contamination by emphasizing good hygiene. 
• Excellent sanitation and providing well-timed preventive treatment especially for pups and kittens.

Final thoughts from Dr. DeForge--It is the responsibility of every veterinarian to explain what a zoonosis is and how to prevent disease spread from animal to human.

Zoonotic: 

Pertaining to a zoonosis: a disease that can be transmitted from animals to people or, more specifically, a disease that normally exists in animals but that can infect humans. There are multitudes of zoonotic diseases.

Toxocariasis is a serious zoonosis!

With properly scheduled laboratory testing of the feces and a routine deworming program, the Toxocariasis zoonosis will never affect your pet or family.

Call your pediatrician if you feel your child has handled or eaten feces or dirt.  Call your pediatrician if you feel your child has contacted the pet's anal area or is playing with their toys or pet toys that could be contaminated with feces.

Keep your pediatrician informed of any positive fecal reports for Roundworm in your pet or other parasites found in the feces by your doctor of veterinary medicine.

Remember a lab test saying "no parasites seen" in your pet is not a statement of no parasites in your pet.  It just means no parasites were found in the sample tested.  Routine deworming programs should be set up through the intercession of your local doctor of veterinary medicine in all pets with positive lab reports or "none seen reports" as part of a routine parasite prevention program. 

Dr. DeForge accepts comments on his blog at DonDeForge100@gmail.com

Silver Sands Veterinary Center and Milford Veterinary Hospital 

17 Seemans Lane Milford, CT 06460