Toxocara species are ascarid roundworms that are a common intestinal parasite of dogs and cats.  These roundworms can cause larval migrans syndromes in persons who accidentally ingest eggs from soil contaminated with the feces of infected animals.  Children’s play habits and their attraction to pets put them at higher risk for infection.  When the eggs are accidentally ingested they hatch and infective stage larvae migrate through the human liver, lungs and other organs where they cause damage and allergic reaction.  Infections may leave children with permanent visual or neurological damage. 

Toxocariasis is not a reportable disease so actual case incidence is unknown.  However, the Centers for Disease Control and Prevention (CDC), state public health laboratories and private laboratories annually receive 3,000 to 4,000 serum specimens from patients with presumptive toxocariasis. 

This survey was a cooperative effort of the Washoe County District Health Department, Vector-Borne Diseases Program, Nevada Department of Agriculture, Animal Disease & Food Safety Laboratory (AD&FSL) and Reno Police Animal Services (RPAS).  The purpose was to determine the prevalence of Toxocara canis in the Reno-Sparks metropolitan area.  Ten fecal specimens were randomly collected from the RPAS impoundment facility weekly for 1 year.  Sampling occurred between March 2002 and March 2003.  Laboratory analysis was performed by the AD&FSL.  The table below shows the parasites identified and their prevalence.   

Of the 483 total dogs examined 141(29.2%) were adults and 342 (70.8%) were dogs under one year old.  Of the 483 dogs surveyed, 8.49% had some kind of internal parasite. For the 41 positive dogs, 8 (19.5%) were adults and 33 (80.5%) were under one year old. 

T. canis was the most commonly identified parasite with nearly 5% of samples positive.  Nation-wide, prevalence varies with climatic conditions, but even in our arid environment these parasites are present.  Practicing good personal hygiene, eliminating intestinal parasites from pets, and preventing children from playing in potentially contaminated areas will greatly reduce the chance of infection. 

Because of the potential for disease in both the pet and pet owner, deworming animals is an extremely important part of routine animal heath care.  When possible, puppies should be treated starting at 2 weeks of age, and continuing at 4, 6, and 8 weeks of age.  The nursing dam should also be treated. No matter what age young animals are first encountered, they should be dewormed.  If they are older than 8-10 weeks (and weaned) a second treatment 2-4 weeks later is recommended. 

Courtesy of Mike Murray, Washoe County District Health Department, Vector-Borne Diseases Program; Gretchen Nelson and Mark Smith, AD&FSL