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Toxocara Survey

Toxocara species are ascarid roundworms that are a common intestinal parasite of dogs and cats. These roundworms can cause illness 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 in the intestine and the infective 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 conducted in cooperation with the Animal Disease Laboratory (ADL), Nevada Department of Agriculture and Reno Police Animal Services (RPAS). The purpose was to determine the prevalence of Toxocara canis (dog roundworm) in the Reno-Sparks metropolitan area. Ten fecal specimens were randomly collected from canines at the RPAS impoundment facility weekly for 1 year. Sampling occurred between March 2002 and March 2003. Laboratory analysis was performed by the ADL. The table below shows the parasites identified and the prevalence of each.

Parasite Survey
Parasite Number Positive n-483
All parasites 41 8.49%
Coccidia 6 1.24%
Giardia 2 0.41%
Isospora 3 0.62%
Strongyloides 2 0.41%
Toxocara canis 24 4.97%
Trichuris vulpis 4 0.83%

T. canis was the most commonly identified parasite with nearly 5% of the samples testing positive. (Over 80% of positive specimens were collected from dogs less than 1 year old.) Nation-wide, the prevalence of T. canis varies with climatic conditions, but the survey shows that even in our arid environment these parasites are present. Hand washing after working or playing outdoors and handling pets is important in preventing this disease. Eliminating intestinal parasites from pets and preventing children from playing in potentially contaminated areas will also greatly reduce the chance of infection.