This capsule is part of Clinician's Brief coverage of the One Health Initiative
Although 2 ascarid parasites of dogs and cats, Toxocara canis and Toxocara cati, can cause ocular toxocariasis (OT) in humans, it is not common and most often affects young children; however, OT can cause debilitating eye disease, including blindness. People become infected when embryonated infectious eggs are accidently consumed. Toxocara larvae emerge and migrate throughout the body, causing severe systemic reactions. Children are especially at risk from exposure at playgrounds and sandboxes contaminated by canine and feline feces.
This web-based survey was conducted in collaboration with the American Academy of Ophthalmology (AAO). Surveys were sent to 3020 ophthalmology specialists; 599 (19%) responded. A total of 68 patients were reported newly diagnosed from September 2009 to September 2010. Of the 44 patients for which demographic information was available, median patient age was 8.5 years (range, 1–60 years). Clinical data for 30 patients were available. Of these, 25 of 30 (83%) experienced vision loss and 17 of these patients (68%) had permanent vision loss. A One Health approach is needed to prevent toxocariasis with collaboration of the groups invested in protecting the health of humans, animals, and the environment. Veterinarians can help by controlling Toxocara infection in dogs and cats.
Commentary: Transmission of Toxocara continues to occur in the US, although it is a preventable disease. As stated by the authors, some of the limitations of the survey included the low response rate, possibility of responder bias (respondents with severe cases might be more likely to report the cases), and possibility of selection bias (people with limited access to health care might not have had access to the ophthalmologic subspecialists who responded to the survey). All of these factors could contribute to underreporting of OT cases. As veterinarians, we need to pay more attention to our role in preventing toxocariasis in our patients and reducing the risk for OT in the human population. Further information about toxocariasis can be found at the website cdc.gov/parasites/toxocariasis.
—Patricia Thomblison, DVM, MS
Ocular toxocariasis—United States, 2009-2010. Lum FC, Hoskins HD, Moorthy RS, et al. MMWR 60:734-736, 2011.