Human trichostrongyliasis in Queensland

Abstract

Trichostrongylus infection, an uncommonly reported zoonosis in Australia, is common in parts of the world where there is close human contact with herbivorous animals. We report 5 cases diagnosed in our laboratory since 1992. Over this period the laboratory has conducted over 46,000 parasitological examinations on feces. All 5 cases were investigated for fecal parasites following detection of a blood eosinophilia. Two of the 5 cases complained of mild abdominal discomfort and diarrhea. It is likely that all obtained their infection following ingestion of contaminated unwashed vegetables which had been fertilized with animal manure. Four of the cases acquired their infection in Queensland and the fifth may have become infected in rural Victoria. All were treated with pyrantel embonate with resolution of the eosinophilia. Follow up fecal specimens showed no parasites. Patients were instructed on the mode of transmission and advised to thoroughly wash any uncooked vegetables prior to ingestion. In our cases, goats and horses were possibly implicated. No published reports of Trichostrongylus spp. in humans in Australia have occurred since the 1930s and it may be more common in Australia than is recognized. The infection may be missed because patients are asymptomatic or have mild gastrointestinal symptoms or only a blood eosinophilia. Trichostrongylus eggs may also be mistaken for hookworm eggs. It is important therefore to distinguish these infections from hookworm infection as the modes of transmission, management and advice regarding prevention differ.