Observations on strongyloidiasis in Queensland aboriginal communities.

Abstract

To report the prevalence and distribution of infections with the parasitic nematode Strongyloides stercoralis in the Aboriginal and Torres Strait Islander communities of Queensland. A 20-year retrospective survey of computerised data and selected files from the former Aboriginal Health Programme (AHP) of the State Health Department of Queensland, based on cases diagnosed by the microscopic examination of preserved faecal specimens. Findings were compared with figures published in annual reports. Children under 15 years of age from 122 Aboriginal and Torres Strait Islander communities. Numbers of specimens examined varied widely according to time and place, as did detected infection rates. In 32,145 faecal samples examined by AHP microscopists during 1972-1991 the overall infection prevalence was 1.97%. Strongyloides larvae were found in only 52 of 122 communities. The parasite was absent from many small, southern inland communities, and the prevalence of infection increased in northern regions with summer wet seasons. On average, it was highest in Doomadgee (12%), where a peak prevalence of 27.5% (92/334 children examined) was detected in a wet season survey. Some infections resolved spontaneously, while others persisted for more than four years. At Gununa (Mornington Island), the prevalence fell from 26.2% to below 7% after thiabendazole treatment of most infected children, and remained at this level for at least four years. Single stool examinations by experienced microscopists may have failed to diagnose at least 26% of infected cases. The records give no indication of the clinical impact of strongyloidiasis. Strongyloidiasis is well established in many Aboriginal communities of north-eastern Australia. Children appear to be the major reservoirs of infection; the prevalence in adults is probably much lower. Failing improvements in community sanitation and hygiene, it may be possible to reduce significantly, if not eradicate, the infection by selectively treating diagnosed children with thiabendazole.