Decreasing prevalence of Trichuris trichiura (whipworm) in the Northern Territory from 2002 to 2012

Abstract

To observe the prevalence, disease associations, and temporal trends in Trichuris trichiura (whipworm) infection in the Northern Territory between 2002 and 2012. Retrospective observational analysis of consecutive microbiologically confirmed cases of T. trichiura infection among members of the NT population from whom a faecal sample was obtained for testing by NT Government health care facilities between 1 January 2002 and 31 December 2012. Annual prevalence of T. trichiura infection; age, sex, Indigenous status and place of residence of infected patients; percentage of infected patients with anaemia (haemoglobin level, ≤ 110 g/L) and eosinophilia (eosinophil count, ≥ 0.5 × 10(9)/L). 417 episodes of T. trichiura infection were identified over the 11 years from 63 668 faecal samples. The median age of patients was 8 years (interquartile range [IQR], 3-36 years). Patients were predominantly Indigenous (95.3%; P = 0.001) and from three main geographical areas (Victoria Daly, East Arnhem Land and West Arnhem Land). Infections were associated with anaemia (40.2%) and eosinophilia (51.6%). There was a downward trend in the prevalence of T. trichiura infection diagnosed at NT Government health care facilities, from 123.1 cases (95% CI, 94.8-151.3 cases) per 100,000 Indigenous population in 2002 to 35.8 cases (95% CI, 21.8-49.9 cases) per 100,000 Indigenous population in 2011. T. trichiura is the most frequently identified soil-transmitted helminth infecting patients in NT Government health care facilities. Cases are identified predominantly in Indigenous patients in remote communities. We have observed a declining prevalence of whipworm infection in the NT.