Objective: To present the findings of Isospora belli infection in two patients with the acquired immunodeficiency syndrome (AIDS).
Clinical features: One patient was part Aboriginal, the other an immigrant recently arrived from Peru. Both men were infected with the human immunodeficiency virus (HIV). They presented with watery diarrhoea, one with severe weight loss. Isospora belli oocysts were detected in multiple faecal specimens from both patients. One patient had a concomitant infection with Cryptosporidium sp.
Intervention and outcome: There was a rapid response to treatment with cotrimoxazole (960 mg, four times a day for 10 days). A complete response was obtained in the patient with concurrent cryptosporidiosis. The diarrhoea recurred after cessation of treatment, necessitating maintenance therapy.
Conclusion: Although Isospora belli is an uncommon cause of gastroenteritis in Australia, it is increasingly recognised as a cause of diarrhoea in travellers, immigrants from endemic areas and immunocompromised people. It has also been reported in the Aboriginal community; this article reports the first case of AIDS-related isosporiasis in an Aborigine. It is likely that both patients acquired Isospora belli before they become HIV seropositive.