Invasive amoebiasis: an emerging parasitic disease in patients infected with HIV in an area endemic for amoebic infection

Objectives: To describe the incidence and presentations of invasive amoebia sis (IA) in patients with HIV infection in an area endemic for amoebic infe ction and to assess the role of the indirect haemagglutination (IHA) assay in the diagnosis of IA in HIV-infected patients. Design: Retrospective study of 18 cases of IA and HIV infection. Setting: A university hospital, the largest centre for management of HIV-as sociated complications in Taiwan. Methods: Medical, microbiological and histopathological records of 296 HIV- infected patients and serological data of IHA assay of 126 HIV-infected pat ients were reviewed to identify cases of IA from 23 June 1994 to 31 March 1 999. An IHA titre greater than or equal to 1 : 128 was considered positive. Clinical characteristics of HIV-infected patients with IA and without IA w ere compared. Results: Eighteen of the 296 patients (6.1%) with HIV infection were diagno sed with IA: 12 patients were diagnosed with definite IA and six with proba ble IA. The clinical manifestations included amoebic colitis (13 patients), amoebic liver abscess (nine), both colitis and abscess (four), and pleural effusion (two). IA was the initial presentation of HIV infection in nine p atients. Go-infection with other enteric pathogens was diagnosed in six pat ients with IA. Compared with the 161 patients without IA who were newly dia gnosed with HIV infection, the nine patients with IA had a higher median CD 4+ lymphocyte count (202 x10(6)/l versus 33 x 10(6)/l; P = 0.0017), were le ss likely to be diagnosed with AIDS (55.6% versus 85.4%; P = 0.039), and ha d fewer concurrent AIDS-defining illnesses (median number 0 versus 2; P = 0 .003). Estimated mean survival duration was not significantly different bet ween the two groups (597 days versus 611 days). Fourteen out of 126 patient s (11.1%) had an IHA titre 2 1 : 128. Of the 18 patients diagnosed with IA, 13 had a titre greater than or equal to 1 : 128. The sensitivity of IHA as say in the diagnosis of IA was 72.2% (13 out of 18) and the specificity was 99.1% (107 out of 108). The positive predictive value of IHA test for IA o f this patient population was 92.9% (13 out of 14) whereas the negative pre dictive value was 95.5% (107 out of 112). Conclusion: IA is an increasingly important parasitic disease among patient s with HIV infection in Taiwan. IHA assay has a good specificity and high n egative predictive value in diagnosis of IA. (C) 1999 Lippincott Williams & Wilkins.