Parenteral transmission during excision and treatment of tuberculosis and trypanosomiasis may be responsible for the HIV-2 epidemic in Guinea-Bissau.

BACKGROUND AND OBJECTIVE: The factors that led to the simultaneous emergence, decades ago, of HIV-1 in central Africa and HIV-2 in West Africa remain unclear. The low HIV-2-associated mortality enables epidemiological assessment of risk factors potentially relevant in the early stages of the epidemic. In Guinea-Bissau, its epicentre, HIV-2 became highly prevalent (approximately 15%) in cohorts of individuals born before 1962, but is now disappearing whereas HIV-1 prevalence is increasing. We sought to verify the hypothesis that parenteral transmission was the key factor in the building-up of the HIV-2 epidemic. DESIGN: Cross-sectional community survey of 1608 individuals aged > or = 50 years in Bissau. METHODS: Capillary blood was obtained for HIV serology. Associations between HIV-2 (alone or in dual HIV-1/HIV-2 infections) and exposures were measured with crude and adjusted odds ratios (AOR) and 95% confidence intervals (CI). RESULTS: Prevalence of HIV-2 was higher in women (160/1063; 15.1%) than men (45/545; 8.3%, P < 0.001). Among women, excision (AOR, 1.54; 95% CI, 1.08-2.18) was independently associated with HIV-2, as were age and being widowed (AOR, 1.88; 95% CI, 1.29-2.74). Among men, HIV-2 was not associated with sexually transmitted infections or transactional sex. In an analysis comprising men and women that was adjusted for age, sex, ethnic group and marital status, HIV-2 was associated with having received injections for the treatment of tuberculosis (AOR, 2.12; 95% CI, 1.11-4.05) or trypanosomiasis (AOR, 1.75; 95% CI, 1.03-2.97). CONCLUSIONS: Parenteral transmission through ritual excision and multiple injections during treatment of tuberculosis and trypanosomiasis contributed to the emergence of HIV-2 in Guinea-Bissau.

Effect of splenectomy on Trypanosoma lewisi infection in young rats.

The effect of splenectomy on animals infected with Trypanosoma lewisi is unclear, and previous reports are inconclusive or conflictive. We splenectomized rats of different ages after they had been infected with T. lewisi. Female Sprague-Dawley rats, Hemobartonella-free, were assigned to four groups according to weight: 80, 108, 140, and 170 g. Each group had splenectomized, sham-operated, and nonoperated control subgroups, all infected with T. lewisi (0.5 ml of 10(6) parasites per ml) 90 h before surgery. Before surgery, parasite levels in host blood were similar. At 24 h after splenectomy in all groups, regardless of weight, blood parasite levels were much higher than they were in sham-operated or control animals (P less than 0.001 to P less than 0.0001; analysis of variance). Younger rats (80 and 108 g) had a higher mortality rate after splenectomy than sham-operated and control animals. Older rats (150 and 170 g) had no mortality. These results show the impact of age and the importance of the spleen on parasite-host interactions in rats infected with T. lewisi.