Infrequent occurrence of HIV-2 in blood donors and pregnant women in a rural community in Ghana.

Abstract

To the Editor: HIV-2 is said to circulate predominantly in West Africa. Reports have increased, however, that HIV-1 is becoming far more common than HIV-2 in many West Africa countries. We examined this situation among 1,077 blood donors and 1,640 pregnant women in the Upper West Region, a rural area in Ghana. The seroprevalence of HIV in blood donors was 1.6%, of which 1.1% and 0.1% were reactive to HIV-1 and HIV-2 respectively. HIV seroprevalence in pregnant women was 1.2%, with 1% and 0.1% being reactive to HIV-1 and HIV-2 respectively. The observed difference between HIV-1 and 2 was statistically significant (P < 0.001, Z score 3.48) after applying the Z test of significance for the difference in 2 proportions. The relative prevalence of HIV-1 and HIV-2 infections vary greatly within Africa. Although there has been some serological evidence of HIV-2 infection in West Africa since 1966,1 and HIV-2 said to circulate predominantly in West Africa, its prevalence is not uniform in the subregion. It has been observed that HIV-2 predominates in the most western parts of West Africa and in countries such as Guinea-Bissau, Cape Verde, and Senegal; its prevalence is greater in certain population groups.2 In contrast, in the easterly parts of the subregion, e.g. Nigeria, HIV-1 is predominant.3 Dual infection with HIV-1 and HIV-2 can be found midway and has been reported from countries such as Cote d'Ivoire, Mali, Burkina Faso4 and Ghana.5 In these populations, HIV-1 was predominant. We report the prevalence of HIV-1 and HIV-2 infections in blood donors and pregnant women in a rural community in Ghana and show the infrequent occurrence of HIV-2 in this population. Blood was collected from 1,077 first-time blood donors (August 1991–July 1992), and 1,640 pregnant women (August–November 1992) at their first prenatal visit to a health facility in the Upper West Region of Ghana. This is a rural community served by 3 hospitals with approximately 250–300 beds among them and a number of Primary Health care centers. The blood was sent to the Regional Public Health laboratory where the sera were screened for HIV-1 and HIV-2 antibodies with a recombinant Enzyme Immunoassay kit (Enzygnost Behring, Germany). Samples reactive on two occasions with the EIA were confirmed with Western blot (Lav blot I and II, Diagnostic Pasteur for HIV-2). Reactivity to gp 41 and P 31 and/or P 17 and/or P 24 constituted a HIV-1 positive blot, whereas reactivity to gp 36 and P 31 and/or P 24 and/or P 17 constituted a HIV-2 positive blot. Dual serologic reactivity was recorded in the presence of reactivity to both gp 41 and gp 36 with or without other bands. The seroprevalence of HIV antibodies in blood donors was 1.6% (17/1,077) of which 12 (1.1%) and 1 (0.1%) were reactive to HIV-1 and HIV-2 respectively. Four (0.4%) blood donors were dually reactive. Among the pregnant women, the seroprevalence of HIV was 1.2% (20/1,640), with 17 (1.0%) and 1 (0.1%) of the women being reactive to HIV-1 and 2 respectively. Dual serologic reactivity in this group was 0.1% (2/1,640). Overall, 1.1% (29/2,717) of the population studied were HIV-1 antibody positive and 0.1%(2/2,717), HIV-2 antibody positive. The observed difference between HIV-1 and HIV-2 positivity was statistically significant (P < 0.001, Z score = 3.48) after applying the Z test of significance for the difference in the 2 proportions. It has been reported from Nigeria4,6 and Cote d'Ivoire7 that HIV-2 is not the predominant Human Immunodeficiency Virus in some West African countries. The low HIV-2 prevalence (0.1%) in blood donors in this rural population compared with a prevalence of 0.9% in an urban population also in Ghana5 is in accordance with other studies that have shown higher HIV-2 prevalence in urban communities in West Africa.8 Dual serologic reactivity was recorded in 6 patients, meaning either they are infected with both HIV-1 and HIV-2 or there is some form of immunological cross reactivity present. The findings of this study add to the knowledge that the majority of morbidity because of HIV infection in certain West Africa countries is caused by HIV-1, and any strategies for control in terms of vaccine design need to take this into account.