Prevalence of and mortality from HIV type 2 in Guinea Bissau, West Africa

Epidemiological characteristics of human immunodeficiency virus type-2 infection in Africa

There are things yet to be clarified about African HIV-2 infection, compared to HIV-1 infection. However, the epidemiological characteristics have gradually been elucidated through various studies. HIV-2 infection is believed to have existed in the 1960s in Africa and is presently epidemic in West Africa. The HIV-2 seropositive rate for the general population is higher in urban regions than in rural areas. The peak age of persons infected with the HIV-2 tends to be higher than that of persons infected with the HIV-1, but no sex difference was recognized between the HIV-2 and HIV-1 seropositive rates. Sexual contact, mother-to-child transmission and blood transfusion have been confirmed as HIV-2 transmission modes. Prostitutes and patients with other STD are recognized as being high-risk groups for the HIV-2 infection. Patients who are infected with both HIV-1 and HIV-2 have also been identified, but it is suggested that the pathogenicity of HIV-2 is lower than that of HIV-1.

Retrospective study of maternal HIV-1 and HIV-2 infections and child survival in Abidjan, Côte d'Ivoire

OBJECTIVES

To compare the effects of maternal HIV-1 and HIV-2 infections on outcome of pregnancy, infant mortality, and child survival, and to measure serological concordance between mothers and children.

DESIGN

Retrospective cohort study with cross sectional study of concordance for HIV antibodies.

SETTING

Hospital, tuberculosis clinic, and maternal and child health centre in Abidjan, Côte d'Ivoire, west Africa.

SUBJECTS

986 women who had had a total of 2758 pregnancies since 1980. The last born children of 194 of these women.

MAIN OUTCOME MEASURES

Pregnancy outcomes; mortality for all children born since 1980; and outcome for last born children. Serological concordance between mothers and last born children.

RESULTS

Women with HIV-1 and HIV-2 infections had higher rates of spontaneous abortion and stillbirth than uninfected women (86/769 in HIV-1 positive women, 48/421 in HIV-2 positive, 31/234 in dually reactive, and 96/1131 in uninfected). Compared with children born to uninfected mothers (mortality 10.3%), greater proportions of children of HIV-1 positive (20.6%) and dually reactive (20.3%) mothers had died; mortality in children of HIV-2 infected women (13.1%) was not significantly increased. Infant mortalities for the last born children of HIV-1 positive, dually reactive, HIV-2 positive, and seronegative women were, respectively, 133, 82, 32, and 40 per 1000 live births. Nine of 77 last born children of HIV-1 positive mothers were concordantly seropositive compared with none of 21 children of HIV-2 infected mothers.

CONCLUSIONS

Maternal HIV-2 infection has less influence on child survival than infection with HIV-1, probably because of a lower vertical transmission rate.

Human immunodeficiency virus type 2 (HIV2)

In the mid 1980's a second human retrovirus, capable of causing the acquired immunodeficiency syndrome (AIDS), was isolated from patients of West African origin. This virus, now called human immunodeficiency virus type 2 (HIV2), was found to be distinct from human immunodeficiency virus type 1 (HIV1) but closely related to simian immunodeficiency viruses (SIV). Although the genomes of HIV1 and HIV2 are similar there are significant differences in nucleotide and amino acid sequences, most marked with the envelope genes and proteins. Both viruses, however, bind to the same CD4 cellular receptor. HIV2 is largely confined to West Africa where it is the dominant HIV, though patients infected with HIV2 have been described in Europe and America. Its transmission, clinical features and immunological effects are similar to those associated with HIV1 infection. However, there is some suggestion that the incubation period from infection to clinical disease may be longer than with HIV1 and that HIV2 may be less pathogenic. Patients with sera that react with both HIV1 and HIV2 antigens have been described, but it is unclear whether this represents serological cross reactivity or true double virus infection. Testing for HIV2 antibodies may become increasingly necessary in HIV2 non-endemic areas.