AEGiS-08IAC: Decreased infectivity of HIV-2 compared to HIV-1: a mathematical model.

8th International AIDS Conference

Amsterdam, Netherlands — July 19-24, 1992

Decreased infectivity of HIV-2 compared to HIV-1: a mathematical model.

Int Conf AIDS 1992 Jul 19-24; 8:We57 (abstract no. WeC 1064)
Leisenring W, Donnelly C, Sandberg S, Kanki P, Awerbuch T; Harvard School of Public Health, Boston, MA.

OBJECTIVE: To use maximum likelihood estimation theory to estimate and compare the infectivity of HIV-1 and HIV-2 in a sexually-active high-risk population.

METHODS: Data was collected in a prospective study (1985-1990) of registered prostitutes from Dakar, Senegal providing information about average number of partners per week, prostitutes' registration date and HIV-1 and HIV-2 status at approximate six month intervals. We used this data to model the probability of the prostitute being positive with either HIV virus as a function of the number of sexual partners, the prevalence of the virus in the partner population, and the male-to-female infectivity per contact. Using maximum likelihood estimation theory we estimated and compared the infectivities of HIV-1 and HIV-2. Estimates of HIV prevalences in the partner population were required for the model, we, therefore, carried out two analyses: one assuming a high risk prevalence (estimated from Senegalese prostitutes) and one assuming a low risk prevalence (estimated from blood donors and pregnant women).

RESULTS: We found that the estimated risk of HIV-1 infection per sexual act to be at least five times that of HIV-2 (p-value less than 0.013). These results were unaffected by assumptions about partner prevalences. Graphical goodness-of-fit methods showed that our model fits the data well.

CONCLUSIONS: Although both HIV-1 and HIV-2 have been associated with AIDS, the natural history, clinical latency and incidence of HIV-2 appears to differ from HIV-1. Our mathematical model supports the biological studies indicating a decreased infectivity of HIV-2 compared to HIV-1.

Keywords: AEGIS, HIV-2, HIV-1, HIV Infections, Prostitution, Acquired Immunodeficiency Syndrome, Sexual Partners, Prevalence, Models, Theoretical, Probability, Models, Statistical, Prospective Studies, Blood Donors, Multivariate Analysis, Risk, Senegal, Female, Male, Pregnancy, Human, ICA8
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