WITTKOWSKI, K.M. (1994) IX International Conference on AIDS, 19-24 August 1994, Yokohama, J (Abstract PC0053)
Keywords: HIV, epidemiology, model
Objective: In Arab countries, the low reported AIDS incidence - even when adjusted for under reporting - might lead to the impression that 'the West has condoms, we have the Quran'. We discuss how different traditions regarding sexual behaviour among young adults may affect the spread of HIV.
Methods: HIV is assumed to spread from a core-group (highly promiscuous homosexual men) via a high-risk group (homo-/bisexual men, injecting drug users) and heterosexual partners to low-risk heterosexuals. The parameters of this model (size of sub-populations, behavioural changes, contact rates) are fitted against back-calculation estimates for HIV incidence in Germany based on reported, delay-corrected AIDS cases. The results are compared with a model, where the higher-risk groups are smaller and have lower contact rates, while behavioural changes are less effective and 5 percent of the heterosexuals have a 5-year period with high risk (e.g. anal) contacts before entering the low risk population.
Results: In western countries, HIV incidence among high-risk groups and their heterosexual partners peaked in 1983-85 and 1987-1989, respectively. Because here the basic reproduction number among heterosexuals can only minimally exceed the critical value of 1, HIV incidence will remain well below 1/100.000 per year for the next few decades, although it may increase thereafter. Where a transient period of high-risk behaviour cannot be excluded, however, HIV can spread much faster into the heterosexual population, and the incidence may reach 3/100.000 among low-risk heterosexuals per year (and the prevalence 30/100.000) by the year 2000, even if only relatively few high-risk persons are infected.
Discussion and Conclusions: A transient period of high-risk behaviour may facilitate the spread of HIV for two reasons. First, even 5 percent of the population are a huge pool for the virus and the short duration hinders saturation. Second, transport (at the end of the transient period) is more effective than transmission (through heterosexual contact). That no peak in incidence among high-risk groups has been observed until now in Arab countries, must not be mistaken as an indication that HIV is spreading as slowly among heterosexuals as in western countries.
WITTKOWSKI, KNUT M., Dept. Med. Biometry, Eberhard-Karls-University, Westbahnhofstr. 55, D-72070 Tübingen, Germany, Telephone (+49)7071-292112, Telefax (+49)7071-183440, E-mail: kmw@uni-tuebingen.de
[1] WITTKOWSKI, K.M. (1988) Über die Bedeutung von Detergentien für die HIV-Prophylaxe unter Heterosexuellen. (On the impact of detergents on HIV prevention strategies for heterosexuals.) AIDS-Forschung 3
[3] WITTKOWSKI, K.M. (1989) Preventing the heterosexual spread of AIDS: What is the best advice if compliance is taken into account? AIDS 3 :143-145
4 ] WITTKOWSKI, K.M., DIETZ, K., KOCH, M.A. (1990) Einfluß vom Modellannahmen auf die Schätzung der HIV-Prävalenz. In: HARTMANN, U., GRUTZA, C. (Eds.) 3. Deutscher AIDS-Kongreß . München, D: Futuramed, 469
[5] WITTKOWSKI, K.M., DIETZ, K., KOCH, M.A. (1991) Estimating HIV prevalence - a sensitivity analysis with German AIDS data. VII International Conference on AIDS , Florence, I, 16-21 June 1991, 358 (M.C.3242)
[6] WITTKOWSKI, K.M., DIETZ, K. (1991) Back-calculation methods and their application for estimating HIV prevalence in Germany. Bulletin of the International Statistical Institute - Contributed Papers, Vol. 2 , 48th I.S.I. Session, Cairo, ET, 9-17 Sept
[7] WITTKOWSKI, K.M. (1992) Estimates of HIV prevalence in Germany and the U.S. - Sensitivity to assumptions concerning reporting delays and incubation time. VIII International Conference on AIDS / III STD World Congress , Vol. 2, Poster Abstracts, 19-24 July 1992, Congrex Holland B.V. P.O. Box 302, NL-1000 AH Amsterdam, C266 (PoC 4127)
[8] WITTKOWSKI, K.M. (1993) Kann sich HIV in Deutschland unter Heterosexuellen ausbreiten ? In: JÄGER, H. (Hrsg.) AIDS: Eine Krankheit wird behandelbar - Materialen zur HIV-Erkrankung im 2. Jahrzehnt. (AIDS-Monographien 3 ) . Landsberg, D: ecomed 281-285
[9] WITTKOWSKI, K.M. (1993) HIV prevalence among European heterosexuals - Trends and implications for testing and prevention. IX International Conference on AIDS / IV STD World Congress, Abstract Book, Vol. 2 , Berlin, D, 688 (PO-C11-2827)
[10] SEYDEL, J., KRÄMER, A., ROSENBERG, P.S., WITTKOWSKI, K.M., GAIL, M.H. (1994) Backcalculation of the number infected with human immunodeficiency virus in Germany. Journal of Acquired Immune Deficiency Syndromes 7 : 74-78