Impact of long-term civil disorders and wars on the trajectory of HIV epidemics in sub-Saharan Africa

From the mid-1970s, seven countries in sub-Saharan Africa have experienced civil disorders and wars lasting for at least 10 years. In two Sierra Leone during 1991-2002, and Somalia from 1988 and continuing adult HIV prevalence remained below 1%. In the Democratic Republic of the Congo, HIV prevalence appears to have stabilised during post-1991 civil disorder and war. Limited information from Angola (civil war 1975 -2002) and Liberia (civil disorder and war from 1989 and continuing) suggests low HIV prevalence. Mozambique's HIV prevalence was near 1% after its 1975 - 1992 civil war, but increased dramatically in the first post-war decade. Across African countries with long-term wars, HIV seems to have spread more slowly than in most neighbouring countries at peace.This evidence contributes to the ongoing debate about the factors that explain differential epidemic trajectories, a debate which is crucial to the design of HIV prevention programmes. One possible explanation for slow epidemic growth in wartime is that unsterile health care accounts for an important proportion of HIV transmission during peacetime, but much less when wars disrupt health services. However, other explanations are also possible.The roles of sex and blood exposures in HIV epidemics in war and peace await empirical determination. SAHARA-J (2004) 1(2): 87-98 Keywords: HIV, epidemiology, Africa, wars, risk factors. RÉSUMÉ A partir du milieu des années 1970, sept pays de l'Afrique sous-Sahara ont connu des désordres civils et des guerres qui ont duré au moins 10 ans. Dans deux pays la Sierra Léone entre 1991 et 2002 et la Somalie depuis 1988 jusque-là la prédominance du VIH chez des adultes est restée sous 1%. Dans la République Démocratique du Congo, la prédominance du VIH s'est stabilisée après le désordre civil et la guerre de 1991. L'information très limitée de l'Angola (guerre civile 1975 - 2002) et de Libéria (désordre et guerre civils depuis 1989) suggère une prédominance du VIH très basse. Au Mozambique, la prédominance du VIH était d'environ 1% après la guerre civile de 1975 à 1992. Cependant, il y a eu une augmentation importante au cours de la première décennie après la guerre. Dans tous les pays africains qui ont subit des guerres à longue durée, le VIH semble se propager plus doucement que dans des pays voisins qui sont en période de paix. Cette preuve contribue au débat actuel portant sur des facteurs responsables aux trajectoires différentielles de l'épidémie. Ce débat est important à la conception des programmes de prévention. Une explication possible de la dissémination lente de l'épidémie durant la guerre est que les soins non-stériles expliquent la proportion importante de transmission de VIH pendant la période de paix. Ce phénomène est encore plus réduit quand les services de santé sont interrompus par la guerre. Néanmoins, il y a d'autres explications possibles. Les rôles que jouent le sexe et la contamination par le sang sur l'épidémie du VIH pendant la guerre et durant la période de paix attendent une détermination empirique. . SAHARA-J (2004) 1(2): 87-98Mots clés: le VIH, I'épidémiologie, I'Afrique, les guerres, les facteurs de risque

Transmission of HIV-1 infection in sub-Saharan Africa and effect of elimination of unsafe injections

During the past year, a group has argued that unsafe injections are a major if not the main mode of HIV-1 transmission\ud in sub-Saharan Africa. We review the main arguments used to question the epidemiological interpretations on the lead\ud role of unsafe sex in HIV-1 transmission, and conclude there is no compelling evidence that unsafe injections are a\ud predominant mode of HIV-1 transmission in sub-Saharan Africa. Conversely, though there is a clear need to eliminate\ud all unsafe injections, epidemiological evidence indicates that sexual transmission continues to be by far the major\ud mode of spread of HIV-1 in the region. Increased efforts are needed to reduce sexual transmission of HIV-1

Concurrent sexual partnerships do not explain the HIV epidemics in Africa: a systematic review of the evidence

The notion that concurrent sexual partnerships are especially common in sub-Saharan Africa and explain the region's high HIV prevalence is accepted by many as conventional wisdom. In this paper, we evaluate the quantitative and qualitative evidence offered by the principal proponents of the concurrency hypothesis and analyze the mathematical model they use to establish the plausibility of the hypothesis

Using shared needles for subcutaneous inoculation can transmit bluetongue virus mechanically between ruminant hosts

Bluetongue virus (BTV) is an economically important arbovirus of ruminants that is transmitted by Culicoides spp. biting midges. BTV infection of ruminants results in a high viraemia, suggesting that repeated sharing of needles between animals could result in its iatrogenic transmission. Studies defining the risk of iatrogenic transmission of blood-borne pathogens by less invasive routes, such as subcutaneous or intradermal inoculations are rare, even though the sharing of needles is common practice for these inoculation routes in the veterinary sector. Here we demonstrate that BTV can be transmitted by needle sharing during subcutaneous inoculation, despite the absence of visible blood contamination of the needles. The incubation period, measured from sharing of needles, to detection of BTV in the recipient sheep or cattle, was substantially longer than has previously been reported after experimental infection of ruminants by either direct inoculation of virus, or through blood feeding by infected Culicoides. Although such mechanical transmission is most likely rare under field condition, these results are likely to influence future advice given in relation to sharing needles during veterinary vaccination campaigns and will also be of interest for the public health sector considering the risk of pathogen transmission during subcutaneous inoculations with re-used needles

Effect of variable transmission rate on the dynamics of HIV in sub-Saharan Africa

<p>Abstract</p> <p>Background</p> <p>The cause of the high HIV prevalence in sub-Saharan Africa is incompletely understood, with heterosexual penile-vaginal transmission proposed as the main mechanism. Heterosexual HIV transmission has been estimated to have a very low probability; but effects of cofactors that vary in space and time may substantially alter this pattern.</p> <p>Methods</p> <p>To test the effect of individual variation in the HIV infectiousness generated by co-infection, we developed and analyzed a mathematical sexual network model that simulates the behavioral components of a population from Malawi, as well as the dynamics of HIV and the co-infection effect caused by other infectious diseases, including herpes simplex virus type-2, gonorrhea, syphilis and malaria.</p> <p>Results</p> <p>The analysis shows that without the amplification effect caused by co-infection, no epidemic is generated, and HIV prevalence decreases to extinction. But the model indicates that an epidemic can be generated by the amplification effect on HIV transmission caused by co-infection.</p> <p>Conclusion</p> <p>The simulated sexual network demonstrated that a single value for HIV infectivity fails to describe the dynamics of the epidemic. Regardless of the low probability of heterosexual transmission per sexual contact, the inclusion of individual variation generated by transient but repeated increases in HIV viral load associated with co-infections may provide a biological basis for the accelerated spread of HIV in sub-Saharan Africa. Moreover, our work raises the possibility that the natural history of HIV in sub-Saharan Africa cannot be fully understood if individual variation in infectiousness is neglected.</p

Wealth and sexual behaviour among men in Cameroon

BACKGROUND: The 2004 Demographic and Health Survey (DHS) in Cameroon revealed a higher prevalence of HIV in richest and most educated people than their poorest and least educated compatriots. It is not certain whether the higher prevalence results partly or wholly from wealthier people adopting more unsafe sexual behaviours, surviving longer due to greater access to treatment and care, or being exposed to unsafe injections or other HIV risk factors. As unsafe sex is currently believed to be the main driver of the HIV epidemic in sub-Saharan Africa, we designed this study to examine the association between wealth and sexual behaviour in Cameroon. METHODS: We analysed data from 4409 sexually active men aged 15–59 years who participated in the Cameroon DHS using logistic regression models, and have reported odds ratios (OR) with confidence intervals (CI). RESULTS: When we controlled for the potential confounding effects of marital status, place of residence, religion and age, men in the richest third of the population were less likely to have used a condom in the last sex with a non-spousal non-cohabiting partner (OR 0.43, 95% CI 0.32–0.56) and more likely to have had at least two concurrent sex partners in the last 12 months (OR 1.38, 95% CI 1.12–1.19) and more than five lifetime sex partners (OR 1.97, 95% CI 1.60–2.43). However, there was no difference between the richest and poorest men in the purchase of sexual services. Regarding education, men with secondary or higher education were less likely to have used a condom in the last sex with a non-spousal non-cohabiting partner (OR 0.24, 95% CI 0.16–0.38) and more likely to have started sexual activity at age 17 years or less (OR 2.73, 95% CI 2.10–3.56) and had more than five lifetime sexual partners (OR 2.59, 95% CI 2.02–3.31). There was no significant association between education and multiple concurrent sexual partnerships in the last 12 months or purchase of sexual services. CONCLUSION: Wealthy men in Cameroon are more likely to start sexual activity early and have both multiple concurrent and lifetime sex partners, and are less likely to (consistently) use a condom in sex with a non-spousal non-cohabiting partner. These unsafe sexual behaviours may explain the higher HIV prevalence among wealthier men in the country. While these findings do not suggest a redirection of HIV prevention efforts from the poor to the wealthy, they do call for efforts to ensure that HIV prevention messages get across all strata of society

Fitting the HIV Epidemic in Zambia: A Two-Sex Micro-Simulation Model

BACKGROUND: In describing and understanding how the HIV epidemic spreads in African countries, previous studies have not taken into account the detailed periods at risk. This study is based on a micro-simulation model (individual-based) of the spread of the HIV epidemic in the population of Zambia, where women tend to marry early and where divorces are not frequent. The main target of the model was to fit the HIV seroprevalence profiles by age and sex observed at the Demographic and Health Survey conducted in 2001. METHODS AND FINDINGS: A two-sex micro-simulation model of HIV transmission was developed. Particular attention was paid to precise age-specific estimates of exposure to risk through the modelling of the formation and dissolution of relationships: marriage (stable union), casual partnership, and commercial sex. HIV transmission was exclusively heterosexual for adults or vertical (mother-to-child) for children. Three stages of HIV infection were taken into account. All parameters were derived from empirical population-based data. Results show that basic parameters could not explain the dynamics of the HIV epidemic in Zambia. In order to fit the age and sex patterns, several assumptions were made: differential susceptibility of young women to HIV infection, differential susceptibility or larger number of encounters for male clients of commercial sex workers, and higher transmission rate. The model allowed to quantify the role of each type of relationship in HIV transmission, the proportion of infections occurring at each stage of disease progression, and the net reproduction rate of the epidemic (R(0) = 1.95). CONCLUSIONS: The simulation model reproduced the dynamics of the HIV epidemic in Zambia, and fitted the age and sex pattern of HIV seroprevalence in 2001. The same model could be used to measure the effect of changing behaviour in the future

Male circumcision for HIV prevention: current evidence and implementation in sub-Saharan Africa

Heterosexual exposure accounts for most HIV transmission in sub-Saharan Africa, and this mode, as a proportion of new infections, is escalating globally. The scientific evidence accumulated over more than 20 years shows that among the strategies advocated during this period for HIV prevention, male circumcision is one of, if not, the most efficacious epidemiologically, as well as cost-wise. Despite this, and recommendation of the procedure by global policy makers, national implementation has been slow. Additionally, some are not convinced of the protective effect of male circumcision and there are also reports, unsupported by evidence, that non-sex-related drivers play a major role in HIV transmission in sub-Saharan Africa. Here, we provide a critical evaluation of the state of the current evidence for male circumcision in reducing HIV infection in light of established transmission drivers, provide an update on programmes now in place in this region, and explain why policies based on established scientific evidence should be prioritized. We conclude that the evidence supports the need to accelerate the implementation of medical male circumcision programmes for HIV prevention in generalized heterosexual epidemics, as well as in countering the growing heterosexual transmission in countries where HIV prevalence is presently low