Hélène Voeten

The impact of pre-exposure prophylaxis (PrEP) on HIV epidemics in Africa and India: a simulation study.

Background Pre-exposure prophylaxis (PrEP) is a promising new HIV prevention method, especially for women. An urgent demand for implementation of PrEP is expected at the moment efficacy has been demonstrated in clinical trials. We explored the long-term impact of PrEP on HIV transmission in different HIV epidemics. Methodology/Principal Findings We used a mathematical model that distinguishes the general population, sex workers and their clients. PrEP scenarios varying in effectiveness, coverage and target group were modeled in the epidemiological settings of Botswana, Nyanza Province in Kenya, and Southern India. We also studied the effect of condom addition or condom substitution during PrEP use. Main outcome was number of HIV infections averted over ten years of PrEP use. PrEP strategies with high effectiveness and high coverage can have a substantial impact in African settings. In Southern India, by contrast, the number of averted HIV infections in different PrEP scenarios would be much lower. The impact of PrEP may be strongly diminished or even reversed by behavioral disinhibition, especially in scenarios with low coverage and low effectiveness. However, additional condom use during low coverage and low effective PrEP doubled the amount of averted HIV infections. Conclusions/Significance The public health impact of PrEP can be substantial. However, this impact may be diminished, or even reversed, by changes in risk behavior. Implementation of PrEP strategies should therefore come on top of current condom campaigns, not as a substitution.

Female sex workers and unsafe sex in urban and rural Nyanza, Kenya: regular partners may contribute more to HIV transmission than clients

Objectives  To compare the sexual behaviour of female sex workers in urban and rural areas in Nyanza province in Kenya, and to compare their unsafe sex with clients and with regular partners.

Patterns of Movement and Risk of HIV Infection in Rural Zimbabwe

BACKGROUND High rates of population movement may have helped spread human immunodeficiency virus (HIV) in southern Africa, including Zimbabwe, but whether mobility continues to influence the epidemic is unclear. METHODS The relationship between movement, risk behaviors, and prevalence of HIV was assessed from a general population survey of >9800 adults in 12 rural communities in Manicaland province in eastern Zimbabwe. RESULTS HIV prevalence varied with socioeconomic development. In community centers, prevalence among women was 49.9% (95% confidence interval [CI], 46.1%-53.6%), compared with 24.7% (95% CI, 22.6%-26.7%) in the least-developed subsistence-farming areas. Mobility was not associated with risk of HIV infection, except for those who migrated between rural locations. Among migrant agricultural workers, prevalence was 38.8% (95% CI, 33.1%-44.6%) for women and 26.4% (95% CI, 23.8%-28.9%) for men, compared with 29.7% (95% CI, 28.3%-31.1%) and 20.9% (95% CI, 19.3%-22.4%) for other sexually active women and men, respectively. Risk was increased if an individual traveled to Harare in the last month, without their spouse, but this risk was not transferred to the partner. CONCLUSION Rural-urban migration does not appear to be responsible for maintaining the high HIV prevalence in rural Zimbabwe, but rates of HIV infection may be affected by rural-rural migration.

Clients of female sex workers in Nyanza province Kenya. A core group in STD / HIV transmission.

Background Commercial sex plays an important role in the spread of HIV and AIDS in Africa, especially in beginning epidemics. Goal The goal was to study the sociodemographic characteristics and sexual risk behavior of clients of female sex workers (FSWs) in Nyanza province, Kenya. Study Design In the town of Kisumu and the rural districts Siaya and Bondo, male clients of FSWs were identified in bars, nightclubs, and lodges. An informal conversation was held with 64 clients. Results The majority of clients were between 25 and 36 years old, were married, and had extramarital partners in addition to FSWs. Most clients had visited several (3–5) different FSWs in the previous year, of whom at least 2 were in long-term, steady client–FSW relationships. Clients visited FSWs an average of once or twice a week. Most clients were not consistently using condoms with FSWs; the main reason given was that they “trusted” their steady FSWs. Conclusion Commercial sex in Nyanza frequently involves multiple steady relationships instead of rapidly changing one-time contacts. Information, education, and communication (IEC) campaigns aimed at risk reduction in commercial sex should promote condom use in steady FSW–client relationships.

Mobility and HIV in Tanzanian couples: Both mobile persons and their partners show increased risk

Objective:To investigate how mobility is related to sexual risk behavior and HIV infection, with special reference to the partners who stay behind in mobile couples. Methods:HIV status, sexual behavior and demographic data of 2800 couples were collected in a longitudinal study in Kisesa, rural Tanzania. People were considered short-term mobile if they had slept outside the household at least once on the night before one of the five demographic interviews, and long-term mobile if they were living elsewhere at least once at the time of a demographic round. Results:Overall, whereas long-term mobile men did not report more risk behavior than resident men, short-term mobile men reported having multiple sex partners in the last year significantly more often. In contrast, long-term mobile women reported having multiple sex partners more often than resident women (6.8 versus 2.4%; P = 0.001), and also had a higher HIV prevalence (7.7 versus 2.7%; P = 0.02). In couples, men and women who were resident and had a long-term mobile partner both reported more sexual risk behavior and also showed higher HIV prevalence than people with resident/short-term mobile partners. Remarkably, risk behavior of men increased more when their wives moved than when they were mobile themselves. Conclusions:More sexual risk behavior and an increased risk of HIV infection were seen not only in mobile persons, but also in partners staying behind. Interventions aiming at reducing risk behavior due to mobility should therefore include partners staying behind.

Perceived risk, anxiety, and behavioural responses of the general public during the early phase of the Influenza A (H1N1) pandemic in the Netherlands: Results of three consecutive online surveys

BackgroundResearch into risk perception and behavioural responses in case of emerging infectious diseases is still relatively new. The aim of this study was to examine perceptions and behaviours of the general public during the early phase of the Influenza A (H1N1) pandemic in the Netherlands.MethodsTwo cross-sectional and one follow-up online survey (survey 1, 30 April-4 May; survey 2, 15-19 June; survey 3, 11-20 August 2009). Adults aged 18 years and above participating in a representative Internet panel were invited (survey 1, n = 456; survey 2, n = 478; follow-up survey 3, n = 934). Main outcome measures were 1) time trends in risk perception, feelings of anxiety, and behavioural responses (survey 1-3) and 2) factors associated with taking preventive measures and strong intention to comply with government-advised preventive measures in the future (survey 3).ResultsBetween May and August 2009, the level of knowledge regarding Influenza A (H1N1) increased, while perceived severity of the new flu, perceived self-efficacy, and intention to comply with preventive measures decreased. The perceived reliability of information from the government decreased from May to August (62% versus 45%). Feelings of anxiety decreased from May to June, and remained stable afterwards. From June to August 2009, perceived vulnerability increased and more respondents took preventive measures (14% versus 38%). Taking preventive measures was associated with no children in the household, high anxiety, high self-efficacy, more agreement with statements on avoidance, and paying much attention to media information regarding Influenza A (H1N1). Having a strong intention to comply with government-advised preventive measures in the future was associated with higher age, high perceived severity, high anxiety, high perceived efficacy of measures, high self-efficacy, and finding governmental information to be reliable.ConclusionsDecreasing trends over time in perceived severity and anxiety are consistent with the reality: the clinical picture of influenza turned out to be mild in course of time. Although (inter)national health authorities initially overestimated the case fatality rate, the public stayed calm and remained to have a relatively high intention to comply with preventive measures.

Sexual Behavior is More Risky in Rural Than in Urban Areas Among Young Women in Nyanza Province, Kenya

Background: HIV/sexually transmitted disease interventions in sub-Saharan Africa have largely been focused on urban areas, where sexual behavior is supposed to be more risky than in rural areas. Goal: The goal of this study was to measure sexual risk behavior among young adults in Nyanza province in Kenya and to compare rural and urban areas. Study: In a cross-sectional study, 584 household members aged 15 to 29 years in Kisumu town and the rural districts Siaya and Bondo were selected by multistage random sampling and were administered a face-to-face questionnaire. Results: For women, sexual behavior was more risky in rural than in urban areas, also after adjusting for sociodemographic differences. Rural women reported less frequently being a virgin at marriage, a higher number of lifetime partners, and less consistent condom use with nonspousal partners. For men, sexual risk behavior was equally high in urban and rural areas. Conclusions: The potential for further HIV spread in rural Nyanza is large. HIV/sexually transmitted disease interventions should be expanded from urban to rural areas in Nyanza.

Perceived threat, risk perception, and efficacy beliefs related to SARS and other (emerging) infectious diseases: Results of an international survey

PurposeTo study the levels of perceived threat, perceived severity, perceived vulnerability, response efficacy, and self-efficacy for severe acute respiratory syndrome (SARS) and eight other diseases in five European and three Asian countries.MethodA computer-assisted phone survey was conducted among 3,436 respondents. The questionnaire focused on perceived threat, vulnerability, severity, response efficacy, and self-efficacy related to SARS and eight other diseases.ResultsPerceived threat of SARS in case of an outbreak in the country was higher than that of other diseases. Perceived vulnerability of SARS was at an intermediate level and perceived severity was high compared to other diseases. Perceived threat for SARS varied between countries in Europe and Asia with a higher perceived severity of SARS in Europe and a higher perceived vulnerability in Asia. Response efficacy and self-efficacy for SARS were higher in Asia compared to Europe. In multiple linear regression analyses, country was strongly associated with perceived threat.ConclusionsThe relatively high perceived threat for SARS indicates that it is seen as a public health risk and offers a basis for communication in case of an outbreak. The strong association between perceived threat and country and different regional patterns require further research.

No difference in HIV incidence and sexual behaviour between out-migrants and residents in rural Manicaland, Zimbabwe.

Objectives  Migration is associated with HIV infection, but the relationship has been mostly assessed in cross‐sectional studies. In a prospective study, we investigated whether out‐migrants are a selection of high‐risk individuals and whether rural‐to‐urban migration results in risky sexual behaviour for HIV incidence.

Strong association between in-migration and HIV prevalence in urban sub-Saharan Africa.

Background: Enormous variation exists in HIV prevalence between countries in sub-Saharan Africa. The contribution of migration to the spread of HIV has long been recognized, but its effect at the population level has never been assessed. In this ecological analysis, we explore how much variation in HIV prevalence in urban sub-Saharan Africa is explained by in-migration. Methods: We performed a linear regression to analyze the association between the proportion of recent in-migrants and HIV prevalence for men and women in urban areas, using 60 data points from 28 sub-Saharan African countries between 1987 and 2005. Results: We found a strong association between recent in-migration and HIV prevalence for women (Pearson R2 = 57%, P < 0.001) and men (R2 = 24%, P = 0.016), taking the earliest data point for each country. For women, the association was also strong within east/southern Africa (R2 = 50%, P = 0.003). For both genders, the association was strongest between 1985 and 1994, slightly weaker between 1995 and 1999, and nonexistent as from 2000. The overall association for both men and women was not confounded by the developmental indicators GNI per capita, income inequalities, or adult literacy. Conclusions: Migration explains much of the variation in HIV spread in urban areas of sub-Saharan Africa, especially before the year 2000, after which HIV prevalences started to level off in many countries. Our findings suggest that migration is an important factor in the spread of HIV, especially in rapidly increasing epidemics. This may be of relevance to the current HIV epidemics in China and India.