Séverin Anagonou

The epidemiology of HSV-2 infection and its association with HIV infection in four urban African populations.

Objectives: To estimate age- and sex-specific herpes simplex virus type-2 (HSV-2) prevalence in urban African adult populations and to identify factors associated with infection. Design and methods: Cross-sectional, population-based samples of about 2000 adults interviewed in each of the following cities: Cotonou, Benin; Yaoundé, Cameroon; Kisumu, Kenya and Ndola, Zambia. Consenting study participants were tested for HIV, HSV-2 and other sexually transmitted infections. Results: HSV-2 prevalence was over 50% among women and over 25% among men in Yaoundé, Kisumu and Ndola, with notably high rates of infection among young women in Kisumu and Ndola (39% and 23%, respectively, among women aged 15-19 years). The prevalence in Cotonou was lower (30% in women and 12% in men). Multivariate analysis showed that HSV-2 prevalence was significantly associated with older age, ever being married, and number of lifetime sexual partners, in almost all cities and both sexes. There was also a strong, consistent association with HIV infection. Among women, the adjusted odds ratios for the association between HSV-2 and HIV infections ranged from 4.0 [95% confidence interval (CI) = 2.0-8.0] in Kisumu to 5.5 (95% CI = 1.7-18) in Yaoundé, and those among men ranged from 4.6 (95% CI = 2.7-7.7) in Ndola to 7.9 (95% CI = 4.1-15) in Kisumu. Conclusions: HSV-2 infection is highly prevalent in these populations, even at young ages, and is strongly associated with HIV at an individual level. At a population level, HSV-2 prevalence was highest in Kisumu and Ndola, the cities with the highest HIV rates, although rates were also high among women in Yaoundé, where there are high rates of partner change but relatively little HIV infection. The high prevalence of both infections among young people underlines the need for education and counselling among adolescents.

Multicentre study on factors determining differences in rate of spread of HIV in sub-Saharan Africa: methods and prevalence of HIV infection

Objective: The objective of this study was to explore whether the differences in rate of spread of HIV in different regions in sub-Saharan Africa could be explained by differences in sexual behaviour and/or factors influencing the probability of HIV transmission during sexual intercourse. Methods: A cross-sectional, population-based study was conducted in two cities with a high HIV prevalence (Kisumu in Kenya and Ndola in Zambia) and two cities with a relatively low HIV prevalence (Cotonou in Benin and Yaoundé in Cameroon). In each of these cities, approximately 1000 men and 1000 women, aged 15-49 years, were randomly selected from the general population. Consenting men and women were interviewed and were tested for HIV, syphilis, herpes simplex virus type 2 (HSV-2), gonorrhoea, chlamydial infection and trichomoniasis (the latter for women only). In addition, a survey was conducted on a random sample of 300 sex workers in each city. The research instruments, including the questionnaires and the laboratory procedures, were standardized to permit comparison of results. Results: The numbers of men interviewed were 1021 in Cotonou, 973 in Yaoundé, 829 in Kisumu, and 720 in Ndola. The corresponding figures for women were 1095, 1116, 1060 and 1130. In Yaoundé, Kisumu and Ndola, the response rates for men were lower than for women due to failure to make contact with eligible men. The proportion of eligible women who were interviewed was 86% in Yaoundé, and 89% in Kisumu and Ndola. In Yaoundé, 76% of eligible men were interviewed, along with 82% in Kisumu and 75% in Ndola. The prevalence of HIV infection in men was 3.3% in Cotonou, 4.1% in Yaoundé, 19.8% in Kisumu and 23.2% in Ndola. For women, the respective figures were 3.4, 7.8, 30.1 and 31.9%. The prevalence of HIV infection among women aged 15-19 years was 23.0% in Kisumu and 15.4% in Ndola. Among women in Kisumu who had their sexual debut 5 years before the interview, the prevalence of HIV infection was 46%; in Ndola, it was 59%. Among sex workers, the prevalence of HIV infection was 57.5% in Cotonou, 34.4% in Yaoundé, 74.7% in Kisumu and 68.7% in Ndola. Conclusions: The HIV prevalence rates in the general population confirmed our preliminary assessment of the level of HIV infection in the four cities, which was based on estimates of HIV prevalence from sentinel surveillance among pregnant women. The very high prevalence of HIV infection among young women in Kisumu and Ndola calls for urgent intervention.

Simplified strategy for detection of recombinant human immunodeficiency virus type 1 group M isolates by gag/env heteroduplex mobility assay

We developed a heteroduplex mobility assay in the gag gene (gag HMA) for the identification of group M subtypes A to H. The assay covers the region coding for amino acid 132 of p24 to amino acid 20 of p7 (according to human immunodeficiency virus type 1 [HIV-1] ELI, 460 bp). The gag HMA was compared with sequencing and phylogenetic analysis of an evaluation panel of 79 HIV-1 group M isolates isolated from infected individuals from different geographic regions. Application of gag HMA in combination with env HMA on 252 HIV-1- positive plasma samples from Bénin, Cameroon, Kenya, and Zambia revealed a high prevalence of a variety of intersubtype recombinants in Yaoundé, Cameroon (53.8%); Kisumu, Kenya (26.8%); and Cotonou, Bénin (41%); no recombinants were identified among the samples from Ndola, Zambia. The AG(IbNG) circulating recombinant form, as determined by gag HMA, was found to be the most common intersubtype recombinant in Yaoundé (39.4%) and Cotonou (38.5%). Using a one-tube reverse transcriptase PCR protocol, this gag HMA in combination with env HMA is a useful tool for rapidly monitoring the prevalence of the various genetic subtypes as well as of recombinants of HIV-1. Moreover, this technology can easily be applied in laboratories in developing countries.ABSTRACT We developed a heteroduplex mobility assay in the gaggene (gag HMA) for the identification of group M subtypes A to H. The assay covers the region coding for amino acid 132 of p24 to amino acid 20 of p7 (according to human immunodeficiency virus type 1 [HIV-1] ELI, 460 bp). Thegag HMA was compared with sequencing and phylogenetic analysis of an evaluation panel of 79 HIV-1 group M isolates isolated from infected individuals from different geographic regions. Application of gag HMA in combination with envHMA on 252 HIV-1- positive plasma samples from Bénin, Cameroon, Kenya, and Zambia revealed a high prevalence of a variety of intersubtype recombinants in Yaoundé, Cameroon (53.8%); Kisumu, Kenya (26.8%); and Cotonou, Bénin (41%); no recombinants were identified among the samples from Ndola, Zambia. The AGIbNG circulating recombinant form, as determined bygag HMA, was found to be the most common intersubtype recombinant in Yaoundé (39.4%) and Cotonou (38.5%). Using a one-tube reverse transcriptase PCR protocol, this gag HMA in combination with env HMA is a useful tool for rapidly monitoring the prevalence of the various genetic subtypes as well as of recombinants of HIV-1. Moreover, this technology can easily be applied in laboratories in developing countries.

The multicentre study on factors determining the differential spread of HIV in four African cities: summary and conclusions

In all regions of sub-Saharan Africa the predominant mode of transmission of HIV is through heterosexual intercourse however there are large variations in the rate and extent of the spread of HIV in different populations. This study was conducted to identify the factors that influence the rapid spread of HIV in four African cities namely Cotonou (Benin) Yaounde (Cameroon) Kisumu (Kenya) and Ndola (Zambia). Results demonstrated that high rates of partner change and being married are risk factors for HIV infection in men in at least one city but are risk factors for women in all four cities. In addition condom use among sex workers did not show a difference between the low and high prevalence cities. Furthermore no evidence of changes towards safer sexual behavior was identified in the high HIV prevalence cities. The only factors that were more common in the two high HIV prevalence cities than in the two low HIV prevalence cities were young age at first intercourse for women young age at first marriage and large age difference between the spouses. It was also noted that the high levels of HIV infection among young people especially among female adolescents in Kisumu and Ndola highlight the importance of interventions targeted at young people and their partners.

Does increased general schooling protect against HIV infection? A study in four African cities

Background  The association between educational attainment and risk of HIV infection varies between populations and over time. Earlier studies in sub‐Saharan Africa have found that those with more education are at increased risk of HIV infection.

The epidemiology of gonorrhoea, chlamydial infection and syphilis in four African cities.

Objectives: To compare the epidemiology of gonorrhoea, chlamydial infection and syphilis in four cities in sub-Saharan Africa; two with a high prevalence of HIV infection (Kisumu, Kenya and Ndola, Zambia), and two with a relatively low HIV prevalence (Cotonou, Benin and Yaoundé, Cameroon). Design: Cross-sectional study, using standardized methods, including a standardized questionnaire and standardized laboratory tests, in four cities in sub-Saharan Africa. Methods: In each city, a random sample of about 2000 adults aged 15-49 years was taken. Consenting men and women were interviewed about their socio-demographic characteristics and their sexual behaviour, and were tested for HIV, syphilis, herpes simplex virus type 2 (HSV-2), gonorrhoea, chlamydial infection, and (women only) Trichomonas vaginalis infection. Risk factor analyses were carried out for chlamydial infection and syphilis seroreactivity. Results: The prevalence of gonorrhoea ranged between 0% in men in Kisumu and 2.7% in women in Yaoundé. Men and women in Yaoundé had the highest prevalence of chlamydial infection (5.9 and 9.4%, respectively). In the other cities, the prevalence of chlamydial infection ranged between 1.3% in women in Cotonou and 4.5% in women in Kisumu. In Ndola, the prevalence of syphilis seroreactivity was over 10% in both men and women; it was around 6% in Yaoundé, 3-4% in Kisumu, and 1-2% in Cotonou. Chlamydial infection was associated with rate of partner change for both men and women, and with young age for women. At the population level, the prevalence of chlamydial infection correlated well with reported rates of partner change. Positive syphilis serology was associated with rate of partner change and with HSV-2 infection. The latter association could be due to biological interaction between syphilis and HSV-2 or to residual confounding by sexual behaviour. At the population level, there was no correlation between prevalence of syphilis seroreactivity and reported rates of partner change Conclusion: Differences in prevalence of chlamydial infection could be explained by differences in reported sexual behaviour, but the variations in prevalence of syphilis seroreactivity remained unexplained. More research is needed to better understand the epidemiology of sexually transmitted infections in Africa.

The epidemiology of trichomoniasis in women in four African cities.

Objectives: To describe the epidemiology of Trichomonas vaginalis infection and its association with HIV infection, in women in four African cities with different levels of HIV infection. Design: Cross-sectional study, using standardized methods, including a standardized questionnaire and standardized laboratory tests, in four cities in sub-Saharan Africa: two with a high prevalence of HIV infection (Kisumu, Kenya and Ndola, Zambia), and two with a relatively low prevalence of HIV (Cotonou, Benin and Yaoundé, Cameroon). Methods: In each city, a random sample of about 2000 adults aged 15-49 years was taken. Consenting men and women were interviewed about their socio-demographic characteristics and their sexual behaviour, and were tested for HIV, syphilis, herpes simplex virus type 2 (HSV-2), gonorrhoea, chlamydial infection, and (women only) T. vaginalis infection. Risk factor analyses were carried out for trichomoniasis for each city separately. Multivariate analysis, however, was only possible for Yaoundé, Kisumu and Ndola. Results: The prevalence of trichomoniasis was significantly higher in the high HIV prevalence cities (29.3% in Kisumu and 34.3% in Ndola) than in Cotonou (3.2%) and Yaoundé (17.6%). Risk of trichomoniasis was increased in women who reported more lifetime sex partners. HIV infection was an independent risk factor for trichomonas infection in Yaoundé [adjusted odds ratio (OR) = 1.8, 95% confidence interval (CI) = 0.9-3.7] and Kisumu (adjusted OR = 1.7, 95% CI = 1.1-2.7), but not in Ndola. A striking finding was the high prevalence (40%) of trichomonas infection in women in Ndola who denied that they had ever had sex. Conclusion: Trichomoniasis may have played a role in the spread of HIV in sub-Saharan Africa and may be one of the factors explaining the differences in levels of HIV infection between different regions in Africa. The differences in prevalence of trichomoniasis between the four cities remain unexplained, but we lack data on the epidemiology of trichomoniasis in men. More research is required on the interaction between trichomoniasis and HIV infection, the epidemiology of trichomoniasis in men, and trichomonas infections in women who deny sexual activity.

HIV-1 subtypes and the HIV epidemics in four cities in sub-Saharan Africa.

Objective: To describe the distribution of HIV-1 subtypes in two cities with high HIV prevalence (Kisumu, Kenya and Ndola, Zambia) and two with relatively low prevalence (Cotonou, Benin and Yaoundé, Cameroon), and to examine whether the differences in prevalence of HIV infection could be due to the predominance within the infected populations of subtypes with differing efficiency of heterosexual transmission. Methods: For around 100 randomly selected HIV-positive sera from the general population and 60 from sex workers in each city, the HIV-1 subtype was determined in the env fragment. For between 19 and 52 of the sera from the general population and 20-32 sera from sex workers, the subtype was also determined in the gag fragment. Results: Over 70% of infections in Cotonou, Yaoundé and Kisumu were with subtype A (by env). However, around one-half of subtype A infections in Cotonou and Yaoundé were found to be the circulating recombinant form CRF02_AG when the gag fragment was also examined. A large number of different HIV strains were found in Yaoundé, including some belonging to group O. Over 20% of infections in Kisumu and around 10% in Yaoundé were with isolated intersubtype recombinant forms. All but a few infections in Ndola were with subtype C and no recombinants were found. Conclusions: The pattern of distribution of subtypes that we found does not suggest that differences in circulating subtypes play a major role in explaining the differences in prevalence of HIV-1 infection between the four cities. The emergence and spread of recombinants requires close surveillance to adapt testing strategies if needed, to inform vaccine development and to ascertain their role in the future spread of HIV.

Family relationship, water contact and occurrence of Buruli ulcer in Benin.

Background Mycobacterium ulcerans disease (Buruli ulcer) is the most widespread mycobacterial disease in the world after leprosy and tuberculosis. How M. ulcerans is introduced into the skin of humans remains unclear, but it appears that individuals living in the same environment may have different susceptibilities. Objectives This study aims to determine whether frequent contacts with natural water sources, family relationship or the practice of consanguineous marriages are associated with the occurrence of Buruli ulcer (BU). Design Case control study. Setting Department of Atlantique, Benin. Subjects BU-confirmed cases that were diagnosed and followed up at the BU detection and treatment center (CDTUB) of Allada (Department of the Atlantique, Benin) during the period from January 1st, 2006, to June 30th, 2008, with three matched controls (persons who had no signs or symptoms of active or inactive BU) for age, gender and village of residence per case. Main Outcomes Measured Contact with natural water sources, BU history in the family and the practice of consanguineous marriages. Results A total of 416 participants were included in this study, including 104 cases and 312 controls. BU history in the family (p<0.001), adjusted by daily contact with a natural water source (p = 0.007), was significantly associated with higher odds of having BU (OR; 95% CI = 5.5; 3.0–10.0). The practice of consanguineous marriage was not associated with the occurrence of BU (p = 0.40). Mendelian disorders could explain this finding, which may influence individual susceptibility by impairing immunity. Conclusion This study suggests that a combination of genetic factors and behavioral risk factors may increase the susceptibility for developing BU.

Evaluation of direct detection of Mycobacterium tuberculosis rifampin resistance by a nitrate reductase assay applied to sputum samples in Cotonou, Benin

ABSTRACT The aim of this study was to evaluate a nitrate reductase assay (NRA) performed on smear-positive sputa for the direct detection of rifampin resistance in Mycobacterium tuberculosis. A total of 213 smear-positive sputa with a positivity score of 1+ or more (>1 acid-fast bacillus per field by fluorescence microscopy) were used in the study. The samples were decontaminated using the modified Petroff method, and portions of the resulting suspension were used to perform the NRA. The NRA results were compared with the reference indirect proportion method for 177 specimens for which comparable results were available. NRA results were obtained at day 10 for 15 specimens (9%), results for 88 specimens (50%) were obtained at day 14, results for 66 specimens (37%) were obtained at day 18, and results for the remaining 8 specimens (4%) were obtained at day 28. Thus, 96% of NRA results were obtained in 18 days. Of the 177 specimens, there was only one discrepancy (susceptible according to the NRA and resistant according to the indirect proportion method). NRA is simple to perform and provides a rapid, accurate, and cost-effective means for the detection of rifampin resistance in M. tuberculosis isolates.