Prevalence of lung function impairment in cured pulmonary tuberculosis patients in Cotonou, Benin.

SETTING: National teaching hospital for the management of respiratory diseases, Cotonou, Benin. OBJECTIVE: 1) To estimate the prevalence of lung function impairment (LFI) and associated factors in patients cured of pulmonary tuberculosis (PTB); and 2) to determine the link between human immunodeficiency virus (HIV) infection and LFI occurrence. DESIGN: We performed a cross-sectional study in cured patients with smear-positive TB (PTB+) treated between 2012 and 2015. We recruited two control groups of 70 HIV-infected (HIV+/TB-) and 70 HIV-negative participants without TB (HIV-/TB-). We performed spirometry in all participants to identify LFI (obstructive, restrictive or mixed) and the 6-min walk test (6-MWT) in PTB+ participants. We assessed the factors associated with LFI using logistic regression. RESULTS: Of 4711 subjects with PTB, 241 were contacted and 189 were included. The median age was 37 years; 128 (68.0%) were male. Overall, 85 cured PTB+ patients had LFI (45.0%). Extent of initial radiological lesions, time between symptom onset and treatment, and female sex were independently associated with LFI. Fifty-five (29.1%) cured PTB+ patients had an abnormal 6-MWT; those with LFI had a higher risk of poor exercise tolerance (OR 2.23; interquartile range 1.16-4.30). We did not find any association between HIV infection and LFI. CONCLUSION: LFI is very common in cured PTB+ patients from Benin and significantly impacts exercise tolerance.

[Tuberculosis in older persons in African setting: Epidemiological, diagnostic and evolutive features]. / La tuberculose du sujet âgé en milieu africain : particularités épidémiologiques, diagnostiques et évolutives au Bénin.

OBJECTIVE: To determine the epidemiological, diagnostic and evolutives features of tuberculosis (TB) in older subjects in Benin. PATIENTS AND METHODS: This was a retrospective cohort study of adults TB patients (age≥15 years) who were notified at all the Basic Management Units (BMU) in Benin from January 1st, 2013 to December 31st. Older subjects (age≥60 years) were compared to those less than 60 years named young subjects. The threshold of significance was set at 5%. RESULTS: The analysis was carried out on 6531 cases adults cases notified during the period. 601 (9.2%) were 60 years old or above. The case notification rate (CNR) in elders was more than twice the CNR in young people (68 cases vs. 31 cases per 100,000 population). Older subjects were less often infected with HIV (9.3%) than young's (16.7%), P<0.0001. In new bacteriologically confirmed pulmonary TB negative for HIV, unfavorable treatment outcomes were more frequent in older subjects than in young subjects with more deaths (7.5% vs. 3.0%). On the other hand, in bacteriological confirmed TB seropositive for HIV and all the other cases, treatment outcomes were comparable between the two groups. CONCLUSION: The high CNR and the high death rate in older subjects should plead for a specific care for an adapted management of TB case in this group.

Implementation of isoniazid preventive therapy in children aged under 5 years exposed to tuberculosis in Benin.

SETTINGS: Two large tuberculosis (TB) centres under a well-functioning National TB Programme (NTP) in Benin, West Africa. OBJECTIVE: To assess the feasibility and results of integrating a programme of isoniazid preventive therapy (IPT) in children aged <5 years exposed to TB as part of the existing routine activities of the NTP. METHOD: All children aged <5 years living in the household of a patient with smear-positive pulmonary TB were examined by a doctor and received IPT if no evidence of TB was detected. The children were followed clinically by a nurse for 6 months. RESULTS: From January 2013 to June 2014, 496 children were examined and prescribed IPT among 499 notified contacts; 86% adhered to IPT for at least 6 months. There were six deaths and three cases of active TB among the children, all during the first 3 months of follow-up. CONCLUSIONS: In an African country with moderate TB incidence and a well-functioning NTP, the integration of IPT into the NTP for children aged <5 years exposed to TB in the family was feasible based on simple tools associated with the follow-up of index cases. The rate of adherence to IPT was high.

Low prevalence of diabetes mellitus in patients with tuberculosis in Cotonou, Benin.

SETTING: The three Basic Management Units (BMUs) of the National Tuberculosis Programme (NTP) in Cotonou, Benin. OBJECTIVE: To determine the prevalence of diabetes mellitus (DM) among tuberculosis (TB) patients in Cotonou. DESIGN: A cross-sectional study of consecutively registered TB patients treated for a minimum of 2 weeks between June and July 2014 in the three BMUs, with measurement of their fasting blood glucose (FBG). A patient was considered as having DM if venous FBG was ⩾7 mmol/l or if they reported a known history of DM. RESULT: There were 159 patients assessed: 114 with new smear-positive pulmonary tuberculosis (PTB), 5 with new smear-negative PTB, 8 with extra-pulmonary TB, 21 retreatment patients with fully susceptible bacilli and 11 with multidrug-resistant TB. Of these, respectively 31 (19%), 18 (11%) and 10 (6%) were human immunodeficiency virus co-infected, smokers and hypertensive. Eight patients (5%) had impaired fasting glucose and three (1.9%) had DM (FBG ⩾ 7 mmol/l), of whom two were already known to have the disease and one was newly diagnosed. CONCLUSION: DM may not be an important risk factor for TB in Cotonou. A larger study on TB and DM in the whole country is needed.

Cadre : Les trois Centres de Dépistage et de Traitement de la Tuberculose (TB) de Cotonou, Bénin.Objectif : Déterminer la prévalence du diabète sucré (DM) parmi les patients tuberculeux à Cotonou.Méthode : Etude transversale avec enrôlement successif de tous les patients tuberculeux traités depuis au moins 2 semaines entre juin et juillet 2014, et mesure de leur glycémie à jeun. Le diagnostic de DM était retenu sur la base d'une glycémie veineuse à jeun ⩾ 7 mmol/l ou d'un antécédent de DM rapporté par le patient.Résultat : Au total, 159 patients étaient inclus : 114 nouveaux cas de TB pulmonaire à microscopie positive, 5 nouveaux cas de TB pulmonaire à microscopie négative, 8 cas de TB extrapulmonaire, 21 cas de retraitement à germes sensibles et 11 cas de TB multirésistante. D'eux, respectivement 31 (19%), 18 (11%) et 10 (6%) étaient co-infectés, fumeurs et hypertendus. Il y avait huit patients (5%) intolérants au glucose et trois (1.9%) diabétiques, dont un nouvellement diagnostiqué.Conclusion : A Cotonou, le DM ne semble pas être un facteur de risque majeur de développement d'une TB-maladie. Une étude à l'échelle nationale s'avère nécessaire pour cerner l'ampleur de cette affection parmi les tuberculeux dans tout le pays.

Marco de referencia: Las tres Unidades Básicas de Tratamiento en el Programa Nacional contra la Tuberculosis de Beni, en Cotonou.Objetivo: Determinar la prevalencia de diabetes (DM) en los pacientes con diagnóstico de tuberculosis (TB) en Cotonou.Método: Fue este un estudio transversal de los pacientes registrados de manera consecutiva y que recibieron tratamiento como mínimo durante 2 semanas, de junio a julio del 2014, en las Unidades Básicas de Tratamiento, a quienes se practicó una glucemia plasmática en ayunas. Se definió el diagnóstico de DM como una glucemia en ayunas ⩾ 126 mg/dl (o 7 mmol/l) o la referencia por el paciente de un diagnóstico conocido de DM.Resultados: Se evaluaron 159 pacientes, de los cuales 114 casos nuevos de TB pulmonar con baciloscopia positiva, 5 casos con baciloscopia negativa, 8 casos de TB extrapulmonar, 21 casos en retratamiento antituberculoso con bacilos normosensibles y 11 casos de TB multidrogorresistente. De estos pacientes, 31 presentaron coinfección por el virus de la inmunodeficiencia humana (19%), 18 eran fumadores (11%) y 10 eran hipertensos (6%). Se detectaron ocho pacientes con una glucemia basal alterada (5%) y tres con DM (1,9%), de los cuales dos ya conocían el diagnóstico.Conclusión: Al parecer la DM no constituye un factor mayor de riesgo de contraer la TB en Cotonou. Es necesario llevar a cabo un estudio más amplio a escala nacional sobre ambas enfermedades.

The burden and outcomes of childhood tuberculosis in Cotonou, Benin.

SETTING: The National Tuberculosis Programme (NTP) and the paediatric ward of the General Hospital (GH), Cotonou, Benin. OBJECTIVE: To describe the burden of tuberculosis (TB), characteristics and outcomes among children treated in Cotonou from 2009 to 2011. DESIGN: Cross-sectional cohort study consisting of a retrospective record review of all children with TB aged <15 years. RESULTS: From 2009 to 2011, 182 children with TB were diagnosed and treated (4.5% of total cases), 153 (84%) by the NTP and 29 (16%) by the GH; the latter were not notified to the NTP. The incidence rate of notified TB cases was between 8 and 13 per 100 000 population, and was higher in children aged >5 years. Of 167 children tested, 29% were HIV-positive. Treatment success was 72% overall, with success rates of 86%, 62% and 74%, respectively, among sputum smear-positive, sputum smear-negative and extra-pulmonary patients. Treatment success rates were lower in children with sputum smear-negative TB (62%) and those with HIV infection (58%). CONCLUSION: The number of children being treated for TB is low, and younger children in particular are underdiagnosed. There is a need to improve the diagnosis of childhood TB, especially among younger children, and to improve treatment outcomes among HIV-TB infected children, with better follow-up and monitoring.

MDR-TB treatment needs in patients previously treated for TB in Cotonou, Benin.

SETTING: Centre National Hospitalier de Pneumo-Phtisi-ologie, Cotonou, Benin. OBJECTIVE: To determine the proportion of individuals needing treatment for multidrug-resistant tuberculosis (MDR-TB) among patients previously treated for TB. DESIGN: A retrospective cross-sectional study of all patients previously treated for TB in Cotonou from 2003 to 2011. RESULTS: Of 956 patients on retreatment, 897 (94%) underwent culture and/or a line-probe assay. For different reasons, 594 (66%) underwent drug susceptibility testing for rifampicin (RMP), of whom 95 (16%) had RMP resistance (68 multidrug-resistance [MDR] and 27 other RMP resistance) and therefore needed treatment for MDR-TB. These represent 39% of patients who failed/relapsed after standardised retreatment, and 20% of those who failed, 19% of defaulters and 11% of relapses after first-line treatment. Residence outside of Benin was associated with a higher risk of RMP resistance (RR 3.13, 95%CI 2.19-4.48, P < 0.01). From 2003 to 2011, the prevalence of RMP resistance decreased from 25% to 5% among patients living in Benin. Human immunodeficiency virus (HIV) prevalence was 25%; no association was found between HIV and RMP resistance. Of patients failing treatment, 48% were fully susceptible, 22% were monoresistant and 8% polyresistant. CONCLUSION: The majority of patients who fail retreatment or first-line treatment in Cotonou do not require empirical treatment for MDR-TB.

Management of tuberculosis and HIV co-infection in Cotonou, Benin.

OBJECTIVES: The authors had for aim to assess the management of tuberculosis and HIV co-infection in Cotonou, Benin. PATIENTS AND METHODS: We made a cross-sectional, retrospective, and descriptive study comparing the clinical presentation and outcome of patients with tuberculosis and HIV co-infection versus patients with tuberculosis alone, all managed at the National Pneumophtisiology Center in Cotonou, Benin, in 2009. RESULTS: The rate of HIV screening in TB patients was 99%. One thousand and eighty-six TB patients were included and 259 were HIV positive. The mean age of co-infected patients was 36 years, versus 34 for TB mono-infected patients. The sex ratio among co-infected was 1.15 versus 2.25 among TB patients. Positive pulmonary sputum was less frequent with co-infection. Two hundred and fifty-seven over 259 patients were treated with cotrimoxazole. One hundred and eighty-five over 234 (79.05%) had CD4 counts<350. Eighty-five (46%) of the 185 patients with CD4<350, were given antiretroviral therapy. Treatment success rate was lower for co-infected (75%) than for patients with TB alone (86%), and death rates were higher in co-infected patients (10% vs. 3%). CONCLUSION: High death rate and high rate of lost to follow-up are arguments for systematic antiretroviral treatment of co-infected patients. Early screening for TB and HIV, and reviewing the current national recommendations, as well as an increased governmental effort to provide medicines to all patients in need of ARV are mandatory.

Smear-negative, culture-positive pulmonary tuberculosis among patients with chronic cough in Cotonou, Benin.

SETTING: The main tuberculosis (TB) centre in Benin, West Africa, where only 2% of adult pulmonary TB cases are sputum smear-negative, all other pulmonary cases being smear-positive. OBJECTIVES: To assess the burden of smear-negative, culture-positive pulmonary TB among TB suspects in Cotonou, and to estimate the total number of non-smear-positive TB cases at country level. DESIGN: For 1 year, one morning sputum culture was performed for every TB suspect (cough lasting >3 weeks, as defined in Benin's national guidelines) with three negative sputum smears (fluorescence technique). RESULTS: Of 214 TB suspects for whom culture was performed, only 22 smear-negative, culture-positive cases were identified. During the same period, 831 sputum smear-positive cases were diagnosed. Culture therefore contributed only 2.6% of the total number of bacteriologically proven cases. CONCLUSION: These results show the relatively low input of culture in TB diagnosis among chronic coughers in Cotonou, Benin, and demonstrates that the expected number of non-smear-positive TB cases in Benin is probably much lower than the World Health Organization's current annual estimates.

Comparison of two LED fluorescence microscopy build-on modules for acid-fast smear microscopy.

SETTING: National Reference Laboratory, Benin. OBJECTIVES: To compare the performance of Fraen FluoLED and LW Lumin light-emitting diode (LED) fluorescence microscopy modules. DESIGN: Acid-fast bacilli (AFB) smears, routinely examined with a classical fluorescence microscope, were blindly re-read with both LED systems at 200x magnification. Smears with discordant results were rechecked on all systems at 200x, and 100 randomly chosen smears were read again at 400x. Confirmed presence of AFB with any system was accepted as a true positive. RESULTS: A total of 1937 smears were examined by all systems. The Fraen and LW detected 895 (46.2%) and 817 (42.2%) positive and scanty positive smears. After rechecking 201 smears, 15 false-positive and 61 false-negative results were declared for Fraen, against 11 and 135 for LW. The systems had similar false-positive rates (1.7% for Fraen and 1.4% for LW), but differed significantly regarding detection of confirmed microscopy positives (93.5% and 85.6% respectively, P < 0.00001). A high correlation between both LED systems was found at 400x magnification. CONCLUSIONS: The Fraen LED fluorescence microscopy module performed significantly better than the LW LED at the most efficient 200x magnification. It was also more appreciated by all users. The LW module may perform equally well at higher magnification.

[Assessment of antibiotics prescribing for outpatients in Cotonou, Benin]. / Evaluation de la prescription des antibiotiques en médecine ambulatoire à Cotonou, Bénin.

The objective was to study antibiotics prescribing in Cotonou health care centres. This prospective study was conducted in two phases. The first consisted in collecting antibiotics prescriptions. In a second phase, the prescriptions were submitted to 4 experts who assessed the correctness of the prescribing. Out of the 588 prescriptions that could be analysed, 173 (29.4%) were correct The quality of the prescribing seems to depend only on the pathology but not on the nature of the basic training of the prescriber

First molecular epidemiological study of tuberculosis in Benin.

OBJECTIVES: To assess the diversity of Mycobacterium tuberculosis strains in Cotonou, Benin, and the risk factors associated with clustering. METHODS: We analysed one sputum sample from 194 consecutive new pulmonary tuberculosis (TB) cases using two genotyping methods: spoligotyping and the 12 loci mycobacterial interspersed repetitive unit-variable number of tandem repeats (MIRU-VNTR). The data obtained were compared to the SpolDB4.0 database. RESULTS: We have found that spoligotype 61, highly predominant in West Africa, was also the most prevalent strain in Cotonou. We observed that the Beijing family represented 10.3% of strains and was associated with resistance to streptomycin. We also confirmed that combining spoligotyping and MIRU-VNTR provided a higher discriminatory power than the two techniques used individually. CONCLUSION: Spoligotype 61 and Beijing genotype are the most prevalent genotypes of M. tuberculosis in Cotonou.

Bulk staining of smears: no demonstrated risk of bacilli transfer from a positive to a negative smear.

Despite a theoretical risk of transfer of bacilli from a positive to a negative smear, bulk staining is routinely performed in many laboratories. To assess this risk in our laboratory, two smears were made from each sputum specimen and stained with auramine: one smear was stained on a rack and the second using the bulk method. Smears were read blind using a fluorescence microscope. A total of 811 sputum specimens were analysed. No acid-fast bacilli transfer was observed even when staining solution jars had not been renewed for 3 days. Bulk staining is rapid and cheap, and could be used in laboratories with a high workload in low-resource settings.

Interventions among male clients of female sex workers in Benin, West Africa: an essential component of targeted HIV preventive interventions.

OBJECTIVES: To assess the impact of interventions targeted towards female sex workers (FSWs) and their male clients on client HIV/STI prevalence and sexual behaviour. METHODS: From 1993 to 2006, an HIV/STI preventive intervention focusing on condom promotion and STI care was implemented among FSWs in Cotonou, Benin, and then expanded to cover their male sexual partners in 2000. The interventions were scaled up to five other cities of Benin in 2001-2002. Serial cross-sectional surveys of HIV/STI prevalence and sexual behaviour were carried out among clients in Cotonou in 1998, 2002 and 2005; and in the five other cities (O/Cotonou) in 2002 and 2005. RESULTS: Significant declines in gonorrhoea prevalence among clients of FSWs: Cotonou, from 5.4% in 1998 to 1.6% in 2005; O/Cotonou: from 3.5% in 2002 to 0.59% in 2005. Chlamydia prevalence also declined O/Cotonou, from 4.8% to 1.8%, while HIV prevalence remained stable. Reported condom use by clients with both FSWs and casual non-FSW partners, but not regular partners, increased significantly. While condom use at last sex with an FSW was similar in Cotonou to O/Cotonou around the time of implementation of the interventions (56% in 1998 vs 49% in 2002, respectively), it had risen to similar levels by 2005 (95% and 96%, respectively). CONCLUSIONS: These results demonstrate that it is possible to implement preventive and clinical services for clients of FSWs, and suggest that such interventions, integrated with those targeted towards FSWs, can have a significant effect on sexual behaviour and STI prevalence (particularly gonorrhoea) among this population.

Anti-tuberculosis drug resistance among new and previously treated pulmonary tuberculosis patients in Cotonou, Benin.

OBJECTIVES: To assess the current anti-tuberculosis drug resistance situation in Cotonou, at the largest anti-tuberculosis centre of Benin. METHODS: A total of 470 isolates of Mycobacterium tuberculosis complex from pulmonary tuberculosis (TB) patients were analysed: 244 from new cases and 226 from previously treated cases. Drug susceptibility testing of isolates against first-line drugs was performed using the proportion method. RESULTS: Primary multidrug resistance (MDR) depends on the patients' origin: MDR in new cases is relatively high (1.6%) when all patients are considered, but low (0.5%) and comparable to 1994 national survey results when only patients residing in Benin are considered. MDR in previously treated patients (11.1%) remains comparable to the study performed in Benin in 1994. No relation was found between human immunodeficiency virus co-infection and anti-tuberculosis drug resistance. CONCLUSION: This study shows the great importance of correct patient identification in epidemiological surveys, where results may vary according to the population(s) studied.

[Clinical and immunological profile of HIV infected patients in Cotonou, Benin]. / Profil clinique et immunologique des patients infectés par le VIH dépistés à Cotonou, Bénin.

OBJECTIVES: This study had for aim to identify the clinical status and the level of immuno-deficiency of HIV-infected patients on their first visit. METHODS: One hundred and thirty-six HIV+ patients were prospectively evaluated from November 1, 2001 to May 31, 2002. RESULTS: One hundred and thirty-four were infected with HIV1 and two with HIV2. The mean age on the first consultation was 37 +/- 2 years. The m/w sex ratio was 0.9. 46.3% were stage C. The main clinical symptoms were: weight loss (88%), fever (80%), cough (71%), diarrhea (51%). BMI was normal in 70% and KI > or =80% in 57% of the cases but immuno-deficiency was severe with CD4 cells count <200 per mm3 in 69%. The main diseases were digestive candidiasis (53%), pneumonia (18%), tuberculosis (12%), non-determined pneumonia (29%), prurigo (20%), zona (16%), cryptosporidiosis (4%), cerebral toxoplasmosis (3%), and Kaposi's sarcoma (1%).

[Risk of HIV-1 or 2 infection associated with transfusion in Benin]. / Risque infectieux VIH 1/2 transfusionnel au Bénin.

OBJECTIVE: To evaluate the residual risk of transmission of HIV 1/2 infection through transfusion of seronegative blood. METHODS: This study was carried out between January and July 2000. It was based on eight hundred and twenty-one (821) blood donors screened negative for HIV antibodies by ELISA using Vironostika Uni-form II plus 0 (Organon Teknika). 675 (82.2%) were men and 146 (17.8%) women all aged between 18 and 56 years with a mean age of 25.5 +/- 7.8 years. Serum aliquots of these seronegative blood donor were frozen and further tested with two tests: Enzymun-Test HIV Combi (Roche Immunodiagnostics) and Murex HIV Antigen Mab (Murex). RESULTS: Twenty six out of 821 (3.2%) seronegative specimens were repeatedly reactive for Enzymun-test. All were tested negative once again for anti-HIV antibodies by ELISA using Vironostika Uni-form II/plus 0. Out of these 26, only one was repeatedly reactive for Murex. For further analysis of the 25 donors tested negative for Murex, only 9 came back for another donation five months later. All of them were tested negative for anti-HIV antibodies by ELISA (Vironostika). CONCLUSION: Our study shows the existence of residual risk of transmission of HIV1/2 infection associated with transfusion of seronegative blood donors. This risk was higher in our countries compared with industrialised nations. Therefore implementing strategies should be a priority to avoid the residual risk and improve blood transfusion safety.

Sexually transmitted infections in male clients of female sex workers in Benin: risk factors and reassessment of the leucocyte esterase dipstick for screening of urethral infections.

OBJECTIVES: (1) To assess risk factors for urethral infections with Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis among male clients of female sex workers (FSWs) in Benin; (2) to study the validity of LED testing of male urine samples compared to a highly sensitive gold standard (PCR) for the diagnosis of urethral infections with the organisms cited above. METHODS: Male clients of FSWs (n=404) were recruited on site at prostitution venues in Cotonou, Benin, between 28 May and 18 August 1998. A urine sample was obtained from each participant just before he visited the FSW, and tested immediately using a leucocyte esterase dipstick (LED) test. It was then tested for HIV using the Calypte EIA with western blot confirmation, and for C. trachomatis, N. gonorrhoeae, and T. vaginalis by PCR. After leaving the FSW's room, participants were interviewed about demographics, sexual behaviour, STI history and current symptoms and signs, and were examined for urethral discharge, genital ulcers, and inguinal lymphadenopathies. RESULTS: STI prevalences were: C. trachomatis, 2.7%; N. gonorrhoeae, 5.4%; either chlamydia or gonorrhoea 7.7%; T. vaginalis 2.7%; HIV, 8.4%. Lack of condom use with FSWs and a history of STI were independently associated with C. trachomatis and/or N. gonorrhoeae infection. Over 80% of these infections were in asymptomatic subjects. The overall sensitivity, specificity, positive and negative predictive values of the LED test for detection of either C. trachomatis or N. gonorrhoeae were 48.4%, 94.9%, 44.1%, and 95.7%, respectively. In symptomatic participants (n=22), all these parameters were 100% while they were 47.4%, 94.7%, 37.5%, and 96.4% in asymptomatic men (n=304). CONCLUSIONS: Since most STIs are asymptomatic in this population, case finding programmes for gonorrhoea and chlamydia could be useful. The performance characteristics of the LED test in this study suggest that it could be useful to detect asymptomatic infection by either C. trachomatis or N. gonorrhoeae in high risk men.

Role of core and bridging groups in the transmission dynamics of HIV and STIs in Cotonou, Benin, West Africa.

The potential for exposure of low and high risk women to HIV and sexually transmitted infections (STI) through unprotected sex with male clients of female sex workers in Cotonou could account for most if not all of the estimated yearly numbers of HIV infections in Cotonou women (approximately 1000). As ongoing transmission of HIV, and also of the most predominant STIs such as gonorrhoea and HSV-2, appears to be largely fuelled by transmission within core and bridging groups in Cotonou, interventions targeted at both female sex workers and their male clients remain of the utmost importance and could have a significant effect on the evolution of HIV/STI epidemics in Benin.

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 envfragment. 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.