Factors associated with CD4 lymphocyte counts in HIV-negative Senegalese individuals.

CD4+ lymphocytes are a primary target of the human immunodeficiency virus (HIV), and CD4 counts are one of the factors used to measure disease progression in HIV-positive individuals. CD4 counts vary in uninfected individuals and across populations due to a variety of demographic, environmental, immunological and genetic factors that probably persist throughout the course of HIV infection. This study sought to determine reference levels and identify factors that influence lymphocyte counts in 681 HIV-uninfected adults in Senegal, where residents are exposed to a variety of infectious diseases and other conditions that may affect CD4 counts. Lymphocyte counts were assessed in commercial sex workers, symptomatic men and women presenting to the University of Dakar infectious disease clinic for out-patient care and women seeking family planning services. CD4 and CD3 lymphocyte counts differed between the four study groups (P < 0.01). Men had the lowest mean CD4 count (711.6 cells/microl), while commercial sex workers had the highest levels (966.0 cells/microl). After adjustment for age and other behavioural and clinical factors, the difference in CD4 counts between the three groups of women did not remain. However, both gender and smoking were associated independently with CD4 counts, as men maintained lower mean CD4 counts (beta = -156.4 cells/microl, P < 0.01) and smokers had higher mean CD4 counts (beta = 124.0 cells/microl, P < 0.01) than non-smokers in multivariable analyses. This study is the first to explore factors that may influence CD4 levels in Senegal and to estimate baseline CD4 levels among HIV-negatives, information that may guide clinicians in interpreting CD4 counts.

Concurrent sexual partnerships and HIV prevalence in five urban communities of sub-Saharan Africa.

OBJECTIVE: To estimate parameters of concurrent sexual partnerships in five urban populations in sub-Saharan Africa and to assess their association with levels of HIV infection and other sexually transmitted infections (STI). METHODS: Data were obtained from a multicentre study of factors which determine the differences in rate of spread of HIV in five African cities. Consenting participants were interviewed on sexual behaviour and at four of the five sites also provided a blood and a urine sample for testing for HIV and other STI. Data on sexual behaviour included the number of partnerships in the 12 months preceding the interview as well as the dates of the start and end of each partnership. Summary indices of concurrent sexual partnerships -- some of which were taken from the literature, while others were newly developed -- were computed for each city and compared to HIV and STI prevalence rates. RESULTS: A total of 1819 adults aged 15--49 years were interviewed in Dakar (Senegal), 2116 in Cotonou (Benin), 2089 in Yaoundé (Cameroon), 1889 in Kisumu (Kenya) and 1730 in Ndola (Zambia). Prevalence rates of HIV infection were 3.4% for Cotonou, 5.9% for Yaoundé, 25.9% for Kisumu and 28.4% for Ndola, and around 1% for Dakar. The estimated fraction of sexual partnerships that were concurrent at the time of interview (index k) was relatively high in Yaoundé (0.98), intermediate in Kisumu (0.44) and Cotonou (0.33) and low in Ndola (0.26) and in Dakar (0.18). An individual indicator of concurrency (iic) was developed which depends neither on the number of partners nor on the length of the partnerships and estimates the individual propensity to keep (positive values) or to dissolve (negative values) on-going partnership before engaging in another one. This measure iic did not discriminate between cities with high HIV infection levels and cities with low HIV infection levels. In addition, iic did not differ significantly between HIV-infected and uninfected people in the four cities where data on HIV status were collected. CONCLUSION: We could not find evidence that concurrent sexual partnerships were a major determinant of the rate of spread of HIV in five cities in sub-Saharan Africa. HIV epidemics are the result of many factors, behavioural as well as biological, of which concurrent sexual partnerships are only one.

Clinical, hematologic, and immunologic cross-sectional evaluation of individuals exposed to human immunodeficiency virus type-2 (HIV-2).

We studied the clinical status and certain hematologic and immunologic parameters in healthy prostitutes from Dakar, Senegal who were seropositive for antibodies to human immunodeficiency virus type-2 (HIV-2). Generalized lymphadenopathy and clinical signs or symptoms similar to those which are seen with human immunodeficiency virus type-1 (HIV-1) infection were not present. Comparison to seronegative prostitutes and minor surgery control patients were made and significant elevations were seen in T8 lymphocytes (p = .03), IgG (p = .0001), and beta 2-microglobulin (p = .03). The mean T4 lymphocyte count in seropositive prostitutes was lower than in seronegative prostitutes (757 vs. 1179, p = .15), but this difference was not statistically significant and appeared to be correlated with age. No significant differences were noted between the seronegative and seropositive prostitutes in lymphocyte stimulation studies to certain mitogens. Antilymphocyte antibodies above background were not present in either population. We conclude that HIV-2 is a sexually transmitted agent that produces immunologic alterations consistent with a persistent viral infection. HIV-2 seropositive prostitutes studied to date do not show clinical signs of immune suppression, as has been described with HIV-1 infection. The pathogenic potential of HIV-2 appears to differ from that of HIV-1, the etiologic agent of the AIDS pandemic.

A simple clinical and paraclinical score predictive of CD4 cells counts below 400/mm3 in HIV-infected adults in Dakar University Hospital, Senegal.

In industrialized countries the decision to start co-trimoxazole (CMX) prophylaxis of HIV-related opportunistic infections is based on the CD4+ cell count. The value of CMX prophylaxis has also been demonstrated in Africa, where CD4+ cell counts are rarely available. We therefore developed a simple score predictive of a threshold CD4+ cell count (400/mm3) below which CMX prophylaxis is indicated. In a retrospective cross-sectional study, we collected clinical and biological data on 211 HIV-infected patients recruited from January 1996 through January 1998 at Fann University Hospital in Dakar, Senegal. Several variables were identified as being predictive of a CD4+ cell count below 400/mm3 by stepwise logistic regression. Each variable was weighted according to its regression coefficient, as follows: male sex (+1), weight loss (+2), body mass index < 22 (+2), herpes zoster (+4), tuberculin induration < 5 mm (+3) and haemoglobin < or = 10 g/dL (+1). A score of > or = 4 (sum of weights) selected patients with CD4+ cell counts below 400/mm3 with a sensitivity of 98% and a negative predictive value of 83%. Such a score should be applicable in the African context and should facilitate the management of HIV-infected patients, especially the prescription of CMX prophylaxis.

[Importance of culture media choice in the isolation of Haemophilus ducreyi. Experience in Senegal]. / Importance du choix d'un milieu de culture dans l'isolement de Haemophilus ducreyi. Expérience du Sénégal.

Genital ulcerations typify one of the major reasons clients seek STD consultation in developing countries. The usual etiologies are syphilis, chancroid and herpes. The ideal diagnostic approach is to undertake complete laboratory examination that are rarely possible in structure destitute of laboratory analysis possibilities which is the case for most of the STD transmission agents. Chancroid is caused by Haemophilus ducreyi, a short Gram negative bacteria. The bacteriological diagnosis is based on direct examination, isolation and identification of the bacteria. The nutritive exigence of the bacteria required 3 medium of isolation (PPLO base Pasteur), GC base (GIBCO) and Muller Hinton base (Becton & Dickinson, with "chocolate" agar) have been tested from the chancre samples of 108 male patients who had a median age of 31 years. Direct exams were positive in 66 cases (61%) and culture exams positive in 53 cases (49%). The Muller Hinton base with "chocolate" agar produced the best results and seems to be the medium of choice for isolated strains in Senegal. The culture mediums currently used in Europe are apparently inappropriate for the germ culture in Senegal. We have also observed that all the isolated strains were producers of beta-lactamase. Antibiotic treatment before the sample swab is taken seems to have an inhibiting effect on the culture. Direct examination with a sensibility of 94.3% and a specificity of 70.9% remains sufficient in routine presumptive diagnosis in endemic areas.

Trends of HIV-1, HIV-2 and dual infection in women attending outpatient clinics in Senegal, 1990-2009.

We assessed trends in the relative prevalences of HIV-1, HIV-2 and dual HIV-1/HIV-2 infection in 10,321 women attending outpatient clinics in Senegal between 1990 and 2009. The relative prevalence of HIV-1 (defined as the proportion of seropositive subjects having HIV-1) rose sharply from 38% in 1990 until 1993 (P < 0.001), whereupon it continued to rise, but at a slower rate, reaching 72% of HIV infections in 2009. As compared with HIV-1, the relative prevalence of HIV-2 decreased sharply from 54% in 1990 until 1993 (P < 0.001) and continued to decrease at a slower rate through 2009. The relative prevalence of dual infection, as compared with HIV-1, was stable from 1990 to 1993, but decreased slightly thereafter (P < 0.001). These study findings indicate that during the early 1990s, the relative prevalence of HIV-1 increased markedly, while the relative prevalence of HIV-2 decreased and the relative prevalence of dual infection remained stable in Senegal. From 1993 to 2009, the relative prevalence of HIV-1 increased at a slower rate, while the relative prevalences of HIV-2 and dual infection decreased. These results confirm trends in HIV prevalence observed in other West African populations and provide a critical update on HIV transmission risk among women in Senegal.

Secretor polymorphism and human immunodeficiency virus infection in Senegalese women.

The FUT2 gene encodes the enzyme alpha (1,2) fucosyltransferase, which determines expression of blood-group antigens on mucosal epithelial cell surfaces and in secretions. Homozygotes for a specific stop mutation in FUT2 (nonsecretors) cannot produce this enzyme and thus are unable to express blood group antigens. Nonsecretor status is associated with a decreased risk of several respiratory viral infections. By use of molecular genotyping, 2 populations of Senegalese women were examined for polymorphisms of the FUT2 gene. Among Senegalese commercial sex workers, absence of FUT2 (nonsecretor genotype) was associated with reduced risk of human immunodeficiency virus (HIV) type 1 infection (odds ratio [OR] adjusted for cervical and vaginal infection, 0.18; 95% confidence interval [CI], 0.04-0.90) and HIV-2 infection (adjusted OR, 0.43; 95% CI, 0.13-1.39), although the latter was not statistically significant. Modification of cell surface carbohydrates at mucosal surfaces determined by the FUT2 gene may underlie the protective association against heterosexual HIV infection.

Molecular epidemiology of genital Chlamydia trachomatis infection in high-risk women in Senegal, West Africa.

The prevalence and heterogeneity of Chlamydia trachomatis infections in a cohort of female sex workers in Dakar (Senegal) were determined by using endocervical-swab-based PCR DNA amplification assays. The overall prevalence of cervical chlamydial infection was 28.5% (206 of 722), and most of these infections were asymptomatic. An increased number of sexual partners was significantly associated with infection (adjusted odds ratio [AOR] = 1.37; 95% confidence interval [CI] = 1.06 to 1.77), while the presence of a yeast infection was negatively associated with chlamydial infection (AOR = 0.28; 95% CI = 0.10 to 0.83). Six different C. trachomatis genotypes were identified based on phylogenetic analysis of the omp1 gene sequences. Interestingly, genotype E predominated (47.6%) and was not associated with visible signs of cervical inflammation compared to non-E genotypes (P < 0.05). Overall, the high rate of asymptomatic C. trachomatis infection by genotype E may suggest genotype-specific properties that confer a transmission advantage in this high risk population.