The rhizosphere of the halophytic grass Sporobolus robustus Kunth hosts rhizobium genospecies that are efficient on Prosopis juliflora (Sw.) DC and Vachellia seyal (Del.) P.J.H. Hurter seedlings

The aim of this study was to survey the abundance and genetic diversity of legume-nodulating rhizobia (LNR) in the rhizosphere of a salt-tolerant grass, Sporobolus robustus Kunth, in the dry and rainy seasons along a salinity gradient, and to test their effectiveness on Prosopis juliflora (SW.) DC and Vachellia seyal (Del.) P.J.H. Hurter seedlings. The results showed a significant decrease in LNR population density and diversity in response to salinity, particularly during the dry season. A phylogenetic analysis of the 16S-23S rRNA ITS region clustered the 232 rhizobium isolates into three genera and 12 distinct representative genotypes: Mesorhizobium (8 genotypes), Ensifer (2 genotypes) and Rhizobium (2 genotypes). Of these genotypes, 2 were only found in the dry season, 4 exclusively in the rainy season and 6 were found in both seasons. Isolates of the Mesorhizobium and Ensifer genera were more abundant than those of Rhizobium, with 55%, 44% and 1% of the total strains, respectively. The abundance of the Mesorhizobium isolates appeared to increase in the dry season, suggesting that they were more adapted to environmental aridity than Ensifer genospecies. Conversely, Ensifer genospecies were more tolerant of high salinity levels than the other genospecies. However, Ensifer genospeciesproved to be the most efficient strains on P. juliflora and V. seyal seedlings. We concluded that S. robustus hosts efficient rhizobium strains in its rhizosphere, suggesting its ability to act as a nurse plant to facilitate seedling recruitment of P. juliflora and V. seyal in saline soils.

Fonio (Digitaria exilis (Kippist) Stapf): A Socially Embedded Cereal for Food and Nutrition Security in Senegal

Agricultural diversification with neglected and underutilized species is a viable way to sustainably increase the productivity of agrosystems. Understanding the social, cultural, and ecological roles of these species is crucial for their promotion. White fonio (Digitaria exilis), a neglected cereal endemic to West African Sahelian countries, is recognized as a crop for the future due to its cultural, nutritional, and economic values. In this study, we described fonio farming systems in Senegal through an ethnobotanical approach. As expected in family farming systems, farmers largely practiced diversified subsistence agriculture on small plots and relied on local seed exchange networks. The importance of fonio varied among agroecological zones, ethnic groups, and gender. In the Groundnut Basin, where agriculture is more mechanized, late-maturing landraces of fonio are cultivated as a cash crop rather than a staple crop. However, in southern Senegal, where food shortages are recurrent, fonio is more widespread and the cultivation of both early- and late-maturing landraces contributes to local food security. These differences also reflect the cultural status of fonio: different among ethnic groups and more important for women than for men. Finally, the regressive dynamics of fonio cultivation in most regions emphasizes the need to develop integrated conservation and promotion strategies that take into account the diversity of social and agronomical roles of the plant.

Pearl Millet Genetic Traits Shape Rhizobacterial Diversity and Modulate Rhizosphere Aggregation

Root exudation contributes to soil carbon allocation and also to microbial C and energy supply, which subsequently impacts soil aggregation around roots. Biologically-driven soil structural formation is an important driver of soil fertility. Plant genetic determinants of exudation and more generally of factors promoting rhizosphere soil aggregation are largely unknown. Here, we characterized rhizosphere aggregation in a panel of 86 pearl millet inbred lines using a ratio of root-adhering soil dry mass per root tissue dry mass (RAS/RT). This ratio showed significant variations between lines, with a roughly 2-fold amplitude between lowest and highest average values. For 9 lines with contrasting aggregation properties, we then compared the bacterial diversity and composition in root-adhering soil. Bacterial α-diversity metrics increased with the "RAS/RT ratio." Regarding taxonomic composition, the Rhizobiales were stimulated in lines showing high aggregation level whereas Bacillales were more abundant in lines with low ratio. 184 strains of cultivable exopolysaccharides-producing bacteria have been isolated from the rhizosphere of some lines, including members from Rhizobiales and Bacillales. However, at this stage, we could not find a correlation between abundance of EPS-producing species in bacterial communities and the ratio RAS/RT. These results illustrated the impact of cereals genetic trait variation on soil physical properties and microbial diversity. This opens the possibility of considering plant breeding to help management of soil carbon content and physical characteristics through carbon rhizodeposition in soil.

Field Trials Reveal Ecotype-Specific Responses to Mycorrhizal Inoculation in Rice

The overuse of agricultural chemicals such as fertilizer and pesticides aimed at increasing crop yield results in environmental damage, particularly in the Sahelian zone where soils are fragile. Crop inoculation with beneficial soil microbes appears as a good alternative for reducing agricultural chemical needs, especially for small farmers. This, however, requires selecting optimal combinations of crop varieties and beneficial microbes tested in field conditions. In this study, we investigated the response of rice plants to inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPB) under screenhouse and field conditions in two consecutive seasons in Senegal. Evaluation of single and mixed inoculations with AMF and PGPB was conducted on rice (Oryza sativa) variety Sahel 202, on sterile soil under screenhouse conditions. We observed that inoculated plants, especially plants treated with AMF, grew taller, matured earlier and had higher grain yield than the non-inoculated plants. Mixed inoculation trials with two AMF strains were then conducted under irrigated field conditions with four O. sativa varieties, two O. glaberrima varieties and two interspecific NERICA varieties, belonging to 3 ecotypes (upland, irrigated, and rainfed lowland). We observed that the upland varieties had the best responses to inoculation, especially with regards to grain yield, harvest index and spikelet fertility. These results show the potential of using AMF to improve rice production with less chemical fertilizers and present new opportunities for the genetic improvement in rice to transfer the ability of forming beneficial rice-microbe associations into high yielding varieties in order to increase further rice yield potentials.

Genetic and genomic diversity studies of Acacia symbionts in Senegal reveal new species of Mesorhizobium with a putative geographical pattern

Acacia senegal (L) Willd. and Acacia seyal Del. are highly nitrogen-fixing and moderately salt tolerant species. In this study we focused on the genetic and genomic diversity of Acacia mesorhizobia symbionts from diverse origins in Senegal and investigated possible correlations between the genetic diversity of the strains, their soil of origin, and their tolerance to salinity. We first performed a multi-locus sequence analysis on five markers gene fragments on a collection of 47 mesorhizobia strains of A. senegal and A. seyal from 8 localities. Most of the strains (60%) clustered with the M. plurifarium type strain ORS 1032T, while the others form four new clades (MSP1 to MSP4). We sequenced and assembled seven draft genomes: four in the M. plurifarium clade (ORS3356, ORS3365, STM8773 and ORS1032T), one in MSP1 (STM8789), MSP2 (ORS3359) and MSP3 (ORS3324). The average nucleotide identities between these genomes together with the MLSA analysis reveal three new species of Mesorhizobium. A great variability of salt tolerance was found among the strains with a lack of correlation between the genetic diversity of mesorhizobia, their salt tolerance and the soils samples characteristics. A putative geographical pattern of A. senegal symbionts between the dryland north part and the center of Senegal was found, reflecting adaptations to specific local conditions such as the water regime. However, the presence of salt does not seem to be an important structuring factor of Mesorhizobium species.

Impact of the energy crop Jatropha curcas L. on the composition of rhizobial populations nodulating cowpea (Vigna unguiculata L.) and acacia (Acacia seyal L.)

Jatropha curcas, a Euphorbiaceae species that produces many toxicants, is increasingly planted as an agrofuel plant in Senegal. The purpose of this study was to determine whether soil priming induced by J. curcas monoculture could alter the rhizobial populations that nodulate cowpea and acacia, two locally widespread legumes. Soil samples were transferred into a greenhouse from three fields previously cultivated with Jatropha for 1, 2, and 15 years, and the two trap legumes were grown in them. Control soil samples were also taken from adjacent Jatropha-fallow plots. Both legumes tended to develop fewer but larger nodules when grown in Jatropha soils. Nearly all the nifH sequences amplified from nodule DNA were affiliated to the Bradyrhizobium genus. Only sequences from Acacia seyal nodules grown in the most recent Jatropha plantation were related to the Mesorhizobium genus, which was much a more conventional finding on A. seyal than the unexpected Bradyrhizobium genus. Apart from this particular case, only minor differences were found in the respective compositions of Jatropha soil versus control soil rhizobial populations. Lastly, the structure of these rhizobial populations was systematically imbalanced owing to the overwhelming dominance of a very small number of nifH genotypes, some of which were identical across soil types or even sites. Despite these weak and sparse effects on rhizobial diversity, future investigations should focus on the characterization of the nitrogen-fixing abilities of the predominant rhizobial strains.

Twelve years of follow-up for patients treated with ARVs in Senegal (ANRS Cohort 1215): description of population and methodology

The ANRS Cohort 1215 brought together the first 400 patients receiving antiretroviral treatments through the government program for ARV treatment in Senegal. These people, infected with HIV-1, began their treatment between 1998 and 2002; they were treated with 2 NRTI + 1 PI or NNRTI. This prospective observational cohort received follow-up over the course of 12 years, from 1999 to 2010, and was one of the earliest established cohorts in Africa and providing the longest duration of ART follow-up. A series of interdisciplinary studies was conducted among these patients to assess the medical and social as well as the individual and collective impact of these treatments over the long term. This article presents the cohort's key methodological characteristics.

Long-term efficacy and tolerance of efavirenz- and nevirapine-containing regimens in adult HIV type 1 Senegalese patients

Owing to their low toxicity, low price, and ease of use, efavirenz (EFV) and nevirapine (NVP) are frequently used as part of antiretroviral regimens for AIDS treatment. Several clinical trials have already studied their efficacy and tolerance. However, long-term observations of the effects of these drugs in patients are limited. We used data from a prospective Senegalese cohort to analyze long-term tolerance and efficacy of these two drugs in a low-resources setting. Patients were included if they started their therapy with EFV or NVP. They were censored after treatment discontinuation. The primary endpoint was the time to treatment discontinuation. Secondary endpoints included time to death, time to disease progression, occurrence of severe adverse effects, CD4 cell recovery, and virological response. Confounding factors were controlled using marginal structural models. The median follow-up time in both EFV and NVP arms was 48 months. The hazard ratio (HR) of drug discontinuation in the EFV arm vs. the NVP arm was 0.84 (0.34; 1.87). There was a borderline difference in virological response [HR 1.38 (0.999; 1.89)] but no differences in time to death [HR 1.15 (0.41; 3.24)], time to AIDS progression [HR 1.25 (0.61; 2.58)], or time to increase in CD4 cell count above 500 cells/mm3. Adverse effects were different between NVP and EFV, but long-term tolerance was good for both. This analysis provided further information on long-term tolerance and efficacy of EFV and NVP in a resource-limited setting.

[Enhancing the anthelminthic activity roots of Annona sengalensis]

INTRODUCTION

Annona senegalensis is a plant largely used in traditional medicine in Africa. The roots showed an antiparsitic activity. The purpose of this work is to determine through bioassay on Rhabditis pseudoelongata the activity of the roots of Annona senegalensis and characterise if any substances responsible for this activity.

MATERIAL AND METHODS

The vegetable material consists of roots of Annona senegalensis collected in Casamance at 1999. The tests of activity are carried out on Rhabditis pseudoelongata, stock L. Lamy, Institut Pasteur, Paris. Powder of roots (1070 g) was extracted with methanol. From this rough extract, we carried out two extractions with the dichloromethane of which one after passages in alkaline and acid medium. Various extracts were subjected to a chromatography on column of silica gel or from alumina gel; some compounds were isolated by high performance liquid chromatography . The identification of compounds was deed using spectrometric techniques (mass, Ultraviolet, Infrared) and nuclear magnetic resonance. The tests of activity related to three extracts and seven molecules isolated from the roots. The percentage of dead worm is determined after two hours of contact with demineralised water containing the sample to be tested.

RESULTS

The neutral extract chloromethylenic showed an important activity on Rhabditis pseudoelongata. Five acetogenines were insulated starting from this extract chloromethylenic (gigantetronenine, squamocine, glaucanisine, glaucanetine, goniothalamicine) and two alkaloids starting from the alkaline extract chloromethylenic (liriodenine and norolivéroline). The tests on Rhabditis pseudoelongata of these compounds showed an activity of the squamocine with a IC50 of 0.1 microg/ml and IC90 0.3 microg/ ml more powerful than that of the levamisole, reference substance (IC50 of 0.8 microg/ml and IC90 13 microg/ml).

CONCLUSION

The study of the biological activity of the roots of Annona senegalensis made it possible to determine the anthelminthic activity of the extract chloromethylenic from where the squamocine was isolated. The presence of this molecule could explain the anthelminthic activity of this plant.

HIV prevalence, previous HIV testing, and condom use with clients and regular partners among Senegalese commercial sex workers

OBJECTIVES

To assess HIV prevalence and risk factors for HIV infection, to investigate condom use among registered female commercial sex workers (CSWs) in Senegal, West Africa, and to examine the association between previous HIV testing, knowledge of HIV serostatus and condom use with both regular sex partners and clients within this population.

METHODS

A cross-sectional study was conducted at three sexually transmitted disease clinics among 1052 Senegalese registered CSWs between 2000 and 2004. Inperson interviews soliciting information concerning demographic characteristics, medical history, sexual behaviour with clients and regular partners, and previous HIV testing history were performed. Blood samples were collected for determination of HIV-1 and/or HIV-2 serostatus. Multivariable, Poisson and log-binomial models were used to calculate prevalence ratios.

RESULTS

The overall HIV prevalence was 19.8%. Over 95% of CSWs reported always using a condom with clients, but only 18% reported always using a condom with their regular partners. A history of previous HIV testing was not associated with condom use with clients (adjusted prevalence ratio (APR) = 0.98, 95% confidence intervals, CI: 0.90 to 1.06). However, prior HIV testing was associated with decreased condom use with their regular partners (APR = 0.44, 95% CI: 0.28 to 0.69), especially in women who tested HIV negative (APR = 0.17, 95% CI: 0.08 to 0.36).

CONCLUSIONS

CSWs in Senegal have a high HIV prevalence; therefore preventing HIV transmission from this population to the general population is important. Condom use with regular partners is low among registered CSWs in Senegal, and a prior HIV negative test is associated with even less condom use with regular partners. Intervention efforts to increase condom use with regular sexual partners are needed.

[Cytotoxic activity of two cyclic peptides from the latex of Jatropha integerrima Euphorbiaceae]

Activity-guided fractionation of the ethyl acetate extract of the latex of Jatropha integerrima Euphorbiaceae combinated with cytotoxic assay against the KB human nasopharyngeal carcinoma cells, resulted to the isolation by chromatographic methods including HPLC of two new cyclopeptides: integerrimacyclopeptide4 and integerrima cyclopeptide B. The amino acid composition was established after hydrolysis and derivatization. All chiral amino acids were L configuration and were hydrophobic. Their sequences were determined by MS fragmentations (ESI-q-TOF, MS/MS) and confirmed by 2D NMR homo- and heteronuclear studies. Integerrimacyclopeptide A was a cyclooctapeptide with m/z 766 corresponding to the molecular formula C37H66N8O9. Analysis of mass spectra gave b(n) and a(n) acylium ion series which the sequence could be deduced: cyclo(Leu-Gly-Ser-Ile-Ile-Leu-Gly-lle). This structure was confirmed by interpretation of HMBC and ROESY spectra. Likewise, integerrimacyclopeptide B was a cycloheptapeptide with m/z 651 and C31H53N7O8 as molecular formula containing one proline residue: cyclo(Pro-Gly-Thr-Ile-Gly-Ile-Leu). These two cyclic peptides exhibited significant cytotoxic activityin vitro against KB tumorales cells with respective IC50 values of 0.46 +/- 0.04 and 0.66 +/-0.08 microg/ml.

HIV infection and sexually transmitted infections among men who have sex with men in Senegal

BACKGROUND

No epidemiological study has been conducted on HIV and vulnerability to sexually transmitted diseases (STI) among men who have sex with men (MSM) in sub-Saharan Africa.

METHOD

A survey including questionnaire, physical examination and detection of HIV and STI was carried out among 463 MSM, aged 18-52 years, recruited through the snowball technique in five urban sites throughout Senegal.

RESULTS

A total of 21.5% of men were found to be infected with HIV [95% confidence interval (CI), 17.8-25.6]. Active syphilis, positive serology for herpes simplex virus (HSV)-2, and polymerase chain reaction detection in urine of Chlamydia and gonorrhea infections were recorded in 4.8, 22.3, 4.1 and 5.4% of participants, respectively. Most respondents reported sex with women (94.1%). In the month preceding the interview, 24% reported at least one unprotected insertive anal intercourse with a male partner, 20% at least one unprotected receptive anal intercourse, and 18% at least one unprotected intercourse with a female partner. Genital examination showed that 5% of participants had at least one clinical sign of STI. Factors associated with HIV infection were age group, the reporting of more than nine lifetime male partners [odds ratio (OR), 3.76; 95% CI, 1.61-8.79], being a waiter or bartender (OR, 3.33; 95% CI, 1.41-7.84), and living in Dakar (OR, 3.33; 95% CI, 1.07-3.43).

CONCLUSION

Men who have sex with men in Senegal are highly infected with HIV and other STI. Intervention programs targeting this population are urgently needed, given their particular vulnerability and because infections are likely to disseminate into the general population given the high proportion of bisexual activity in this community.

Rhizobial populations in soils from natural Acacia senegal and Acacia nilotica forests in Mauritania and the Senegal river valley

Eighty-two strains of rhizobia were isolated from soils taken from several sites in Mauritania and Senegal. These soil samples were collected from natural stands of Acacia nilotica and Acacia senegal. The soils from Mauritania were less rich in native rhizobia than the soils from Senegal. The strains were characterized using polymerase chain reaction-restriction fragment length polymorphism and by sequencing the rDNA 16S-23S intergenic spacer region (IGS). They were sorted into seven IGS groups. These groups were not associated with the geographical origin of the strains or with the host-plant species at the site where the soils were collected. Most of the strains were in three of the IGS groups (I, IV, and V). One representative strain from each IGS group was sequenced and showed that the strains were from the genus Mesorhizobium. IGS groups I, IV, and VI were close to the species M. plurifarium (AF34563), IGS groups IIand III were close to the species Mesorhizobium sp. (AF510360), IGS group V was close to the species Mesorhizobium sp. (AF510366), and IGS group VII was close to Mesorhizobium sp. (AF510346).

Long-Term Benefits of Highly Active Antiretroviral Therapy in Senegalese HIV-1-Infected Adults

OBJECTIVES

To assess the long-term survival, as well as the immunologic and virologic effectiveness, adherence, and drug resistance, in HIV-infected patients receiving highly active antiretroviral therapy (HAART) in one of the oldest and best-documented African cohorts.

METHODS

A prospective observational cohort study included the first 176 HIV-1-infected adults followed in the Senegalese government-sponsored antiretroviral therapy initiative launched in August 1998. Patients were followed for a median of 30 months (interquartile range, 21-36 months). HAART comprised 2 nucleoside reverse transcriptase inhibitors and either 1 protease inhibitor or 1 nonnucleoside reverse transcriptase inhibitor.

RESULTS

At baseline, 92% of patients were antiretroviral naive and 82% had AIDS; the median CD4 count was 144 cells/mm, and median viral load was 202,368 copies/mL. The survival probability was high (0.81 at 3 years; 95% CI, 0.74-0.86) and was independently related to a baseline hemoglobin level <10 g/dL and a Karnofsky score <90%. Antiviral efficacy was consistently observed during the 3 years of treatment (-2.5 to -3.0 log10 copies/mL; 60-80% of patients with viral load <500 copies/mL) and the CD4 count increase reached a median of 225 cells/mm. Most patients reported good adherence (80-90%). The emergence of drug resistance was relatively rare (12.5%).

CONCLUSION

This study shows that clinical and biologic results similar to those seen in Western countries can be achieved and sustained during the long term in Africa.

The early-stage ectomycorrhizal Thelephoroid fungal sp. is competitive and effective on Afzelia africana Sm. in nursery conditions in Senegal

This study was conducted to evaluate the competitiveness and effectiveness of Thelephoroid fungal sp. ORS.XM002 against native ectomycorrhizal fungal species colonizing potted Afzelia africana seedlings during 3 months of growth in different forest soils collected from under mature trees. Using morphotyping and restriction fragment length polymorphism (RFLP) analysis of the nuclear rDNA internal transcribed spacer (ITS), we were able to distinguish the introduced Thelephoroid fungal sp. ORS.XM002 among native ectomycorrhizal fungal species that form ectomycorrhizae in A. africana seedlings. The morphotype (MT) of the introduced fungus showed some color variation, with a shift from light- to dark-brown observed from younger to older mycorrhizal tips. We were able to differentiate the ITS type xm002 of the introduced fungus from the 14 ITS-RFLP types characterizing the 9 native MT that occurred in forest soils. The frequency of ITS type xm002 ranged from 40% to 49% depending on the forest soil used, and was always higher than those of ITS types from native dark-brown MT that occurred in inoculated seedlings 3 months after inoculation. We considered Thelephoroid fungal sp. ORS.XM002 to be responsible for stimulation of mycorrhizal colonization of inoculated A. africana seedlings when compared with control seedlings in forest soils. This fungus appeared to be more effective in increasing the root dry weight of A. africana seedlings. To identify the unknown introduced fungal species and native MT, we sequenced the ML5/ML6 region of the mitochondrial large subunit rRNA. Sequence analysis showed that these fungi belong to three ML5/ML6 groups closely related to the Cortinarioid, Thelephoroid, and Sclerodermataceous taxa. The molecular evidence for the persistence of Thelephoroid fungal sp. ORS.XM002 despite competition from native fungi argues in favor of using this fungus with A. africana in nursery soil conditions in Senegal.

Mobility and the spread of human immunodeficiency virus into rural areas of West Africa

BACKGROUND

In eastern and southern Africa, the human immunodeficiency virus (HIV) epidemic appeared first in urban centres and then spread to rural areas. Its overall prevalence is lower in West Africa, with the highest levels still found in cities. Rural areas are also threatened, however, because of the population's high mobility. We conducted a study in three different communities with contrasting infection levels to understand the epidemiology of HIV infection in rural West Africa.

METHOD

A comparative cross-sectional study using a standardized questionnaire and biological tests was conducted among samples in two rural communities of Senegal (Niakhar and Bandafassi, 866 and 952 adults, respectively) and a rural community of Guinea-Bissau (Caio, 1416 adults). We compared the distribution of population characteristics and analysed risk factors for HIV infection in Caio at the individual level.

RESULTS

The level of HIV infection was very low in Niakhar (0.3%) and Bandafassi (0.0%), but 10.5% of the adults in Caio were infected, mostly with HIV type 2 (HIV-2). Mobility was very prevalent in all sites. Short-term mobility was found to be a risk factor for HIV infection among men in Caio (adjusted odds ratio (aOR) = 2.06; 95% CI: 1.06-3.99). Women from Caio who reported casual sex in a city during the past 12 months were much more likely to be infected with HIV (aOR = 5.61 95% CI: 1.56-20.15). Short-term mobility was associated with risk behaviours at all sites.

CONCLUSIONS

Mobility appears to be a key factor for HIV spread in rural areas of West Africa, because population movement enables the virus to disseminate and also because of the particularly risky behaviours of those who are mobile. More prevention efforts should be directed at migrants from rural areas who travel to cities with substantial levels of HIV infection.

Prevalence of HIV and other sexually transmitted infections, and risk behaviours in unregistered sex workers in Dakar, Senegal

OBJECTIVES

To estimate the prevalence rates of HIV and other sexually transmitted infections (STI) among unregistered sex workers, and to describe their sociodemographic characteristics and sexual behaviours, and the reasons why they were not officially registered as sex workers, in order to design specific public health interventions.

METHODS

A one-stage cluster-sample survey was conducted in Dakar in 2000. Unregistered sex workers were interviewed in randomly selected establishments (official and clandestine bars, brothels and nightclubs), and blood, endocervical and vaginal samples were collected for laboratory diagnosis.

RESULTS

A total of 390 women with a median age of 29 years were recruited. One-seventh of them were under the legal age for prostitution in Senegal (21 years). The median length of prostitution was 24 months and 73.5% of the women stated regular prostitution. Three-quarters of the women were found to have markers for at least one infection. The prevalence rates were as follows: HIV-1, 6.0%; HIV-2, 3.6%; HIV-1+2, 0.4%; syphilis, 23.8%; gonorrhea, 22.0%; chlamydial infection, 20.0%; trichomoniasis, 22.4%; candidiasis, 19.0%; and bacterial vaginosis, 28.8%. The main reported reason for non-registration was ignorance of the legal system and its procedures (19.4%); 18.9% of the women refused to register. One-third of the women reported that their clients used condoms inconsistently or never.

CONCLUSION

This survey suggests that a multidimensional public health response is needed in Senegal, comprising legal information, downwards revision of the legal age for prostitution, and specific medical follow-up based on education, condom promotion and management of STI for non-registered sex workers.

Low rate of genotypic HIV-1 drug-resistant strains in the Senegalese government initiative of access to antiretroviral therapy

OBJECTIVE

To monitor the prevalence of antiretroviral (ARV)-resistant HIV-1 viruses, and the genotypic mutations in patients enrolled in the Senegalese initiative for access to antiretroviral treatment (ART).

METHODS

A total of 80 patients with a virological follow-up of at least 6 months were selected, 68 were ART-naive and 12 ART-experienced. Genotypic resistance to ARV was studied at baseline for a random subset of patients and at each rebound in plasma viral load during ART, by sequencing the protease and reverse transcriptase genes.

RESULTS

At baseline, 66 patients received highly active antiretroviral therapy (HAART) [2 nucleoside reverse transcriptase inhibitors (NRTIs) +1 protease inhibitor (PI) (n = 64) or 2 NRTIs + 1 non-nucleoside reverse transcriptase inhibitor (NNRTI) (n = 2)] and 14 patients (17.5%) started with a dual therapy because of ongoing antitubercular therapy or efficient previous bitherapy for the ART-experienced patients. The emergence of drug-resistant viruses (n = 13) during follow-up was more frequent in ART-experienced patients than in ART-naive patients, 41.7 versus 11.8%, resistant viruses emerged at comparable follow-up periods, a median of 17.8 and 18.3 months, respectively. In patients receiving zidovudine and lamivudine in their drug regimen, resistance to lamivudine was more frequent than to zidovudine. Two of the three patients, with viruses resistant to PIs, acquired mutations associated with cross-resistance. Strikingly, five (39%) of the 13 patients developed resistances to drugs that they had never received (n = 3) or that they received 18 or 36 months ago (n = 2). Didanosine/stavudine pressure had selected zidovudine-resistant viruses in four patients, and indinavir had selected a nelfinavir-resistant virus in one patient.

CONCLUSION

In contrast to other reports from developing countries where patients had received ARVs in an uncontrolled manner, our study showed that implementation of HAART together with good clinical, biological and logistical monitoring can reduce the emergence of resistant strains in Africa.

Adherence to HAART and its principal determinants in a cohort of Senegalese adults

BACKGROUND

Access to programmes providing highly active antiretroviral therapy (HAART) is recent in Africa. In Senegal, a national initiative was launched in 1998. The capacity of African patients to adhere to complex antiretroviral treatments (ARV) is largely unknown.

METHODS

We assessed adherence and identified the main reasons for treatment interruption in a prospective observational cohort of patients participating in an ARV access programme in Dakar, Senegal. Adherence was estimated each month on the basis of the patients' stated consumption and on the proportion of the prescribed dose returned unused to the dispensing pharmacy. A total of 158 patients were studied between November 1999 and October 2001.

RESULTS

A cross-section analysis showed that the stated level of adherence was high: on average, over the study period, the patients said they had taken 91% of each monthly dose and that they had taken the full monthly dose during two-thirds of the months studied. Adherence tended to be better among patients who were required to make little or no contribution to the cost of their treatment, through an appropriate pricing structure. Adherence was also better with efavirenz-containing regimens than with indinavir-containing regimens.

CONCLUSION

These results show that adherence to HAART can be as high in Africa as that generally observed in industrialized countries, and that the cost and type of drug regimen must be taken into account when designing ARV access programmes for poor communities.

Access to antiretroviral drugs and AIDS management in Senegal

OBJECTIVES

Description and analysis of the Senegalese Antiretroviral Drug Access Initiative (ISAARV), the first governmental highly active antiretroviral therapy (HAART) treatment programme in Africa, launched in 1998.

METHODS AND RESULTS

ISAARV was initially an experimental project designed to evaluate the feasibility, efficacy and acceptability of HAART in an African context. It was based on four principles: collective definition of the strategy, with involvement of the health professionals who would be called on to execute the programme; matching the objectives to available means (gradual enrollment according to drug availability); monitoring by several research programmes; and ongoing adaptation of treatment and follow-up according to the latest international recommendations. Persons qualifying for antiretroviral (ARV) therapy are selected on the basis of immunological and clinical criteria, regardless of economic and social considerations. A system of subsidies was created to favor access to ARV. Following the ARV price reductions that occurred in November 2000, 100% subsidies were created for the poorest participants. Optimal adherence was ensured by monthly follow-up by pharmacists and support groups held by social workers and patient associations. The chosen supply and distribution system allowed drug dispensing to be strictly controlled.

CONCLUSION

The ISAARV programme demonstrates that HAART can be successfully prescribed in Africa. This experience has served as the basis for the creation of a national treatment programme in Senegal planned to treat 7000 patients by 2006.

Once-a-day highly active antiretroviral therapy in treatment-naive HIV-1-infected adults in Senegal

OBJECTIVES

To study the effectiveness, adherence and tolerance of a once-a-day highly active antiretroviral therapy regimen in adults in Senegal.

DESIGN AND METHODS

In a prospective, open-label one-arm study, 40 treatment-naive HIV-1-infected patients took the following three drugs once a day at bedtime: didanosine, lamivudine and efavirenz. The primary endpoint was the percentage of patients with plasma HIV-1 RNA below 500 copies/ml at 6 months. The analysis was done on an intent-to treat basis.

RESULTS

Eighty-five per cent of patients were at Centers for Disease Control and Prevention stage B or C and the plasma HIV RNA level was 5.4 +/- 0.4 log(10) copies/ml at baseline. The percentage of patients with plasma HIV-1 RNA below 500 copies/ml at 6 months was 95% [95% confidence interval (CI), 83-99]. The proportions of patients with plasma HIV-1 RNA below 50 copies/ml at months 3, 6, 9, 12 and 15 were 26% (n = 39; 95% CI, 12-39), 78% (n = 40; 95% CI, 65-90), 70% (n = 40; 95% CI, 56-84), 77% (n = 39; 95% CI, 64-90) and 69% (n = 39; 95% CI, 55-84), respectively. The CD4 cell count was 164 +/- 75 x 106/l at baseline and increased by a mean of 199 +/- 101 x 106/l at month 15. Permanent treatment discontinuation was never necessary for serious adverse effects. Adherence was excellent, as shown by plasma drug concentrations and according to the results of the questionnaire.

CONCLUSIONS

The once-daily regimen of didanosine, lamivudine and efavirenz was safe, easy-to-take and demonstrated strong antiretroviral and immunologic effects in African patients with advanced HIV infection.

Treponemal infection rates, risk factors and pregnancy outcome in a rural area of Senegal

A rural population of east Senegal has been under demographic surveillance for more than 30 years and a high rate of infertility has been reported. The aim of the study is to describe HIV and treponemal infection epidemiology and association with outcome of pregnancy in a population of rural Senegal. A population-based cross-sectional study was conducted among 952 randomly-selected adults of a rural community of Senegal. No participant was found to be infected with HIV, 11% had evidence of past syphilis and 5% of active syphilis. Active syphilis was associated among men with age, long-term mobility and having partners in an urban area in the last 12 months and among women with being divorced or widowed. No association was found between past or active syphilis and abortion or stillbirth but women aged 40 and more with past or active syphilis were significantly more likely to have had no history of gestation than women with no evidence of syphilis infection. In conclusion our results call for more research to understand the epidemiology of treponemal infection and to elucidate types of Treponema pallidum involved.

Phenotypic and genotypic diversity of rhizobia nodulating Pterocarpus erinaceus and P. lucens in Senegal

A total of fifty root nodules isolates of fast-growing and slow growing rhizobia from Pterocarpus ennaceus and Pterocarpus lucens respectively native of sudanean and sahelian regions of Senegal were characterized. These isolates were compared to representative strains of known rhizobial species. Twenty-two new isolates were slow growers and twenty-eight were fast growers. A polyphasic approach was performed including comparative total protein sodium dodecyl sulphate polyacrylamide gel (SDS-PAGE) profile analysis; 16S rDNA and 16S-23S rDNA intergenic spacer (IGS) sequence analysis. By SDS-PAGE the slow growing isolates grouped in one major cluster containing reference strains of Bradyrhizobium sp. including strains isolated in Africa, in Brazil and in New Zealand. Most of the fast-growing rhizobia grouped in four different clusters or were separate strains related to Rhizobium and Mesorhizobium strains. The 16S rDNA and 16S-23S rDNA IGS sequences analysis showed accurately the differentiation of fast growing rhizobia among the Rhizobium and Mesorbizobium genospecies. The representative strains of slow growing rhizobia were identified as closely related to Bradyrbizobium elkanii and Bradyrhizobium japonicum. Based on 16S rDNA sequence analysis, one slow growing strain (ORS199) was phylogenetically related to Bradyrbizobium sp. (Lupinus) and Blastobacter denitrificans. This position of ORS 199 was not confirmed by IGS sequence divergence. We found no clear relation between the diversity of strains, the host plants and the ecogeographical origins.

The Senegalese government's highly active antiretroviral therapy initiative: an 18-month follow-up study

OBJECTIVE

To study the feasibility, effectiveness, adherence, toxicity and viral resistance in an African government HAART initiative.

METHODS

A prospective observational cohort study started in Dakar in August 1998. Initial treatment consisted of two nucleoside reverse transcriptase inhibitors and one protease inhibitor. The patients attended monthly medical examinations. Plasma HIV-1 RNA and CD4 cell counts were determined at baseline and every 6 months. Intention-to-treat analyses were performed.

RESULTS

Fifty-eight treatment-naive patients, mostly infected by HIV-1 strain CRF02-AG, were enrolled. Most were at an advanced stage of HIV disease (86.2% had AIDS). Adherence was good in 87.9% of patients and treatment was effective in most of them. Thus, HIV-1 RNA was undetectable in 79.6, 71.2, 51.4 and 59.3% of patients at months 1, 6, 12 and 18, respectively and the median viral load reduction was approximately 2.5 log10 copies/ml. The CD4 cell count rose by a median of 82, 147 and 180 x 106 cells/l at months 6, 12 and 18, respectively. At the same time points, the cumulative probability of remaining alive or free of new AIDS-defining events was 94.8, 85.0 and 82.3%. Most adverse effects (80.8%) were mild or moderate and only two cases of drug resistance occurred.

CONCLUSION

This study shows that HAART is feasible and well tolerated in African patients. Clinical and biological results were comparable to those seen in western cohorts, despite differences in the HIV-1 subtype distribution and an advanced disease stage when the treatment was initiated. Contrary to other recent studies in Africa, viral resistance rarely emerged.

Full-length genome sequencing of HIV type 1 group O viruses isolated from a heterosexual transmission cluster in Senegal

In a polygamous marriage in Senegal, the husband and his two spouses were infected with HIV-1 group O. This study provides new full-length genome sequences for the two spouses (99SE-MP1299 and 99SE-MP1300) and the 3'-end LTR-tat fragment (6084 bp) for the husband (98SE-42HALD). Phylogenetic tree and diversity plot analysis revealed that the new viruses belong to HIV-1 group O and that they are closely related to each other in a cluster around ANT-70. The intrafamilial transmission occurred at most 6 years ago. The interpatient variability was highest in the envelope region, and in some regions of the envelope the strains from the two spouses do not cluster together anymore. The source of infection was in Cameroon and confirms a slow but continuous spread of HIV-1 group O viruses.

Prevalence and risk factors of cervicovaginal HIV shedding among HIV-1 and HIV-2 infected women in Dakar, Senegal

OBJECTIVES

To assess the risk determinants and prevalence of cervicovaginal shedding of HIV-1 and HIV-2 among women in Dakar, Senegal.

METHODS

We conducted a cross sectional study of 153 HIV seropositive female sex workers (FSW) and another 142 HIV seropositive women attending an infectious diseases unit, based on an interview, physical examination, and laboratory screening for major sexually transmitted infections (STI). Cervicovaginal lavage fluid was tested for HIV-RNA by means of nested PCR. Links between cervicovaginal shedding of HIV-1 and HIV-2 and sociodemographic, clinical, and laboratory variables were identified by using odd ratios and 95% confidence intervals. Logistic regression analysis was used to identify independent links with HIV shedding.

RESULTS

The detection rate of HIV-RNA in cervicovaginal lavage fluid was low among FSW, with no difference between HIV-1 (7/90: 8%) and HIV-2 (3/48: 6%). The rate was far higher among the other women (41%, 48/117; 33%, 7/21 for HIV-1 and HIV-2, respectively). In multivariate analysis, high plasma viral load (>40 000 copies/ml) (AOR = 2.4 (1.0-5.6) p = 0.04) and basic vaginal pH (AOR = 2.2 (1.3-3.7) p = 0.002) were independently associated with HIV-1 shedding. For HIV-2 a CD4 count < 200 cells x 10(6)/l was the only factor associated with the shedding of HIV-2 (AOR = 9.0 (0.9-93)). The genital shedding rate was higher with HIV-1 than with HIV-2 (OR = 2.1 (0.9-4.8), but this difference disappeared after adjustment for the CD4+ cell count (AOR = 1.2 (0.5-2.9)).

CONCLUSION

Advanced disease stage and immunosuppression are the major risk determinants for shedding of both HIV-1 and HIV-2. Basic vaginal pH is also a risk determinant for HIV-1 shedding.

Primary prevention with cotrimoxazole for HIV-1-infected adults: results of the pilot study in Dakar, Senegal

OBJECTIVES

To assess the efficacy and tolerance of chemoprophylaxis with cotrimoxazole compared with placebo among HIV-1-infected adults.

DESIGN

Randomized, double-blind, placebo-controlled clinical trial in the urban community of Dakar, Senegal.

METHODS

Eligibility criteria were age greater than 15 years, HIV-1 or HIV-1 and HIV-2 dual seropositivity, CD4 cell count lower than 400 copies/mm3, no progressive infection, no previous history of intolerance to sulphonamide, lack of severe anemia or neutropenia, and renal or hepatic failure. Written informed consent was obtained. Recruited patients received 80 mg of trimethoprim and 400 mg of sulphamethoxazole daily or a matching placebo. The main outcomes were survival and the occurrence of clinical events defined as Pneumocystis carinii pneumonia, cerebral toxoplasmosis, bacterial pneumonia, infectious enteritis, bacterial meningitis, urinary tract infection, bacterial otitis and sinusitis, and pyomyositis.

RESULTS

Between September 1996 and March 1998, 297 patients were screened, and 100 were randomized in the study. Demographic, clinical, and biological characteristics of the two groups were similar as was the mean length of follow-up (7.7 months for the cotrimoxazole group vs. 8.0 months for the placebo group). There was no significant difference between the two groups in survival (hazard ratio = 0.84; 95% confidence interval [CI]: 0.36-1.94) in the probability of severe event occurrence, defined as death or hospital admission (hazard ratio = 1.10; 95% CI: 0.57-2.13), or in the probability of clinical event occurrence (hazard ratio = 1.19; 95% CI: 0.55-2.59). Adjustment for initial CD4 cell count did not change these results. A low dose of cotrimoxazole was tolerated well clinically as well as biologically; only one treatment interruption occurred as the result of a moderate cutaneous eruption (grade 2).

CONCLUSION

Our study does not show a beneficial effect of chemoprophylaxis with low-dose cotrimoxazole on survival or occurrence of opportunistic or nonopportunistic infections for HIV-1-infected patients in Dakar, Senegal.

Preventive attitudes towards the threat of AIDS: process and determinants in rural Senegal

This report is intended to identify the determinants of preventive attitudes and thereby enable the further elaboration of effective prevention programs in a country where the HIV epidemic has remained controlled. Across-sectional survey using a standardized questionnaire was conducted among a sample of 866 adults of the general population of the rural area of Niakhar, Senegal. The analysis identified psychosocial determinants related to preventive attitudes and the influence of sociodemographic characteristics and of sources of AIDS information on these determinants. Psychosocial determinants of preventive attitudes differed according to gender: Among men, personal risk perception was associated with preventive attitudes. Among women, level of AIDS-related knowledge, communication about AIDS, and optimism about the future were associated with preventive attitudes. Sociodemographic factors and sources of information were similar for men and women: Preventive attitudes were adopted primarily by young, educated subjects who had been exposed to urban life. Religion appeared to be a major obstacle to preventive attitudes. Preventive messages broadcast on radio or television may be determinative. Our results call for a strengthened collaboration with religious leaders and a focus on risk perception to rationalize preventive actions. We also encourage the targeting of vulnerable populations, such as women in rural areas, by developing preventive messages to be delivered through national media (radio, television) and by staff from health centers, which most women visit, at least for prenatal care.

Religion and protective behaviours towards AIDS in rural Senegal

OBJECTIVES

To describe the association between religion and factors related to sexually transmitted diseases (STD)/AIDS in a country where religious leaders were involved early in prevention.

DESIGN

A cross-sectional study conducted in a rural area in central Senegal.

METHODS

Questionnaire-based interviews of a random sample of 858 adults from the general population aged 15-59 years and in-depth interviews of four religious leaders and 50 people.

RESULTS

Seventy-six per cent of the respondents were Muslim, 24% Catholic, 1% Animist and 0.2% Protestant. A total of 86% of men and 87% of women reported religion to be very important to them. Important prevention-related variables were inversely associated with the importance of religion. Men who considered religion to be very important were less likely to cite AIDS as a major health problem [odds ratio (OR) 0.4, P = 0.008] and were less likely to feel at risk of getting HIV (OR 0.5, P = 0.0005). Women who considered religion to be very important were less likely to report an intention to change to protect themselves from AIDS (OR 0.2, P = 0.0001), less likely to report having discussed AIDS with others (OR 0.4, P = 0.01) and much more likely to feel at risk of getting HIV (OR 9.3, P = 10(-4)). Individuals who considered religion to be very important were not more likely to report intending to or actually having become faithful to protect themselves from AIDS.

CONCLUSION

These findings stress the need to intensify the involvement of religious authorities in HIV/STD prevention at the local level.

Differences in nitrogen metabolism of Faidherbia albida and other N2 -fixing tropical woody acacias reflect habitat water availability

The activities of nitrate reductase and glutamine synthetase were evaluated in young plants of Faidherbia albida, a tropical woody legume, fed with different N sources under hydroponic conditions. Results showed that assimilation of both NO₃ ^- and NH₄ ⁺ preferentially took place in shoots. A basal amount of nitrate reductase activity was detected in shoots of plants grown with an NO₃ ^- -free solution or placed under N₂ -fixing conditions, and also in nodules of N₂ -fixing plants. This strongly suggests that constitutive nitrate reductase activity is present in these organs. Analyses of the soluble nitrogenous content showed that the major form of N in the different organs was α-amino acids (particularly amides), irrespective of the N status of the culture conditions. The same result was obtained for nodulated plants grown in local sandy soil. In this case, amide-N generally accounted for more than 40% of the total soluble N. This was especially true in nodules. Ureide-N never exceeded 9% of the total soluble N and did not appear to increase with increasing nodule nitrogenase activity. Amides were also predominant in three N₂ -fixing Sahelian acacias (Acacia seyal, A. nilotica and A. tortilis), showing that F. albida does not differ from Sahelian Acacia in terms of the metabolism of fixed N. However, like another Sahelian acacia growing preferentially near water (A. nilotica), F. albida can be distinguished from acacias growing strictly in arid zones (A. seyal and A. tortilis) in terms of initial growth, water and nitrate management.

Identification of all HIV type 1 group M subtypes in Senegal, a country with low and stable seroprevalence

A total of 343 HIV-1-positive samples obtained between June 1996 and March 1999 was genetically characterized in the envelope region by HMA and/or sequencing. The env subtype distribution was as follows: 290 (84.6%) A, 22 (6.5%) B, 16 (4.7%) C, 8 (2.5%) D, 1 (0.03%) E, 1 (0.03%) F1, 4 (1.2%) G, and 1 (0.03%) H. For 77 samples the p24 region from the gag gene was also sequenced, and for 9 (11.6%) the subtypes between env and gag were different. Phylogenetic tree analysis showed the predominance of AG-IBNG-like viruses among gag and env subtype A sequences. HMA is relatively simple and requires less sophisticated technical facilities compared with sequencing, and in Senegal 323 (94.2%) of the 343 samples could be identified by this technique. However, in the actual configuration of the assay, discrimination between the recombinant AG-IBNG-like recombinant viruses, which are predominant in Senegal, and the nonrecombinant subtype A viruses is not possible.

Low and stable HIV infection rates in Senegal: natural course of the epidemic or evidence for success of prevention?

OBJECTIVES

To document the level of HIV infection in Senegal and also to review evidence of the impact of efforts in prevention, developed by the National AIDS Control Programme and the Civil Society, on the level of the HIV epidemic.

METHODS

Research, compilation and critical review of all relevant data on HIV and sexually transmission diseases (STDs) epidemiology, sexual behaviour, and the efforts in prevention developed in Senegal.

RESULTS

From 1989 to 1996, the levels of HIV infection estimated in four sentinel urban regions remained stable at around 1.2% in the population of pregnant women, and at 3% in male STD patients. It had increased to 19% in female sex workers. A strong political and community commitment led to an early response to the HIV/AIDS epidemic that has been extended since 1986. Blood transfusion safety was established at the start of the HIV epidemic. The level of knowledge of preventive practices relating to HIV/AIDS among the general population exceeded 90% in the early 1990s. From 1991 to 1996, a 30% to 66% decrease of the STD prevalence rates was observed in pregnant women and sex workers in Dakar. In 1997, 33% of men aged 15-49 years in Dakar reported having had sex with non-regular partners. Among them 67% reported condom use.

CONCLUSIONS

It is not possible to know what the course of the HIV epidemic in Senegal would have taken in the absence of efforts at prevention. Certainly, several factors that pre-dated the occurrence of AIDS in Senegal laid the groundwork for a positive response. However, data from a number of sources do reveal the successfulness of efforts in prevention. From available data, Senegal can rightfully claim to have contained the spread of HIV by intervening early and comprehensively to increase knowledge and awareness of HIV/AIDS and to promote safe sexual behaviour.

Risk factors for negative sputum acid-fast bacilli smears in pulmonary tuberculosis: results from Dakar, Senegal, a city with low HIV seroprevalence

SETTING

Two teaching hospitals in Dakar, Senegal, a West African country with a low prevalence of human immunodeficiency virus (HIV) infection.

OBJECTIVE

To determine whether patients with HIV-associated pulmonary tuberculosis have fewer acid-fast bacilli (AFB) in their sputum as assessed by routine microscopy, and to correlate the findings with systematically obtained clinical, radiographic and laboratory variables.

DESIGN

Prospective study from November 1995 to October 1996 of 450 consecutive patients diagnosed with pulmonary tuberculosis.

RESULTS

Tuberculosis was diagnosed in 380 patients (84.4%) by positive bacteriology, in 61 (13.6%) by a favorable response to anti-tuberculosis chemotherapy, and in nine (2.0%) by the presence of a miliary radiographic pattern. Forty (8.9%) patients were HIV-seropositive. AFB-negative smears were found in 14/40 (35.0%) of the HIV-seropositive patients with pulmonary tuberculosis compared with 71/410 (17.3%) of the seronegative patients (risk ratio [RR] = 2.02, 95% confidence interval [CI] 1.26-3.24, P = 0.01). Multivariate analysis revealed that AFB smear negativity was associated with absence of cavitation (P = 0.002), lack of cough (P = 0.005), the presence of HIV seropositivity (P = 0.02), a CD4+ cell count above 200/mm3 (P = 0.02), and age over 40 years (P = 0.03).

CONCLUSIONS

Compared with HIV-seronegative patients with pulmonary tuberculosis, seropositive patients in Dakar, Senegal, are more likely to have negative sputum-AFB smears. This phenomenon has now been observed in seven of eight sub-Saharan African countries with varying HIV seroprevalence from which reports are available.

Diagnosis of sexually transmitted infections in female prostitutes in Dakar, Senegal

OBJECTIVE

To study the validity and performance of a number of rapid indicators for the diagnosis of sexually transmitted infections (STIs) in female prostitutes in Dakar, Senegal; characteristics of these indicators were rapidly obtainable, easy to perform, accurate, useful at district level, and reasonable cost.

METHODS

An STI prevalence study in female prostitutes (n = 374) seen at the STD clinic in Dakar, Senegal was done; a history, clinical examination, simple laboratory tests, and "gold standard" microbiological tests were performed. For a number of sociodemographic data, actual or past symptoms of STI, clinical signs, and rapid laboratory tests, validity variables, performance characteristics, and likelihood ratios for detection of gonococcal or chlamydial cervical infection were determined.

RESULTS

Cervical infection (chlamydial or gonococcal) was present in 24.9% of prostitutes; 46% had trichomoniasis and 29.4% had syphilis. Young age, abnormal vaginal discharge, endocervical mucopus, a positive leucocyte esterase test on urine, and 10 or more leucocytes in Gram stained smears of vaginal, cervical, or urine samples were significantly associated with cervical STI. Some of the rapid indicators had high sensitivity, others high specificity but none had acceptable overall validity. None of the indicators had at the same time a sensitivity above 50% and a positive predictive value above twice the background prevalence of cervical infection. 10 or more leucocytes in the cervical smear had a likelihood ratio of 1.83 increasing pretest probability of 24.9% to post-test probability of 38%, the best result obtained by any of the rapid indicators.

CONCLUSIONS

Rapid indicators of cervical STIs are insufficiently valid, which largely restricts their usefulness to high STI prevalence situations for instance, in prostitute populations and in STD patient management.

Sexually transmitted diseases and risk of HIV infection in men attending a sexually transmitted diseases clinic in Dakar, Senegal

This cross-sectional study was carried out among male outpatients with symptoms of STDs at the STD reference centre at the Institute of Social Hygiene (IHS), Dakar, Senegal, from March 1989 through May 1991. This study was used to determine the prevalence of STDs and HIV among male patients attending an STD clinic and to identify their socio-demographic characteristics and risk factors. A total of 975 patients were enrolled in the study. The most common syndromes were urethritis (76%) and genital ulcers (22%). Considering single infections, the major STD agents were Neisseria gonorrheae (N.gonorrheae, 30%), Chlamydia trachomatis (C.trachomatis, 15%), Treponema pallidum (T.pallidum, 12%), and Haemophilus ducreyi (H.ducreyi, 7%). HIV prevalence was 2.6 percent (25/975). After multivariate analysis, the risk factors associated with HIV infection were a history of sex with prostitutes (odds ratio [OR] = 8.6, 95% confidence interval [CI] = 2.0-37.8), unprotected sexual contact (OR = 5.6, 95% CI = 1.2-25.0), a history of urethritis (OR = 3.4, 95% CI = 1.3-8.9), current STDs due to H.ducreyi or T.pallidum (OR = 6.1, 95% CI = 2-18.8), and mixed STD infection (OR = 5.3, 95% CI = 1.3-21.8). HIV prevalence was quite low in this population compared to similar studies of STD patients from other sub-Saharan African countries. Neisseria gonorrheae and Chlamydia trachomatis were the leading causes of STDs. A history of risky sexual behaviour, previous STDs, current genital ulcers, and mixed STD infections were associated with HIV infection. Further studies are necessary to determine changes in the relationship of STDs and HIV infection in this population.

Periodontal status of HIV-1 and HIV-2 seropositive and HIV seronegative female commercial sex workers in Senegal

Comprehensive studies of 92 commercial sex workers in Senegal, Africa included an oral examination in which we obtained measurements of decayed, missing, and filled (DMF) teeth; plaque index; gingival index; recession; probing depth (PD); clinical attachment loss (CAL); and the presence of HIV-associated periodontal lesions, under conditions wherein the examiner was unaware of the subject's HIV status. Twenty-seven subjects (29%) were HIV seropositive, 19 of whom were positive for HIV-1, 7 positive for HIV-2, and 1 positive for both. Most subjects were not taking any medications and previous dental care was limited. HIV-seronegative and HIV-seropositive subjects were similar in mean age, number of DMF teeth, percentage of sites with visible plaque, and number of sites with recession. However, the frequency of sites with gingival bleeding, with PD > or = 6 mm, and with CAL > or = 6 mm was significantly greater in seropositive than seronegative subjects. No differences were observed between HIV-1 and HIV-2 positive subjects. About 26% of HIV-seropositive subjects and about 5% of the seronegative subjects exhibited at least one site with concurrent PD > or = 6 mm and CAL > or = 6 mm. HIV-associated periodontal lesions were seen in 3 HIV-seropositive subjects (2 linear gingival erythema, 1 necrotizing periodontitis). One HIV-seronegative subject exhibited necrotizing gingivitis. In this population with multiple risks to oral health, both HIV-1 and HIV-2 infections were associated with a significantly increased prevalence of periodontal disease.

The Sesbania Root Symbionts Sinorhizobium saheli and S. teranga bv. sesbaniae Can Form Stem Nodules on Sesbania rostrata, although They Are Less Adapted to Stem Nodulation than Azorhizobium caulinodans

Sesbania species can establish symbiotic interactions with rhizobia from two taxonomically distant genera, including the Sesbania rostrata stem-nodulating Azorhizobium sp. and Azorhizobium caulinodans and the newly described Sinorhizobium saheli and Sinorhizobium teranga bv. sesbaniae, isolated from the roots of various Sesbania species. A collection of strains from both groups were analyzed for their symbiotic properties with different Sesbania species. S. saheli and S. teranga bv. sesbaniae strains were found to effectively stem nodulate Sesbania rostrata, showing that stem nodulation is not restricted to Azorhizobium. Sinorhizobia and azorhizobia, however, exhibited clear differences in other aspects of symbiosis. Unlike Azorhizobium, S. teranga bv. sesbaniae and S. saheli did not induce effective stem nodules on plants previously inoculated on the roots, although stem nodulation was arrested at different stages. For Sesbania rostrata root nodulation, Sinorhizobium appeared more sensitive than Azorhizobium to the presence of combined nitrogen. S. saheli and S. teranga bv. sesbaniae were effective symbionts with all Sesbania species tested, while Azorhizobium strains fixed nitrogen only in symbiosis with Sesbania rostrata. In a simple screening test, S. saheli and S. teranga bv. sesbaniae were incapable of asymbiotic nitrogenase activity. Thus, Azorhizobium can easily be distinguished from Sinorhizobium among Sesbania symbionts on the basis of symbiotic and free-living nitrogen fixation. The ability of Azorhizobium to overcome the systemic plant control appears to be a stem adaptation function. This last property, together with its host-specific symbiotic nitrogen fixation, makes Azorhizobium highly specialized for stem nodulation of the aquatic legume Sesbania rostrata.

HIV-1, HIV-2, human papillomavirus infection and cervical neoplasia in high-risk African women

OBJECTIVE

To determine the effect of HIV-1 and HIV-2 infection on the prevalence of cervical human papillomavirus (HPV) and squamous intraepithelial lesions (SIL) in a population of high-risk women in Senegal.

DESIGN AND PARTICIPANTS

Cross-sectional study among 759 female commercial sex workers, including 68 with HIV-1, 58 with HIV-2, 14 with HIV-1 and 2, and 619 without HIV infection.

RESULTS

Overall, HPV was detected in 43% of women by polymerase chain reaction (PCR), and in 7% by Southern transfer hybridization, with 7.4% of all women having SIL. The mean CD4 count was 820, 1205, and 727 x 10(6)/l for those with HIV-1, HIV-2, and dual HIV-1 and 2 infections, respectively, and 1447 x 10(6)/l for those without HIV infection. Both HIV-1 and HIV-2 were associated with HPV, as detected by PCR [HIV-1 odds ratio (OR), 2.9; 95% confidence interval (Cl), 1.7-4.9; HIV-2 OR, 1.7; 95% Cl, 1.0-2.9]. HIV-2 was also associated with cervical SIL, and although the association between HIV-1 and SIL did not attain statistical significance, a trend was apparent (HIV-1 OR, 1.8; 95% Cl, 0.7-4.7; HIV-2 OR, 2.9; 95% Cl, 1.2-7.2).

CONCLUSIONS

Despite less immunosuppression with HIV-2, both HIV-1 and HIV-2 were associated with detection of HPV. HIV-2 was also associated with SIL. Further studies are needed to examine the risks of high-grade SIL and invasive cervical cancer with HIV-1 versus HIV-2 infection.

[Phenotypic differences of nosocomial bacterial strains isolated in the obstetric-gynecology service of the University Hospital Center of Dakar]

A study on nosocomial infections was conducted in the Laboratory of Bacteriology-Virology of Aristide Le Dantec's Hospital, in collaboration with the Gynecology Obstetrics clinic located both in the same Dakar's hospital, during May 1995. The aim of the study was to define the phenotypical characteristics of various bacterial strains isolated from the atmosphere health care staff's hands, medical equipment (material, antiseptics) and patients (hospitalized pregnant and newborns in day Nursery). A total of 133 strains were collected and the most frequent isolates were Staphylococcus aureus (27 strains) and Klebsiella pneumoniae (10 strains) encountered mainly in the atmosphere. Otherwise, Escherichia coli (11 strains) and Enterococcus faecalis (11 strains) were more present in hospitalized patients. Results obtained after antimicrobial agents susceptibility (Antibiotics and Heavy metal salts) by Antibiogramm and Minimal inhibitory concentrations (MIC) and also data from biotyping of Klebsiella strains have allowed us to say there's a probable contamination of hospitalized patients by the bacteria from the atmosphere but manuportage too.