Genetic structure and invasion history of the house mouse (Mus musculus domesticus) in Senegal, West Africa: a legacy of colonial and contemporary times.

Knowledge of the genetic make-up and demographic history of invasive populations is critical to understand invasion mechanisms. Commensal rodents are ideal models to study whether complex invasion histories are typical of introductions involving human activities. The house mouse Mus musculus domesticus is a major invasive synanthropic rodent originating from South-West Asia. It has been largely studied in Europe and on several remote islands, but the genetic structure and invasion history of this taxon have been little investigated in several continental areas, including West Africa. In this study, we focussed on invasive populations of M. m. domesticus in Senegal. In this focal area for European settlers, the distribution area and invasion spread of the house mouse is documented by decades of data on commensal rodent communities. Genetic variation at one mitochondrial locus and 16 nuclear microsatellite markers was analysed from individuals sampled in 36 sites distributed across the country. A combination of phylogeographic and population genetics methods showed that there was a single introduction event on the northern coast of Senegal, from an exogenous (probably West European) source, followed by a secondary introduction from northern Senegal into a coastal site further south. The geographic locations of these introduction sites were consistent with the colonial history of Senegal. Overall, the marked microsatellite genetic structure observed in Senegal, even between sites located close together, revealed a complex interplay of different demographic processes occurring during house mouse spatial expansion, including sequential founder effects and stratified dispersal due to human transport along major roads.

Lysophosphatidic acid mediates fibrosis in injured joints by regulating collagen type I biosynthesis.

OBJECTIVE: Articular cartilage is a highly specialized tissue which forms the surfaces in synovial joints. Full-thickness cartilage defects caused by trauma or microfracture surgery heal via the formation of fibrotic tissue characterized by a high content of collagen I (COL I) and subsequent poor mechanical properties. The goal of this study is to investigate the molecular mechanisms underlying fibrosis after joint injury. DESIGN: Rat knee joint models were used to mimic cartilage defects after acute injury. Immunohistochemistry was performed to detect proteins related to fibrosis. Human fetal chondrocytes and bone marrow stromal cells (BMSCs) were used to study the influence of the lipid lysophosphatidic acid (LPA) on COL I synthesis. Quantitative PCR, ELISA and immunohistochemistry were performed to evaluate the production of COL I. Chemical inhibitors were used to block LPA signaling both in vitro and in vivo. RESULTS: After full-thickness cartilage injury in rat knee joints, stromal cells migrating to the injury expressed high levels of the LPA-producing enzyme autotaxin (ATX); intact articular cartilage in rat and humans expressed negligible levels of ATX despite expressing the LPA receptors LPAR1 and LPAR2. LPA-induced increases in COL I production by chondrocytes and BMSCs were mediated by the MAP kinase and PI3 Kinase signaling pathways. Inhibition of the ATX/LPA axis significantly reduced COL I-enriched fibrocartilage synthesis in full-thickness cartilage defects in rats in favor of the collagen II-enriched normal state. CONCLUSION: Taken together, these results identify an attractive target for intervention in reducing the progression of post-traumatic fibrosis and osteoarthritis.

[Relationship between the obstructive character of the tonsils and the sagittal cephalometric measurements]. / Relations entre le caractère obstructif des amygdales palatines et les mensurations céphalométriques du sens sagittal.

INTRODUCTION: The role of obstructive tonsils in the sagittal dimension of the skeleton-dental abnormalities is widely discussed in the literature but remains controversial. Data on the probable relationship between obstructive tonsils and the presence of these abnormalities were subjective. The objective of this study was to quantify the relationship between the obstructive character of the tonsils and the sagittal cephalometric measurements. MATERIALS AND METHODS: A cross-sectional study was performed in children aged between 6 to 12 years divided into 2 groups (A and B) according to the obstructive character of the tonsils. Cephalometric measurements were recorded on each child. Data were analyzed using SPSS 20.0 for Windows. At Student test was used to compare quantitative variables according to the obstructive character of the tonsils. Significance was set at p = 0.05. RESULTS: Subjects with obstructive tonsils (group B) are significantly more trend to have a convex facial profile and a skeletal class II with more mandibular retrusion and retroclined incisor compared with subjects without obstructive tonsils (group A). CONCLUSION: Early evaluation of children with obstructive tonsils can prevent sagittal dimension of the squeleto-dental abnormalities caused by upper airway obstruction. Thus late and more aggressive treatments which are not always as efficient as when they were performed during childhood will be avoided.

[Sagittal photogrammetric evaluation of the soft tissue profile between two different racial groups: a comparative study]. / Caractéristiques photogrammétriques sagittales de profil des tissus mous chez deux groupes raciaux. Etude comparative.

INTRODUCTION: Facial soft-tissue analyses made from photographic records (photogrammetric analysis of the soft tissues) showed interracial dimorphism. Standard of these facial analyses, originally obtained from Caucasian might not be appropriate for the diagnosis and treatment planning of other groups of orthodontic patients. The purpose of this study was to compare the sagittal photogrammetric soft tissue profile characteristics between Senegalese and Moroccan adults. MATERIALS AND METHODS: A cross-sectional study was performed in a group of Senegalese and Moroccan students in the Faculty of Medicine, Pharmacy and Dentistry of Dakar. Standardized facial-profile photographs were taken with each student in natural head position, centric relation, and relaxed lip posture. Twenty four linear parameters were measured on paper sheet using a graduated ruler. For each variable mean and SD were calculated. In addition independent samples t-test was performed to detect sexual and racial dimorphism. Results were regarded as significant at p = 0.05. RESULTS: Senegalese subjects had significantly more lips protrusion than Moroccan who had significantly a more elongated and more anterior positioned nose, a more chin prominence and a tendency to cutaneous class II than Senegalese. CONCLUSION: Further studies including different age groups subjects would allow having longitudinal data according to age.

[Disease modifying antirheumatic drugs]. / Traitement de fond de la polyarthrite rhumatoïde.

The natural history of rheumatoid arthritis, previously burdened with high morbidity, has been strongly modified by appropriate treatment. Early diagnosis and treatment, and follow-up by a specialist, with the aim to achieve remission or low disease activity, are essential for the functional outcome of patients. Disease-modifying anti-rheumatic drugs include "conventional" treatments like methotrexate, biologic therapies such as TNF-inhibitors, abatacept, tocilizumab and rituximab, and targeted synthetic therapies such as tofacitinib (a JAK kinase inhibitor). New treatments currently under study should allow rheumatologists to successfully treat even more patients than nowadays.

[Relationships between the dental arches measurements and the peak nasal inspiratory flow (PNIF): a cross sectional study on 78 Senegalese teenagers]. / Relations entre les mensurations des arcades dentaires et le débit nasal inspiratoire de pointe: etude transversale sur 78 adolescents Senegalais.

INTRODUCTION: Upper airways obstruction can result in the reduction of the transversal dimensions of the maxillary arch which affect the vertical and the sagittal dimensions. The PNIF measure is an objec- tive and cheap way to assess the upper airways permeability. The aim of this study was to determine the relationship between PNIF and dental arch sizes. MATERIALS AND METHODS: Seventy eight patients (40 girls and 38 boys) age ranged 10-15 years were included in this cross sectional study. The PNIF was measured with a Youlten peak flow meter (Clement Clarke International, London, United Kingdom). The sagittal, vertical and transversal dimensions of the dental arches were evaluated on dental casts with a digital caliper (Mitutoyo Corporation, Tokyo, Japan). T test was used to assess differences in PNIF and dental arches variables between subjects grouped according to sex (male and female). The Pearson's correlation coefficient was used to analyze the relationship between the dental arches sizes and the PNIF. The significance was set at p < 0.05. RESULTS: PNIF rate was higher in girls than in boys but the difference was not significant. There were sexual dimorphism regarding the anterior and total lengths of the upper arch, the total length of the lower arch and the maxillary intermolar width which are significantly more important for boys (p respectively equal to 0.05; 0.03; 0.04 and 0.04). The PNIF was significantly and negatively correlated with the total length of the upper arch (r = -0.25). The others measurements did not show significant correlation with PNIF. CONCLUSION: Others parameters are needed to complement the peak nasal inspiratory flow rate for the respiratory disorders related dental arches sizes abnormalities diagnosis.

Mechanisms of persistence and impact of ordinary heterotrophic organisms in aerobic granular sludge.

The stability of granules, contaminant removal and microbial structure of an aerobic granular sludge (AGS) process were investigated with a focus on ordinary heterotrophic organisms (OHOs). Long-term stable granules and high removals of COD (97 %), NH4+ (98 %), P (85 %) and total N (77 %) were achieved. Sequencing analyses identified 6.6 % of phosphorus-accumulating organisms in the sludge, concordant with the observed bio-P removal capacity. However, OHOs were the most abundant bacteria in the sludge (70-93 %) without resulting in unstable aggregates. Under current dogmas of microbial competition in activated sludge, it seemed contradictory that OHOs could persist in the long term in the AGS where COD was depleted beginning in the anaerobic phase. Microbial analyses showed that OHOs could survive in granules by micropredation, proteolysis, fermentation and EPS consumption. Heterotrophic-nitrification/ aerobic-denitrification was an active pathway in the AGS. These findings contribute to a better understanding of microbial competition in AGS and its stability.

COD fractionation and biological treatability of mixed industrial wastewaters.

This study was conducted at a centralized wastewater treatment plant that receives discharges from nearly 160 industries. The chemical oxygen demand (COD) was fractionated for two objectives: delineation of the limits of the activated sludge process being used at the plant, and evaluation of the potential environmental impact of the treated effluent. Physico-chemical analyses, respirometric and biodegradation tests, as well as COD fractionation were carried out. Molasses-wastewaters were determined to be the major contribution to the plant. The influent was dark brown in color, with a relatively high content of both organics (2503 mg/L COD) and salts (5459 µS/cm conductivity), but a low biochemical oxygen demand (568 mg/L BOD(5)) and BOD(5)/COD ratio (0.24). The degradability of the organics was limited by the high content of inert soluble COD (S(I)). The COD fractionation pattern was 40-20-40% for S(I), X(I) (inerts) and S(H) (soluble hydrolyzable), respectively. More than 90% BOD(5) removal was obtained, which was sufficient for the plant to meet the national Standards. However, the effluent discharged into the river was intensely colored and polluted (>1000 mg/L COD, >5000 µS/cm), emphasizing the need for legislation regulating COD, color and salinity, and for upgraded treatment methods worldwide for molasses wastewaters.

Development of Trichosomoides nasalis (Nematoda: Trichinelloidea) in the murid host: evidence for larval growth in striated muscle fibres.

Trichosomoides nasalis (Trichinelloidea) is a parasite of Arvicanthis niloticus (Muridae) in Senegal. Female worms that harbour dwarf males in their uteri, occur in the epithelium of the nasal mucosa. Young laboratory-bred A. niloticus were either fed females containing larvated eggs or intraperitoneally injected with motile first-stage larvae recovered from female uteri. Both resulted in successful infection. Organs examined during rodent necropsy were blood and lymphatic circulatory systems (heart, large vessels, lymphnodes), lungs, liver, kidneys, thoracic and abdominal cavities, thoracic and abdominal muscular walls, diaphragm, tongue, and nasal mucosa. Development to adult nasal stages took three weeks. Recovery of newly hatched larvae from the peritoneal fluid at four-eight hours after oral infection suggests a direct passage from the stomach or intestinal wall to the musculature. However, dissemination through the blood, as observed with Trichinella spiralis, cannot be excluded even though newly hatched larvae of T. nasalis are twice as thick (15 µm). Developing larvae were found in histological sections of the striated muscle of the abdominal and thoracic walls, and larvae in fourth moult were dissected from these sites. Adult females were found in the deep nasal mucosa where mating occurred prior to worms settling in the nasal epithelium. The present study shows a remarkable similarity between T. nasalis and Trichinella species regarding muscle tropism, but the development of T. nasalis is not arrested at the late first-larval stage and does not induce transformation of infected fibres into nurse cells. T. nasalis seems a potential model to study molecular relations between trichinelloid larvae and infected muscle fibres.

Trichosomoides nasalis (Nematoda: Trichinelloidea) in the murid host Arvicanthis niloticus: migration to the epithelium of the nasal mucosa after intramuscular development.

Knowledge of the biology of the trichinelloid subfamily Trichosomoidinae is poor. Trichosomoides nasalis is a common parasite of Arvicanthis niloticus (Muridae) in Senegal, and a procedure for experimental infections has been established. It has been demonstrated that larvae develop in striated muscle fibres, similar to Trichinella spp., but they are not arrested in the first stage, and they reach the adult stage within three weeks. In the present histological study it is shown that T. nasalis females and dwarf males migrate from the abdomen and thorax to the host's muzzle, moving through connective tissues and between muscles. A few migrating specimens were also found in the blood vessels of the nasal mucosa. While sexes were still separated in the lamina propria of the mucosa, females recovered from the epithelium contained intra-uterine males. Worms were found between the incisors in the mucosa of the anterior and median conchae which are rich in mucous cells. Only the pseudostratified epithelium was parasitized. Under natural conditions, the inflammation of the nasal mucosa that is induced by the parasites might reduce the competitiveness of infected rodents when foraging or looking for potential mates.

[Passive correction of an anterior open bite related to non-nutritive sucking habits: report of a case]. / Correction passive de l'infraclusion antérieure associée une Habitude de Succion Non-Alimentaire (HSNA): rapport de cas.

The term anterior open bite refers to a vertical space between the upper and lower front teeth in maximum intercuspation. This malocclusal trait can accompany many malocclusions of the Angle's classification. Two types of anterior open bite have been described: skeletal and dental open bite. The latter may have Non Nutritive Sucking Habits (NNSH) as causal factor and is deemed to aggravate without treatment. This article presents an interceptive approach based on the use of a fixed passive appliance interfering with sucking habit. It consists of a crib soldered to bands adjusted to the maxillary first permanent or temporary second molars. The device was globally well accepted by the patient and has been effective in breaking the sucking habit and subsequently in closing the bite after only 5 month. When psychological approach is not effective, a fixed deterrent device may be recommended for weaning children off nonnutritive sucking habits.

Geographic patterns of inversion polymorphisms in a wild African rodent, Mastomys erythroleucus.

By suppressing recombination and reducing gene flow, chromosome inversions favor the capture and protection of advantageous allelic combinations, leading to adaptive polymorphisms. However, studies in non-model species remain scarce. Here we investigate the distribution of inversion polymorphisms in the multimammate rat Mastomys erythroleucus in West Africa. More than 270 individuals from 52 localities were karyotyped using G-bands and showed widespread polymorphisms involving four chromosome pairs. No significant deviations from Hardy-Weinberg equilibrium were observed either through space or time, nor were differences retrieved in viability or sex contribution between cytotypes. The distribution of chromosomal variation, however, showed perfect congruence with that of mtDNA-based phylogeographic clades. Thus, inversion diversity patterns in M. erythroleucus appeared more related to historical and/or demographic processes than to climate-based adaptive features. Using cross-species chromosome painting and G-banding analyses to identify homologous chromosomes in related out-group species, we proposed a phylogenetic scenario that involves ancestral-shared polymorphisms and subsequent lineage sorting during expansion/contraction of West African savannas. Our data suggest that long-standing inversion polymorphisms may act as regions in which adaptation genes may accumulate (nucleation model).

[HIV sentinel surveillance of pregnant women in Mauritania from 2001 to 2007]. / Surveillance sentinelle du VIH chez les femmes enceintes en Mauritanie entre 2001 et 2007.

According to the 2008 report on global AIDS epidemic, 33 millions of people are living with HIV/AIDS. Subsaharian Africa is the most affected part of the world. The first case of AIDS in Mauritania was reported in 1987. The national prevalence of HIV/AIDS in the country is estimated at less than 1%. The HIV serosurveillance among pregnant women started in country in 2001. This work has focused on HIV sentinel surveillance among pregnant women in antenatal clinics, attending health centres in different wilayas (regions) of the country in order to assess evolution of prevalence between 2001 and 2007. An anonymous and non-correlated method is used for this survey. A questionnaire was administered and venous sampling made for eligible women. Analyses were performed with an algorithm based on two screening tests (ELISA) and another test for confirmation (New Lav Blot). Despite some disparities between the sites considered, the results have shown a low prevalence rate (between 0.1 and 1.48). The average prevalence of HIV infection samples collected increased from 0.57% [0.34-0.80] in 2001 to 0.61% [0.40-0.82] in 2007 with 95% confidence interval. Statistical analysis showed no significant changes between 2001 and 2007 at all these sites. HIV1 is the most frequent type with a proportion of 93.5% in 2007. After several years of classic HIV sentinel surveillance, and to better understand disparities between sites, we recommend a second generation sentinel surveillance (behavioural and serological) approach.

[Hematemesis in Togo: findings of a 12-month study in an intensive care unit]. / Hématémèses au Togo: expérience d'un an en réanimation.

This prospective study was conducted over a 12-month period on patients who underwent upper digestive endoscopy for hematemesis in the medical intensive care unit (ICU) of the Tokoin University Hospital Center in Lomé, Togo. A total of 44 patients with a mean age of 44 years were included. The sex-ratio was 2.61. Risk factors included use of non-steroid anti-inflammatory (NSAI) in 16 patients (36.4%) and alcohol abuse in 13 (29.6%). At the time of admission to the ICU, 21 patients (47.7%) were in hemodynamic shock and 11 (25%) presented signs of portal hypertension. The underlying etiology was peptic ulcer in 18 cases (40.9%) including 13 cases of duodenal ulcer and 5 cases of stomach ulcer, rupture of esophageal varicosities in 8 (18.2%), gastric tumor in 6 (13.6%), Mallory Weiss syndrome in 5 (11.4%), gastritis in 4 (9,1%), and esophagitis in 3 (6.8%) due to peptic inflammation in 2 and mycotic infection in 1. The mortality rate was 45.5%. The main causes of hematemesis were peptic ulcer and rupture of esophageal varicosities. The death rate was high due to inadequate care facilities.

[Cephalometric features of patients referred for orthodontic treatment at the Dentistry Department of Dakar University]. / Caractéristiques céphalométriques de sujets reçus en consultation d'orthodontie à la clinique du Département d'odontologie de Dakar.

INTRODUCTION: Each ethnic group has its own characteristics. The aim of this study was to determine the morphological characteristics of a Senegalese population. MATERIALS AND METHODS: Sixty two lateral cephalograms of Senegalese patients were assessed in a cross sectional study. All lateral cephalometric films were traced on a transparent cellulose acetate sheet by the same operator. Conventional cephalomebic analysis was performed with 17 measurements (6 linear and 11 angular) t test was used to assess differences in age and cephalometric variable between subjects grouped according to sex (male and female). A P value of < or = 0.05 was considered statistically significant. RESULTS: No statistically significant differences were found between Senegalese men and women. This study shows an increase in the maxillary protrusion and a decrease in the mandibular protrusion with his corollary of skeletal class II. The mean of the vertical dimension measurements suggest a hyperdivergence. Protrusive lips were associated with incisors protrusion. CONCLUSION: These results which show morphological differences between Senegalese subjects and other populations consolidate the idea that the racial and ethnic characteristics must be taken into account during orthodontic diagnosis and treatment planning.

A baseline assessment of hydrologic alteration degree for the Mexican catchments at gauged rivers (2016).

River regime has been modified in several freshwater bodies around the world. This alteration has led to species loss, water pollution, higher or lesser economic profits, changes in magnitude, timing, duration and rate change of flow, among others. Thus, hydrologic alteration assessment allows evaluating the regime parameters so that stakeholders, decision-makers, and dams managers may take efficient actions to mitigate or rehabilitate riparian ecosystems. In the present study, Hydrologic Alteration Indexes on Rivers (IAHRIS, for its acronym in Spanish) and the Mexican standard approach were considered to evaluate 1150 gauged catchments in Mexico and come up with an alteration baseline for 67.03% of the country surface. The comparison may assist stakeholders to propose potential changes in the Mexican standard approach. Results reveal that 232 analyzed catchments can be considered as non-altered according to IAHRIS. In stark contrast, there are 281 non-altered catchments in Mexico in agreement with the official standard approach. Altered catchments are mainly impacted by minimum flow metrics and connectivity discharge. Additionally, the correlation between alteration indexes and 5 socio-economic variables was checked to identify which variables may greatly impact hydrologic alteration evolution or mitigation. From the five selected variables, the Human Development Index is significatively correlated to extreme minimum metrics (p = 0.94) while the Gross Domestic Product to extreme maximum metrics (p = 0.90).

Mobilisation efficacy in young patients with different stages of degenerative disc disease.

BACKGROUND: Lumbar vertebrae carry the greatest load from the spinal column, often leading to several pathologies, including degenerative disc disease (DDD), potentially disturbing spinal movement patterns. Mobilisation increases hypomobile segment mobility, however there is little evidence on mobilisation in patients suffering from different types of DDD. OBJECTIVE: To assess the efficacy of mobilisation in young patients with DDD, as diagnosed by MRI. METHODS: Thirty patients (24-35 years) participated in this study, and were divided into two groups, based on progression levels of DDD diagnosed by MRI (protrusion-PRO/extrusion-EXT). Twenty sessions of sustained stretch mobilisation (grade III) were applied to both groups over four weeks. Numeric Rating Scale (NRS), Oswestry Disability Index (ODI), straight leg raise (SLR), passive lumbar extension (PLE) and lumbar range of motion (ROM) assessed outcome variables. Three trial stages were investigated: pre-therapy (1), post-therapy (2) and follow-up (3). RESULTS: Age (p= 0.007) and NRS (p= 0.002) were significantly different before therapy. Patient outcomes were significantly improved for all parameters in both groups, except SLR which improved in the EXT group only (p= 0.043). CONCLUSIONS: Applied treatments improved patient outcomes and were statistically significant in both groups, however, better outcomes were observed in the EXT group during follow-up. Mobilisation was a safe and effective procedure for the treatment of DDD.

[Upper digestive tract endoscopy in rural Africa: Togo]. / Endoscopie digestive haute en milieu rural africain au Togo.

The purpose of this report was to describe the profile of esogastroduodenal disease diagnosed by upper digestive tract endoscopy (UDTE) in a rural area of Togo. This prospective study combines data collected during two two-week screening campaigns carried out in the Kara region. Patients were informed of the presence of the endoscopy team by means of a bulletin on a rural radio station. All male and female patients 15 years or older were included. A total of 220 UDTE procedure reports were recorded and analyzed including 107 men and 113 women with a mean age of 37.7 years (range: 15-84 years). Disease was detected in 72 procedures mainly in the 21 to 41 year age group (47.2 %) with a higher proportion of men than women: 38% versus 27% respectively. The most frequent indications for UDTE were epigastralgia (47.7 %) including 39% of procedures leading to the discovery of disease and diffuse abdominal pain (21.8 %). The procedure was carried out for follow-up purposes in 19.1% of cases. The most common lesions were peptic ulcer (34.2%), inflammatory disease including esophagitis, gastritis, and bulboduodenitis (32.4%), gastroduodenal bile reflux (9.3%), pylorobulbar stenosis (5.5%), tumoral disease (3.7%), and esophageal varicosities (3.7%). This study based on UDTE diagnostic procedures provided insight into the profile of esogastroduodenal disease in rural Africa. These screening campaigns required special organization using appropriate equipment and personnel.

[Comparison of the perception of esthetic and orthodontic treatment need between an African and a Caucasian population]. / Comparaison de la perception de l'esthetique et du besoin de traitement orthodontique entre des populations Africaine et Caucasienne.

INTRODUCTION: Improvement of dentofacial appearance is often the main motives of patient seeking orthodontic treatment. However perception of aesthetic and orthodontic treatment need may be different among populations of different cultural background. The aim of the present study was to compare the perception of aesthetic and orthodontic treatment need between Caucasian (French) and African (Senegalese) MATERIALS AND METHOD: In the present study the perception of the attractiveness of 98 colours photographs of dentitions were assessed by 34 Caucasian and 31 African lay judges by mean of a Power Point presentation. Each slide were displayed for evaluation during 20 seconds RESULTS: The two populations share the same perception of orthodontic aesthetic with respect to some occlusal traits. However they diverge in their appreciation of 70% of the dentitions with midline diastemas. There were also significant differences in the perception of orthodontic treatment need with the Caucasian judges suggesting treatment more often than Africans. CONCLUSION: The results are discussed in term of accessibility in orthodontic treatment in association with socioeconomic status.

[Serological and Behavioral Survey on HIV/AIDS among prisoners in Nouakchott (Mauritania)]. / Enquête comportementale et sérologique sur le VIH/sida chez les détenus à Nouakchott (Mauritanie).

In Mauritania, epidemiological data estimate national HIV prevalence to less than 1%. Our study is the first joint survey on HIV/AIDS conducted among prisoners in Mauritania. It is a cross-sectional survey with anonymity and informed consent. The study covered a sample of 296 prisoners enrolled in a population of 706 prisoners held in Nouakchott. The sex ratio was 14.6. The refusal rate of blood sample was 4.7%. HIV prevalence in the sample was 3.9%. 53.37% of prisoners knew the concept of seropositivity but only 7.4% had a perfect knowledge of the ways of HIV transmission untainted by false beliefs. The results showed that 99% of prisoners knew that the condom is a means of protection against HIV infection, but they also showed many false beliefs about protection against HIV in the majority of prisoners. Indeed, 98.49% of respondents said they protected themselves by avoiding sex with strangers and 94.97% of them thought that sex with young girls or virgins are protection against HIV. Nearly one quarter of the prisoners did not have a good perception of risk of contracting HIV in prison although homosexual relations between prisoners have been reported. This study showed that prisoners in Mauritania are a vulnerable group to HIV because the prevalence of HIV in this group was higher than the national prevalence and this sub-population was unfamiliar with the disease and adopt risk behaviors.