[Serological and Behavioral Survey on HIV/AIDS among prisoners in Nouakchott (Mauritania)]

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.

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.

Effects of bone morphogenetic protein-4 (BMP-4) on adipocyte differentiation from mouse adipose-derived stem cells

OBJECTIVES

As mesenchymal stem cells (MSCs) can be isolated easily from adipose tissues while retaining their self-renewal and multi-potential differentiation capacities, they hold promising possibilities for being applied extensively in tissue engineering. Bone morphogenetic protein (BMP) family members have been reported to provide instructive signals to MSCs for them to differentiate into several different cell lineages. The study described here aims to investigate whether BMP-4 could promote adipose-derived stem cell (ASC) differentiation into adipocytes under various concentrations.

MATERIALS AND METHODS

ASCs were isolated from mouse inguinal adipose pads and cultured in vitro. 10 ng/ml and 50 ng/ml BMP-4 were added to adipogenic media for 8 days. Oil red-O staining, reverse transcription/polymerase chain reaction and immunocytofluorescence staining were performed to examine differentiation of the ASCs.

RESULTS

As indicated by increased expression of adipogenic and lipogenic genes (PPAR-γ, APN and LPL) and proteins, 50 ng/ml BMP-4 seemed to induce mASCs to differentiate into the adipo-lineage compared to 10 ng/ml BMP-4, and control groups. In addition, lipid droplets accumulated within the adipocytes under 50 ng/ml BMP-4 stimulation, as shown by oil red-O staining.

CONCLUSIONS

Our present study suggests that BMP-4, as an adipo-inducing factor, promoted adipogenesis of ASCs at higher concentrations (50 ng/ml) and can perhaps be considered as a candidate for use in adipose tissue engineering.

Mechanical compressive force inhibits adipogenesis of adipose stem cells

OBJECTIVE

The aim of this study was to investigate effects of mechanical compressive force on differentiation of adipose-derived stem cells (ASCs) in vitro.

MATERIALS AND METHODS

Mice ASCs were treated with compressive force (2000 με, 1 Hz) for 2 or 6 h after adipogenic induction for 3 days, then oil red O staining was used to examine oil droplet-filled cells. Adipogenic genes, PPAR-γ1 and APN, were examined by real-time PCR and immunofluorescence (IF) staining was performed to test expression of de-PPAR-γ and ph-PPAR-γ at the protein level.

RESULTS

Our data showed that mechanical compressive force reduced numbers of oil droplet-filled cells, and down-regulated mRNA levels of both PPAR-γ1 and APN and protein level of PPAR-γ, in ASCs.

CONCLUSIONS

In culture medium containing adipogenic stimuli, mechanical compressive force inhibited adipogenesis of ASCs.

Osteogenic differentiation of adipose-derived stem cells prompted by low-intensity pulsed ultrasound

OBJECTIVES

Based on in vivo studies, low-intensity pulsed ultrasound (LIPUS) stimulation has been widely used in the clinic for advancing bone growth during healing of non-union alignment, fractures and other osseous defects. In this study, we have investigated osteogenic differentiation of adipose stem cells (ASCs) regulated by LIPUS, and also in a preliminarily manner, we have discussed diverse effects of different duty ratio parameters.

MATERIALS AND METHODS

Mouse adipose stem cells were isolated and osteogenically induced. Then they were treated with LIPUS for 10 min/day for 3 days, 5 days and 7 days, respectively. Finally, effects of LIPUS on osteogenic differentiation of the ASCs were analysed by real-time PCR, western blotting and immunofluorescence.

RESULTS

Our data indicated that LIPUS promoted mRNA levels of runt-related transcription factor 2, osteopontin and osterix in the presence of osteo-induction medium; moreover, protein levels of runt-related transcription factor 2 and osteopontin were upregulated.

CONCLUSIONS

We successfully demonstrated that LIPUS enhanced osteogenesis of ASCs, specially at the duty ratio of 20%.

Low-intensity pulsed ultrasound induced enhanced adipogenesis of adipose-derived stem cells

OBJECTIVE

The aim of this study was to investigate effects of low-intensity pulsed ultrasound (LIPUS) on differentiation of adipose-derived stem cells (ASCs), in vitro.

MATERIALS AND METHODS

Murine ASCs were treated with LIPUS for either three or five days, immediately after adipogenic induction, or delayed for 2 days. Expression of adipogenic genes PPAR-γ1, and APN, was examined by real-time PCR. Immunofluorescence (IF) staining was performed to test for PPAR-γ at the protein level.

RESULTS

Our data revealed that specific patterns of LIPUS up-regulated levels of both PPAR-γ1 and APN mRNA, and PPAR-γ protein.

CONCLUSIONS

In culture medium containing adipogenic reagents, LIPUS enhanced ASC adipogenesis.

Jagged-1-mediated activation of notch signalling induces adipogenesis of adipose-derived stem cells

OBJECTIVES

Notch signalling plays an important role in many cell activities, involving proliferation, migration, differentiation and cell death. The aim of this study was to investigate effects of such signalling on adipogenesis of mouse adipose-derived stem cells (mASCs).

MATERIALS AND METHODS

Jagged1 (50 and 100 ng/ml) was added to mASCs to activate Notch signalling, 2 days before adipogenic induction. At 5 and 7 days after induction, oil red-O staining was performed to evaluate lipid accumulation. Then real-time PCR was performed to examine expression of Notch downstream genes (Notch-1, -2, Hes-1 and Hey-1) and adipogenic transcription factor (PPAR-γ). Expressions of Hes-1 and PPAR-γ at protein level were confirmed by immunofluorescence staining.

RESULTS

Our data indicated that Jagged1 promoted adipogenic differentiation of mASCs. Moreover, Jagged1 also increased expression of Notch downstream genes and PPAR-γ. Expressions of Hes-1 and PPAR-γ were found to be enhanced in Jagged1 pre-treated mASCs when compared to controls.

DISCUSSION

The results led to the conclusion that activation of Notch signalling had stimulated adipogenesis of mASCs in the presence of adipogenic medium by promoting expression of PPAR-γ.

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.

Correlation between imaging features and epithelial cell proliferation in keratocystic odontogenic tumour

OBJECTIVES

this study was undertaken to investigate the relationship between radiographic appearance and epithelial cell proliferations in keratocystic odontogenic tumours (KCOTs).

METHODS

a retrospective radiographic analysis was performed on 284 cases of KCOT to gain insight into the radiographic characteristics. Expression of Ki-67 in 30 of the 284 cases was detected by the labelled streptavidin-biotin (LSAB) method and evaluated by an image analysis system.

RESULTS

the radiographic presentation of KCOT was divided into four types: unilocular, multilocular, multiple and naevoid basal cell carcinoma syndrome (NBCCS). The expression of Ki-67 in NBCCS was significantly different from the solitary and multiple KCOTs (P = 0.018, 0.002). In multilocular KCOTs it was also significantly different from the unilocular and syndrome-associated lesions (P = 0.000). In contrast, no significant differences were observed between the solitary and multiple lesions (P = 0.220).

CONCLUSIONS

a high correlation exists in KCOT between its biological behaviour and imaging features. The solitary KCOT seems less biologically aggressive and it should be classified as a cyst rather than a tumour. This means that more than half of KCOTs manifest themselves as ordinary cysts.

Mosquito vectors of the 1998-1999 outbreak of Rift Valley Fever and other arboviruses (Bagaza, Sanar, Wesselsbron and West Nile) in Mauritania and Senegal

Following an outbreak of Rift Valley fever (RVF) in south-eastern Mauritania during 1998, entomological investigations were conducted for 2 years in the affected parts of Senegal and Mauritania, spanning the Sénégal River basin. A total of 92 787 mosquitoes (Diptera: Culicidae), belonging to 10 genera and 41 species, were captured in light traps. In Senegal, Culex poicilipes (41%) and Mansonia uniformis (39%) were the most abundant species caught, whereas Aedes vexans (77%) and Cx. poicilipes (15%) predominated in Mauritania. RVF virus was isolated from 63 pools of Cx. poicilipes: 36 from Senegal in 1998 and 27 from Mauritania in 1999. These results are the first field evidence of Cx. poicilipes naturally infected with RVFV, and the first isolations of this virus from mosquitoes in Mauritania - the main West African epidemic and epizootic area. Additional arbovirus isolates comprised 25 strains of Bagaza (BAG) from Aedes fowleri, Culex neavei and Cx. poicilipes; 67 Sanar (ArD 66707) from Cx. poicilipes; 51 Wesselsbron (WSL) from Ae. vexans and 30 strains of West Nile (WN) from Ma. uniformis, showing differential specific virus-vector associations in the circulation activity of these five arboviruses.

Histological study of Trichosomoides nasalis (Nematoda: Trichinelloidea) in the nasal cavities of the murid Arvicanthis niloticus, with associated pathology

Histological study of the nasal cavities and upper maxillae of Arvicanthis niloticus naturally infected with Trichosomoides nasalis shows that the female worms reside in the epithelial monolayer of the nasal mucosa of the posterior and median cavities. Eggs laid by T. nasalis were infiltrated between the female body wall and the epithelial lining. Small groups of eggs, mixed with mucus and polymorphonuclear cells, were found in the nasal lumen, freed by rupture of the stretched epithelium. Two females and a few eggs were also found in the connective tissues. One male was found in a female uterus and two were apparently in the lumen of the nasal cavity but the surrounding tissues were disrupted. No male was identified in the lamina propria of the mucosa. However, significant inflammatory lesions occurred in the lamina propria, similar to those induced by the males of Anatrichosoma spp. which live in this part of the mucosa. In rodents, the lesions resulted in rhinosinusitis characterised by a lymphocytic infiltration leading to nasal obstruction.

[Salmonella enteritidis splenic abscess complicating a Plasmodium falciparum malaria attack]

INTRODUCTION

Salmonella splenic abscesses are rare and usually occur on pre-existing lesions.

OBSERVATION

A Moorish 16 year-old woman from Senegal presented with a S. enteritidis abscess without any factor other than an attack of P. falciparum malaria. Treatment associated quinine salts, antibiotherapy and splenectomy.

COMMENTS

P. falciparum malaria attacks not only induce humoral and then cellular immunodepression but are also at the origin of infarction or splenic hematoma that may enhance bacterial infection and the development of abscesses. Splenectomy or percutaneous drainage associated with antibiotherapy is the usual treatment for splenic abscesses. Prognosis remains severe (13 to 16% mortality).

[Hypothalamo-hypophyseal-adrenal hypofunction caused by the use of bleaching cosmetics in Senegal]

Cosmetic use of bleaching agents to clear skin is widespread among black West African women. In Dakar, most products used for whole body applications contain highly potent corticosteroids. Whereas cutaneous adverse effects are well described, little is known about possible systemic consequences. In order to assess transcutaneous absorption of glucocorticoids, hypothalamo-pituitary-adrenal axis functionality can be tested. We measured plasma cortisol concentration at 8 h and 1 h after intramuscular injection of 250 micrograms of cosyntropin (Synacthen) in 12 women with a more than 10 years use of bleaching agents. Cortisol at 8 H was also measured in 9 non exposed women without disease or treatment able to disturb glucocorticoids metabolism. All controls had 8 H cortisol concentration (mean = 521 +/- 113 nmol/l) above the minimal normal level considered by our laboratory. The 8 H cortisol concentrations were under the minimal normal level in 9 exposed women and the overall mean value was significantly lower than the one observed in controls (264 +/- 81 nmol/l; p < 0.001). After cosyntropin, cortisol concentrations were elevated among all exposed women (469 +/- 196 nmol/l), and less so in 3 of them. Most of the bleaching agents users present a functional inertia of hypothalamo-pituitary adrenal axis. While there is no absolute evidence for risk of stress-induced adrenal insufficiency, our results show conclusively that an excessive corticosteroids charge among users who could be exposed to systemic adverse effects.

Rift Valley fever outbreak, Mauritania, 1998: seroepidemiologic, virologic, entomologic, and zoologic investigations

A Rift Valley fever outbreak occurred in Mauritania in 1998. Seroepidemiologic and virologic investigation showed active circulation of the Rift Valley fever virus, with 13 strains isolated, and 16% (range 1.5%-38%) immunoglobulin (Ig) M-positivity in sera from 90 humans and 343 animals (sheep, goats, camels, cattle, and donkeys). One human case was fatal.

First isolation of the Rift Valley fever virus from Culex poicilipes (Diptera: Culicidae) in nature

Following the reemergence of Rift Valley fever (RVF) virus in southeastern Mauritania in 1998, an entomological survey was undertaken in the boundary area in Senegal to assess the extent of the virus circulation. During this study, RVF virus (36 strains) was isolated for the first time from Culex poicilipes in nature. The possible role of Cx. poicilipes as an RVF vector is discussed regarding its biology and ecology.

Increase of intestinal schistosomiasis after praziquantel treatment in a Schistosoma haematobium and Schistosoma mansoni mixed focus

The recent emergence of a mixed focus of Schistosoma haematobium-Schistosoma mansoni, in the lower delta of the Senegal river, requires adapted control programmes. A mass treatment with praziquantel was organised in April 1994 by local authorities in three villages where populations had been examined. A total of 2042 subjects participated. In Savoigne S. haematobium prevailed (53% for prevalence), in Diagambaly S. haematobium (64%) and S. mansoni (76%) were both abundant, and in Boundoum S. mansoni prevailed (53%). Therapeutic coverage (80%) was assessed on a representative sample. A cohort of 968 treated subjects were followed-up 40, 100, 200 and 300 days after treatment. Six weeks after treatment, the average of egg excretion decreased by 95% for S. haematobium, ranging from 23 to one egg(s)/10 ml at Savoigne and from 14 to one egg(s)/10 ml at Diagambal. Conversely, egg excretion only decreased by 75% for S. mansoni, from 23 to six eggs/g at Boundoum and from 69 to 16 eggs/g at Diagambal, showing evidence of the low susceptibility of S. mansoni local strain to praziquantel. Ten months after treatment, reinfections with S. haematobium remained weak at Savoigne (two eggs/10 ml) while those with S. mansoni were so high at Boundoum (24 eggs/g) that they compensated the reduction of load induced by the treatment. At Diagambal, where the two parasites were present before treatment, the disappearance of the urinary schistosomiasis after treatment concurred with a dramatic increase of intestinal schistosomiasis. S. manoni egg excretion was seven times higher than before treatment (478 eggs/g). These different effects of treatment are discussed according to the ecology of transmission in the three villages.

The impact of the local water-development programme on the abundance of the intermediate hosts of schistosomiasis in three villages of the Senegal River delta

The populations of the potential intermediate hosts of Schistosoma mansoni and S. haematobium were studied for a year at transmission sites near three villages in the lower delta of the Senegal River. Biomphalaria pfeifferi, found to be widely distributed and increasingly abundant, appears to be well adapted to the new areas of irrigation (created by the dams at Diama and Manantali) thanks to its ability to withstand changes in temperature and to aestivate. This species is responsible for intense transmission of S. mansoni during the rainy season. In contrast, Bulinus globosus, the species responsible for the transmission of S. haematobium (which occurs during the dry season), had a more limited distribution. The changing distributions of these two snail species appear to be linked to changes in local ecology, themselves the result of the recent programme of water-development in the delta.

[Tetralogy of Fallot. Anatomo-clinical, prognostic and therapeutic features]

Between Feb. 1992 and Aug. 1995 during a prospective study Tetralogy of Fallot (TF) has been diagnosed in 34 children among 207 with congenital heart disease (CHD). Our purpose is to assess prevalence of TF among CHD, to analyse clinical and paraclinical aspects in patients with TF and to point out associated abnormalities in that disease. In all patients diagnosis was made by echocardiography-Doppler (ATL MK 600). In our patients with CHD, TF represent the third abnormality encountered accounting for 16.49% after ventricular septal defect (30.9%) and persistent ductus arteriosus (18.8%). Mean age of patients with TF is 8.36 years. History showed cardiopathy in the family of one patient. The brother had persistent ductus arteriosus. In our patients with TF, clubbing is present in 70.58% of the cases, cyanosis in 79.41% and squatting in 76.47%. Anoxic spells are present in six patients. On chest x-ray mean cardio-thoracic ratio is 0.57 +/- 0.076. On ECG mean QRS axis is +121 +/- 22.91 degrees. In one patient with Cornélia Delange syndrome TF is associated with complete endocardial cushion defect. Mean follow-up is 332,42 days. Endocarditis on the pulmonary valves is present in one case. Four patients died after complications. Because of poor clinical tolerance and complications, surgery is indicated for all our patients. Only 7 patients underwent surgery. Two of them were operated in Dakar. There was two postoperative complications, one patient had brain abscess which necessitate reoperation, and the other had hypertension in the right ventricle and atrial right to left shunt. Our study shows that TF is an important nosologic group. In our country this frequent malformation have a poor prognosis in the majority of cases because late detection and frequent complications. Because palliative surgery for TF is now available in Senegal prognosis of the patients is going to improve. Future Development of open heart surgery will offer a corrective approach for patients with TF in Senegal.

[Left ventricular aneurysm of indeterminate etiology revealed by an episode of ventricular tachycardia]

INTRODUCTION

We present a case history of a 39 years old woman with parieto-apical left ventricle aneurysm of unknown etiology. The etiologies are being discussed in the light of our case and literature review.

METHODS

We have analysed clinical data, 12 leads ECG recording, chest X-ray and biological data of our patient. We have used an ATL MK 600 for echo-Doppler examination. Coronaro-ventriculography has not been performed. The results are compared with data from the relevant literature.

RESULTS

Our patient presents at admission tachycardia (150 beat per min) and congestive heart failure. ECG recording showed a sustained tachycardia with large QRS complex (140 msec). At oesophageal ECG recording, atrio-ventricular dissociation was present confirming ventricular tachycardia. The tachycardia has been stopped by lidocaine and amiodarone IV. Chest X-ray shows cardiomegaly (cardio-thoracic index: 0.70) and a protruding left cardiac border. At echocardiographic examination a left dyskinetic anterior and apical aneurysm of the left ventricle has been documented. Surgical repair has not been performed because of the large aneurysm and the reduced function of the non aneurysmal contractile zones.

CONCLUSION

In our case, myocardial infarction was not evident, regarding history and examinations. In the etiologic discussion of left ventricle aneurysms, coronaro-ventriculography must be performed. Dilated cardiomyopathy complicated by left ventricle aneurysm can be postulated in our patient.

[Congenital cardiopathies: anatomo-clinical, prognostic, and therapeutic features apropos of 103 cases seen at the Cardiology Clinic of the Dakar University Hospital Center]

We have studied retrospectively 103 patients with congenital heart disease from july 1989 to december 1991. The mean age is 7.8 years +/- 8.6. Epidemiological factors, clinical, morphological and prognostic data have been reviewed. All the patients had been evaluated with echocardiography based on an anatomical and segmental approach. Sex-ratio is 1.11. Situs is solitus in 101 cases (98%). Atrio-ventricular connexions are concordant in 97 patients (94%). The ventriculo-arterial connexions are concordant in 91 patients (88%). We found an anomaly of the spatial relation between great vessels in 9 cases (8.7%). Echocardiographic diagnosis have been confirmed by catheterism and at surgery in 10 patients, and by post-mortem examination in 2 cases. Isolated ventricular septal defect is the most frequent anomaly (19.4%), followed by Tetralogy of Fallot (17.5%). Only 13 patients among the 75 (17.3%) needing surgery have been operated. Six patients (5.8%) died following complications of the malformation. The prognosis without surgery is poor for the majority of our patients with congenital heart disease. Improved early detection and acquisition of adequate diagnosis technology are needed to realize surgical corrections.

[Rupture of a sinus of Valsalva aneurysm into the right ventricle. A case report in the cardiology clinic at the University Hospital Center of Dakar]

We report a case with ruptured aneurysm of the sinus of Valsava into the right ventricle, diagnosed during heart failure in a 22 years old patient. Etiology and prognosis based on our observation and the literature are discussed. Our patient benefited from clinical examination, ECG (15 derivations), pulmonary X ray and standard laboratory test. Pulsed-Doppler and contrast echocardiography have been realized with an ATL MK 600 echocardiograph. These data are discussed and compared to the literature. Cardiac examination revealed a continuous murmur predominantly diastolic 5/6 and an increase of peripheral artery pulsatility. Chest x-ray showed cardiomegaly and ECG bilateral atrial and left ventricular hypertrophy. Two-dimensional echocardiography revealed the diastolic prolapse of an aneurysmal right coronary sinus in the right ventricle. The rupture was confirmed by contrast echocardiography and pulsed-Doppler. Rupture which is a major complication of aneurysm of the sinus of Valsava, is the usual feature of detection. The consequences of rupture are heart failure and pulmonary edema. Our observation shows that conventional Doppler and contrast echocardiography are important for diagnosis and follow-up of aneurysm of the sinus of Valsava. Aortography, hemodynamic and angiocardiographic data, are also important for a precise diagnosis and the detection of associated malformations when pre-operative investigations of aneurysm of the sinus of valsava are needed.

[Annulo-aortic ectasia syndrome apropos of 4 cases]

The authors present four cases of annuloaortic ectasia recently observed in Dakar Principal Hospital; two cases are MARFAN's syndrome, one is complicated by aortic dissection. Third cause of aortic regurgitation, this disease must be diagnosed early on account of its bad prognosis with the risk of the dissection of the aorta and issue to cardiac insufficiency. The diagnosis is more often affirmed by transthoracic echocardiography. Treatment is surgical with low operative mortality and excellent long term result.

[Congenital heart disease surgery in Senegal. Indications, evaluation and perspectives]

In Senegal, congenital heart diseases (CHD) raise important issues. Their late detection makes more complicated the non yet resolved issue of the medico-surgical care. 108 patients with congenital heart diseases have been studied prospectively from February 1992 to May 1994. Epidemiological, clinical, paraclinical data are analysed. Prognosis and treatment are discussed. Congenital heart diseases represent 1% of the outpatient cardiovascular pathology. Diagnosis of the malformation based on echocardiography shows that most of congenital heart diseases are ventricular septal defect (25%); followed by Tetralogy of Fallot (13%). Average age of the patients is 6.86 years. 31% of the cases have heart failure. ECG is abnormal in 103 patients. On the radiologic side, average cardio-thoracic ration is 0.61. Because of heart failure, pulmonary hypertension and hypoxia, the spontaneous prognosis is cautious in 71 patients (66%) who should receive surgical treatment. Among them, 5 patients non operated died and 10 (14%) have been operated. Among the 10 patients who got surgery, 3 with wide persistent ductus arteriosus got in Dakar. All these patients have excellent operative results. In Senegal, only close heart surgery is available and prognosis of the vast majority of patients, including those with valvular and coronary heart diseases, is very cautious. Intervention of Europe-based aid organizations for evacuation is not useful. It is very important to promote, in Senegal, open heart surgery.

Four years' entomological study of the transmission of seasonal malaria in Senegal and the bionomics of Anopheles gambiae and A. arabiensis

From 1993 to 1996, an entomological survey was conducted in the village of Ndiop, Senegal, as part of a research programme on malaria epidemiology and the mechanisms of protective immunity. Mosquitoes were captured on human bait and by indoor spraying. Species from the Anopheles gambiae complex were identified using the polymerase chain reaction, and Plasmodium falciparum infections were detected by enzyme-linked immunosorbent assay for circumsporozoite protein. The vector species identified were A. gambiae (33.9%), A. arabiensis (63.2%), A. melas (0.3%) and A. funestus (2.5%). Similar proportions of A. gambiae (74.2%) and A. arabiensis (73.8%) contained human blood; 27.0% of A. gambiae and 28.3% of A. arabiensis had fed on cattle. The sporozoite rates were similar for A. gambiae (3.2%) and A. arabiensis (3.7%). The annual entomological inoculation rates varied greatly depending on the year. There were 63, 17, 37 and 7 infected bites per person per year in 1993, 1994, 1995 and 1996 respectively. Transmission was highly seasonal, from July to October. A. arabiensis was responsible for 66% of malaria transmission, A. gambiae for 31%, and A. funestus for 3%.

Comparison of behavior and vector efficiency of Anopheles gambiae and An. arabiensis (Diptera:Culicidae) in Barkedji, a Sahelian area of Senegal

The ecology, population dynamics, and malaria vector efficiency of Anopheles gambiae and An. arabiensis were studied for 2 yr in a Sahelian village of Senegal. Anophelines were captured at human bait and resting indoors by pyrethrum spray. Mosquitoes belonging to the An. gambiae complex were identified by polymerase chain reaction. Of 26,973 females, An. arabiensis represented 79% of the mosquitoes captured and remained in the study area longer than An. gambiae after the rains terminated. There were no differences in nocturnal biting cycles or endophagous rates between An. gambiae and An. arabiensis. Based on an enzyme-linked immunosorbent assay test of bloodmeals, the anthropophilic rate of these 2 vectors were both approximately 60%, when comparisons were made during the same period. Overall, 18% of the resting females had patent mixed bloodmeals, mainly human-bovine. The parity rates of An. gambiae and An. arabiensis varied temporally. Despite similar behavior, the Plasmodium falciparum circumsporozoite protein (CSP) rates were different between An. gambiae (4.1%) and An. arabiensis (1.3%). P. malariae and P. ovale only represented 4% of the total Plasmodium identified in mosquitoes. Transmission was seasonal, occurring mainly during 4 mo. The CSP entomological inoculation rates were 128 bites per human per year for the 1st yr and 100 for the 2nd yr. Because of the combination of a high human biting rate and a low CSP rate, An. arabiensis accounted for 63% of transmission. Possible origin of differences in CSP rate between An. gambiae and An. arabiensis is discussed in relation to the parity rate, blood feeding frequency, and the hypothesis of genetic factors.

Body size variability and water balance: a comparison between mainland and island populations of Mastomys huberti (Rodentia: Muridae) in Senegal

Generally rodents are found to be larger on islands than on the mainland. However, there are some exceptions to this rule, and the aim of this paper is to examine one of them. On the mainland of Senegal, Mastomys huberti occupies humid habitats. However, it occurs also on dry and sandy islands (Saloum delta), where its representatives are dwarf. Since water availability appeared to be the limiting factor in these islands when compared to the mainland, we studied water turnover characteristics in relation to body size, in mainland and island populations at the end of the dry season, under both field and laboratory conditions. All populations were found to be water balanced in their natural habitats. They presented similar rates of water turnover, even though island animals were subjected to stronger constraints than mainland ones. Laboratory experiments suggested that the physiological plasticity of one of the island populations may be reduced. Island populations have a higher kidney size to body weight ratio than those from the mainland. We propose that smaller size in the islands allows the maintenance of water balance with a smaller amount of water, and that a higher ratio of kidney filtration surface to body size may help Mastomys huberti to survive in dry islands. We discuss the factors responsible for body size variability and variation in water exchange characteristics and conclude that different factors could explain body size variation among island populations, depending on the species considered and the ecological constraints met within the islands.

Rift Valley fever in rural northern Senegal: human risk factors and potential vectors

To investigate past infection in and transmission of Rift Valley fever (RVF) virus to humans within an endemic focus, we undertook a retrospective cohort study of the seminomadic Peul people living in sub-Saharan northcentral Senegal. Residents of the rural settlement of Yonofere five years of age or older were studied during February-May 1989. Anti-RVF virus IgG was found in blood samples of 22.3% of 273 persons who responded to a standard questionnaire; none had IgM antibodies. Seropositivity was similar for males (25.4%) and females (21.1%), increased markedly with age for both sexes, and varied considerably among compounds (groups of huts) (0-37.5%). Risk factors for past RVF virus infection were nursing sick people, assisting animals during abortions/births, and treating sick animals. In all age groups, odds ratios (ORs) for RVF viral antibody among females who reported treating sick animals were three to six times greater than for those who did not. The ORs for males who reported assisting with animal births/abortions and nursing sick people were approximately five times those for males who did not. Serologic prevalence of RVF viral antibody among sheep averaged 30.1% overall (0.8% IgM), but varied among compounds (0-66.7%) in a manner different from that of humans. The seasonal abundance and relative density of potential mosquito vectors were estimated by monthly samples captured in Centers for Disease Control and Prevention-type traps. Mosquito abundance varied seasonally with rainfall (> 90% captures during four months). Species diversity was large (28 spp.), dominated by Aedes and Culex. Rift Valley fever virus was not isolated from 142 pools of 2,956 unengorged mosquitoes tested, although three other arboviruses were found. Results indicate that RVF is endemic in this region, people are at considerable risk of infection, and that a heretofore unrecognized mode of human infection under nonepizootic conditions may be transmission via contact with infected animals or humans.

A longitudinal survey of Borrelia crocidurae prevalence in rodents and insectivores in Senegal

We report results of a longitudinal survey designed to determine the importance and the dynamics of Borrelia crocidurae, the spirochete responsible for tick-borne relapsing fever in West Africa in rodents and insectivores in a rural area of northern Senegal. A total of 954 animals were caught during bimonthly capture sessions over a two-year period. Positive thick blood smears were recorded in 17.6% of the 740 rodents and 7.3% of the 55 musk shrews tested. Variations of prevalence were analyzed in Arvicanthis niloticus and Mastomys huberti, which represented 62.7% and 28.3%, respectively. of the animals captured, and 65.7% and 27.6%, respectively, of the animals found infected. Borrelia crocidurae prevalence was significantly different between captures and fluctuated separately for each species. Age-specific prevalence of B. crocidurae showed distinct patterns, decreasing with age from 50% in younger juveniles to 3% in older adults for A. niloticus, while increasing with age from 8% to 23% for M. huberti. No relationship was observed with animal abundance or with the season of the year for either species. These findings suggest that the diversity of the population dynamics of host-vector-parasite associations in the Sahel region of Senegal may be a key factor for the relative stability of the borreliosis reservoir.

Risk factors for Crimean-Congo hemorrhagic fever in rural northern Senegal

The extent of infection among 722 residents of an enzootic focus of Crimean-Congo hemorrhagic fever (CCHF) virus in rural northern Senegal and putative modes of transmission were studied by a cross-sectional seroprevalence survey done from February through May 1989. Anti-CCHF virus IgG was found in 13.1% of 283 persons who completed a standard questionnaire and provided blood samples. Seropositivity rates were similar between sexes and increased significantly with age among nomadic persons. Behavior patterns providing exposure to multifactorial risk factors were gender-based. Male risk factors, primarily associated with herding activities, included sleeping outside during seasonal migrations (also a risk factor for nomadic women), bite by a tick (adult male Hyalomma truncatum), tick bite during the cool dry season, and contact with sick animals. Human infection of CCHF occurred more frequently or with less mortality in the region studied than has been found elsewhere in Africa; however, the rate of seroconversion-associated illness is undetermined. Hyalomma ticks appear to be the primary transmission mode.