The introduction of new hosts with human trade shapes the extant distribution of Toxoplasma gondii lineages

Toxoplasma gondii is a zoonotic protozoan with a worldwide occurrence, but the determinants of the current pattern in the geographical distribution of T. gondii lineages and strains remain poorly understood. To test the influence of human trade on T. gondii populations, we conducted a population genetic study of 72 T. gondii animal isolates from Senegal, a West African country in which the ongoing inland progress of invasive murine hosts (introduced in port cities of Senegal since the 16th century by European sailors) is well described. Isolates were mainly collected on free-range poultry, which are considered as relevant bioindicators of T. gondii strain diversity in the domestic environment. Sampling was conducted in two port cities of Senegal (Dakar and Saint-Louis) and in one inland region (Kedougou). Population genetic analyses using 15 microsatellite markers revealed different patterns between port cities where lineages non-virulent for mice (type II, type III, and Africa 4) were predominant, and Kedougou where the mouse-virulent Africa 1 lineage was the most common. By considering the current spatial pattern in the inland progress of invasive rodents in Senegal, our results suggest that the invasive house mouse Mus musculus domesticus counter-selects the Africa 1 lineage in the invaded areas. The comparison of the microsatellite alleles of type II strains from Senegal to type II strains from other areas in Africa and Western Europe, using discriminant analysis of principal components and Network analysis, point to a mainly Western European origin of the type II lineage in Senegal. Collectively, these findings suggest that human-mediated intercontinental migrations of murine hosts are important vectors of T. gondii strains. Differential susceptibility of endemic and introduced murine hosts to various T. gondii strains probably determines the persistence of these strains in the environment, and therefore their availability for human and animal infection.

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.

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.

Transmissivity evolution through interface of composite liners under applied constraint

In landfill liners, geomembranes have defects that constitute preferential passages of leachate from rainwater percolation. Non-woven geotextiles are widely used in wastelandfills as materials having the functions of protection, separation, filtration and drainage. This study seeks to select geotextiles through an investigation conducted among landfill operators who commonly arise a geotextile in the geomembrane-clay interface to facilitate geomembrane welding and to prevent its puncture by angular materials. It also attempts to find out the influence of geotextile in a decimetric transmissivity cell size under 50 kPa stress and smooth ground surface. The results show that the transmissivity in composite liner interface is almost the same as the one calculated with the European standard EN ISO 12958. Transmissivity depends on the mechanical stress applied to the bottom liner, on the geotextile type in the interface and on the ground surface.

[Dermatomyositis and polymyositis: 21 cases in Senegal]

Dermatopolymyositis (DPM) is a term describing a group of disorders comprising multiple distinct entities depending on interactions between genetic and environmental factor. There is a paucity of studies on DPM in black Africa. The purpose of this report is to describe epidemiological, clinical, laboratory and therapeutic aspects of dermatomyositis (DM) and polymyositis (PM) observed at the Principal Hospital in Dakar, Senegal. A retrospective review as conducted of patients hospitalized for DM and PM in Medical Departments of Principal Hospital. Diagnosis of DRM was based on the criteria of Bohan and Peter's in all cases. A series of 21 black African patients was compiled including 15 with DM and 6 with PM. Mean age was 52 years and the M/F sex ratio was 0.6. The mean delay for diagnosis was 6 weeks (range, 3 to 12 weeks). Initial signs were dermatological in 12 patients, pulmonary in one and muscular in the remaining cases. The most common dermatological sign was erythema characterized by a zebra-like aspect on the extended limbs. Erythema was frequently pruriginous with a flagellate aspect on the back. Muscular signs were observed in 18 patients and included pharyngeal manifestations in 10 patients. Amyopathic DM was not observed. Cardiac abnormalities included tachycardia (4 cases), AVB (1), ischemic lesion (1), relaxation disturbances (4), pericardial effusion (3), myocarditis (2) and pulmonary hypertension (1). The most common pulmonary manifestation was interstitial lung disease observed in 6 patients. Gastrointestinal signs were noted in 9 patients including endoscopic evidence of superficial erosion in 4 cases. Electromyography (EMG) tracings revealed myogenic disease in 14 cases including 2 associated with reduced peripheral nervous conduction speed. Severe lymphopenia was observed in 3 patients but HIV serology was negative in all cases. Paraneoplasic DM was observed in 3 cases. Death occurred in 5 cases due to the cancer-related, pulmonary and infectious complications. Based on the findings of this study, the three main features of DM and PM in Senegal are flagellated and often pruriginous erythema, cardiac and interstitial lung disease, and peripheral neural involvement.

[Acute transverse myelopathy after intramuscular injection of benzathine-benzylpenicillin. Case report in Dakar, Senegal]

Intramuscular injection of benzathine-benzylpenicillin can cause acute transverse myelopathy. The purpose of this report is to describe a case of acute transverse myelopathy observed after injection of benzathine-benzylpenicillin in a 38-year-old man. The patient who was married and had a history of eczema was admitted to the Department of Neurology of the Fann University Teaching Hospital in 2006. All laboratory findings were normal except high serum immunoglobulin E level. An immunoallergic reaction involving inflammatory transverse myelopathy secondary to vasculitis was proposed as the most likely underlying mechanism. Treatment with corticosteroid and physiotherapy led to a favorable outcome. Health personnel should know the indications for use of benzathine-benzylpenicillin and be aware of the possible medullary complications.

[Epilepsy in a cohort of Senegalese children]

Epilepsy is a significant health public problem in Senegal with an estimated prevalence of 8 to 14%. The aim of this study was to determine the clinical and electroencephalographic features of epilepsy in a cohort of Senegalese infants, search for etiological factors and determine the impact of disease on school life. This retrospective study concerned 459 children who attended the neurological outpatients clinic at the Fann hospital, Dakar, Senegal, between July 2003 and December 2006. All were aged under 19 years. Among the 135 children with idiopathic epilepsy, 23.7% had parental consanguinity and 37.77 % familial epilepsy. Rolandic epilepsy and epilepsy with absences were more frequent but several infants with idiopathic epilepsy were not classified. Non-idiopathic epilepsy was noted in 312 children. In this group, estimates of parental consanguinity and familial epilepsy were of 21.79 and 17.94%, respectively. Etiological factors were predominantly pregnancy and birth abnormalities (28.84%) and central nervous system infection (20.19%). Twelve children had febrile seizures. Of patients with idiopathic epilepsy, 65.18% were attending school versus only 9.29 with non-idiopathic epilepsy.

[Evaluation of the cost of stroke management in Dakar, Senegal]

The purpose of this one-year cross-sectional study conducted in 1997 was to estimate the direct cost of stroke management in the Neurology Department of Fann University Hospital in Dakar, Senegal. Data were collected about the type of care services required and related spending. Cost analysis was made in CFA Francs (CFAF), the Senegalese currency (1 USD = 500 CFAF in 1997). A total of 1260 patients were hospitalized in the department including 383 for stroke (30.4%). Mean age was 60.8 +/- 14.2 years and men accounted for 49.2% of the population. The mortality rate was 46.2% among hospitalized patients. A total of 33,573 medical acts were carried out including 12,052 (35.9%) for stroke management. The direct cost of stroke management was 32,614,442 CFAF with a mean cost of 78,426 CFAF per patient. The cost was 18,839 CFAF in the patient care unit (57.8%) and 4,954,635 CFAF in the neuroradiology unit (15.2%). The cost of health care personnel was 19,373,172 CFAF (59.4%) and the cost for drugs and other medical products was 8,253,246 CFAF. Health education programs aimed at increasing awareness of risk factors are needed to reduce the cost of stroke management in this difficult economic period.

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.

[Peripheral neuropathies and antiretroviral drugs. Preliminary results]

INTRODUCTION

In order to appreciate the antiretroviral drugs impact in the HIV positive patients with peripheral neuropathy, a clinical, electrophysiological and neurpathological study of nerve biopsies was performed.

PATIENTS AND METHODS

A group of 8 HIV seropositive patients with peripheral neuropathy was compared with an other group of 10 HIV seropositive patients treated with multiple antiretroviral drugs. Electrophysiological examination with motor nerve conduction velocity (MNCV) mesure of the median and the sciatic popliteal nerve was followed by nerve biopsy. Nerve fragments carried out the neuropathological technics for morphological examination.

RESULTS

Eighteen seropositive HIV patients (16 HIV-1 and 2 HIV-2) were included in this study. Six patients among them had motor and sensitive neuropathy of the four limbs and 2 patients had sensitive neuropathy associated with pyramidal signs. In fine, 1 patient had sensitive neuropathy with distal amyotrophy of the four limbs. Slow MNCV was observed in all the patients and more severe in the lower limbs. Nerve were unexciting in the lower limbs in 2 patients. Nerve biopsy showed severe axonal loss in all the patients treated but one. They associated axonal lesion in 5 cases and myelinated lesions in 2 cases. Two patients non treated had normal nerve biopsy. Axonal loss was mild in 2 cases and very severe in one case associated with non inflammatory demyelinated lesions.

CONCLUSION

we observed more severe and more frequent nerve lesions in treated patients than in no treated patients, as at the clinical, electrophysiological and neuropathological examination. Antiretroviral drugs cause more frequently pain motor and sensitive neuropathies at usual posologies. The occurence of recrudescence of pain peripheral neuropathy under antiretroviral treatment allows to reconsider drugs posologies.

[Diabetic neuropathies in Neurological Clinic of Dakar]

INTRODUCTION

Common diabetic mellitus complication, neuropathies present various clinical forms. OBJECTIVE to evaluate the hospital frequency and clinical features of diabetic neuropathies.

PATIENTS AND METHOD

It is a retrospective study concerning peripheral neuropathies observed in "clinique neurologique" of Dakar between January 1991 and December 2001 in diabetic patients treated for a long time. Inclusion criterion are distal and/or proximal sensitive and/or motor neuropathies with abolition or reduction of patellar reflex. Are excluded neuropathies of others aetiologies. Electrophysiological examination with motor conduction velocity measure is performed in about half of them . One neuro-muscular biopsy was performed using current neuropathological examination including teased fiber technic.

RESULTS

17 cases of peripheral neuropathy are observed on 10,000 documents (0.17%). They were 11 males and 6 females, aged from 27 to 77 years (means 56.41). Among them, 10 cases of distal motor sensitive neuropathy are identified; 2 cases of sensitive neuropathy, 3 cases of pure motor neuropathy and 2 cases of multiple mononeuritis neuropathy with dysautonomic disorders of sphincter and genital type in one of them. Glucose serum level was between 1.25 to 4.25 g/l . Diabetes was 18 months to 20 years of duration at the moment of admission . Normal serum level glucose was rapidly obtained with insulin treatment. The evolution was favourable in 82.9% of cases under anti-diabetic treatment, vitamin B and kinesitherapy.

CONCLUSION

diabetes mellitus neuropathies are rare in "Clinique n eurologique" of Dakar where diverse clinical forms are observed. Favourable outcome in most of cases occurred when serum glucose equilibration is rapidly obtained.

[Role of Anopheles melas Theobald (1903) on malaria transmission in a mangrove swamp in Saloum (Senegal)]

From June 1995 to January 1998, entomological studies carried out in five villages located in the Delta's Saloum have allowed to better understand the contribution of An. melas Theobald (1903) to malaria transmission in mangrove swamp. Among the five villages studied, three of them (Simal, Djilor and Marlothie) located along the Saloum river, are colonised by An. arabiensis; the two others (Djifere and Diakhanor) located between the sea and the river, are colonised by An. melas. During the rainy season and at the beginning of the dry season, An. melas and An. arabiensis are sympatric. The ratio of An. melas/An. arabiensis increases when we go closer the coast where An. melas becomes quite exclusive. When An. melas is predominant, endophagy, endophily and anthropophily are very marked. The parturity rates are lower in An. melas than in An. arabiensis. In the predominance area of each species, transmission is on the same level. During the period of sympatry, An. arabiensis is responsible for the transmission and when it is absent, An. melas carries on. Transmission occurs from July to March with a maximum at the beginning of the dry season. In the villages of the mangrove swamp, its prolongation until the middle of the dry season is due to An. melas.

[Anatomophysiologic and clinical study of the association of epilepsy and Parkinson's disease: apropos of 2 cases]

The authors described the first cases in Senegal (West Africa) of the association Parkinson's disease and epilepsy. Almost studies on this feature, stressed on their different pathophysiology basis epilepsy is related on excess of neuronal excitation, and Parkinson disease is an expression of lack of motor neuromodulation. The diagnosis has been done because of the coming out two seizures in the year on two patients one 59 years old and the other 70 years old experiencing Parkinson disease well documented before and treated. Biological study, ultrasonography and Doppler, CT Scan lead to rule out a vasculopathy. Good outcome with antiparkinsonian and anticonvulsant medications confirm the diagnosis.

Use of reverse transcriptase PCR in early diagnosis of Rift Valley fever

Reverse transcriptase PCR (RT-PCR) for diagnosis of Rift Valley fever (RVF) was evaluated by using 293 human and animal sera sampled during an RVF outbreak in Mauritania in 1998. Results of the RT-PCR diagnostic method were compared with those of virus isolation (VI) and detection of immunoglobulin M (IgM) antibodies. Our results showed that RT-PCR is a specific, sensitive tool for RVF diagnosis in the early phase of the disease and that its results do not differ significantly from those obtained by VI. Moreover, the combined results of RT-PCR and IgM antibody detection were in 100% concordance with the results of VI.

[Cerebral palsy in Dakar]

The objective of the study was to describe risks factors of cerebral palsy and to determine clinical forms. From November 1998 to July 2000,we conducted a prospective study to select outpatients showing cerebral palsy symptoms: so 93 children with age between 5 months and 11 years old entered on this study. For 44.08% cerebral palsy was related on pregnancy abnormalities, 32.26% have central nervous system infection and 8.6% have convulsions unknown cause . The cause of cerebral palsy was untraceable in 13.98% of the cases. 82.8% of the children have cerebral palsy associated with other handicaps. The commonest type of cerebral palsy was spastic forms (74.2%) followed by hypotonic cerebral palsy (16.13%), dystoniaathetosis and ataxic forms in 5.37% and 4.3% of the cases respectively. The overall prevalence of epilepsy was 46.23%. The other handicaps were neurosensoriel abnormalities (visual impairment, deafness), speech disorders and behavioural problems. Computerised tomography (CT), performed in 45 cases showed cortical/subcortical atrophy as the commonest brain lesions. The electroencephalographic abnormalities were identified frequently.

Fastigiovestibular projections in the rat: retrograde tracing coupled with gammaamino-butyric acid and glutamate immunohistochemistry

In this study, a double labeling technique using retrograde tracing with protein-gold complex (gold-HRP) in conjunction with a gammaamino-butyric acid (GABA) and glutamate immunohistochemical procedure was performed to identify GABA (GABA-IR) and glutamate (Glu-IR) immunoreactive neurons in the cerebellar fastigial nucleus (FN) that projects to the vestibular nuclei (VN). The results show that FN neurons projecting to the VN consist of both GABA-IR and Glu-IR neurons with a predominance of glutamatergic ones. Because GABAergic neurons in the cerebellar nuclei project to the inferior olive (IO), double retrograde labeling experiments were performed with injections of gold-HRP in the IO and of biotilynated dextran amine in the VN. This showed that the GABA-IR fastigiovestibular neurons project by axon collaterals to both the VN and the IO.

Dentatovestibular projections in the rat

The dentatovestibular connections were investigated using anterograde and retrograde tracing methods. All parts of the cerebellar nucleus lateralis (NL) or dentate nucleus sent fibers onto the ipsilateral vestibular nuclear complex. In spite of their apparently widespread area of termination, dentatovestibular fibers were distributed differentially, according to the subregion of the NL they arose from. Fibers from the main, magnocellular region and the dorsolateral hump (dlh) reached the four main vestibular nuclei, but preferentially the superior (SV) and inferior (IV) vestibular nuclei. The projections to the lateral and the medial vestibular nuclei, which were less abundant, essentially originated from neurons located in the dlh. Fibers arising from the parvocellular subregion of Flood and Jansen terminated within the SV and IV only. Some rare reciprocal vestibulodentate projections were observed. These observations suggest highly integrated activities of dentatovestibular connections related to postural, but also vestibulo-oculomotor functions.

[Trichosomoides nasalis Biocca & Aurizi, 1961 and T. spratti n. sp. (Nematoda: Trichinelloidea), from the nasal cavity of murids]

The nematode parasite of the nasal mucosa of rodents, Trichosomoides nasalis, is common in the murid Arvicanthis niloticus, in Senegal. The morphological study of this material allowed us to augment the original description, made with specimens recovered in Italy from Rattus norvegicus. This analysis shows that specimens from Rattus fuscipes in Australia, which had been identified to this species, represent a distinct species (smaller, with an average of five intrauterine males per female instead of one), which we name T. spratti n. sp.

[Peyronie's disease and peripheral neuropathies]

The association between Peyronie's disease and diabetes mellitus or Dupuytren's disease is well described in the literature with a certain frequency. Through our 10 patients with Peyronie's disease, when have noticed that only one of them is undergoing diabetes mellitus and no one has Dupuytren's disease. But 7 of them presented clinical and/or electromyographical signs of peripheral neuropathy. So after clinical examination in neurology and urology, we performed measurement of motor conduction velocity of tibial posterior nerves and peroneal nerves, then, we measured sensitive vetocity of sural nerves and dorsal nerve of the penis and we studied the cortical somesthesic evoked potential of the internal hontous nerve and the sympathetic evoked response of the skin. So we hypothesize that peripheral neuropathy with or without autonomic disorders might be an etiological co-factor of Peyronie's disease.

[Neuroepidemiology of epilepsy in Senegalese school milieu]

The authors proceeded to a 7 month long prevalence survey on epilepsy in the schools of the regions of Dakar and Thies in Senegal, West africa. It consisted to a cross sectional descriptive study targeting the children between 3 and 10 years old. The W.H.O. questionnaire on epilepsy was used for data collection. Among the 2803 children of the population study, 58 were detected suffering from epilepsy, realizing a prevalence rate of 21%. The males were more represented (62% of the epilepsies). All the epileptic children presented generalized seizures represented either by "Grand Mal" generalized tonic-clonic form (84.4% of the epilepsies), or by "Petit Mal" absences (15.6% of the epilepsies). The etiological forms were dominated by idiopathic epilepsies. Secondary generalized cases represented 31% of the epilepsy and were essentially detected in rural areas. They were usually related to obstetrical traumas (61.1% of the secondary generalized epilepsies) or to child encephalopathy with seizure attacks (38.9% of the secondary generalized epilepsies). It appears also from this study that epilepsy remains a dramatic public health reality and is more frequent among low economy income people who have less access to the health care system.

[Epidemiological, clinical and progressive aspects of neurological manifestations associated with retroviral infections: eleven year retrospective study]

Through a cohort of 93 neuroaids which has been diagnosed at Dakar in our Neurology Department, the authors evaluated the hospital prevalence of retrovirus, detected socio-demographic factors, related AIDS outline the mean neurological picture and try to correlate survival and neurological involvement of these patients. Among 1151 patients who got retroviral blood test, 93 were seropositive (8.1%). On these repartitions 36 were females (38.7%) and 57 males (61.3%). The age goes from 19 to 76 years old. 45 patients (48.4%) have been found positive for HIV-1 blood test, 21 patients (22.6%) for HIV-2 blood test, 11 patients (11.8%) for both HIV2, 11 patients (11.8%) for HTLV1, 3 patients (3.2%) for both HIV-1 and HTLV1, and 2 patients (2.2%) for both HIV-2 and HTLV1. In our study the transmission of AIDS occur mainly through heterosexual inter course and multiple parternship is a high risk group. The central nervous system deseases represented 68.8% of cases. The pathology were dominated by stroke, myelopathies, meningoencephalotis and spinal cord compression. The peripheral nervous system desease were found in 7.5% of cases. The peripheral facial paralysis occupied the first place in HIV infections of peripheral nervous system deseases (57.1% of cases). When neurological involvement set up the letality is higher for HIV-1 (57% of global letality) and for central system nervous involvement (76.2%).

[Aetiological aspects of neurological diseases in Dakar: follow-up after 10 years (1986-1995)]

Because of the apparition of new risk factors and numerous progresses in investigation methods, authors take stock of neurological diseases of patients admitted in Clinique Neurologique of Fann during the last ten years. The 8539 cases repartition is as followed: 4736 males and 3803 female. Their ages ranged between 3 and 80 years with 2130 deaths corresponding to 24.94%. Annual mean of admission is 853 +/- 42 cases. Aetiological data are: stroke (3910 cases 45.78% with 60.56% of death). The following is peripheral neuropathieswith 714 cases(8.61%) and the spinal cord compression with 692 cases (8.10%). Comparision of frequencies of different aetiologies with those of previous studies shows that the small capacity of the neurological department is a restricting factor for the entry frequencies of neurological patients; the principal pathologies got small variations from one decade to another. In the opposite, some aetiologies have disappeared (neurological syphilitis, trypanosomiasis, neurocyticercosis, cerebral mycosis). Some eatiologies remain unprecised (infectious diseases, peripheral neuropathies, degenerative diseases).

[Friedreich's disease in the department of neurology in Dakar]

A retrospective study of Friedreich's ataxia was conducted from january 1960 to december 1997. Eighten cases had been collected. Friedreich's ataxia was the second disorder after Pierre Marie's ataxia among inherited ataxia. Parental consanguinity has been found in 27.77% of cases. The sex-ratio was 2.6 for males. 66,67% of Friedreich's ataxia cases began after 25 years. Clinical signs were: cerebellar ataxia, sensitive disorders in 70%, pyramidal syndrom and cardiomyopathy in 22.22%, bones dysmorphy in 50% of cases. Electromyography indicated severe axonopathy of members with decreased somesthesic potentials in six cases. Glycaemia was normal in all cases. Clinical future presented wide variation between one and fourth years old.

[Guillain-Barre syndrome in children: experience in the neurology service of Dakar]

A retrospective survey has been conducted from january 1979 to january 1999 about the young inpatients file records of the department of neurology of Dakar. 19 cases of Guillain-Barré's syndrome have been collected, representing 2.3% of the children admitted in the department of neurology. The children were 18 months to 16 years old. The sex ratio was 1.4. Infectious disease has been reported in 68.4% of the cases during the 4 weeks preceding the neurological features. The notion of vaccination was found in 5.3% of the cases. The motor deficit was frequent, represented by paraparesis in 63.2% and quadriparesis in 36.8% of the cases. The mean duration of the hospitalisation was 28 days. 52.6% of the patients have completely recovered from their motor deficit and this recovery was unachieved in 36.8%. No fatal event has been detected. The therapeutical means were represented by vitaminotherapy B1B6B12 associated with kinesitherapy. Our results reveal a less severe evolution and better prognosis of Guillain-Barré's syndrome affecting children, instead of the absence of more appropriate means of treatment such as plasma exchange and intravenous immune globulin.

Cellular immune responses of a Senegalese community recently exposed to Schistosoma mansoni: correlations of infection level with age and inflammatory cytokine production by soluble egg antigen-specific cells

A recently reported epidemic of Schistosoma mansoni infection in Senegal provided an opportunity to study the dynamics of the development of immunity to human schistosomiasis. We report here on the cell-mediated immune response in a population of 99 females and 95 males, with particular emphasis on the relationship between intensity of infection and age. We found that the intensity of infection correlated negatively with age in females but not in males. In men and women, both Th1- and Th2-type cytokines were detected upon in vitro stimulation of PBMCs with soluble egg antigen (SEA) or soluble adult worm antigens (SWAP). In the female group, SEA-induced PBMC proliferation was associated with the production of IFN-gamma, IL-2 and IL-5, all of which correlated negatively with intensity of infection. Most cytokine production correlated positively with age. Spontaneous production of TNF-alpha, IL-6 and IL-10 was higher in the infected population than in an uninfected control group. Our results suggest that immunity to infection could be more pronounced in the female population and associated with a Th0/1 + 2 pattern of cytokine secretion mediated by soluble egg antigen (SEA).

[Impact of the use of permethrin pre-impregnated mosquito nets on malaria transmission in a hyperendemic village of Senegal]

The efficacy of permethrin-treated bednets was evaluated in Wassadou, a hyperendemic village located in the Sudanese grasslands of southeast Senegal. Pretreatment data were collected between 1992 and 1993. Bednets were distributed to the whole population in June 1995 and impact of their use on vector populations and malaria transmission was evaluated until November 1995. This period corresponds to the rainy season during which malaria transmission is highest. Data were compared with a control village in which bednets were not distributed. Findings showed that use of bednets led to a sharp decrease in the density of the vector population and malaria transmission. The number of bites by Anopheles gambiae s.1. decreased 69%. The density of blood-laden and pregnant females inside dwellings decreased 91% and 96% respectively. The sporozoite index of females captured on the skin decreased 76% and the daily rate of entomological inoculation decreased 88%. This impact was not great enough to eliminate the risk of infection. Prolonged study over a period of 4 to 5 years is needed to evaluate the impact of long-term use of insecticide-treated bednets on vector population and malaria transmission.

[Drug resistant epilepsy in Senegal: therapeutic, clinical and socioeconomic factors]

The aim of our study was to emphasize factors which support pharmaco-resistance in Senegal. For this purpose, 23 patients with partial or generalized epilepsy were studied, after determining the plasmatic concentration of the antiepileptic drugs. The aetiologies were numerous: encephalitis, injuries, neonatal encephalitis. All patients were under traditional treatment before coming to the hospital. So antiepileptic drugs were taken a long time after the beginning of epilepsy later, they were Phenobarbital, Carbamazepine, Phenytoin, and Valproic acid. Only seven patients had sufficient plasmatic level of the antiepileptic drug. The low socio-economic conditions of patients which limit the choice of the most adapted drug in each case, is one of the most important reason of the pharmaco-resistance. Another factor of the pharmaco-resistance is cultural and is linked with the absence of notion of chronic disease necessitating long and regular treatment in senegalese traditional society.

Brainstem efferents from the interface between the nucleus medialis and the nucleus interpositus in the rat

In a previous report (Buisseret-Delmas et al. [1993] Neurosci. Res. 16:195-207), the authors identified the interface between the cerebellar nuclei medialis and interpositus as the origin of the nuclear output from cortical zone X. They named this nuclear interface the interstitial cell group (icg). In this study, the authors analyzed the icg efferents to the brainstem by using the anterograde and retrograde tracer biotinylated dextran amine. The main targets of these efferents are from rostral to caudal: 1) the accessory oculomotor nuclear region, essentially, the interstitial nucleus of Cajal; 2) the caudoventral region of the red nucleus; 3) a dorsal zone of the nucleus reticularis tegmenti pontis; 4) restricted regions of the four main vestibular nuclei; and 5) three restricted areas in the inferior olive, one that is caudal in the medial accessory subnucleus and two others that are rostral and caudal in the dorsal accessory subnucleus, respectively. These data support the notion that the icg contributes to the control of gaze-orientation mechanisms, particularly those that are related to the vestibuloocular reflex.

[Polyneuropathies of pregnancy. Clinical neurophysiological, and anatomo-pathological study apropos of 38 cases collected at the Neurology Clinic of the the Fann University Hospital Center]

Authors are studying the clinical, electrophysiological, and anatomical aspects of polyneuropathies of 28 observations in Clinic Neurologic of Fann, the onset occurred in pregnancy. Relations with Tropical Neuro-myelopathies (TNM) are emphasized. 28 observations concerning young women between 17 and 35 years old, the onset of neuropathy occurred in pregnancy or immediate post-partum period or miscarriage. Electrophysiological examination and neuromuscular biopsy are performed. Current neuropathological technics were done with the biopsy material including teased fiber and electron microscope examination. Three clinical forms were individualized: polyneuritis form; polyradiculoneuritis form, and the combined sclerosis of the spinal cord. Aetiological conditions were discussed for each clinical form with their evolution course. None of these patients had positive retroviral serology (HIV or HTLV-I). No clinical particularity was found with polyneuritis form; polyradiculoneuritis form was of axonal type; combined sclerosis of the spinal cord showed demyelinating neuropathy. A good electrical and clinico-anatomical correlation was found in each clinical form. Clinical, biological, electrophysiological and anatomical aspects are discussed. Pregnant polyneuropathies are bad known clinical entity, but are frequent in women of childbearing age (21% of PN and 38.7% of TNM) in young women. 50% are from 28 to 36 years old multiparous. Three clinical forms have identical features with TNM with a poor economic and nutritional condition but no relation with HTLV-I. Clinical, electrophysiological and histological finding are correlated with evolution and prognosis.

[Pyramido-lunar fusion in black Africans. Apropos of 32 cases]

Lunotriquetral coalition is a congenital carpal anomaly rarely discovered in a white population. In the black population, most cases have concerned blacks in America, Australia and South Africa. In the Sub-Saharia area, in Senegal, the authors, after 8 incidental cases, report 32 lunotriquetral coalitions collected in 20 patients. This retrospective study comparatively analysed 361 X-rays of the wrist performed between February 1989 and July 1992 in the Orthopaedic and Traumatologic Center (CTO) in Dakar. The bony coalition was bilateral in 12 patients and unilateral in the other 8 cases. The complete form (type III) was the most frequent (46.8%). In the bilateral forms, 5 patients presented this complete form. Lunotriquetral coalition was associated, in absence of congenital abnormalities, with a synovial cyst of the wrist (2 cases), scaphoid fracture (1 case), non-union of a scaphoid fracture (1 case) and osteoarthritis of the wrist (2 cases). After review of the literature, the authors discuss racial factors, anatomo-radiographic forms and associated injuries.

Human IgE responses to rSm22.6 are associated with infection intensity rather than age per se, in a recently established focus of Schistomiasis mansoni

In studies of schistosomasis mansoni-endemic communities, individuals with IgE responses to a 22 kD adult worm antigen (rSm22.6) suffered lower intensities of reinfection after treatment. It is of interest to define the factors that lead to the production of rSm22.6-specific IgE because it is a marker for resistant individuals and it may be involved in the development of resistance to reinfection. In endemic populations rSm22.6-specific IgE increases linearly with age. However, it is not possible to distinguish between age per se and 'history of infection' in endemic populations because individuals are exposed to the parasite at an early age. We have, therefore, quantified pre- and post-treatment isotype responses to rSm22.6 in a comparatively 'epidemic' Senegalese community where the patients were infected at different ages and where pre-treatment intensity of infection can be taken as a reasonable measure of antigen exposure. Post-treatment isotype responses to rSm22.6 correlated positively with pre-treatment intensities of infection but were not shown to be related to age. IgG1, IgG4 and IgE responses to rSm22.6 were significantly higher after treatment with the difference increasing with the pre-treatment level of infection. These results from a recently established focus of infection suggest that isotype responses to rSm22.6 are antigen-exposure dependent rather than dependent on age per se.

Connections between the cerebellar nucleus interpositus and the vestibular nuclei: an anatomical study in the rat

Interposito-vestibular connections were analysed, using the anterograde and retrograde tracer biotinylated dextran amine. The interposito-vestibular projections mainly arise from medial portions of the cerebellar nuclei interpositi anterior (NIA) and posterior (NIP), and reach each of the main vestibular nuclei, ipsilaterally. The highest density of projections is found throughout nucleus vestibularis lateralis. Fibres also reach the peripheral part of nucleus superior, the caudal part of nucleus inferior, and the lateral part of nucleus medialis. Some fibres also reach groups I, x and f. Contralaterally, few fibres reach zones of the vestibular nuclei symmetric to the ipsilateral projection. A small, reciprocal, vestibulo-interposed projection is sent from the vestibular nuclei onto NIA-NIP. Possible influences of the interposito-vestibular projections upon the major targets of the vestibular nuclei, spinal motoneurones and oculomotor neurones, are discussed.

Ivermectin and moxidectin in two filarial systems: resistance of Monanema martini; inhibition of Litomosoides sigmodontis insemination

Effects of ivermectin and moxidectin were compared on two filarial species: Monanema martini which presents dermal microfilariae and induces Onchocerca-like lesions in its natural murid host Lemniscomys striatus, and Litomosoides sigmodontis (= L. carinii). M. martini microfilariae showed an unusual resistance to ivermectin, in vitro and in vivo; moxidectin was no more efficient. However, the two drugs used at high concentrations deeply altered the uterine embryogenesis, but had no lethal effect on adult filariae. L. sigmodontis blood microfilariae showed a great susceptibility to moxidectin, similar to that previously described for ivermectin. The two drugs also induced a long term effect because they inhibited the insemination of the female filariae. This result reinforces the observations made by other authors on the human parasite, Onchocerca volvulus.

The fate of the filaria Litomosoides sigmodontis in susceptible and naturally resistant mice

The fate of Litomosoides sigmodontis was compared in susceptible BALB/c and resistant B10D2 mice, presenting the same major histocompatibility complex (H-2d), with an attempt to dissociate the different elements of the life cycle in order, later, to dissociate the different mechanisms involved. Each female mouse was inoculated once with a small dose of infective larvae (25 L3) or a large dose (100 or 200 L3). In total, 92 BALB/c and 49 B10D2 were studied. Necropsies were performed up to D85 following infection with 25 larvae. The early fate was similar in B10D2 and BALB/c mice; particularly the recovery rate of worms was almost identical during the first month p.i. and represented a quarter of the inoculated larvae. Resistance in B10D2 mice appeared progressively, as judged by retardation of growth and of the fourth moulting, the presence of very small sterile female worms and male worms with abnormal left spicule, and a high frequency of live filariae coated with inflammatory cells and encapsulated dead worms. The L. sigmodontis life span in B10D2 was about half that in BALB/c. Necropsies were carried out up to D20 following infection with 100-200 L3. The recovery rate was increased in BALB/c. Growth was retarded earlier in B10D2 mice, this crowding effect already apparent at D10; this may indicate a role for metabolic factors. The pattern of the life cycle in both mouse strains confirms recent conclusions on Onchocercinae: the recovery rate is established as soon as the second day during "phase 1 of massive destruction", then it is stable during "phase 2 of insignificant mortality". During phase 1, the infective larvae are immediately destroyed in the subcutaneous tissue if they are not able to escape the inflammatory process by penetrating in local lymphatic vessels. By contrast, phase 2, which is longer than the duration of the third larval stage, indicates there is no mortality linked to the third moulting, at least following a single inoculation.

Effect of ivermectin on two filaria-vector pairs. Brugia malayi-Aedes aegypti; Litomosoides sigmodontis-Bdellonyssus bacoti

The effect of ivermectin was studied on two filaria-vector pairs, Brugia malayi-Aedes aegypti and Litomosoides sigmodontis-Bdellonyssus bacoti. The rodent hosts, respectively Mastomys coucha and Meriones unguiculatus, were treated with ivermectin doses of 0.05 mg/kg, or 0.2 mg/kg or 2 mg/kg. Batches of vectors were fed on rodents, infected or not, treated or not, from H7 to D43 post-ivermectin. Vector survival was observed and dissections were performed to study the filarial development. It appears that ivermectin has no systemic effect on vectors, or very little. The drug acts on transmission because it affects the microfilariae. Transmission of L. sigmodontis is blocked because microfilariae are eliminated from the blood. Transmission of B. malayi is blocked although microfilaremia remains present at a low level. Two particular features are observed: microfilariae are hyper-ingested, but they do not cross the stomach wall (in contrast, they cross at a high rate in the control batch of Aedes, due to the "stomach wall limitation"). These events might be explained by a muscular passivity of the microfilariae treated with ivermectin. Transmission of the two filarioid species is restored normally about D25-40 post ivermectin because a new population of microfilariae has appeared. These ivermectin experiments emphasize the diversity and complexity of two important phases of the filarial cycle in the vector: the ingestion of microfilariae and the passage through the stomach wall.

Maturation of the filaria Litomosoides sigmodontis in BALB/c mice; comparative susceptibility of nine other inbred strains

When inoculated subcutaneously, the infective larvae of L. sigmodontis undergo complete development and produce a patent microfilaraemia in mice of the BALB background (BALB/c, BALB/K and BALB/B, with respectively the H-2d, H-2k et H-2b haplotypes). The most susceptible strain is BALB/c with all mice harbouring adult filariae and 47% of mice presenting with a patent microfilaraemia. Mice with the B10 background (B10, B10Br and B10D2, with respectively the H-2b, H-2k et H-2d haplotypes) are almost completely resistant to infection. Adult filariae were recovered from all mice of the CBA/Ca, CBA/HN, C3H/HeN, DBA/2N strains. However, the site and structural development of the parasite varied in each strain. Absence of microfilaraemia is associated with absent or abnormal spicules, reduced number of female filariae and small size of female filariae. These results show that the Major Histocompatibility Complex only modulates the developmental pattern of filariae within the limits imposed by background genes. Male CBA/HN and C3H/HeN were more susceptible to infection than female mice. Inverse phenomenon was observed with strains BALB/c; and, no host sex effect was seen in DBA/D2N.

The filaria Litomosoides galizai in mites; microfilarial distribution in the host and regulation of the transmission

The mites, Bdellonyssus bacoti, are engorged on rodents having 800 to 60,000 microfilarie/10 mm3 blood. Quantitation of L. galizai larval development shows that an additional blood meal improves development and that high microfilaremiae do not result in a proportional increase in the number of infective larvae. The first important stage of transmission regulation occurs during ingestion of microfilariae: the numbers of ingested microfilariae are lower than expected in cases of high microfilaremia. This phenomenon cannot be ascribed to the mite vector that engorges a constant blood meal whatever the level of microfilaremia. Contrarily, one finds that microfilarial density in the small peripheral blood vessels (blood drawn from incision of the dorsal skin) increases less than in large blood vessels (retro-orbital sinus). A similar observation was reported by Dickerson et al. (1989) working with Wuchereria bancrofti. We assume that in both cases, the high microfilaremiae cause the small blood vessles accessible to the vector to become saturated with parasites. Although regulation during engorging is not the sole factor to monitor the infection in B. bacoti (another one operates during larval development of L. galizai), demonstrating its existence seems to us fundamental: it points out the concept that sub-ingestion, as well as over-ingestion, shows the inequalities of microfilarial densities in the host which seem to be dependent on mechanical factors such as the diameter of blood vessles and the size of microfilariae.

[Litomosoides, parasites of rodents; taxonomic consequences]

A redescription of the type specimens of the three following species is given: L carinii (Travassos, 1919) from Sciurus sp. in Brazil. L, sigmodontis Chandler, 1931 from Sigmodon hispidus and L. scotti Forrester et Kinsella. 1977 from Oryzomys palustris in North America. A description of two brazilian species is also given: L. galizai n. sp. from (Ecomys trinitatus tapajinus and L. kohnae n. sp. from Nectomys squamipes. The conclusions are: The type species of the genus Litomosoides: L. sigmodontis, and L.carinii are two distinct species. As a result, the filaria which is widely used in drug trials has to be reinstated sigmodontis and not curinii. With the exception of the two parasite species of Geomyid rodents, which show affinities with the genus Litomosa, the species of Litomosoides may be devided into two groups, principally based on the morphology of the spicules: the sigmodontis group, with 13 species; the carinii group, with 8 species. Each group includes parasites of Chiuroptera, Marsupials and Rodents. The two new species (L. galizai and L. kohnae) belong to the group sigmodontis; they are characterised by the shape of the buccal capsule, the size of the spicules, the structure of the female body-wall and the microeilaria.

[Development of the filaria Litomosoides galizai in the acarian vector]

L. galizai develops in the gamasid B. bacoti in 11 days at 28 degrees C. Molts I and II take place respectively 5 and 7 days after feeding. The development is studied in the adult female mites; as for the laboratory filaria L. sigmodontis, the interstitial tissue is the main parasitized organ; microfilariae penetrate in the two cell types which constitute it: adipose cells and secretory cells (these secretory cells are described here for the first time). The filariae develop also in the salivary glands, the digestive wall, the genital envelopes and exceptionally in the coxal and vaginal glands. The filariae produce the formation of syncytia. Larvae which stay in the haemocele do not develop.