Serological HLA class I alleles in Senegalese blood donors detected HBs Ag positive.

We analysed the HLA class I alleles in 96 blood donors HBs Ag positive compared with 93 healthy control individuals (HBs negative). The most frequent HLA-A, -B, -C alleles found were, A23 (33.6%); A2 (25%); A30 (25%); B8 (31.5%); B7 (16.3%); B58 (11.9%); B35 (11.9%); B49 (11.9%); B53 (10.8%); Cw7 (39.1%); Cw3 (36.9%); Cw4 (36.9%). Significant differences (P<0.001) were found between the blood donors and the controls for the following HLA alleles, A1; A23; B8 and Cw3. The detection of HBe antigen was positive in 26/84 blood donors. It was observed a significant difference (P<0.01; odds ratios (OR)=6.25) between positive and negative HBe antigens blood donors for HLA-A1 allele.

Phenotypic and genotypic characterization of Vibrio cholerae isolates from a recent cholera outbreak in Senegal: comparison with isolates from Guinea-Bissau.

A total of 127 strains of Vibrio cholerae (117 V. cholerae O1 and 10 nonagglutinating strains) isolated from a recent cholera outbreak in Senegal and four strains isolated in Guinea-Bissau (during the survey of a cholera epidemic that occurred 10 months before the Senegalese one) were analyzed. Strains were characterized by conventional methods (biochemical and serologic identification, susceptibility to antimicrobial agents), polymerase chain reaction for genes encoding cholera toxin (CtxA), zonula occludens toxin (Zot), and accessory cholera enterotoxin (Ace), and by ribotyping. Conventional methods showed that all strains of V. cholerae O1 belonged to serotype Ogawa, biotype El Tor and were resistant to the vibriostatic agent O129 (2,4-diamino 6,7-diisopropylpteridine phosphate), cotrimoxazole, and chloramphenicol; all strains were sensitive to tetracycline, a drug that has been extensively used in cholera therapy. Most of these V. cholerae O1 (112 strains from Senegal and four strains from Guinea-Bissau) had an intact core region (virulence cassette) and amplified a 564-basepair (bp) fragment of ctxA, a 1083-bp fragment of zot, and a 314-bp fragment of ace. Ribotyping of V. cholerae O1 strains after Bgl I restriction of total DNA revealed that ribotype B5a, which is the predominant ribotype of this seventh pandemic of cholera, was not isolated. Instead, a new ribotype was identified and designated B27 in our data bank. Since O1 isolates from Guinea-Bissau and Senegal have the same biotype, serotype, and ribotype and as the Guinea-Bissau outbreak that preceded the one in Senegal, this emerging ribotype probably came from Guinea-Bissau. Nonagglutinating strains exhibited no resistance to the O129 agent and to the tested antibiotics, they were all negative for virulence cassette, except for one strain with the ctxA and zot genes isolated from a patient with diarrhea, and there was a great variability of ribotypes among these strains. There was no difference between environmental O1 strains isolated from water and strains isolated from patients with cholera, suggesting that fecally contaminated water is an important reservoir for infection.

Re-emergence of yellow fever in Senegal in 1995.

An outbreak of yellow fever (YF) occurred in the central part of Senegal during October 1995. Thirty-one probable cases were detected and 79 cases were confirmed either by IgM ELISA or by virus isolation (30 strains isolated). The case fatality rate was 18.9%. Incidence of the infection was evaluated by a serosurvey in the area. Males 10-29 years old belonging to the Peul ethnic group were more affected. Moreover, 28 YF virus strains were isolated from mosquitoes and larvae pools and vertical transmission of YF virus by Aedes aegypti was also demonstrated for the first time in the field. This outbreak occurred after the major amplification of the wild cycle of YF virus in 1993 in West Africa. This epidemic represented a typical example of intermediate transmission of YF: both humans and wild vertebrates are involved in the virus cycle through wild mosquitoes with semidomestic habits, mainly Ae. furcifer, Ae. luteocephalus, and domestic vector Ae. aegypti. It was controlled by a prompt immunization campaign. The impact of inclusion of YF vaccine in the Expanded Program of Immunization, which has been conducted in Senegal for eight years, is discussed.

[Pathogenic approach of thrombopenia in dengue and its hemorrhagic complications]. / Approche pathogénique de la thrombopénie dans la dengue et dans ses complications hémorragiques.

Dengue is a frequent viral infection in the intertropical countries. The frequency and the severe forms of this infection are a real problem of public health. The haemorrhagic forms of the disease are constantly associated with thrombocytopenia. Its pathophysiology is still unclear. Among the different hypothesis, immune mechanisms play the main role. The authors discussed here the responsibility of the binding of immune complexes and the role of cytokines.

[Malaria in the republic of São Tomé and Principe. Epidemiologic evaluation and chemoresistance of P. falciparum]. / Le paludisme en république de São Tomé et Principe. Evaluation épidémiologique et chimiorésistance de P. falciparum.

The authors report the results of a valuation of paludometric indices during mai 1990 in Democratic São Tomé e Príncipe Republic (RDSTP). These investigations (parasitic index and spleen index) suggest that malaria is mesoendemic in these area. Plasmodium susceptibility to chloroquine at posology of 25 mg/kg per os was evaluated (WHO standard 7 days field test). Among 58 children, ranging from 5 to 11 years old, resistance at level R I was observed in 9% of cases, at level R II in 14%. Among 10 strains of P. falciparum, 9 were chloroquine resistant in vitro. 2 strains were also less sensible to quinine.

[Pemphigoid and acquired hemophilia]. / Pemphigoïde et hémophilie acquise.

INTRODUCTION: The association of bullous pemphigoid and acquired haemophilia is reported. CASE-REPORT: A 74 year-old man developed a bullous pemphigoid after decreasing corticotherapy, ecchymosis and haematomas revealing a high level of acquired anti-VIII antibodies (110 Bethesda UB units; TCA 98 s). Immunosuppressive treatment (cyclosporine, prednisone, azathioprine and bolus of cyclophosphamide) did not stop the disease. Perfusion of recombinant factor VIIa, human immunoglobulins and prednisone-azathioprine association permitted clinical and biological remission. DISCUSSION: Acquired haemophilia is idiopathic half the time. It can appear in autoimmmune diseases. Mortality is high. Only 4 cases of association with bullous pemphigoid have been reported in the literature. At the haemorrhagic phase, porcine factor VIII or more recombinant activated factor VII with human immunoglobulins are necessary. Immunosuppressive treatment is used to decrease production of anti-factor VIII antibodies.

[Canine ehrlichiosis in Senegal: human and canine seroepidemiological survey in Dakar]. / L'ehrlichiose canine au Sénégal: enquête séroépidemiologique humaine et canine à Dakar.

Since 1986, several cases of human ehrlichiosis due to Ehrlichia canis have been reported in the U.S.A. Suspecting a pathology transmissible from dog to man the authors conducted an epidemiologic survey in an ehrlichiosis zone in Senegal on a population of 42 men and 66 dogs. In 1987, this rickettsiosis accounted for the deaths of a good half of the military dogs stationed in Dakar. Yet two years after implementing a prophylactic policy the seroprevalence rate in the kennel dropped from 53% to 13%. Among the dog population of the Gendarmerie Nationale Sénégalaise, the seroprevalence rate is very high (78%) and in the sample of civil, native dogs, seroprevalence was 37%. The fact that no positive human serology was observed among the working-dog handlers in permanent contact with the infected dogs leads the authors to conclude that man is not receptive to Ehrlichia canis.

[HTLV1 and coinfections]. / HTLV1 et coinfections.

After reminding the epidemiology of the HTLV1 infection the authors sum up the actually recommended diagnosis procedure. --Case finding by ELISA, confirmation by WESTERN-BLOT and/or RIPA (anti-gag and anti-env specificities), or even PCR which makes specific diagnosis of HTLV1/2. --Or if possible directly by PCR which has helped some authors to find provirus in seronegative people. Coinfections caused by HIV and by Strongyloides are the best documented. As a rule, HTLV1 seems to have rather a worsening effect on evolutiveness and on seriousness of the clinical picture caused by mixed infections, than the contrary (possibly for lack of experience and owing to slow evolution of HTLV1 pathology). Several mechanisms have been proposed concerning coinfections with HTLV1 and HIV (in vitro studies). --Immortalization of CD4 lymphocytes infected with HTLV1 by stimulating both IL2 and its receptor, and by activating lymphocytes with translocation of the replicating factor NF k B in the nucleus, on a promoting sequence of HIV-LTR by stimulating its replication. --The product of HTLV1 tax gene would also have a transactivating effect on the provirus HIV-LTR replication. And finally infection with HTLV1 may facilitate HIV by inducing CD4, molecule expression in non-expressing cells. In Strongyloides modulating effects of HTLV1 on the immune response would facilitate and predispose Strongyloides stercoralis multiplication. As far as other coinfections are concerned (caused by viruses, by parasites: such as malaria, filariasis, trypanosomiasis or by bacteria), epidemiological convergence (risk factors, and geographic distribution) on the one hand, and immunological dysregulation induced by the other, on the other hand, would be of varying importance. In conclusion, these data ask more questions than they answer. But it seems to be established that detection of HIV and Strongyloides should performed in every case HTLV1 carries and vice versa.

[The Quantitative Buffy Coat test (Q.B.C. test). Monofluo Kit Falciparum. Comparative value in the rapid diagnosis of malaria]. / Quantitative Buffy Coat test (Q.B.C. Test Monofluo Kit Falciparum. Intérêt comparé dans le diagnostic rapide du paludisme.

New emerging atypical forms of malaria, characterized by weak parasitemia, among peoples without premunition, back from Plasmodium falciparum resistant areas, make it necessary to use rapid, sensitive, reliable methods of parasitologic diagnosis. This work concerned two different populations: 394 expatriates back from a 4 months stage in endemic areas. 12 patients admitted for suspected of proved malaria. Authors have studied, by double blind method, versus thin film, two fluorescent techniques: a direct immunofluorescence, the Monofluo kit Falciparum of Diagnostic Pasteur. A nucleic acid fluorescence, on blood samples centrifuged in capillary tubes, the Q.B.C. test of Becton-Dickinson. Both methods seem of great interest for epidemiological surveys. The Q.B.C. test has showed more sensitivity than the thin film: it's rapidity of realisation indicates it for urgent diagnosis.

[Evaluation of the OptiMal test in the diagnosis of imported malarial outbreak]. / Evaluation du test OptiMal dans le diagnostic des accès palustres d'importation.

The OptiMal test is an immuno-chromatographic dipstick test that permits indiscriminate detection of Plasmodium falciparum and other species of human malaria. The purpose of this study was to evaluate the efficacy of the test for diagnosis of imported malaria. A total of 244 patients with a presumptive diagnosis of imported malaria in France were included during the study period. The reference test, i.e., combined thick and thin blood films, demonstrated infection by Plasmodium falciparum in 58 cases, Plasmodium vivax in 12, P. ovale in 8 and Plasmodium malariae in 2. The OptiMal test detected only 46 of the 55 Plasmodium falciparum cases. The sensitivity of the test for diagnosis of that species was 80%, its specificity was 98%, and its positive and negative predictive values were 95 and 93% respectively. Parsitemia studies showed poor test reliability for densities lower than 150/ul. Detection of other species was accurate in 21 out of 22. The results of this study demonstrate that the current version of the OptiMal test should be used with great caution for the diagnosis of malarial infection in hospital practice.

[Hepatitis C virus and chronic hepatopathies in Dakar: case-control study]. / Virus de l'hépatite C et hépatopathies chroniques à Dakar: étude cas-témoins.

In Black Africa, the role of hepatitis C virus (HCV) in the onset of chronic hepatic disease is unclear. This is particularly true in Senegal where the prevalence of HCV is moderate. To gain insight into this question, a case-control study including 73 patients and 73 controls was carried out at Principal Hospital in Dakar in 1995. The patients included in this study presented chronic hepatitis in 2 cases cirrhosis in 25 and hepatocellular carcinoma in 46. Patients and controls underwent serologic testing for HCV (ELISA screening test followed by 3rd generation ELISA test in case of positive results and confirmation by immunoblot) with determination of HCV serotype using the immunoenzymatic method. Testing also included research for infection by hepatitis B virus and for anti-delta antibodies. Anti-HCV antibodies were detected in two patients (3 p. 100) and serology was suspicious in two others. Serotype 2 was detected in one of these patients. No positive results were recorded in controls. Fifty-four patients (74 p. 100) and 15 controls (21 p. 100) presented the HBs antigen including 13 patients (24 p. 100) and I control (7 p. 100) with anti-delta antibodies. This study shows that HCV currently plays a minor role in the onset of hepatic disease in hospitalized patients in Senegal. It also confirms the predominant role of hepatitis B and complicating effect of the delta hepatitis virus. These findings are compared with reported data for Black African countries. The impact of HCV appears to be lower in Senegal than in central Africa.

[Pathologies associated with HTLV-1 virus in Dakar (1992-1995)]. / Pathologies associées au virus HTLV-1 à Dakar (1992-1995).

A clinical and laboratory study was conducted in Dakar (Senegal) to assess the involvement of HTLV-1 virus (human T lymphotrophic virus type 1) in various diseases. Patients were enrolled at three locations: the Dermatology Department of the Fann University Hospital Center (845 patients) from 1992 to 1995, the Dermatology Department of the Le Dantec University Hospital Center and the Oncology Department of the Principal Hospital (7 patients) in 1994 and 1995. The incidence of involvement of human retroviruses in neurologic complications seemed low (HTLV-1: 2%, HIV: 3%) and only 6 cases of tropical spastic paraparesis associated with specific anti-HTLV-1 antibodies were diagnosed in 3 men and 3 women with a mean age of 51 years. These cases which were identical to those previously described cases in the West Indies and Japan confirms the existence of this disease in Senegal. In addition 3 cases of isolated facial paralysis were observed in HIV positive patients. Combined HIV/HTLV-1 infection was observed in 3 cases and was not associated with special clinical findings. Adult T-cell leukemia/lymphoma (ATL) was detected in 4 patients including leukemia with proliferation of CD4 and CD25 in two cases and lymphoma in one case. In one case of ATL two proviruses were identified in circulating tumor cells. These are the first cases of ATL to be reported in Senegal. Molecular characterization of part of the envelope gene (gp 21) from patients with PST hospitalized in a neurology ward showed that the virus present in Senegal belonged to the universal HTLV-1 A type. This study indicates that two types of diseases are associated with HTLV-1 infection in Senegal. Further epidemiologic studies will be needed to evaluate the incidence of the virus and of the diseases associated with it. Prevention will depend partly on screening blood donors as has now been started at the Blood Transfusion Center of Dakar.

[Cytological study of deep lung in spondyloarthritis. Apropos of 34 cases]. / Etude cytologique du poumon profond au cours des spondylarthropathies. A propos de 34 observations.

Bronchoalveolar lavage (BAL) was performed in 34 consecutive patients with spondyloarthropathy (SA) compared with 9 controls. Lymphocytic alveolitis was found in the SA group with decrease in the ratio of the CD4/CD8 subsets in both lung and blood. Neutrophilic alveolitis was also found in 5 patients with SA of long duration. As with other inflammatory diseases, it seems that a subclinical alveolitis is present in SA patients.

[Prevalence of hepatitis B and C viruses in a chronic hemodialysis center in Dakar]. / Prévalence des virus des hépatites virales B et C dans un centre d'hémodialyse chronique à Dakar.

In endemic areas of hepatitis B and C, hemodialysis patients are highly exposed to these infections. So the authors studied the prevalence of hepatitis B and C viruses among chronic hemodialysis patients of CHU A. Le Dantec of Dakar in a cross study carried out from June 1996 to June 1997, in order to identify risk factors and suggest appropriate prophylaxis. The study concerned fifteen chronic hemodialysis patients in an unit of hemodialysis in Dakar. For each patient, clinical and biochemical data were collected serological markers of B and C viruses were tested and HCV-RNA in case of seropositivity to C virus. The mean age of patients were 48 years and average duration of hemodialysis was 40 months. Hepatic injury was silent in all cases. Only one patient (6.7%) was AgHBs carrier while 9 patients (60%) were positive for antibodies anti HBs without previous hepatitis B vaccine. Twelve patients (80%) were found to be HCV-antibody positive and half of them were HCV. RNA positive. Average value of alanine amino transferase was higher in HCV-viremic patients than in seropositive but non viremic patients, although normal. Genotype 2 ac was found in 3 HCV viremic patients but it could not be determined in 3 other patients. Hemodialysis duration and number of blood transfusions were found to be risk factors of HCV infection. The high prevalence of HCV seropositivity among chronic hemodialysis patients in Dakar has led to strengthen precautions in our hemodialysis unit. HCV serological screening in blood donors is advocated.

[Association between Class I HLA alleles and HBs antigen carrier status among blood donors in Senegal]. / Association entre allèles HLA de classe I et portage de l'antigene HBs chez des donneurs de sang au Sénégal.

The course of hepatitis B virus (HBV) infection may be influenced by the host immune response. A prospective study was carried out in ninety-eight subjects (mean age = 23 years) HBs antigens carriers of hepatitis B and living in Dakar, Senegal. We analysed the HLA-A, -B, and C antigens distribution compared to that one of a control (HBs negative) healthy senegalese population (n = 96) living in Dielmo village where a longitudinal study was set-up since 1990. The HLA class I typing was performed by microlymphocytotoxicity assays. The most frequent HLA-A, -B, -C antigens found were: locus A: A23 (33.6%), A2 (25%), A30 (25%), locus B: B8 (31%), B7 (16.3%), B58 (11.9%), B35 (11%), B49 (11%), B53 (10.8%) and locus C: Cw7 (39.1%), Cw17 (39.1%), Cw3 (36.9%), Cw4 (36.6%). Significant differences (P < 0.001) were found between the donors and the control group for the following HLA antigens: A1, A23, B8 and Cw3. The detection of HBe antigen was positive in 26/84 blood donors. It was observed a significant difference (p < 0.01) between positive and negative HBe donors for HLA-A1 allele with an odds ratio of 6.25. All the donors carrying the HLA haplotype: A1-B8-Cw7 (11.5%) were positive in HBe antigen. HLA: B8-Cw7 haplotype (detected in 8.5% of positive donors) seems to be likely associated with a liver cancer according to many reports. An adequate follow-up should be set-up for positive HBe subjects carrying a susceptible HLA type.

[Demonstration of subclinical pulmonary alveolitis in spondylarthropathies]. / Mise en évidence d'une alvéolite pulmonaire infraclinique au cours des spondylarthropathies.

Restrictive ventilatory dysfunction, lowered diffusing capacity, and apical fibrosis have been reported in ankylosing spondylitis. To investigate the pathogenesis of these abnormalities, we studied distal airspace cytology by performing bronchoalveolar lavage in 34 spondyloarthropathy patients (ankylosing spondylitis, n = 16; reactive arthritis, n = 4; axial psoriatic arthritis, n = 2; and undifferentiated spondyloarthropathy with HLA B27-positivity in every case but one, n = 12). Mean age was 32.4 +/- 13.7 years. None of the study patients had apical fibrosis, lower respiratory tract infection, or exposure to airborne pollutants other than tobacco smoke. The control group was composed of nine subjects who had no lung or inflammatory diseases and were not using medications. Significantly higher proportions of lymphocytes were found in bronchoalveolar lavage specimens from patients, as compared with controls. This difference was not influenced by smoking or medication use (non steroidal antiinflammatory drugs, sulfasalazopyridine). Alveolar lymphocytosis was not correlated with laboratory tests for disease activity (erythrocyte sedimentation rate, serum IgA levels) or with the presence of restrictive ventilatory dysfunction. Increases in the proportion of lymphocytes were of similar magnitude in patients with ankylosing spondylitis and in those with other spondyloarthropathies. Absolute total cell counts and relative neutrophil counts were similar in patients and controls. However, among the patients with spondyloarthropathies, those with a disease duration of more than five years had a significantly higher proportion of neutrophils than those with a disease duration of less than five years. These findings demonstrate that spondyloarthropathy patients have subclinical lymphocyte alveolitis. Although of unclear significance, this alveolitis may be related to the development of apical fibrosis in some patients with ankylosing spondylitis.