Role of contaminated aspiration tubes in nosocomial outbreak of Klebsiella pneumoniae producing SHV-2 and CTX-M-15 extended-spectrum beta-lactamases.

Klebsiella pneumoniae resistant to ceftazidime was isolated from ten neonates hospitalised between February and March 2006 in two Antananarivo hospitals, Madagascar. The main environmental source, for one hospital in particular, was the liquid used to rinse aspiration tubes in the paediatric wards. The risk of contamination from aspiration tubes is very high in the hospitals of Antananarivo since tap water used to rinse the tubes is not regularly changed. Phenotypical (biotyping and antibiotyping) and genotypical (pulsed-field gel electrophoresis) analysis of all the clinical isolates indicated that nine cases were due to a single clone. This clone carried the genes encoding SHV-2 and CTX-M-15 beta-lactamases. This is the first description of an epidemic due to an ESBL-producing member of the family Enterobacteriaceae in Malagasy hospitals.

[Characterization of hepatitis B virus strains from the Central African Republic: preliminary results]. / Caractérisation des souches de virus de l'hépatite B circulant en République centrafricaine: résultats préliminaires.

OBJECTIVES: Genotyping of Hepatitis B virus (HBV) strains from patients in Central African Republic and comparison with results obtained in other African countries. PATIENTS AND METHODS: Sera were collected from patients admitted with symptoms of acute or chronic hepatitis to the "Hôpital de l'Amitié de Bangui", Central African Republic (CAR). The complete sequence of preS2/S gene has been defined for determining genotypes. RESULTS: Hundred and ninety-six sera were collected from 112 men and 84 women. Ninety-two percent of patients had contact with HBV (anti-HBc postitive) and the HBsAg prevalence was about 62%. HBV DNA was detected in 66% of HBsAg positive sera. No HBV-DNA was evidenced among patients with negative HBsAg. Ninety-three percent of the HBV strains belonged to genotype E; one (3.4%) belonged to genotype A1, and one (3.4%) belonged to genotype D. CONCLUSIONS: The high prevalence of HBV infection in the studied population is due to their recruitment. The genotype E is predominant in CAR and the intragroup variability of HBV genotype E reached only 1.8%. Genotypes A and D were less common in CAR their presence may be explained by importation.

Efficacy of chloroquine-proguanil malaria prophylaxis in a non-immune population in Bangui, Central African Republic: a case-control study.

A case-control study was conducted to evaluate the efficacy of the combination of chloroquine plus proguanil as malaria prophylaxis in a non-immune population living in the Central African Republic. Cases were patients presenting with a malaria attack confirmed by a positive blood film and/or an HRP2 positive antigen test at the Pasteur Institute of Bangui. Two control subjects were included per case: one was a relative or close friend and the other was matched to the patient with respect to the length of stay. A questionnaire assessing malaria prophylaxis habits and malarial risk factors over the 2-month period prior to inclusion in the study was given to 48 cases and 96 controls. A conditional logistic regression was used to identify risk factors. The efficacy of the chloroquine plus proguanil regimen was found to be high (95.5%, 95% CI 74.0-99.2%) in this country known for high chloroquine resistance. Our data lend some support to the use of chloroquine plus proguanil in Bangui, and the protective efficacy of chloroquine plus proguanil should now be studied prospectively as part of a randomised controlled trial of various prophylactic drugs.

Secretion of flaviviral non-structural protein NS1: from diagnosis to pathogenesis.

Flaviviruses are major arthropod-borne human pathogens responsible for life-threatening encephalitis, hepatitis and haemorrhagic fevers. These enveloped, single-stranded, positive-sense RNA viruses encode a polyprotein precursor of about 3400 amino acids, processed into three structural and seven non-structural proteins. The non-structural glycoprotein NS1 is essential for flavivirus viability. During host-cell infection in vitro, NS1 is found associated with intracellular organelles as a requisite for its role in viral replication, or is transported to the cell surface where it may trigger specific signalling pathways. In addition, a secreted form of the protein is released from flavivirus-infected mammalian cells. We have previously shown that the NS1 protein circulates during the acute phase of the disease in the plasma of patients infected with dengue virus type 1 and have extended our retrospective studies to dengue type 2 and type 3 cohorts, confirming the value of the NS1 antigen as an alternative diagnostic marker. Interestingly, detection of the NS1 protein in yellow fever virus and West Nile virus infections suggests that NS1 secretion is a hallmark of human flavivirus infections. The objectives of our current studies are to define the biological properties of the secreted form of the NS1 protein, to evaluate its possible contribution to viral pathogenesis, and to validate this protein as a candidate target for passive immunoprophylaxis against flaviviruses.

Serological surveillance of brucellosis and Q fever in cattle in the Central African Republic.

No data are available concerning the seroprevalence of brucellosis in Central African Republic (CAR) and the last report concerning the seroprevalence of Q fever in CAR is from 1995. The aim of our study was to determine the prevalence of these diseases in CAR, especially in Zebu cattle. We used the Rose Bengal Plate Test to test 2032 bovine serum samples for antibodies to Brucella spp. and an indirect immunofluorescence assay to test 784 bovine serum samples for antibodies to Coxiella burnetii (the species responsible for Q fever). The mean seroprevalences of antibodies to Brucella and Coxiella were 3.3 and 14.3%, respectively. Significant differences were found between regions and herds for both diseases. However, relation with differences of climate or vegetation were not evident. Therefore, further data are necessary to better understand the epidemiology of these diseases in CAR and evaluate losses to the farmers.

Surveillance of drug-resistant childhood tuberculosis in Bangui, Central African Republic.

SETTING: Bangui, the capital of the Central African Republic, where overall drug resistance and multidrug resistance among adult new tuberculosis (TB) cases were respectively 16.4% and 1.1% in 1998. OBJECTIVE: To determine the prevalence of drug resistance among children with tuberculosis and to compare the epidemiological and clinical features of TB in children with drug-resistant and drug-susceptible TB. METHODS: All strains of Mycobacterium tuberculosis obtained from children aged 0-15 years at Bangui Paediatric Hospital were prospectively collected from April 1998 to June 2000, and susceptibility testing was performed for each specimen. The children's epidemiological and clinical data were recorded. RESULTS: Susceptibility results were available for 165/190 children with M. tuberculosis. Overall drug resistance and multidrug resistance were 15.2% and 0.6%, respectively. Isoniazid and streptomycin were the only drugs associated with TB monoresistance. No significant difference was found in the epidemiological or clinical data of children infected with a resistant strain and those infected with a susceptible strain. CONCLUSION: The prevalence of drug resistance in childhood is similar to that observed in adult new TB cases in the same period. Surveillance will continue to be performed in Bangui periodically to assess the trend of true drug resistance among new TB cases.

The low evolutionary rate of human T-cell lymphotropic virus type-1 confirmed by analysis of vertical transmission chains.

The evolutionary rate of the human T-cell lymphotropic virus type-1 (HTLV-1) is considered to be very low, in strong contrast to the related human retrovirus HIV. However, current estimates of the HTLV-1 rate rely on the anthropological calibration of phylogenies using assumed dates of human migration events. To obtain an independent rate estimate, we analyzed two variable regions of the HTLV-1 genome (LTR and env) from eight infected families. Remarkable genetic stability was observed, as only two mutations in LTR (756 bp) and three mutations in env (522 bp) occurred within the 16 vertical transmission chains, including one ambiguous position in each region. The evolutionary rate in HTLV-1 was then calculated using a maximum-likelihood approach that used the highest and lowest possible times of HTLV-1 shared ancestry, given the known transmission histories. The rates for the LTR and env regions were 9.58 x 10(-8)-1.25 x 10(-5) and 7.84 x 10(-7) -2.33 x 10(-5)nucleotide substitutions per site per year, respectively. A more precise estimate was obtained for the combined LTR-env data set, which was 7.06 x 10(-7)-1.38 x 10(-5)substitutions per site per year. We also note an interesting correlation between the occurrence of mutations in HTLV-1 and the age of the individual infected.

Suburban transmission of Q fever in French Guiana: evidence of a wild reservoir.

The annual incidence of Q fever in French Guiana was found to have increased in 1996 and was 37/100,000 population over the last 4 years. Subsequent investigations in Cayenne and its suburbs indicated that a wild reservoir of the bacteria was responsible for the epidemiologic pattern. A case-control study showed that residence near a forest and occupations and activities that result in exposure to aerosols of dusts from the soil are risk factors for Q fever. By means of time-series analysis, a strong positive correlation between rainfall and the incidence of Q fever with a time lag of 1-3 months was found. The spatial distribution of the cases showed that transmission occurs widely throughout greater Cayenne, which is incompatible with a pinpoint source of contamination. Transmission from livestock and dissemination of the bacteria by the wind appeared to be unlikely, which strengthens the hypothesis that a wild reservoir is responsible for transmission.

Tonate virus infection in French Guiana: clinical aspects and seroepidemiologic study.

Two recent cases of human infection with Tonate virus, one of which was a fatal case of encephalitis, have renewed interest in these viruses in French Guiana. The clinical aspects of confirmed and probable cases of infection with this virus indicate that it has pathogenic properties in humans similar to those of other viruses of the Venezuelan equine encephalitis complex. To determine the prevalence of antibodies to Tonate virus in the various ethnic groups and areas of French Guiana, 3,516 human sera were tested with a hemagglutination inhibition test. Of these, 11.9% were positive for the virus, but significant differences in seroprevalence were found by age, with an increase with age. After adjustment for age, significant differences were found between places of residence. The prevalence of antibody to Tonate virus was higher in savannah areas, especially in the Bas Maroni (odds ratio [OR] = 22.2, 95% confidence interval [CI] = 15.2-32.4) and Bas Oyapock areas (OR = 13.4; 95% CI = 9.8-18.4). The ethnic differences observed in this study were due mainly to differences in place of residence, except that whites were significantly less frequently infected than other ethnic groups. This study indicates that Tonate virus infection is highly prevalent in French Guiana, especially in savannah areas.

Genetic diversity and phylogenetic analysis of human immunodeficiency virus type 1 subtypes circulating in French Guiana.

We investigated the characterization of different HIV-1 subtypes present in French Guiana by use of three different methods. Serological methods were used for the initial screening, which were then confirmed by the heteroduplex mobility assay (HMA). The V3 env region was subsequently sequenced for phylogenetic analysis, to confirm the subtype of the samples, and to assign a subtype to samples that gave results that were difficult to interpret or discordant by serology or HMA. A total of 221 HIV-1 seropositive samples were typed; 110 of them were confirmed by HMA and 16 were sequenced. Of the 221 samples tested 210 patients (95%) were found to be infected with subtype B, 10 (4.5%) were infected with subtype A, and one patient was infected with subtype F. Phylogenetic analysis demonstrated that the strains from French Guiana were closely related to the subtype A and B subtypes, and that one strain was closely related to an F subtype (100% bootstrap value). Four strains from French Guiana clustered in the subtype A (99% bootstrap value) and the other strains were associated with subtype B (100% bootstrap value). The geographic position of French Guiana suggested that HIV-1 was probably introduced into the country via several routes, and thus the pattern of the HIV-1 epidemic might evolve in the near future.

Immunogenicity and protective efficacy of recombinant human T-cell leukemia/lymphoma virus type 1 NYVAC and naked DNA vaccine candidates in squirrel monkeys (Saimiri sciureus).

We assessed the immunogenicities and efficacies of two highly attenuated vaccinia virus-derived NYVAC vaccine candidates encoding the human T-cell leukemia/lymphoma virus type 1 (HTLV-1) env gene or both the env and gag genes in prime-boost pilot regimens in combination with naked DNA expressing the HTLV-1 envelope. Three inoculations of NYVAC HTLV-1 env at 0, 1, and 3 months followed by a single inoculation of DNA env at 9 months protected against intravenous challenge with HTLV-1-infected cells in one of three immunized squirrel monkeys. Furthermore, humoral and cell-mediated immune responses against HTLV-1 Env could be detected in this protected animal. However, priming the animal with a single dose of env DNA, followed by immunization with the NYVAC HTLV-1 gag and env vaccine at 6, 7, and 8 months, protected all three animals against challenge with HTLV-1-infected cells. With this protocol, antibodies against HTLV-1 Env and cell-mediated responses against Env and Gag could also be detected in the protected animals. Although the relative superiority of a DNA prime-NYVAC boost regimen over addition of the Gag component as an immunogen cannot be assessed directly, our findings nevertheless show that an HTLV-1 vaccine approach is feasible and deserves further study.

Molecular characterization and phylogenetic analysis of a human T cell leukemia virus type 2 strain from French Guiana.

Extensive studies have been carried out on native Amerindian populations living in French Guiana in an attempt to detect human T cell leukemia virus type 2 (HTLV-2). However, the first strain of this virus identified in this region was not detected in these populations, but in a Brazilian woman of Amerindian origin. Comparative analyses of the nucleotide sequences of 589 bp of the gp21 env gene and of 625 bp of the long terminal repeat (LTR) showed that this new HTLV-2 strain (HTLV-2 GUY) was of subtype A. Sequence comparison and phylogenetic analyses demonstrated that HTLV-2 GUY was closely related to a group of distinct variants of HTLV-2 subtype A strains originating mostly from Brazilian inhabitants and formerly called HTLV-2 subtype C. As there is a high level of immigration from Brazil in French Guiana, we carried out a seroepidemiological study of 175 Brazilians, mostly women (obtained from a serum databank) and 72 female Brazilian prostitutes living in French Guiana to determine whether HTLV-2 is likely to become an emerging infection in this area. No HTLV-2 infection was detected, indicating that this virus is unlikely to become prevalent in the near future.

Use of the squirrel monkey Saimiri sciureus to optimize serological tests for diagnosis of Bunyavirus infection in humans.

Several arthropod-borne viruses of the large Bunyaviridae virus family have been isolated in South America. There are few data about the incidence of these viruses in man, except for the Oropuche virus. Since haemagglutination inhibition tests are difficult to perform, only enzyme-linked immunosorbent assays (ELISAs) are used. Nevertheless, positive controls are necessary for ELISA, and infected humans are rare. Squirrel monkeys (Saimiri sciureus) were therefore infected experimentally to assess their value as positive controls in such assays. The kinetics of viraemia and of antibody responses after infection with eight Bunyaviruses present in the Amazonian forest were studied. No viraemia was seen in most cases, but, with every virus studied, immunoglobulin (Ig)M and IgG antibody responses were observed, beginning between days 5 and 14 after infection for IgM and days 14--18 after infection for IgG. This model thus provides reliable positive controls for ELISAs in humans. Their availability will allow determination of the seroprevalence of Bunyaviruses in the human population of French Guiana.

High variability of HTLV-I in a remote population of Gabon as compared to that of a similar population of French Guiana.

An anomalous high frequency of ATL was observed in a remote 'noir maroons' village of French Guiana. Since it is not clear if HTLV-I is responsible for different frequencies of disease in different geographical areas, we undertook a comparison of the population with a similar one located in Gabon. We found a much higher degree of gp46 surface envelope glycoprotein sequence conservation in the Guianese village than in the Gabonese one.

Surveillance of dengue fever in French Guiana by monitoring the results of negative malaria diagnoses.

Surveillance of dengue fever is mainly based on specific laboratory tests. However non-specific systems, such as clinical surveillance, are also required. In French Guiana, we have tested a non-specific laboratory surveillance system where different biological examinations performed for other reasons than the diagnosis of dengue fever were analysed as methods for dengue fever surveillance. The number of negative malaria diagnoses in Cayenne and Kourou was found to be the best indicator of dengue fever infections in these towns. This surveillance system appears to be very simple and reliable, and a test which could serve as an indicator that is likely to be found everywhere.

High circulating proviral load with oligoclonal expansion of HTLV-1 bearing T cells in HTLV-1 carriers with strongyloidiasis.

Adult T cell leukemia (ATLL) develops in 3 - 5% of HTLV-1 carriers after a long period of latency during which a persistent polyclonal expansion of HTLV-1 infected lymphocytes is observed in all individuals. This incubation period is significantly shortened in HTLV-1 carrier with Strongyloides stercoralis (Ss) infection, suggesting that Ss could be a cofactor of ATLL. As an increased T cell proliferation at the asymptomatic stage of HTLV-1 infection could increase the risk of malignant transformation, the effect of Ss infection on infected T lymphocytes was assessed in vivo in HTLV-1 asymptomatic carriers. After real-time quantitative PCR, the mean circulating HTLV-1 proviral load was more than five times higher in HTLV-1 carriers with strongyloidiasis than in HTLV-1+ individuals without Ss infection (P<0.009). This increased proviral load was found to result from the extensive proliferation of a restricted number of infected clones, i.e. from oligoclonal expansion, as evidenced by the semiquantitative amplification of HTLV-1 flanking sequences. The positive effect of Ss on clonal expansion was reversible under effective treatment of strongyloidiasis in one patient with parasitological cure whereas no significant modification of the HTLV-1 replication pattern was observed in an additional case with strongyloidiasis treatment failure. Therefore, Ss stimulates the oligoclonal proliferation of HTLV-1 infected cells in HTLV-1 asymptomatic carriers in vivo. This is thought to account for the shortened period of latency observed in ATLL patients with strongyloidiasis. Oncogene (2000) 19, 4954 - 4960

Detection of a major gene predisposing to human T lymphotropic virus type I infection in children among an endemic population of African origin.

Human T lymphotropic virus type I (HTLV-I) is a human oncoretrovirus that causes an adult T cell leukemia/lymphoma and a chronic neuromyelopathy. To investigate whether familial aggregation of HTLV-I infection (as determined by specific seropositive status) could be explained in part by genetic factors, we conducted a large genetic epidemiological survey in an HTLV-I-endemic population of African origin from French Guiana. All of the families in 2 villages were included, representing 83 pedigrees with 1638 subjects, of whom 165 (10.1%) were HTLV-I seropositive. The results of segregation analysis are consistent with the presence of a dominant major gene predisposing to HTLV-I infection, in addition to the expected familial correlations (mother-offspring, spouse-spouse) due to the virus transmission routes. Under this genetic model, approximately 1. 5% of the population is predicted to be highly predisposed to HTLV-I infection, and almost all seropositive children <10 years of age are genetic cases, whereas most HTLV-I seropositive adults are sporadic cases.

Lymphoid organs as a major reservoir for human T-cell leukemia virus type 1 in experimentally infected squirrel monkeys (Saimiri sciureus): provirus expression, persistence, and humoral and cellular immune responses.

The aim of this study was to investigate the distribution of human T-cell leukemia virus type 1 (HTLV-1) in various organs of serially sacrificed squirrel monkeys (Saimiri sciureus) in order to localize the reservoir of the virus and to evaluate the relationship between viral expression and the humoral or cellular immune response during infection. Six squirrel monkeys infected with HTLV-1 were sacrificed 6, 12, and 35 days and 3, 6, and 26 months after inoculation, and 20 organs and tissues were collected from each animal. PCR and reverse transcription-PCR (RT-PCR) were performed with gag and tax primers. Proviral DNA was detected by PCR in peripheral blood mononuclear cells (PBMCs) of monkeys sacrificed 6 days after inoculation and in PBMCs, spleens, and lymph nodes of monkeys sacrificed 12 and 35 days and 3, 6, and 26 months after inoculation. Furthermore, tax/rex mRNA was detected by RT-PCR in the PBMCs of two monkeys 8 to 12 days after inoculation and in the spleens and lymph nodes of the monkey sacrificed on day 12. In this animal, scattered HTLV-1 tax/rex mRNA-positive lymphocytes were detected by in situ hybridization in frozen sections of the spleen, around the germinal centers and close to the arterial capillaries. Anti-HTLV-1 cell-mediated immunity was evaluated at various times after inoculation. Anti-p40(Tax) and anti-Env cytolytic T-cell responses were detected 2 months after infection and remained detectable thereafter. When Tax peptides were used, this response appeared to be directed against various Tax epitopes. Our results indicate that squirrel monkeys represent a promising animal model for studying the early events of HTLV-1 infection and for evaluating candidate vaccines against HTLV-1.

Association of Tonate virus (subtype IIIB of the Venezuelan equine encephalitis complex) with encephalitis in a human.

Tonate virus, subtype IIIB of the Venezuelan equine encephalitis (VEE) complex, was first isolated in 1973 in French Guiana, South America. However, very little is known about its pathogenicity; it was considered to be responsible for only mild dengue-like syndromes. In 1998, a 2-month-old boy living along the Oyapock river in French Guiana was hospitalized for fever and generalized status myoclonus, and despite treatment the patient died 72 h after admission. Testing showed the presence of IgM specific for viruses of the VEE complex. A sensitive seminested polymerase chain reaction derived from a previous study was developed to detect viruses from the VEE complex, since no virus could be recovered from clinical specimens cultured on mosquito cells or from intracerebral inoculation into newborn mice. The genome of a virus from the VEE complex was detected in postmortem brain biopsies, and Tonate virus was identified by direct sequencing. This is the first reported case of human encephalitis due to Tonate virus.

[Dengue fever and pregnancy. A study of 38 cases in french Guiana]. / Dengue et grossesse. Etude de 38 cas en Guyane française.

OBJECTIVES: Evaluation of the consequences of a dengue fever infection on mother and foetus during pregnancy. PATIENTS AND METHODS: Between February 1, 1992 and December 31, 1999, 172 patients with non malaria hyperthermia were tested for dengue fever infection at the maternity of the Saint-Laurent-du-Maroni hospital in French Guyana. The diagnosis was considered positive when specific IgM was present and/or with virus isolation or viral ARN detection using RT-PCR. Among the 38 cases of mothers infected by dengue fever throughout the three trimesters of pregnancy, it was possible to take 19 fetal blood samples. RESULTS: The major consequences for the mothers were risk of premature delivery in 55% of the cases, one case of severe hemorrhagic complications during a cesarean section, and one case of abruptio placentae. The consequences for the fetus were premature birth in 22% of the cases, 5 in utero fetal deaths, 4 cases of acute fetal distress during labor and 2 cases of mother-to-child transmission. CONCLUSION: In case of dengue fever infection of the mother during pregnancy, there is a serious risk of premature birth and fetal death. In case of infection close to term, there is a risk of hemorrhage for both the mother and the newborn.