Archives de l'Institut Pasteur de Madagascar最新文献

The transmission of Yersinia pestis is intense among rats in the wholesale market Tsenabe Isotry in the capital Antananarivo (anti-F1 sero-prevalence 80%, flea index 8.4 for a cut-off risk index of > 1). However, the number of plague-suspected (not laboratory confirmed) human cases has only been 3 in this district during a four years period from 1995 to 1999. A seroepidemiological survey among the market vendors was undertaken in June 1999 to test the hypothesis that the low incidence of human plague is due to acquired immunity. In addition, surveillance of the rat and the flea populations in the market was carried out. Only 3 (3.2%) of 95 screened vendors were anti-F1 IgG positive, whereas the markers of plague transmission among rodents and fleas were still high. This result suggests that the low incidence of human plague was not due to acquired immunity but to other factors such as the limited contact between humans and the rat fleas because of the abundance of rats, the absence of epizootic due to the resistance of rats in the capital and a particular behaviour of the predominant rat Rattus norvegicus.

An outbreak of puffer fish poisoning in a family with four cases of which one was fatal is reported. The outbreak occurred in July 1998 in Nosy Be, an island located at the north-western part of Madagascar. Diagnostic investigation with application of the mouse bioassay suggested poisoning with a tetrodotoxin as the etiology. The amount of the toxin was 16 MU (mouse unit) per gram meal. A continuing surveillance of the seafood intoxications either in the country or in the west Indian Ocean region is needed.

The general health status of the population in the capital, Antananarivo, is determined by a number of different socio-economical and environmental factors. A study was undertaken in 1998 by which the Geographic Information System (GIS) was implemented in order to describe characteristics in town areas (fokontany) suffering from a high disease burden. It was observed that there was a heterogeneous distribution of health care supporting facilities in comparison to population density in the different areas of the capitol. A risk-score system by use of an image-technique was elaborated. The most important problem encountered in the study was the reduced availability of standardized collected data. The results suggest that GIS constitutes a useful tool in assessment of urban health problems in order to identify fokontany in particular need of additional health care support.

A voluminous trichobezoar was discovered in an 11-year-old girl without major clinical implications. The diagnosis was made by endoscopy and surgery was performed without complications.

Madagascar was cholera free until March 1999. The first case was reported in Mahajanga, a north west coast harbor. Ten months later and despite a massive use of tetracycline as prophylactic drug, cholera had reached every region of the island. All suspected cholera samples were analysed at the Pasteur Institute of Madagascar where susceptibility to tetracycline was systematically performed. On February 2000, a multidrug resistant strain of V. cholerae was isolated. We studied this strain by performing Minimal Inhibitory Concentration (MIC) and by plasmidic and conjugative assay. As the original strain, this multiresistant V. cholerae showed a resistance to cotrimoxazole, to streptomycin and chloramphenicol but, in addition to, appeared strongly resistant to ampicillin and tetracycline. This strain harboured a 26 kb self-transmissible plasmid. Conjugation tests showed the possibility of plasmidic segregates or acquisition of two different plasmids. The weak transfer rate could explain why we have isolated only one multiresistant strain. The emergence of a such multiresistant strain should encourage the medical authorities to reinforce the epidemic survey in every medical Malagasy district and to carry out new antimicrobial surveys to describe the mechanisms of the spread of these resistances.

In Madagascar, as in other places in the world, infertility is associated with social stigmatism and an underlaying long-term risk for separation of the couple. A 12 months prospective study was carried out in 1999 in the Department of Gynecology, Obstetrics and Reproductive Health at the University Hospital in Mahajanga in order to collect data related to possible causes of infertility. For the women, serologic tests for Treponema pallidum (syphilis) and Chlamydia trachomatis were performed. And, in addition to sonography and hysterosalpingography, cervico-vaginal smears were obtained as part of the pelvic examination. A semen sample was obtained from each male partner. Of the 37 couples enrolled in the study 35 were classified as primary infertile (n = 9) or secondary infertile (n = 28). The mean age of the women and the men was 30.7 years (ranged 20 to 41 years) and 34.3 years (ranged 24 to 46 years), respectively. Various potential causes of infertility among the women were observed, such as hormonal disturbance (76%), tubal occlusion (76%), genital infection (70%). The figures indicate that there seems to coexist the possibility of multiply causes of infertility. Of 37 semen samples 24 (65%) were found with abnormalities, predominantly of oligospermia type. In 21 couples a possibly cause of infertility was observed in both partners.

African Swine Fever (ASF) was diagnosed for the first time in Madagascar in 1998. ASF has apparently been introduced from the African continent to the southern part of the island with a subsequent spread to other regions except for areas in the north and in the west. The epidemic has had severe economic consequences for the home market of pork meat production. This article reviews the course of the epidemic with particular emphasis on the vectors involved in the transmission of the virus, such as the soft tick, Ornithodoros moubata porcinus. Presence of this vector and of the bushpig, Potamochoerus larvatus, as a potential wild reservoir, are some of the major obstacles in control of ASF in Madagascar. A veterinary disease surveillance system has to be urgently warranted.

Plague was introduced to Madagascar in 1898, and it has been characterized by a predominant distribution to the central highlands in the following decades. An increase of plague cases has been observed in the past 20 years, in particular in the capital, Antananarivo, and in the coastal town, Mahajanga, after long periods of silence in 28 and 63 years, respectively. A total of 2,982 confirmed or presumptive cases were reviewed in order to describe the changes in the epidemiological pattern of the disease from 1980 through 1999. The mean annual number of plague cases has increased from 33 during the 1980-1984 period to 298 during the 1995-1999 period. A similar trend of distribution has been observed from the first period to the second by an increase of endemic districts above 800 m altitude from 17 to 37. However, the lethality rate has in the same 20 years observation period decreased from 41.6% to 20.7%, probably due to re-enforcing measures as part of the national control program.

Following the severe malaria outbreak in the central highlands in Madagascar in 1986, a vector control program by use DDT pm 75 house-spraying has been implemented to operate in areas located at altitudes between 1000 and 1500 m. Early treatment with chloroquine has also been incorporated in the control program. To detect areas at particular high risk for malaria outbreak the Geographic Information System (GIS) has been applied and tested. The study has shown that the system can be used in malaria surveillance in order to identify areas in which an intense distribution of Anopheles funestus can be anticipated and, hence, targeted in spraying campaigns. The system may also be used to monitor changes in anti-malarial drug resistance, in addition, to control of other vector-born diseases.

A polymerase chain reaction (PCR) technique was used for detection of the Leptospira interrogans rrs gene in kidney tissue from 115 rats, 50 zebu cattles and 13 pigs in an attempt to identify a possible animal reservoir of leptospirosis in Madagascar. In addition, serological testing of 105 individuals in close contact with animals was carried out. The PCR analysis was negative for all the samples tested and only one person was found seropositive at a low titer. The findings suggest that leptospirosis, if prevalent in Madagascar, is likely rare.