Archives de l'Institut Pasteur de Madagascar最新文献

This study aims to evaluate the prevalence and density of haemoparasites in native Malagasy birds. Among the 387 birds, belonging to 43 species sampled at six localities in different bio-climatic zones of the island, 139 (35.9%) showed at least 1 hemoparasite with, by order of frequency, Plasmodium and/or Haemoproteus (19.9%), microfilariae (13.7% of 387 birds), Leucocytozoon (11.1%) and Trypanosoma (1.0%). An analysis to further elucidate these observations took into account the interaction of different environmental variables (altitude, season, site of collection) or aspects of the birds (age, weight, sex). There is evidence that some parasites preferentially infect some bird species or families. The largest male birds harboured the highest prevalences and densities of haemoparasite, regardless of species. These findings extend knowledge of bird/blood parasite relationships of Malagasy birds and provide interesting insights, especially concerning the pathogenicity of this type of parasitism and the parasite transmission by insect vectors.

Breast cancer is a great problem of public health all over the world. In developed countries, breast cancer represents the most common cancer in females. Its incidence is also increasing in developing country. In Madagascar, no data is available to estimate the real incidence and prevalence rates of breast cancer. However, the data at the Institut Pasteur de Madagascar can confirm the extent of the problem even if it is not at a national scale. The authors report the results of a retrospective study from histological examination at the Laboratory of pathological anatomy of the IPM, during 7 years. Among 2,337 cases of cancer, 16% (373) were breast cancer. Most of them were a female breast cancer (356 cases). The average age is 48 years old. 30% of the tumors were more than 2 cm in size, corresponding at least to the T2 stade from the International Union Against Cancer anatomoclinical classification. The current histological type is the infiltrating ductal carcinoma (80%), about 2/3 belong to the grade 3 of the Scarff-Bloom-Richardson histopronostical classification. Early diagnosis of the cancer is difficult because of the insufficiency of the sanitary infrastructure, particularly for cervical and breast cancers. A national policy for screening must be set up in order to decrease the rate of these invasive carcinomas. In the meantime, informing women and training all the medical staff is a priority. Recording all the data in Madagascar would be desirable.

To redefine strategy and policy to cure or to prevent malaria, there is a need to get relevant and updated data on Plasmodium sp sensitivity level to antimalarial drugs. Thus, in September 1999, the Madagascan Ministry of Health and the Institut Pasteur de Madagascar (IPM) formed a network named RER for malaria resistance surveillance. To alleviate the lack of experienced medical teams within the health centres, and due to technical and logistic matters, as part of the network activities, it was decided to give a start with the in vitro studies which are carried out at IPM. In vitro sensitivity testing is done by use of the isotopic method. Results from the study done in 2001 demonstrate that the Madagascan P. falciparum isolates are susceptible to amodiaquine (n = 215), to cycloguanil (n = 56), to pyrimethamine (n = 98) and to quinine (n = 214). One isolate (1/110 i.e. 0.9%) of mefloquine-resistant phenotype is detected from the Eastern region. P. falciparum susceptibility to chloroquine is satisfactory with 95.4% (206/216) of in vitro sensitive isolates. RER arises from the partnership and collaboration between the Madagascan Ministry of Health and the IPM. The network set-up is presented. The usefulness of the in vivo approach, and the in vitro investigations (chemosusceptibility test and screening of mutations accounting for resistance to chloroquine) to monitor the emergence and the dissemination of drug-resistant parasites in Madagascar as well as in the subregion of the Indian Ocean is discussed.

Fluorescent pteridines are photosensitive pigments of mosquito cuticle. Their quantity decreases with time during the adult life of mosquitoes. In order to test the feasibility of the reversed-phase HPLC (High Pressure Liquid Chromatography) technique, to measure pteridine fluorescence and to estimate the calendar age, reared Anopheles gambiae of known age are used. Head and thorax were studied on mosquitoes aged 0, 5, 10, 20 days after emergence. There was significant difference between male and female of 0 and 5 days of age; the difference was not significant at 10 days of age. The level of fluorescence between a female's head and thorax non separated does not differ from the sum of fluorescence level of separated head and thorax. Pteridin fluorescent of female's head and thorax does not correlate. It decreases significantly with chronological age between 0 and 5 days either for head + thorax or for head alone. Conversely, this fluorescence quantity is weak and maintained constant beyond 5 days. The use of thorax alone of the female mosquito allows the differentiation of mosquito aged less than 5 days, between 5 and 10 days and aged more than 10 days. Reversed-phase HPLC technique, at least in the way we have demonstrated, does not appear sensitive enough to estimate the age of the species An. gambiae reared in an insectarium. It seems that this technique, relatively complex to manage, does not bring a substantial advantage compared to the method of Detinova, which allows the separation of nulliparous and parous females (i.e. < or = 3 days versus > 3 days).

In 1991, the National Tuberculosis control Program (NTP) of Madagascar adopted the short treatment course and the Directly Observed Treatment Strategy (DOTS), according to the recommendations of the OMS/UICTMR. Development of M. tuberculosis primary resistance to the four antituberculosis drugs (streptomycin [S], rifampicine [R], isoniazid [H], ethambutol [E]) is an indicator of the NTP efficiency. We report results from a five-year survey among patients with new smear positive pulmonary tuberculosis. Acquired resistance is assessed among recurrent cases. During the first survey, carried out in 1994-1995 in four large cities, multidrug resistance (MDR) rate to the major antituberculosis drug H and R was low, 0.25% for primary MDR and 5% for acquired MDR. No primary MDR was found in Antananarivo; on the other hand, acquired resistance rate was the highest there (22%). Because of logistical reasons, the second survey (1999-2000) was only carried out in the capital, Antananarivo. Results obtained among 789 new patients with smear positive pulmonary tuberculosis and 79 recurrents cases in 9 diagnostic centres showed low primary and acquired resistance of 11.1% to any drug. Primary resistance to one drug was 10.6%, mainly due to streptomycin 8.5%. MDR rates are comparable with those observed in 1994-1995: 0.1% for primary MDR and 4% for acquired MDR. These results show that ten years after the new NTP implementation, only a few MDR strains are circulating in Antananarivo, which suggests that NTP has been effective.

The genus Coquilletidia includes some of the mosquitoes involved in the transmission of numerous arbovirosis. Adults are locally abundant and very aggressive for men. In Madagascar, thus genus concerns 3 species among which 2 are endemic and had not been described at larval stage this far. The authors describe a single larva of Coquilletidia collected at Ankazobe in the Middle West of Madagascar, at an altitude of 1200 meters. The geographical distribution of Coquilletidia adults collected in various bio-climatic zones in Madagascar, combined with observed morphological characters, permit us to attribute this larva to Cq. grandidieri.

Cultivation of Plasmodium falciparum has been a major research success, leading to a greater understanding of the parasite. Despite the fact that several P. falciparum clones have been maintained in continuous culture in different laboratories, research in genomics and proteomics would require parasitic material produced from fresh wild isolates. We have tested the effect of the supernatant from primary culture of mice hepatocytes on in vitro growth of P. falciparum isolates. Parasitized blood samples were collected from Madagascan malarious patients naturally infected. Isolates proliferation was assessed by use of isotopic method. The asexual erythrocytic stages of P. falciparum were grown for 42 hours in RPMI 1640-based medium plus L15 medium-based supernatant from mice liver cells culture, and in standard RPMI 1640-based medium alone. The mean of parasite growth was 1.5 times greater when the standard medium was enriched with the liver cells layer supernatant at a proportion of 10% and 15% (v/v). The usefulness of P. falciparum ex-vivo culture and of the hepatocytes in vitro primary culture is discussed.

Reduction of morbidity is the main component in the National Schistosomiasis Control Program in Madagascar. The lot quality assurance sampling (LQAS) method has previously been shown as a useful tool in assessment of immunization coverage. A study was carried in the western part of Madagascar aiming to evaluate the applicability of the method in measuring the level of Schistosoma haematobium endemic level in different communities. Parasitological examination of urine samples from 1,124 children aged 5 to 19 years from 12 different schools by use of filtration technique constituted the reference in determining the prevalence. Three schools were found hyper-endemic (prevalence more than 60%), 5 schools were intermediate-endemic (prevalence between 30 to 59%), and 4 were hypo-endemic (prevalence less than 30%). Those figures indicate a heterogeneous distribution of S. haematobium in the study area. A sampling plan (16.6) was then tested in the same area while other sampling plans were simulated in the laboratory. School teachers randomized under supervision the children to participate in this study and collected urine samples. All sampling plans (16.6), (14.5), (12.4), (10.3), (8.2), (6.1) et (4.0) allowed correct identification of hyper-endemic and hypo-endemic areas. Misclassifications occurred frequently for intermediate-endemic areas. The study confirms that the LQAS method by use of a (16.6) sampling plan constitute a valuable tool for large scale screening of hyper-endemic areas for therapeutic intervention as part of the control program. The study has also shown that school teachers may offer a potential source of manpower locally in such screening operations.

The central highlands in Madagascar are characterized by an unstable occurrence of malaria with the risk of sporadic outbreaks. In major parts of the region DDT indoor spraying campaigns have been carried out from 1993 to 1998. This strategy was in 1999 replaced by another anti-vector intervention program targeting residual foci as detected by a surveillance and early warning system. This system is based on monitoring of presumptive malaria cases in the communities by which the number of presumptive cases exceeded a defined warning threshold value per month. The system was in the follow-up period shown to be very sensitive to variation of the coverage of anti-vector interventions: the number of presumptive cases decreased in the villages in which indoor spraying had been carried out and a minor increase was observed in those villages, where indoor spraying has been suspended. An increase of malaria cases was observed in 44 (20.8%) out of 212 study sites in the same period. The increase was in particular predominant in areas at lower attitude at the outer zones of the central highlands.

Ticks are traditionally considered being host-specific parasites. The pattern of tick-host relationship was elucidated by exhaustive collection from a considerable number of potential hosts from numerous sites in the Malagasy mid-altitude forest. It can from the findings be concluded that the Malagasy ticks found on small mammals may be distinguished as either having a broad host-specificity or being highly host-specific. The results may provide important information in respect to phylogenetic studies with regards to the geological history of Madagascar and its endemic fauna.