Anopheles mascarensis est un vecteur de paludisme humain sur la Cote Est de Madagascar. Ce present article expose des donnees originales acquises entre 1996 et 2003 sur la repartition, la biologie et la capacite vectrice d'An. mascarensis dans le Moyen-Ouest de Madagascar. Cette espece est fondamentalement exophile tant pour son comportement trophique que son comportement de repos, ce qui explique qu les pulverisations domicilaires d'insecticide ne sont pas suivies d'effet evident sur les populations de cet anophele. Celle espece est principalement zoophile, mais peut piquer l'homme, ce qui concourt a expliquer un indice sporozoitique particulierement bas (1/2218 = 0,045%). Les densites agressives pour l'homme sont ordinairement faibles sauf lors du pic observe entre mai et aout en debut de saison seche. Il en resulte que son role vecteur, sans etre nul, est faible dans le Moyen-Ouest. a contrario de ce qui est observe sur la cote Est. L'addition des roles vecteurs. d'An arabiensis et An. mascarensis est probablement capable de maintenir une faible, endemie palustre dans le Moyen-Ouest de Madagascar en absence du vecteur principal An funestus.
Une investigation epidemiologique conjointe (Ministere de la Sante/Institut Pasteur de Madagascar) a ete menee en juillet 2002, dans deux districts d'une meme province (Fianarantsoa : Fianarantsoa il et Ikongo) face a la frequence anormale de survenue de deces dans un tableau d'infection respiratoire aigue (IRA). Les donnees de morbidite et de mortalite ont ete collectees au niveau du Centre de Sante de Base (CSB) ayant motive la premiere alerte (village de Sahafata, district de Fianarantsoa II). L'exploitation des rapports mensuels d'activite (RMA) a permis le calcul des taux d'incidence etr leur analyse. Les donnees virologiques ont ete obtenues par analyse des prelevements nasopharynges realises lors des deux missions. La symptomatologie clinique et l'homogeneite des resultats de laboratoire permettent de rattacher indiscutablement l'origine de ces episodes epidemiques a la circulation d'un virus grippal de type A et de sous type H3N2. Les taux d'attaque releves sont exceptionnels. La letalite etait significativement plus elevee pour les sujets de moins de 1 an el de 65 ans et plus. Ces donnees sont confirmees par les enquetes posterieures des equipes OMS/Ministere de la Sante. L'ampleur de l'epidemie parait surprenante compte tenu du virus en cause et certaines hypotheses pourraient expliquer ce constat : isolement prolonge puis reouverture de certaines zones a l'egard de la circulation du virus, statut nutritionnel. Conclusion : Les episodes epidemiques d'infections respiratoires aigues a Madagascar investigues en juillet 2002 etaient dus a un virus A (H3N2) sans caracteristiques genotypiques ni phenotypiques particulieres. Divers facteurs peuvent avoir explique l'ampleur de l'epidemie et la letalite elevee constatee dans certains groupes d'âge. Ce contexte epidemique illustre la relative impuissance d'un pays en developpement face a la gestion d'une epidemie de grippe due a un virus grippal classique.
Liee au peril fecal, la cysticercose se contracte lors de l'ingestion d'œufs de ver solitaire (Taenia solium) contaminant les aliments on par autoinfestation par les mains sales. Ces œufs vont se transformer en larves appelees cysticerques (Cysticercus cellulosae). La cysticercose demeure frequente dans de nombreux pays en developpement, en particulier a Madagascar, ou persistent des conditions d'hygiene defectueuse. Pour determiner l'importance de cette parasitose dans la pathologie malgache, deux tests immunologiques pouvant etre appliques a de grandes series ont ete developpes: un test de depistage (ELISA) et un test de confirmation (EITB ou Enzyme-linked Immunoelectro Transfer Blot). Un profil de reconnaissance montrant en EITB les bandes hautement specifiques de 13 et/ou 14 kDa est lie a la forme active (vesicule) des cysticerques, seule forme pouvant reellement justifier l'utilisation d'un cestocide. Ces bandes sont absentes dans les formes transitionnelles (kystes) et calcifiees. Des etudes seroepidemiologiques realisees dans diverses provinces de Madagascar entre 1994 et 1999, et portant sur un total de 4 375 serums, montrent que la cysticercose est une affection frequente a travers l'Ile. Les resultats des tests immunologiques indiquent en effet une seroprevalence de la cysticercose active variant de 7 a 21%: inferieure a 10% dans les regions cotieres (Mahajanga et Toamasina) et plus elevee jusqu'a 20% dans les regions centrales de l'Ile (Ihosy, Ambositra et Mahasolo). La cysticercose peut toucher les sujets de tous les âges. Elle est generalement plus frequente chez les femmes que chez les hommes. Elle est presente tant en milieu urbain que rural. La prevalence nationale de la cysticercose active peut etre estimee a environ 10%, indiquant une forte endemieile qui place Madagascar parmi les pays les plus touches dans le monde. Cette etude confirme que la cysticercose constitue un probleme de sante puiblique a Madagascar. Elle met en exergue lanecessite de la mise en route rapide d'un programme national de lutte contre la cysticercose et le taeniasis.
A Madagascar, les donnees epidemiologiques actualisees concernant le cancer du col uterin ne sont pas disponibles du fait de l'absence de registre du cancer. Le but de ce travail est de realiser une premiere evaluation du probleme, de completer les connaissances epidemiologiques, de reflechir sur les moyens de depistage precoce des lesions precancereuses, de proposer des mesures visant a ameliorer la prise en charge des malades et le contribuer a l'instauration d'un registre du cancer. Il s'agit d'une etude retrospective sur les cancers du col observes de 1992 a 2002 a partir de 23 908 prelevements adresses a l'Institut Pasteur de Madagascar pour examen anatomopathologique et de 12 605 frottis cervicaux pour examen cytologique. En anatomie pathologique, sur 4 136 cas de cancer diagnostiques, 621 cas (63,4%) ont ete observes chez la femme. Sur le total des cancers feminins confirmes, 687 cas (26,2%) ont une localisation cervicale. Trois-quart des cancers du col uterin diagnostiques sont invasifs avec un âge moyen de 48,2 ans au moment du diagnostic. La cytologie de depistage n'a pour sa part diagnostique que 74 cas de cancer. Les lesions precancereuses du col etaient au nombre de 274 dont 61% diagnostiques par la cytologie. Malgre un recrutement non representatif de la population generale, ces resultats apportent des donnees epidemiologiques qui justifient l'institution de programmes de depistage des lesions precancereuses a l'echelon national.
Le cancer de l'intestin est une localisation rare des cancers digestifs. Pour sa reconnaissance a Madagascar, une etude retrospective a ete menee a l'Institut Pasteur de Madagascar sur des pieces operatoires et des fragments biopsiques provenant du Centre Hospitalier de Soavinandriana (CenHoSoa) et du Centre Hospitalier Universitaire d'Antananarivo/Hopital Joseph Ravoahangy Andrianavalona (CHUA/JHRA). Elle a pour but de rechercher les particularites epidemiologiques et diagnostiques, ainsi que les mesures therapeutiques et leurs resultats. Seulement 25 cas ont ete trouves en 10 ans (de 1992 a 2001). Ils representent 5,4% des cancers digestifs diagnostiques par l'Institut Pasteur de Madagascar (IPM). Le sex-ratio est de 0,78/1. La moyenne d'âge est de 36 ans au moment du diagnostic. Le duodenum est le siege de predilection des cancers du grele (50%), suivi par l'ileon (25%) et le jejunum (10%). Une forme diffuse a ete observee dans 15% des cas. Le type histologique le plus frequent est le lymphome (40%) suivi par l'adenocarcinome (32%).
Cette etude evalue la prevalence et la densite parasitaire des hemoparasites chez 440 chauves-souris appui-tenant a 14 especes, et collectees sur 5 sites repartis dans differents milieux bioclimatiques de Madagascar. 93 (21%) chauves-souris se sont revelees positives a l'examen microscopique d'un frottis sanguin, avec par ordre de frequence Haemoproteidae (15,7% des 440 chauves-souris), microfilaires (7,0%) et Trypanosoma (0,7%). Ces 93 chauves-souris appartiennent a seulement 4 especes; et 92 d'entre elles (99%) appartiennent a la famille des Vespertilionidae. Ces quatre especes presentant des parasites sont endemiques de la region malgache : Miniopterus manavi pour Haemoproteidae (38% des 129 individus), microfilaires (23%) et Trypanosoma (2%); Myolis goudoti pour Haemoproteidae (24% des 68 individus) et microfilaires (1%); Miniopterus gleni pour Haemoproteidae (23% des 13 individus); et Triaenops furculus pour Haemoproteidae (4% des 28 individus). Le portage parasitaire n'est pas lie au sexe des chauves-souris. Chez Miniopterus manavi, les individus les plus lourds ont une prevalence de microfilaires nettement superieure; et parmi les individus parasites, les plus lourds sont ceux qui ont la plus forte charge microfilarienne. Dix especes de chauve-souris (avec 202 individus examines) se sont revelees negatives a l'examen microscopique des hemoparasites. Cette etude est la premiere a mettre en evidence des hemoparasites chez les chauves-souris malgaches; elle souleve nombre de questions relatives a la distribution de ces parasites par especes et familles de chauve-souris, a leur pathogenicite, et a leur mode de transmission vectorielle.
La large dispersion geographique du virus West Nile et le regain de virulence observe depuis 1994 dans le bassin mediterraneen, en Europe centrale et en Amerique du nord, avec plusieurs epidemies d'encephalites mortelles, justifie l'importance d'une surveillance reguliere des donnees epidemiologiques concernant ce virus dans le monde. Plusieurs travaux menes par l'Institut Pasteur de Madagascar entre 1975 et 1990 avaient montre que cet arbovirus etait le plus abondant a Madagascar ou il circulait de facon endemique. Aucune etude n'a ete realisee depuis celte epoque. Afin d'evaluer le niveau de circulation, une mesure de la seroprevalence des anticorps anti-West Nile chez les enfants de moins de 15 ans a ete realisee sur deux serotheques provenant d'enquetes en population realisees l'une en 1996 dans la region d'Ambositra sur lea Hautes terres et l'autre en 1999 dans la ville de Mahajanga sur la cote nord-ouest. Les seroprevalences etaient respectivement de 2,1% et 10,6% demontrant une circulation toujours importante de ce virus modulee par les facies climatiques de la grande ile.
Nous presentons ici un cas de tuberculose pulmonaire chronique chez un patient habitant la region d'Antsohihy, chez qui une souche de Mycobacterium bovis multiresistante (MDR) aux antibiotiques a ete isolee.
En vue d'une eventuelle decentralisation progressive de la surveillance de l'efficacite des antipaludiques a Madagascar, il s'avere necessaire d'etablir et de suivre un protocole simplifie et adapte aux contraintes de terrain. Nous avons conduit une etude preliminaire et evalue l'efficacite de sulfadoxine-pryimethamine (SP) dans le traitement de l'acces palustre simple a Plasmodium falciparum, avec un protocole simplifie dans deux villages en zone rurale. Apres le diagnostic du paludisme par examen microscopique d'etalement sanguin, la dose de SP a ete administree a J0 en prise unique; avec du paracetamol. Les personnes traitees ont accepte la re-intervention de membres de l'equipe medicale a J14 et a J28 post traitement. Dix neuf malades, âges de 3 a 63 ans, ont ete inclus dans le cadre de cette etude preliminaire. L'efficacite clinique et parasitologique de la combinaison paracetamol/SP a ete notee chez les 19 patients. Ces resultats indiquent que P. falciparum est sensible au SP a Madagascar. Puisque SP sera utilisee en traitement preventif intermittent chez les femmes enceintes, il faut (a) limiter son utilisation dans la population generale pour eviter la selection de parasites resistants, et (b) continuer a surveiller son efficacite par des etudes pilotes selon le protocole preconise par l'OMS (lourd pour les structures de sante peripheriques - avec des examens cliniques et/ou parasitologiques aux jours J0, J1, J2, J3, J7, J14, J21 et J28), et aussi selon le protocole simplifie, tel qu'on l'a teste, pour une observation dans plusieurs districts de sante. Les limites et l'interet de l'etude du protocole simplifie sont discutes.
Being associated to fecal-oral transmission, cysticercosis is contracted either by auto-infection or by ingestion of food contaminated with eggs from the pork tape worm (Taenia solium). In the stomach, the larvae named cysticercus (Cysticercus cellulosae) hatches from the eggs and invades the host through the mucosa membrane. Human cysticercosis occurs in highly prevalent proportions in many developing countries including Madagascar where hygiene conditions are deplicable. Serology tests applicable to epidemiological surveillance of cysticercosis and associated pathology in the Malagasy population have been developed: an enzyme-linked immunosorbent assay (ELISA) for screening purpose, and an enzyme-linked immunoelectrotransfer blot assay (EITB) for confirmative testing. Two specific bands (13 and 14 kDa) have been identified as significant markers of the cysticercus in an active (vesicle) stage of the infection when cestocidal treatment is strongly indicated. The same bands may on the other hand be absent at early (cyste) as well as late (calcified) stages of the infection. Series of studies, including 4,375 serum samples, have been undertaken from 1994 until 1999 aiming at determinating the cysticercosis sero-prevalence in different provinces of Madagascar. It was confirmed that cysticercosis is highly frequent on the island, and that there exists a marked variation in the prevalence from 7 to 21% between the different provinces: less than 10% in coastal regions (Mahajanga and Toamasina) increasing to 20% in central regions (Ihosy, Ambositra and Mahasolo). It has also been observed that cysticercosis may occur in individuals at any age, and that it is equally distributed in urban as in rural areas. However, it is more frequently detected in women than in men. Madagascar is an endemic country for cysticercosis, which causes major and severe disease with implications in the public health sector. A national control program is, therefore, urgently warranted.
We report a chronic case of pulmonary tuberculosis in a Malagasy citizen from Antsohihy (West of Madagascar), who was infected with a multi-drug resistant Mycobacterium bovis strain. This is the first case reported of the isolation of such a strain in Madagascar.
The "Institut Pasteur de Madagascar" virology laboratory is the National WHO Centre for Influenza surveillance in Madagascar. On this surveillance collaborate the Ministry of Health with 9 sentinel centres. In the present article, the authors relate the results of influenza surveillance in Antananarivo between 1995 and 2002. Among 6341 patients with nasal and/or pharyngeal swabs, influenza virus were isolated from 427 patients (6.7%): 307 (68.4%) influenza virus A (H3N2), 124 (27.1%) influenza virus B, 8 (4.0%) influenza virus A (H1N1). The virus had been continually spreading all year long. The weak and the strong points of the influenza sentinel surveillance are also discussed in order to ameliorate the collection processes of influenzal and respiratory morbidity data.
An epidemiological investigation (Ministry of Health/Institut Pasteur de Madagascar (IPM)) was conducted in July 2002, in two districts of a same province (Fianarantsoa: Fianarantsoa II and Ikongo) considering the high frequency of deaths linked with acute respiratory infection (ARI). Morbidity and mortality data was collected in the Centre de Santé de Base (CSB) which gave the alert (village of Sahafata, district Fianarantsoa II). Analysis of monthly activity reports (MAR) allowed calculation of incidence rates of ARI/pneumonia in Fianarantsoa province. Virological data was based on the analysis of nasopharyngeal samples collected during the investigations. Clinical symptoms and homogeneity of laboratory results are consistent with an origin of these epidemics being related to the circulation of an influenza virus A subtype H3N2. Attack rates were very high. CFR was significantly higher in individuals of less than 1 year and more than 65 years. This data was confirmed by posterior investigations of teams from MoH/WHO. Surprisingly, this large epidemic was due to a known influenza virus that previously circulated in countries of northern hemisphere (the year before) and even in Antananarivo weeks before. Different hypothesis could be proposed to explain such phenomenon: great restriction of exchanges between different geographical zones, nutritional status....The epidemic episodes of acute respiratory infections in Madagascar in July 2002 were due to an influenza virus A subtype H3N2 without any genotypic or phenotypic features. Various factors, could explain the importance of the epidemic and particular high lethality found in some age groups. This epidemic illustrates the relative incapacity for a developing country, to face and manage a flu epidemic caused by a classical influenza virus.
The purpose of this paper is to actualize the historical data on influenza in Madagascar. The first outbreak of flu probably occurred in 1890. The first epidemic fully described was in 1893. Between 1890 and 1957, 11 outbreaks of influenza were registered. Since 1978, the unit of virology of the Institut Pasteur de Madagascar is the National Reference Center of the World Health Organization for influenza in Madagascar. Between 1975 and 2002, 12 epidemics of flu were registered confirmed by viral isolation. Madagascan terms used to design fever diseases are discussed.
Anopheles mascarensis has been demonstrated to be a vector of human malaria in the East coast of Madagascar. Here, we present original data obtained from 1996 to 2003 on the distribution, biology and vectorial capacity of An. mascarensis in the Middle-West of Madagascar. This species is consistently exophilic both for its trophic and resting behaviour. This accounts for the absence of clear impact of any indoor insecticide spraying. This species is mainly zoophilic, but can occasionally bite humans, which explains a low sporozoitic index (1/2218 = 0.045%). The densities of human landing mosquitoes are most of the time very low, with the exception of a peak between May and August at the beginning of the dry season. It implies that the vector's efficiency is very low but not insignificant in the Middle-West of Madagascar, a situation opposite to what is observed on the East coast. The vectorial efficiency of An. mascarensis and An. arabiensis would enable to maintain a low malarial endemicity in the Middle-West, even in the complete absence of An. funestus.
In Madagascar, the epidemiological data actualized concerning the cancer of the collus of uterus are not available because of the absence of register of cancer. The objective of this study is to achieve a first assessment of the problem, to complete the epidemiological knowledge, to point out the tool of precoce detection of the precancerous lesions, to propose the measures aiming to improve the management of the patients and to contribute to the institution of a register of cancer. This is a retrospective survey on the frequency of the cancer of the cervix observed from 1992 to 2002 about 23,908 withdrawals addressed to the Institut Pasteur de Madagascar for anatomopathological exam and 12,605 cervical smears for cytological exam. In pathological anatomy, 2,621 (63.4%) of 4,136 cases of diagnosed cancer, have been observed in women. 687 cases (26.2%) of them were localized in the collus. The 3/4 of the cancers of the cervix is invasive and the mean age is 48.2 years old at the time of diagnosis. The cytology detects only 74 cases of invasive cancer of which most don't have an histological confirmation. 274 pre-lesions of cervix cancer were diagnosed for this period, the majority lesions are cytological diagnosis. In spite of a non representative recruitment of the general population, and by the number of withdrawals considered, these results may represent indicators of the epidemiological situation and justify the institution of program to detect the precancerous lesions in a national scale.
A retrospective survey of cases of cancer of the small intestine observed in the Institut Pasteur de Madagascar (IPM), in the Centre Hospitalier de Soavinandriana (CenHoSoa) and in the Centre Hospitalier Universitaire d'Antananarivo/Hôpital Joseph Ravoahangy Andrianavalona (CHUA/HJRA), has been undertaken with the goal to find out epidemiological and diagnostical particularities, as well as the therapeutic measures and their results. Only 25 cases have been found in 10 years (from 1992 to 2001). They represent 5.4% of the digestive cancers diagnosed by the Institut Pasteur de Madagascar. They concern 14 women and 11 men with a mean age of 36 years old at the time of diagnosis. The motive of hospitalization was an acute abdomen (peritonitis, perforation, occlusive syndrome, König's syndrome) in 64.3%, and a chronic abdominal pain often associated with abdominal mass in 35.7%. The duodenum is the predilection seat of the small bowel cancers (50%), followed by the ileum (25%) and the jejunum (10%). A diffuse shape has been observed in 15% of the cases. The most frequent histological type is the lymphoma (40%) followed by the adenocarcinoma (32%).
To alleviate the insufficient number of experienced medical teams invited to and accepting to monitor the effectiveness of drugs prescribed to patients with a diagnosis of uncomplicated malaria and to insure the surveillance of the susceptibility of P. falciparum to current antimalarials used in Madagascar, there is a need to draw a feasible study protocol carefully discussed with them. We carried out a preliminary study in two rural areas and assessed the efficacy of sulfadoxine-pyrimethamine (SP) for curing uncomplicated P. falciparum malaria, with a simplified protocol based on the principle of observational study. A single dose of SP was given on day 0 with paracetamol. The persons to whom the drugs were administered accepted two other interventions of one member of the medical teams on day 14 and day 28. Nineteen patients, 3-63 years old, fulfilled the follow-up. The efficacy of this combination was noted for the 19 persons. Our results show that P. falciparum strains are susceptible to SP. Since SP will be used in intermittent preventive treatment in pregnant women in Madagascar, one way to delay the occurrence of SP resistant parasites will be (a) to avoid massive use of SP for the non pregnant persons and (b) to monitor susceptibility of P. falciparum to SP as part of pilot studies using standard WHO protocol (which is not really easy for most of the peripheral health facilities--with the follow-up procedures with clinical examination and parasitological control at Days 0, 1, 2, 3, 7, 14, 21 and 28), and routinely with simplified protocol such as the analytical observational study illustrated in this present study. Limit and advantage of observational study are discussed.
The wide geographic distribution of the West Nile virus and the increase in virulence observed since 1994 in the Mediterranean basin, central Europe and North America, with several outbreaks of lethal encephalitis, demonstrate the importance of regular surveillance of the epidemiological data regarding this virus in the world. The Institut Pasteur de Madagascar has shown between 1975 and 1990 that this arbovirus was most abundant in Madagascar, where it had an endemic circulation. There has been no further study since that time. In order to evaluate the level of circulation, the seroprevalence of anti-West Nile antibodies in children that are 15 or less was measured on two different collections of sera. These collections came from population studies realised respectively in the region of Ambositra in the Highlands in 1996 and in the city of Mahajanga on the north west coast in 1999. The seroprevalence were 2.1% and 10.6% respectively, these results indicate that the circulation of this climatic dependent virus is still significant.
The authors reported the first case of leiomyomatosis peritonealis disseminata or diffuse peritonealis leiomyomatosis in a patient of 36 years old. The hyalin degeneration of leiomyomatosis with intra and extra peritonealis extension is an uncommon pathology. The right etiology of this complication of leiomyomatosis is unknown. Its detection is a fortuitous event during laparotomy. It is characterized by an extension to the serosa, a break-in of the tissues and unpredictable invasion of the contiguous organs, and it can touch the heart. Despite its rapid evolution, often accompanied by mechanical complications, it remains a benign tumour.
