Plague, a reemerging disease in Madagascar.

Human cases of plague, which had virtually disappeared in Madagascar after the 1930s, reappeared in 1990 with more than 200 confirmed or presumptive cases reported each year since. In the port of Mahajanga, plague has been reintroduced, and epidemics occur every year. In Antananarivo, the capital, the number of new cases has increased, and many rodents are infected with Yersinia pestis. Despite surveillance for the sensitivity of Y. pestis and fleas to drugs and insecticides and control measures to prevent the spread of sporadic cases, the elimination of plague has been difficult because the host and reservoir of the bacillus, Rattus rattus, is both a domestic and a sylvatic rat.

Epidemiological and diagnostic aspects of the outbreak of pneumonic plague in Madagascar.

BACKGROUND: Plague is a re-emerging disease and pneumonic plague is the most feared clinical form. We describe a well-documented outbreak of pneumonic plague in Madagascar. METHODS: Field epidemiological data were collected. Biological tests (microscopy, culture of Yersinia pestis, F1 antigen ELISA and dipstick assays, IgG anti-F1 ELISA) were done on sputum, serum, or necropsy samples. The infection rate among 154 contacts was assessed by anti-F1 serological techniques. FINDINGS: The index case was a bubonic patient with a secondary lung infection, who contaminated a traditional healer and his family. Funeral ceremonies and attendance on patients contaminated other villagers. In total 18 cases were recorded, and eight died. F1 antigen could be detected in sputum by ELISA and dipstick tests as early as the second day after the onset of the symptoms and also 48 h after treatment. Among the contact population 13 of 154 (8.4%) have been exposed to the plague bacillus (symptomless or latent infections). INTERPRETATION: The F1 dipstick assay on sputum is an invaluable diagnostic tool for pneumonic plague. Treatment of patients and chemoprophylaxis of contacts were efficient in stopping the epidemic.

[Recrudescence and geographic extension of the plague in Madagascar from 1980 to 1999]. / Recrudescence et extension géographique de la peste à Madagascar de 1980 à 1999.

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.

[Epidemiological data on the plague in Madagascar]. / Actualités épidémiologiques de la peste à Madagascar.

The first case of plague was introduced in Madagascar in 1898 in the east coast by way of boat from India. In 1921, plague reach the highlands and a large epidemic over the next twenty years. Until the beginning of the 80's, only of few case were identified, notified mostly in rural setting. However gradually it has re-emerged as a public health problem. Urban plague is located in the city of Antananarivo (resurgence in 1978 after 28 years of apparent silence) and in Mahajanga port (resurgence in 1991 after 63 years of silence). The reactivation of the Plague National Control Program from 1994 will allow better surveillance. The aim of this analysis is to update the epidemiological data on human plague in Madagascar based on reported cases obtained from the Central Lab of the Pasteur Institute of Madagascar from 1980 to 2001 (16,928 suspected cases of which 3,500 are likely positives or confirmed positives). The Plague season runs from October to March on the central highlands and July to November on the north-western coast. Sex-ratio male/female is 1.3/1, and the age-group of 5 to 25 years is more affected. The case fatality rate was 40% in the beginning of the 1980's, and decreased to 20% by the end of the 1990's. The percentage of case with pulmonary plague decrease from 15% to less than 5%. However, geographical extension is demonstrated: 4 districts in 1980, 30 districts in 1999 and 21 districts in 2001. In 2002, the diffusion of a new rapid test (reagent strip) in the primary health centres (CSB) in 42 endemic districts may help to decrease the morbidity and the letality due to plague and improve its control at the national level.

La peste : maladie réémergente à Madagascar

La peste est aujourd'hui considérée par l'OMS comme une maladie résurgente dans le monde. A Madagascar, on assiste à sa recrudescence : 150 à 250 cas par an sont notifiés confirmés ou probables. La peste sévit surtout sur les Hauts-Plateaux où 32 Services de Santé de District sont concernés. Parmi eux, le district d'Antananarivo-ville où 23 cas contrôlés ont été recensés en 1996. Sur les côtes, la maladie a réapparu en 1991, dans la ville portuaire de Mahajanga après 63 années de silence apparent; entre 1991 et 1997, 3 épidémies sont survenues : 180 cas ont été confirmés ou probables de peste. A Antananarivo, la surveillance de la population murine a montré une circulation intense du bacille pesteux. Fait préoccupant, les puces vectrices, Xenopsylla cheopis, récoltées des rats capturés ont montré une résistance aux principales familles d'insecticides dont les pyréthrinoïdes. Cette situation alarmante exige un système d'alerte et de riposte. La mise à disposition d'un test de diagnostic simple, très rapide et sûr aux services sanitaires périphériques devrait améliorer les mesures de riposte devant un cas confirmé de peste

Recrudescence et extension géographique de la peste à Madagascar de 1980 à 1999

Après avoir touché Madagascar en 1898, la peste a atteint Antananarivo en 1921 et s'est étendue sur les Hautes Terres Centrales où elle persiste jusqu'à nos jours. Une recrudescence des cas a été constatée depuis une vingtaine d'années pendant lesquelles, la peste a réemergé dans la capitale Antananarivo et, dans le port de Mahajanga après respectivement 28 et 63 ans de silence apparent. Le programme national de lutte et de surveillance a, de ce fait, été renforcé. L'évolution de l'endémie dans le temps et dans l'espace au cours de cette période a été analysée à partir de 2 982 cas bactériologiquement confirmés ou probables(sex-ratio H/F : 1,3/1). L'incidence annuelle moyenne des cas de peste confirmés ou probables est passée de 33 pendant la période 1980-1984 à 298 pendant la période 1995-1999. Cette augmentation s'est accompagnée d'une large extension géographique de la zone d'endémie, passant de 17 à 37 districts pour la plupart situés à plus de 800 m d'altitude, sauf le port de Mahajanga. Par contre, le taux de létalité a baissé pendant la même période, passant de 41,6% à 20,7%. Un des objectifs des recherches actuelles est une meilleure compréhension des différents cycles épidémiologiques de la peste à Madagascar, afin d'améliorer les stratégies de lutte