Risk of maritime introduction of plague from Madagascar to Mayotte.

Plague is a rodent-borne disease caused by Yersinia pestis. Most human infections are bubonic plague, as a result of being bitten by infected rodent fleas. Madagascar, Democratic Republic of Congo and Peru are the three most affected countries. Plague was introduced into eastern Madagascar in 1898 by boat from India. It is estimated that the risk of introduction of plague from Madagascar to neighboring islands is very high due to the maritime links. We conducted a study of plague reservoirs and vectors in Longoni Port in Mayotte and Mahajanga Port in Madagascar during two seasons to highlight a non-negligible risk of introduction of Y. pestis to Mayotte. The results showed that two main reservoirs of plague in Madagascar Suncus murinus and Rattus rattus and the main flea vector Xenopsylla cheopis exists in and surrounding the port of Longoni. Y. pestis was isolated from Rattus norvegicus captured close to the port of Mahajanga during this study. Plague bacteria circulate within populations of rodent without causing rodent die-off in Mahajanga. The risk of introduction of plague from Madagascar to Mayotte exists due to the regular exchanges. Continuous surveillance of rat, shrew and flea populations is therefore necessary in all the surrounding countries that have regular exchanges with Madagascar to prevent the spread of the plague.