Understanding the Persistence of Plague Foci in Madagascar

Voahangy Andrianaivoarimanana,Elisabeth Carniel,Nohal Elissa,Katharina Kreppel,Jean-Marc Duplantier,Minoarisoa Rajerison,Ronan Jambou,Craig R Roy

doi:10.1371/journal.pntd.0002382

Abstract

Plague, a zoonosis caused by Yersinia pestis, is still found in Africa, Asia, and the Americas. Madagascar reports almost one third of the cases worldwide. Y. pestis can be encountered in three very different types of foci: urban, rural, and sylvatic. Flea vector and wild rodent host population dynamics are tightly correlated with modulation of climatic conditions, an association that could be crucial for both the maintenance of foci and human plague epidemics. The black rat Rattus rattus, the main host of Y. pestis in Madagascar, is found to exhibit high resistance to plague in endemic areas, opposing the concept of high mortality rates among rats exposed to the infection. Also, endemic fleas could play an essential role in maintenance of the foci. This review discusses recent advances in the understanding of the role of these factors as well as human behavior in the persistence of plague in Madagascar.

Highlights

Plague is a flea-borne fatal zoonosis caused by the bacillus Yersinia pestis
Rodent surveillance initiated in the 1990s documented the replacement of R. rattus by R. norvegicus in the town (Table 1), favored by the construction of modern houses and sewage networks [3]
This review highlights the complexity of the epidemiology of plague in Madagascar and the effort made by past and present investigators to understand the reasons for the continuous presentation of human plague cases

Summary

Introduction

Plague is a flea-borne fatal zoonosis caused by the bacillus Yersinia pestis. Due to its wildlife reservoirs, plague is still endemic in Asia, the Americas, and Africa. It is reemerging in countries where the disease was thought to have disappeared [2,3]. The infection rapidly disseminates to reach the spleen, liver, and sometimes the lungs, causing a fatal septicaemia. Pneumonic plague is rare but even deadlier It may arise from a bubonic form, by haematogenous spread to the lungs, or from inhalation of aerosols during human-to-human transmission. After one to three days of latency, the onset is sudden and always fatal without early efficient treatment.

Methods

Findings

Conclusion