How human practices have affected vector-borne diseases in the past: a study of malaria transmission in Alpine valleys

Julien Sérandour,Guy Lemperière,Muriel Raveton,Jacky Girel,Sebastien Boyer,Patrick Ravanel

doi:10.1186/1475-2875-6-115

Abstract

BackgroundMalaria was endemic in the Rhône-Alpes area of eastern France in the 19th century and life expectancy was particularly shortened in Alpine valleys. This study was designed to determine how the disease affected people in the area and to identify the factors influencing malaria transmission.MethodsDemographic data of the 19th century were collected from death registers of eight villages of the flood-plain of the river Isère. Correlations were performed between these demographic data and reconstructed meteorological data. Archive documents from medical practitioners gave information on symptoms of ill people. Engineer reports provided information on the hydraulic project developments in the Isère valley.ResultsDescription of fevers was highly suggestive of endemic malaria transmission in the parishes neighbouring the river Isère. The current status of anopheline mosquitoes in the area supports this hypothesis. Mean temperature and precipitation were poorly correlated with demographic data, whereas the chronology of hydrological events correlated with fluctuations in death rates in the parishes.ConclusionNowadays, most of the river development projects involve the creation of wet areas, enabling controlled flooding events. Flood-flow risk and the re-emergence of vector-borne diseases would probably be influenced by the climate change. The message is not to forget that human disturbance of any functioning hydrosystem has often been linked to malaria transmission in the past.

Highlights

Malaria was endemic in the Rhône-Alpes area of eastern France in the 19th century and life expectancy was shortened in Alpine valleys
Despite the severity of the climate during the Little Ice Age (15th–19th century), malaria was still transmitted by Anopheles maculipennis s.l. mosquitoes, which survived by over-wintering in human habitations and cattle shelters [5,8]
Two reasons were advanced for the increase of marsh fever transmission in the population: first, the embankment operation of the river Arc resulted in the raising of the water level, not suitable for the discharge of the tributaries; and second, the artificial silting of the waterholes on the sides of the dike was not undertaken

Summary

Introduction

Malaria was endemic in the Rhône-Alpes area of eastern France in the 19th century and life expectancy was shortened in Alpine valleys. Malaria remains a major global public health problem, responsible for the death of one million people each year, and threatening more than three billion people in 107 countries [1] This ancient disease is transmitted to people by anopheline mosquitoes and has been controlled in many countries, and eradicated in some. Despite the severity of the climate during the Little Ice Age (15th–19th century), malaria was still transmitted by Anopheles maculipennis s.l. mosquitoes, which survived by over-wintering in human habitations and cattle shelters [5,8] It is, assumed that Plasmodium vivax was the major malaria pathogen in Europe until its official eradication in 1975, judging from the symptoms described in humans infected by the parasites (tertian fever) and in view of its ability to survive cold winters. The P. vivax vector, Anopheles atroparvus, may have been able to transmit P. falciparum, in southern Europe [11]

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