While the number of vector-borne diseases and their incidence in Europe is much less than that of the tropical, developing countries, there are, nevertheless, a substantial number of such infections in Europe. Furthermore, the incidence of many of these diseases has been on the rise, and their distribution is spreading. This publication reviews the distribution of all of the vector-borne diseases of public health importance in Europe, their principal vectors, and the extent of their public health burden. Such an overall review is neces- sary to understand the importance of this group of infections and the resources that must be allocated to their control by public health authorities. Medical personnel must be aware of these infections and their distribution to ensure their timely diagnosis and treat- ment. New combinations of diseases have also been noted, such as the appearance and spread of co-infections of HIV virus and leishmaniasis. The effect of global warming may lead to the resur- gence of some diseases or the establishment of others never before transmitted on the continent. Tropical infections are constantly being introduced into Europe by returning tourists and immigrants and local transmis- sion of some of these, such as malaria, has already taken place as a result. World Health Organization Tel.: +45 39 17 17 17 Regional Offi ce for Europe Fax: +45 39 17 18 18 Scherfi gsvej 8 E-mail: [email protected] DK-2100 Copenhagen Ø, Denmark Web site: www.euro.who.int E82481 THE VECTOR-BORNE HUMAN INFECTIONS OF EUROPE THEIR DISTRIBUTION AND BURDEN ON PUBLIC HEALTH Keywords DISEASE VECTORS PARASITIC DISEASES – epidemiology COMMUNICABLE DISEASES – epidemiology COMMUNICABLE DISEASE CONTROL HEALTH PERSONNEL – organization and administration RISK MANAGEMENT PUBLIC HEALTH EUROPE Address requests about publications of the WHO Regional Office to: • by e-mail [email protected] (for copies of publications) [email protected] (for permission to reproduce them) [email protected] (for permission to translate them) • by post Publications WHO Regional Office for Europe Scherfigsvej 8 DK-2100 Copenhagen Ø, Denmark © World Health Organization 2004 All rights reserved. The Regional Office for Europe of the World Health Organization welcomes requests for permission to reproduce or translate its publications, in part or in full. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Where the designation “country or area” appears in the headings of tables, it covers countries, territories, cities, or areas. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omis- sions excepted, the names of proprietary products are distinguished by initial capital letters. The World Health Organization does not warrant that the information contained in this publication is complete and correct and shall not be liable for any damages incurred as a result of its use. The views expressed by authors or editors do not neces- sarily represent the decisions or the stated policy of the World Health Organization. THE VECTOR-BORNE HUMAN INFECTIONS OF EUROPE THEIR DISTRIBUTION AND BURDEN ON PUBLIC HEALTH ABSTRACT While the number of vector-borne diseases and their incidence in Europe is much less than that of the tropical, developing countries, there are, nevertheless, a substantial number of such infections in Europe. Furthermore, the incidence of many of these diseases has been on the rise, and their distribution is spreading. This publication reviews the distribution of all of the vector-borne diseases of public health importance in Europe, their principal vectors, and the extent of their public health burden. Such an overall review is necessary to understand the importance of this group of infections and the resources that must be allocated to their control by public health authorities. Medical personnel must be aware of these infections and their distribution to ensure their timely diagnosis and treatment. New combinations of diseases have also been noted, such as the appearance and spread of co-infections of HIV virus and leishmaniasis. The effect of global warming may lead to the resurgence of some diseases or the establishment of others never before transmitted on the continent. Tropical infections are constantly being introduced into Europe by returning tourists and immigrants and local transmission of some of these, such as malaria, has already taken place as a result. This publication was supported and funded by the Roll Back Malaria programme of the WHO Regional Office for Europe. Because the literature on these subjects is widely scattered throughout various public health, medical and entomological journals, extensive bibliographical references are provided. Dr Norman G. Gratz 4 ch du Ruisseau, 1291 Commugny, Switzerland E-mail: [email protected] Cover illustration by Karen Lund CONTENTS Introduction 1 Arboviruses 2 Mosquito-borne viruses 3 Mosquito-borne diseases – Malaria 13 Sandfly-borne diseases – Viruses 25 Sandfly-borne diseases – Leishmaniasis 27 Ceratopogonidae – biting midge borne diseases 30 Flea-borne diseases 31 Louse-borne diseases 34 Tick-borne diseases – Viruses 37 Tick-borne bacterial infections 54 Tick-borne rickettsial infections 67 Filariasis infections 87 Mite infections and infestations 90 Arthropod pest control 93 Factors augmenting the incidence, prevalence and distribution of vector-borne diseases 94 The problem and risk of introduced vectors 96 The risk of imported vector-borne diseases being established 99 The possible effect of climate change on vector-borne diseases 100 Conclusions 102 References 104 1 INTRODUCTION While the number of vector-borne diseases and their incidence in Europe is much less than that of the tropical, developing countries, there are, nevertheless, a sub- stantial number of such infections in Europe. Furthermore, the incidence of many of these diseases has been on the rise, and their distribution is spreading. Several reviews have been made of the status in Europe of individual diseases or groups of diseases, e.g. the arboviruses, (Hubalek and Halouzka, 1996), (Lundstrom, 1999), malaria (Sabatinelli et al, 2001), Lyme disease (Weber, 2001) and oth- ers. This publication reviews the distribution of all of the vector-borne diseases of public health importance in Europe, their principal vectors, and the extent of their public health burden. Such an overall review is necessary to understand the importance of this group of infections and the resources that must be allocated to their control by public health authorities. Medical personnel must be aware of these infections and their distribution to ensure their timely diagnosis and treat- ment. Special reference will be made to both emerging diseases and to diseases once thought to be under control that are now resurging in Europe. Ecological changes have resulted in the virtual disappearance of some infections or the vec- tors that transmit them; now, other ecological and environmental changes are resulting in the re-emergence of some diseases. New combinations of diseases have also been noted, such as the appearance and spread of co-infections of HIV virus and leishmaniasis (Desjeux et al, 2001). The effect of global warming may lead to the resurgence of some diseases or the establishment of others never before transmitted on the continent. Tropical infections are constantly being introduced into Europe by returning tourists and immigrants and local transmission of some of these, such as malaria, has already taken place as a result. Well into the twentieth century, vector-borne diseases were the cause of some of the most important public health problems in Europe. Malaria was a serious problem in much of southern and eastern Europe as well as in England after the First World War. The seasonal transmission of malaria extended as far as northern Europe. In 1927–1928, a massive epidemic of dengue with high mortality was witnessed in Athens, Greece Epidemic, or louse-borne typhus, relapsing fever and trench fever were scourges of armies and of civilians during the First World War, and, to a lesser extent, during World War II. This publication reviews vec- tor-borne diseases in Europe and the extent to which they present public health problems; their epidemiology, incidence, and distribution, as well as the distribu- tion of their vectors and reservoirs, is presented. 2 ARBOVIRUSES There are between 500 and 600 known arthropod-borne viruses, or arboviruses, in the world, of which some 100 may give rise to disease in humans. There are four families of arboviruses: Togaviridae, Flaviviridae, Bunyaviridae and Reoviridae. By 1996, 51 arboviruses had been reported from Europe and reviewed by Hubalek and Halouzka (1996 ibid). Many of these viruses are not known to cause human illness; some have only been isolated from arthropods, birds or animals, and their public health significance is unknown. Others may cause significant human ill- ness. These arboviruses will be considered