Malaria Mosquitoes as a pest nuisance

Public Health Significance of Urban Pests Mosquitoes 355 354 et al., 1969a,b; Moore et al., 1974. It is a febrile, but usually not fatal disease transmitted by Aedes spp., especially the subgenera Aedimorphus, Diceromyia and Stegomyia Jupp McIntosh, 1988; Diallo et al., 1999. Recently, epidemics of chikungunya fever have occur- red on several islands in the Indian Ocean, such as the Union of the Comoros, Madagascar, Mayotte, Mauritius, Seychelles and Réunion, as well as in southern Asia India and Malaysia Institut de Veille Sanitaire, 2006; WHO, 2006a. As of 29 March 2006, the Réunion outbreak has affected more than a fourth of the total population and has brought about extraordinarily severe cases, including meningoencephalitis and multi- organ failure, and even 155 deaths associated directly or indirectly with the infection ProMED Mail, 2006. As the virus vector in the Indian Ocean is the Asian tiger mos- quito, which had been introduced at least a century ago Fontenille Rodhain, 1989; Salvan Mouchet, 1994, there is great concern that the virus will be imported by tra- vellers and be transmitted and established in Europe by the Asian tiger mosquito. In fact, 160 cases of chikungunya disease were imported to France between April 2005 and 31 January 2006 Institut de Veille Sanitaire, 2006, and several others were imported to Germany, Italy, Norway and Switzerland WHO, 2006b. As a consequence, the ECDC, together with a group of experts, is at present conducting a risk assessment for Europe.

11.4.5. Malaria

With a high level of morbidity, but moderate mortality, malaria pestered Europe even northern Europe until the middle of the 20th century. The Second World War provided an opportunity to install wide-ranging control programmes and to rehabilitate previously neglected areas. Thus, countries in southern Europe saw a large reduction of the ende- mic disease, which finally disappeared, due to such factors as improvement of sanitary conditions, drainage of swampy areas, effective medical treatment, separation of animal and human dwellings, and the instability of the Plasmodium cycle in temperate climate zones. Malaria was declared eradicated from Europe in the early 1970s Bruce-Chwatt de Zulueta, 1980. In contrast, it has never disappeared from the south-eastern part of Turkey where, although there were considerably fewer cases in the 1970s, malaria increa- sed to the former endemic level after control programmes were largely discontinued Ça˘glar Alten, 2000. In some eastern countries of the WHO European Region, such as Armenia, Azerbaijan and Tajikistan, the number of cases of malaria increased after the dissolution of the Union of Soviet Socialist Republics, owing to the collapse of the infras- tructure and public health services Majori, Sabatinelli Kondrachine, 1999. Unlike the endemic situation in the eastern European countries, there are sporadic cases of autochthonous malaria in central and southern Europe and in the United States. These locally acquired infections result mainly from bites of Anopheles mosquitoes that have become infected by feeding on malarial tourists, immigrants, seasonal workers and other sources. In particular, travellers often return home with a case of malaria when they have underestimated the risk of becoming infected in tropical holiday destinations, have dis- regarded chemical malaria prophylaxis regimens or have been misinformed about the malaria situation at their holiday destination by travel agencies. Moreover, during the Crosse encephalitis viruses. As with WNV, SLEV has been involved in large urban epi- demics, resulting in thousands of human deaths since 1933 CDC, 2001; Day, 2001.

11.4.3. Dengue haemorrhagic fever and yellow fever