2010 was a good year for mosquitoes in Europe. They managed to infect humans with the West Nile virus (WNV), dengue fever, malaria and chikungunya; diseases for which there is no vaccine and no specific treatment, diseases which were thought to be largely eliminated in continental Europe. Dr. Wim Van Bortel, from the European Centers for Disease Control and Prevention (ECDC) spoke in Vienna at the International Meeting on Emerging Infectious Diseases and Surveillance about the alarming increase in mosquito-borne diseases in Europe.
WNV was first isolated in Uganda in 1937 and first identified in 1958 in Europe, in two Albanian males. Since then, the virus has been isolated in a number of other European countries including Portugal, Slovakia, Hungary, Romania, Italy and others. Before 2010, the number of WNV cases was very low, and often only isolated in mammals, with the last outbreak in humans occurring in Romania in 1996-1997. In 2010, however, many European countries have seen an intensified rate of WNV infections, including a large outbreak in Greece.
Dengue fever does not naturally occur in Europe. In 2010 France and Croatia reported the first autochthonous cases of dengue fever in continental Europe since the outbreaks of 1927 and 1928 in Greece. Increased frequency of travel to Southeast Asia, the Americas or the Caribbean has been the major cause of imported cases of dengue in Europe.
Similarly to dengue, malaria and chikungunya are not indigenous to Europe and the increased number of imported infections of malaria and chikungunya has been blamed on international travelers, aid workers or immigrants returning from the endemic areas. Unlike in other years, where only imported cases of the diseases were identified, in 2007 the first indigenous transmission of chikungunya in Europe was reported from Italy. In 2010, France reported two autochthonous cases of chikungunya. Similarly, Spain reported a local malaria case.
Climate change and other variables have a proven impact on the transmission of infectious diseases. Alongside these factors, increased international travel and increased infections in endemic areas in Asia and Africa are heightening the risk of re-emergence of WNV, malaria, dengue and chikungunya in Europe.
Vector-borne diseases are not the only re-emerging infectious diseases in Europe and elsewhere in the developed world, including the U.S. The World Health Organization has identified six diseases whose worldwide re-emergence should be monitored: diphtheria, cholera, dengue fever, yellow fever, and (as unbelievable as it may sound) bubonic plague. But this is however another story.
What needs to be done in the fight against the re-emerging vector borne diseases? Dr. Wim Van Bortel said integrated surveillance systems and response plans need to be developed and implemented immediately, and we need to strengthen our knowledge of these diseases’ transmission in Europe. Furthermore, training and awareness of clinical presentations of the different diseases needs to be increased.
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