Saturday, November 24, 2012

European Dengue Outbreak: Etiology & Implications

Here is a link to a Reuters story reporting on the large outbreak of dengue ("breakbone") fever in Madeira (a Portuguese-controlled series of islands in the Atlantic just west of Morocco).  Over 1,300 cases have been reported since the outbreak was first recognized in October; significantly, this is the first sustained European dengue outbreak since the 1920s.

Dengue fever is a viral infection transmitted by Aedes aegypti (and Aedes albopictus) mosquitoes; it is the most common mosquito-borne viral infection. This is a febrile illness associated with high morbidity and low mortality; the disease can be deadly, however, as it can cause shock and an illness characterized by widespread hemorrhaging.

It is believed that the virus crossed species from monkeys to humans in Southeast Asia or Africa sometime in the past 1,000 years, with rapid dissemination of the disease around the world in the 20th century. Per WHO estimates 50-100 million infections occur each year with 22,000 deaths; see the CDC's site for great information about the disease.

Dengue fever is an excellent example of a disease that has emerged and expanded due to globalization; it is believed that rural-urban migration, explosive population growth, increased international trade and poor urban infrastructure all have played roles in the rapid expansion of this disease.

Dengue infections have made a resurgence in the United States as well, with cases reported in Key West in 2009 and recent cases being reported in Hawaii and in Texas, also. There is concern that climate change and global warming are playing a role in the re-emergence of dengue in the US: see a thoughtful commentary on this in the Lancet.; Areas in red
represent areas where dengue has emerged since 1960
What are the implications of the outbreak of dengue in Madeira and the sporadic cases being seen in the United States? It is clear that "tropical" infections can emerge and expand rapidly, and that infectious diseases are affected by globalization and do not respect traditional borders. Any solution to the dengue problem must involve a trans-national approach that emphasizes collaboration and brings together professionals across disciplines.; Aedes aegypti mosquito
It is also clear that this is not a static issue: the public health community must be vigilant with dengue surveillance and early intervention (such as improved mosquito control) when disease expansion is detected.

Finally, here is a nice CBS News piece with a general discussion of the scope of the dengue problem, as well as an interview with Dr. Anthony Faucci, director of the National Institutes of Allergy and Infectious Diseases.

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