Poll: Chikungunya in the South-Eastern United States

Do you think a chikungunya epidemic is credible threat in the South-Eastern United States?

On one hand, a competent vectors (Aedes albopictus) is present, climatic conditions are favorable, and international tourism offers plenty of opportunities for the importation of this disease. However, the human density is low compared to parts of the world where chikungunya epidemics occured, and the American lifestyle (driving cars, air-conditioning and window screens) limits the contact with vectors.

Please indicate your opinion using the online poll on the right. I will report back on its results.

First isolation of WNV in the Caribbean from sentinel chickens and mosquitoes

ProMedMail carries an interesting report on the first isolation of WNV from IgM seropositive sentinel chickens and mosquitoes in Puerto Rico (see the original paper in the American Journal of Tropical Medicine and Hygiene as well as in the Pan American Journal of Public Health). According to these sources, seroconversions started on June 4th 2007, peaked at 45% during June and July, and then fell steeply in August to 2%. However, seroconversions continued to occur at a low rate (2-6%) until October. Quite surprisingly, the article states that only 3 out of 4370 previously analyzed blood samples from dead birds, horses, pigs, monkeys and people were seropositive for IgG antibodies. Thus, sentinel chickens seem to be a highly valuable tool to detect the local activity of West Nile virus. ProMedMail also refers to an earlier review article in the Pan American Journal of Public Health on the spread of West Nile in Latin America. That paper invokes an interesting hypothesis for the apparent lack of human and equine cases of neuroinvasive West Nile in Latin America. They conjecture that a virulent strain of West Nile would be less likely to reach South America as it inhibits the reservoir bird to complete its difficult journey through the Caribbean. Apparently, a similar pattern is documented for St Louis Encephalitis virus where South American strains are less viremogenic than North American strains.