CHIKV was first identified in Tanzania in 1953, the authors noted, and the severe joint and muscle pain, fever, fatigue, headaches, rashes and nausea that can result are sometimes confused with symptoms of dengue fever.
Few patients die of the illness, and about one-quarter show no symptoms whatsoever. Many patients, however, experience prolonged joint pain, and there is no effective treatment for the disease, leaving physicians to focus on symptom relief.
Disease spread is of paramount concern in the week following infection, during which the patient serves as a viral host for biting mosquitoes. Infected mosquitoes can then transmit the virus and cause a full-blown outbreak.
The U.S. Centers for Disease Control and Prevention became aware of the growing threat of a global outbreak in 2005 and 2006, following the onset of epidemics in India, Southeast Asia, Reunion Island and other islands in the Indian Ocean. In 2007, public health concerns mounted following an outbreak in Italy.
To assess the risk of a U.S. epidemic, the authors collected data concerning regional mosquito population patterns, daily regional weather and human population statistics.
They ran the information through a computer simulation designed to conservatively crunch the numbers based on the likelihood that an outbreak would occur in the coming year after just one CHIKV-infected individual entered any of the three test regions.
The results suggested that because environmental factors affect mosquito growth cycles, the regional risk for a CHIKV outbreak is, to a large degree, a function of weather. The authors said that public health organizations need to be "vigilant," while advocating for region-specific planning to address varying levels of risk across the country.
However, Dr. Erin Staples, a CDC medical epidemiologist based in Fort Collins, Colo., said that although the study was "carefully and nicely done" the inves
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