The Pan American Health Organization (PAHO) released its latest data on the chikungunya epidemic in the Americas on June 6. They have received reports of 4,486 confirmed cases of chikungunya and another 130,941 which are suspected. Their total number is 135,427.
The PAHO does not have all the known cases of chikungunya recorded. Media reports show that Chile, Costa Rica and Venezuela have all discovered an imported case of the mosquito borne illness in the last week. In the United States, there have been at least 32 imported cases through June 6. News 13 in Orlando announced today that an imported case has been found in Brevard County FL. News4Jax, also today, reported an imported case in Duval County FL.
Scott Weaver, M.S., Ph.D. is Director, Institute for Human Infections and Immunity at the University of Texas Medical Branch in Galveston TX. He returned from an investigation of the chikungunya outbreak in the Dominican Republic about two weeks ago and answered some questions about his observations in an e-mail on June 6.
The Asian strain of chikungunya is the one circulating in the Western Hemisphere at this time, according to Dr. Weaver. It is transmitted exclusively by Aedes aegypti, the Yellow Fever mosquito.
Female mosquitoes bite to obtain blood which is necessary for the mosquito's reproductive cycle. The mosquito is infected with chikungunya by biting a human suffering the illness. Weaver says that in two days to a week, the mosquito will be capable of transmitting the disease. Only one bite is necessary to infect another person.
Dr. Weaver feels that it will be difficult to project the number of chikungunya cases since so few are being confirmed with laboratory tests. His observations in the Dominican Republic suggest that some of the suspected cases have other illnesses. He feels that the number of actual cases will be in the hundreds of thousands over the next year and not in the tens of millions.