[W]ith Ebola dominating headlines across the globe, many people have either forgotten or never knew about the troublesome virus called Chikungunya. My husband and I started discussing this disease several years ago on our program, PID Radio, but since its emergence in Tanzania in 1952, the virus and the mosquito that carry it have arrived in the Western Hemisphere, and even the United States.
Chikungunya is said to be a Kimakonde (Southeast Africa) word that best translates as ‘that which bends up or becomes contorted’, referring to the stooped appearance of sufferers. Incubation is from 2-5 days, and initial symptoms are high fever, joint pain, and sometimes a rash. Though some recover within days, others suffer for weeks or even months. The virus can cause gastrointestinal, ocular, and even cardiac problems.
Chikungunya is a vector-borne disease, transmitted by A. aegypti (yellow fever) and A. albopictus (Asian tiger) mosquitoes. The former type only recently arrived in the US, but A. albopictus thrive across the entire United States. A. aegypti is the most likely to carry Chikungunya virus–for now. Eventually, as more people carry the virus, there is greater chance for mutation, which could make A. albopictus a more efficient vector for the disease. Recent sequencing indicates that the virus is mutating; in fact a ‘second strain’ has now appeared in Brazil:
Brazil has more than 200 confirmed cases of chikungunya. Presently, the new strain appearing in Brazil has not developed the mutations seen in the Southeast Asia strain, according to Vasconcelos.
“Genetic adaptations, if present, could make the virus as much as 100 times more infectious to mosquitoes,” said Stephen Higgs, a chikungunya expert at Kansas State University.
“Such single-point mutations could still develop, however, and it is hard to predict how likely that will be,” Vasconcelos said. “The mutations effectively lower the threshold for what it takes for a mosquito to become infected with chikungunya, replicate the virus in its body and pass it on to humans with its bite.”