Chikungunya outbreak may become a major US public health problem: scientist

A Yale scientist warns that an outbreak of the mosquito-borne illness chikungunya, which was recently discovered on the Caribbean island of St. Martin, might spread to other nations in the western hemisphere, including the United States.

''It is hard to predict the outcome of such events, but I believe this one has the potential to become a major public health problem for the Americas,'' said Durland Fish, a professor of epidemiology in the Yale School of Public Health.

Chikungunya causes fever, headache, tiredness, nausea, vomiting, rashes, and muscle or joint pain in the ankles and wrists. Symptoms can linger for a few days to a few weeks, but exhaustion usually stays for an extended period of time. It is rarely fatal, but there is no vaccine.

The disease is spread by the same mosquito species that carries the viral disease dengue, which is already widespread in much of the Caribbean and Central and South America, notes Fish.

''Unlike West Nile virus, which circulates in birds that infect mosquitoes, humans are the only reservoir host for both chikungunya and dengue,'' said the Yale researcher.

''An outbreak of chikungunya on French-owned Reunion Island in the Indian Ocean during 2005 caused 255,000 cases, over one-third of the entire population, within one year. Since the Reunion outbreak, chikungunya has appeared in India causing millions of cases and in Italy, which has a temperate climate,'' Fish notes.

Health officials believe that the appearance of the disease in the western hemisphere is caused by infected travellers. ''There are five flights daily from St. Martin to San Juan, Puerto Rico, two to Miami, and more than 20 daily flights to other islands in the Caribbean,'' said Fish, who is also a faculty member at Yale's School of Forestry & Environmental Science.

''I think the potential for it to spread through the Americas and even the United States is very real,'' he added. ''I would like to see a massive effort to contain the virus to this island, but the CDC (Center for Disease Control) and PAHO (Pan American Health Organization) response seems to be restricted to surveillance of cases - which, to me, means just watching it spread.''