What a difference a year makes. Last summer, chikungunya fever was virtually unknown in the Western Hemisphere. Since then, over a quarter of a million people in the Caribbean have contracted the mosquito-borne disease and the CDC reports that 112 people have brought the illness into 27 states in the U.S. So far, no locally acquired cases of the disease have been reported within the United States, but experts warn that it is only a matter of time before the cripplingly painful disease establishes a foothold in the country. That’s in part because climate change has vastly expanded the range and season of the Asian tiger mosquito which spreads the disease.
Chikungunya fever was first identified in Tanzania in the 1950s. The Swahili name means “walking bent over,” a reference to the debilitating joint pain caused by the illness. Sufferers report barely being able to walk and struggling to use their hands. The pain usually only last for a few weeks, but in some cases can linger for months or even years. The paralyzing pain is accompanied by headache, rash, and fever. There is no vaccine or treatment for the disease, and patients are usually told to just ride out the infection with the help of pain killers and fluids. Chikungunya is rarely fatal, but has claimed 21 lives so far in the Caribbean according to the Pan American Health Organization (PAHO).
While there have always been a few cases of people with the disease reported in the Western Hemisphere each year, they have all been cases acquired abroad, in Africa or Asia. But last December, the first case of locally acquired chikungunya was reported in the Caribbean, on the tiny island of St. Martin. Since then, the disease has spread like wildfire. The Dominican Republic has been hardest hit, with 135,000 suspected cases. Guadeloupe has had about 40,000, Haiti comes in third with 39,000, and Martinique reports 35,000.
In all, local transmission has been reported in about 20 nations or territories in the region, from the Virgin Islands, Dominica, Martinique, and Puerto Rico.
There is no direct person-to-person transmission of the disease, but once an infected person is bitten by one of the species of mosquitoes that can incubate the disease — the Asian tiger mosquito in the U.S. — the mosquito’s next human meal gets a case of chikungunya as well as an annoying bite.
As more and more people come back from the Caribbean carrying chikungunya, the chances increase that the disease will start being transmitted within the U.S., and will then be here to stay. The likelihood of this happening is increasing as climate change drives up temperatures and moisture levels in the U.S., opening up new territory for the Asian tiger mosquito.
“There is plenty of habitat in the U.S. that is now suitable for the mosquito,” George Luber, an epidemiologist and the Associate Director of Climate Change at the Centers for Disease Control and Prevention told ThinkProgress in March.
Asian tiger mosquitoes, which first cropped up in Texas in the 1980s, have been spreading northwards ever since. Their habitat is currently restrained by temperature — they need annual average temperatures of 50 degrees Fahrenheit or warmer — but that border is expanding. And as summers arrive earlier and last longer into what used to be the fall, the breeding season of the mosquito has also lengthened. The mosquitoes are now commonplace in Washington D.C. and extend up into Chicago and New York City.
“These changes are happening just when chikungunya, an infectious disease carried by this and other mosquitoes, is rapidly spreading throughout the Caribbean. Pieces are falling into place for a historic epidemic on U.S. shores,” warned three Yale University professors in a recent column for CNN.
“Right now, we are worried about chikungunya in the U.S.,” Roger Nasci, of the CDC told NPR. “In fact, we expect that over the course of the next months or years — as this virus spreads through the American tropics, and we see more travelers coming into the U.S. — we will see local transmission.”
The Asian tiger mosquito also spreads yellow fever and dengue.