CDC: New Concerns about CHIKV

Chikungunya (CHIKV) virus infection can be hard to distinguish from dengue. Both of these mosquito-borne, acute febrile illnesses have become endemic in the Caribbean and the Americas, with locally acquired cases also starting to turn up in Florida. A new proactive household CHIKV surveillance program begun in January 2014 in Puerto Rico found that cross-testing for dengue and CHIKV found that the actual incidence of CHIKV is higher than thought. By visiting households in addition to getting reports from public health agencies, the CDC found 282 cases per 100,000 residents.

Chikungunya (CHIKV) virus infection can be hard to distinguish from dengue virus infection. Both of these mosquito-borne, acute febrile illness have become endemic in the Caribbean and the Americas, with locally acquired cases also starting to turn up in Florida.

In Puerto Rico, a new proactive household CHIKV surveillance program begun in January 2014 found that cross-testing for dengue and CHIKV reveaked that the actual incidence of CHIKV is higher than thought. By visiting households in addition to getting reports from public health agencies, the CDC and public health workers in Puerto Rico found 282 CHIKV cases per 100,000 residents.

In a report in the Dec. 5 issue of the US Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report the CDC’s Tyler Sharp, PhD and colleagues urge travelers to Puerto Rico—and residents—to take greater precautions to prevent being bitten by mosquitoes.

“Residents of and travelers to areas of the tropics with ongoing CHIKV and dengue virus transmission should employ mosquito avoidance strategies to prevent illness. Such strategies should include use of mosquito repellent, wearing long sleeves and pants, and staying in residences with air conditioning and screens on doors and windows,” the authors warn.

“The household investigations conducted during the chikungunya epidemic in Puerto Rico identified cases that had not been reported, suggesting that the magnitude of the epidemic is larger than suggested by passive surveillance,” Sharp wrote.

In 4,433 cases where doctors were not sure whether patients had CHIKV or dengue, 9.6% were positive for dengue. When those patients were tested for CHICKV 14% were positive. Of 761 suspected CHIKV cases, 14% were positive for dengue. None of the patients had both viruses.

The authors recommend that patients should always be tested for both viruses.

The illness can be fatal. It can also cause long-term joint pain. But unlike dengue infection, CHIKV fever also confers immunity to future infections for those who recover. Additional information on chikungunya, including up-to-date case counts and affected areas, is available here.