Chronic chikungunya symptoms have large public health impact
Prolonged and chronic symptoms of chikungunya fever, persisting up to six months after the acute infection period, were found to have substantial impact on individuals' daily routines and ability to work, and required additional medical resources to manage, according to research presented at the 2015 International Conference on Emerging Infectious Diseases.
Since the introduction of chikungunya virus to the Americas in December 2013, there has been a sharp increase in the number of chikungunya fever cases reported in the United States. In Florida, 520 cases were reported in 2014. In Africa and Asia, chikungunya virus infections have been shown to cause persistent symptoms including arthralgia and myalgia that last months after infection in some patients.
"Assessing the long-term impact of chikungunya infections and identifying those most at risk for developing chronic symptoms can aid in diagnosing and preventing future cases," said Katherine Kendrick, an Applied Epidemiology Fellow with the Florida Department of Health.
Florida Department of Health epidemiologists attempted to follow all Florida chikungunya fever cases with onset in 2014 in order to assess its impact and to determine which groups have an increased risk of experiencing chronic symptoms.
"We found that a large proportion of Florida's chikungunya fever cases were still experiencing symptoms three or more months after infection," said Kendrick. Of the 374 chikungunya fever cases interviewed three months after infection, 169 (45%) were still symptomatic, and of the 326 cases interviewed six months after infection, 76 (23%) were still symptomatic.
Chronic symptoms not only disrupted daily lives, but also required additional medical visits. In the first three months of illness over half of patients returned to a health care provider since their initial diagnosis, the majority making two or more visits. About 76% of patients took medication to manage their symptoms, the majority taking it nearly every day.
By conducting telephone interviews with patients during the acute phase of the disease, three months after onset and six months after onset, the researchers found that chronic symptoms also impeded patients' ability to work, and disrupted daily routines. Individuals lost a median of 14 days of work, and 34 percent reported having lost the ability to perform essential work duties.
"To identify who was most at risk for developing chronic symptoms associated with chikungunya, we also looked at race, gender, and age," said Kendrick, "which all showed significantly different associations with chronic symptoms." Whites were about three times more likely than blacks to report chronic symptoms, while females and those over the age of 45 were about twice as likely to report chronic symptoms compared to males and those 45 years and younger, respectfully.
The findings from this study are important as assessing the long-term impact of chikungunya can lead to improvements in the diagnosis of the disease as well as its prevention.
