Chikungunya virus, a mosquito-borne alphavirus, causes acute febrile illness with polyarthralgia. Groups at risk for severe disease include neonates, people with underlying medical conditions, and those aged 65 years. Several chikungunya vaccines are in late clinical development with licensure expected in the United States during 2023. We administered a questionnaire to randomly selected households in the U.S. Virgin Islands (USVI) to assess interest in a hypothetical chikungunya vaccine. Estimates were calibrated to age and sex of USVI population, and univariate and multivariable analyses were performed. Of 966 participants, 520 (adjusted 56%, 95% CI = 51-60%) were interested in receiving the vaccine. Of 446 participants not interested in vaccination, 203 (adjusted 47%, 95% CI = 41-52%) cited safety concerns as the reason. Educational efforts addressing vaccine safety concerns and risk factors for severe disease would likely improve vaccine acceptability and uptake among those most at risk.

Chikungunya virus (CHIKV), an alphavirus that causes fever and severe polyarthralgia, swept through the Americas in 2014 with almost 2 million suspected or confirmed cases reported by April 2016. In this study, we estimate the direct medical costs, cost of lost wages due to absenteeism, and years lived with disability (YLD) associated with the 2014-2015 CHIKV outbreak in the U.S. Virgin Islands (USVI). For this analysis, we used surveillance data from the USVI Department of Health, medical cost data from three public hospitals in USVI, and data from two studies of laboratory-positive cases up to 12 months post illness. On average, employed case-patients missed 9 days of work in the 12 months following their disease onset, which resulted in an estimated cost of $15.5 million. Estimated direct healthcare costs were $2.9 million for the first 2 months and $0.6 million for 3-12 months following the outbreak. The total estimated cost associated with the outbreak ranged from $14.8 to $33.4 million (approximately 1% of gross domestic product), depending on the proportion of the population infected with symptomatic disease, degree of underreporting, and proportion of cases who were employed. The estimated YLDs associated with long-term sequelae from the CHIKV outbreak in the USVI ranged from 599-1,322. These findings highlight the significant economic burden of the recent CHIKV outbreak in the USVI and will aid policy-makers in making informed decisions about prevention and control measures for inevitable, future CHIKV outbreaks.

When introduced into a naive population, chikungunya virus generally spreads rapidly, causing large outbreaks of fever and severe polyarthralgia. We randomly selected households in the U.S. Virgin Islands (USVI) to estimate seroprevalence and symptomatic attack rate for chikungunya virus infection at approximately 1 year following the introduction of the virus. Eligible household members were administered a questionnaire and tested for chikungunya virus antibodies. Estimated proportions were calibrated to age and gender of the population. We enrolled 509 participants. The weighted infection rate was 31% (95% confidence interval [CI]: 26-36%). Among those with evidence of chikungunya virus infection, 72% (95% CI: 65-80%) reported symptomatic illness and 31% (95% CI: 23-38%) reported joint pain at least once per week approximately 1 year following the introduction of the virus to USVI. Comparing rates from infected and noninfected study participants, 70% (95% CI: 62-79%) of fever and polyarthralgia and 23% (95% CI: 9-37%) of continuing joint pain in patients infected with chikungunya virus were due to their infection. Overall, an estimated 43% (95% CI: 33-52%) of the febrile illness and polyarthralgia in the USVI population during the outbreak was attributable to chikungunya virus and only 12% (95% CI: 7-17%) of longer term joint pains were attributed to chikungunya virus. Although the rates of infection, symptomatic disease, and longer term joint symptoms identified in USVI are similar to other outbreaks of the disease, a lower proportion of acute fever and joint pain was found to be attributable to chikungunya virus.

Infection with La Crosse virus can cause meningoencephalitis, but it is not known to cause acute flaccid paralysis (AFP). During 2008-2014, nine confirmed or probable La Crosse virus disease cases with possible AFP were reported in Ohio, USA. After an epidemiologic and clinical investigation, we determined no patients truly had AFP.

Zika virus is an emerging mosquito-borne flavivirus that typically causes a mild febrile illness with rash, arthralgia, or conjunctivitis. Zika virus has recently caused large outbreaks of disease in southeast Asia, Pacific Ocean Islands, and the Americas. We identified all positive Zika virus test results performed at U.S. Centers for Disease Control and Prevention from 2010 to 2014. For persons with test results indicating a recent infection with Zika virus, we collected information on demographics, travel history, and clinical features. Eleven Zika virus disease cases were identified among travelers returning to the United States. The median age of cases was 50 years (range: 29-74 years) and six (55%) were male. Nine (82%) cases had their illness onset from January to April. All cases reported a travel history to islands in the Pacific Ocean during the days preceding illness onset, and all cases were potentially viremic while in the United States. Public health prevention messages about decreasing mosquito exposure, preventing sexual exposure, and preventing infection in pregnant women should be targeted to individuals traveling to or living in areas with Zika virus activity. Health-care providers and public health officials should be educated about the recognition, diagnosis, and prevention of Zika virus disease.