DOH Says No Dengue Cases Since 2017, But Outbreak Still A Possibility

Aedes aegypti, the principal mosquito vector of dengue viruses, is closely associated with humans and their dwellings. (Photo: CDC)

Jamaica’s recent report of a dengue outbreak resulted in the British Virgin Islands issuing a dengue alert earlier this week despite it not reporting any new cases of the mosquito-borne disease. For now, the U.S. Virgin Islands, which has not reported a new case of dengue since January 2017, will not issue an alert.

Territorial epidemiologist Esther Ellis said that the V.I. Department of Health is closely monitoring the situation in the USVI, since “any outbreak of dengue in a neighbor is a threat to the USVI.”

Ellis said it’s possible that dengue is circulating in the territory but has not been detected yet. The DOH is testing approximately 50 samples a week for dengue, chikungunya and Zika, and has not had a confirmed positive case yet. The USVI has not had a dengue outbreak since 2012, and there have been less than a dozen cases of dengue since January 2016 in the territory.

Ellis did caution that outbreaks usually occur every three to five years, which means the USVI could have an outbreak anytime now. Outbreaks are related to the concept of herd immunity. People who have had dengue before are immune to that strain of it and cannot be reservoirs for the virus helping to spread it along, so if a new strain that people haven’t had is in transmission or enough people who have never been infected by dengue before are around, an outbreak is more likely to happen.

The Centers for Disease Control and Prevention defines an outbreak as “an occurrence of disease greater than expected at a particular time and place.”

“Providers as well as the public will be informed if we do confirm a case in the territory,” Ellis said.

There are four different types of dengue that can cause the illness. It is possible for there to be an outbreak of multiple strains at once too.

Zika is still on Health’s watch list too with the last confirmed case in January 2018.

“We continue to test pregnant women throughout pregnancy as a precaution. Because 80 percent of people that get Zika are asymptomatic we are being diligent to have a robust surveillance system in order to catch a case if Zika returns to the territory,” Ellis said.

For more information on dengue virus, visit the CDC.