Location St. Lucie & Martin Counties
In 2009, after an absence of nearly 60 years - locally acquired Dengue fever was again reported in Florida - no doubt due to repeated introductions of the virus by travelers coming from regions where the virus remains endemic.
Cases of dengue in returning U.S. travelers have increased steadily during the past 20 years (8). Dengue is now the leading cause of acute febrile illness in U.S. travelers returning from the Caribbean, South America, and Asia (9).
Many of these travelers are still viremic upon return to the United States and potentially capable of introducing dengue virus into a community with competent mosquito vectors.
The total number of Florida dengue cases in 2009 was 28, but that rose to 65 in 2010 (63 in Key West, 1 each in Broward and Miami-Dade County) in 2010. The number of cases dropped markedly in 2011-12, and up until this week, we’ve seen no locally acquired cases reported in 2013.
What we have seen are imported cases of Dengue, as described in the most recent Florida Arbovirus Surveillance Report.
Imported Dengue: Fifty-seven cases of dengue with onset in 2013 have been reported in individuals with travel history to a dengue endemic country in the two weeks prior to onset. Countries of origin were: Angola, Bangladesh, Barbados, Bolivia, Brazil (3), The Caribbean, Columbia (3), Costa Rica, Dominican Republic (5), Haiti (2), Honduras, Indonesia, Jamaica (4), Nigeria, Panama, Philippines, Puerto Rico (27) and Saint Martin (2). Counties reporting cases were: Alachua, Brevard, Broward (4), Clay, Duval, Indian River, Lee, Miami-Dade (17), Orange (12), Osceola (4), Palm Beach (8), Pasco, Seminole (3), St. Lucie and Volusia. Seven of the cases were reported in non-Florida residents.
It may take many such introductions of Dengue to an area before the right combination of weather, insect vectors, and ongoing transmission occur to enable it to get a foothold in a community.
But given enough opportunities . . .
Which brings us to this report this morning from WPTV.
TREASURE COAST, Fla. - Residents of Martin and St. Lucie counties are being urged to take precautionary measures against mosquito-borne illness after three cases of locally acquired dengue fever were confirmed in those counties, according to the Florida Department of Health in Martin County.
The affected individuals had no history of recent international travel. An investigation conducted by the health department in Martin and St. Lucie counties concluded that exposure may have come from local mosquitoes in the Rio neighborhood near Jensen Beach.
The virus was likely reintroduced to the area by an infected traveler or visitor who was bitten by a local mosquito, and that mosquito went on to bite others.
Like many viral infections (influenza, West Nile, etc), not everyone who is infected experiences symptoms serious enough to seek medical care. With Dengue, it is often the second or third infection (there are 4 sub-types) that proves the most serious.
In order to spread, Dengue requires the right mosquito vector. And the two species best suited to transmit the virus are the Aedes aegypti and Aedes albopictus mosquitoes, which also can spread such diseases as West Nile, Malaria, Yellow Fever, and Chikungunya.
Map showing the distribution of dengue fever (red) and the distribution of the Aedes aegypti mosquito (cyan) in the world, as of 2006. – Credit Agricultural Research Service of the US Department of Agriculture.
Map showing the native habitat (blue) and recent spread (green) of the Aedes albopictus mosquito. --Credit Wikipedia
According to a 2009 report, as many as 28 states in the US have at least one of the these mosquito vectors, a factoid that has some epidemiologists worried that Dengue, Chikungunya, and Malaria could one day become serious threats in the United States.
Although the overall risk of contracting a mosquito-borne illness in Florida remains very small, sporatdic reports of Dengue (along with West Nile, EEE, SLEV, and other rare arboviral threats) are reason enough that health departments continue to urge people to remember to follow the `5 D’s’: