Saturday, December 22, 2012

Dengue: Already Entrenched in Southern Florida?

Dengue activity over the past 3 months (blue areas = areas of ongoing
transmission risk);
Here is a nice article on the potential for dengue virus to re-emerge in the United States. The article links to a poster presentation by Shin and colleagues from the University of Florida that was presented at last month's American Society of Tropical Medicine and Hygiene annual meeting. These authors isolated a distinct strain of dengue virus from an outbreak of dengue fever in Key West in 2010 and note that this strain may circulate in the region. Only their abstract is available for review so it is not possible to comment on their research further at this time.

Dengue is a viral infection transmitted by Aedes aegypti (and Aedes albopictus) mosquitoes; it is the most common mosquito-borne viral infection. It causes an acute febrile illness characterized by severe pain (which gives the disease its colloquial name: "breakbone" fever). Although not associated with high mortality, the disease is nonetheless associated with significant morbidity.

Aedes albopictus mosquito (one of the mosquitoes
that carries dengue in the United States);
It is worth taking a second to orient yourself to the map that appears at the beginning of this post; this map shows areas of dengue activity over the past three months, and areas of sustained transmission appear in blue. The research by Shin and colleagues begs the question: should southern Florida also appear in blue on this map?

In recent years we have seen outbreaks of dengue in multiple areas of the United States, including Hawaii, Texas and Florida (as noted above). It is possible that climate change, with global increases in mean temperatures, is playing a role in expanding the disease by increasing the geographic range of the mosquitoes that carry the dengue virus.

Anything that can capture rainwater can become a breeding
ground for the mosquitoes that carry dengue (
Here is an abc news story on dengue in Florida that provides a lot of nice background information on this problem. The article also discusses the use of genetically modified mosquitoes to help control the disease; see here for a previous discussion of this practice.

More examples of potential breeding grounds
for mosquitoes (
The environment in southern Florida (and many other areas of the United States) can support endemic dengue transmission. To boot, we already have the mosquito vectors that carry this disease (as well as other diseases such as chikungunya). As both of these mosquito-borne viral illnesses have seen geographic expansion in recent years, the medical and public health communities in the US need to be especially vigilant in looking for cases of these diseases and controlling the mosquitoes that transmit them.

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