Credit Martin County Health Department
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With ever increasing international travel in recent years we’ve seen an increase in people arriving in, or returning to the United States who have been infected with dengue while visiting a country or region where the virus is endemic. While not contagious in the classical sense,those infected can pass on the virus to others if they donate blood, either intentionally, or via a mosquito proxy.
After an absence of 6 decades, Florida has reported sporadic locally acquired dengue cases over the past four year (see Florida: Dengue Forces Suspension Of Blood Donations In Two Counties). The virus is believed to have been introduced into the local mosquito population by infected (viremic) international visitors.
So far, the virus hasn’t managed to establish itself as a permanent fixture. But there are researchers who are seriously concerned that with a susceptible mosquito population and repeated introductions of the virus, that dengue could get a foothold in Florida, and many other areas of the nation.
In 2009 the Natural Resources Defense Council (NRDC) released a report outlining the risks that Dengue could re-establish itself in North America, that included this map showing the areas of the United States that are vulnerable to the introduction of Dengue.
Northern climes are far less likely to see dengue take hold than say, Florida or Southern Texas. Still, in the 18th and 19th century, both Malaria and Yellow Fever were endemic up and down the mid-Atlantic coast.
While not exactly a hotbed of tropical disease infections, we’ve a story out of Long Island, New York yesterday regarding a local resident – who had not traveled outside of the metropolitan area in recent months – who was hospitalized with dengue in September. The 50-year-old man has since recovered (see CBS-TV2 news report New York State’s First Known Dengue Fever Infection Found On Long Island).
From the Suffolk County Health Department we get the following statement.
November 20, 2013
Health Commissioner Reports Dengue Virus Case
Suffolk County Commissioner of Health Services James Tomarken reported today that health officials have identified a case of dengue virus in a resident of Suffolk County. A male over 50 years of age from the Township of Babylon was hospitalized in September 2013 with symptoms consistent with dengue virus. He has since fully recovered.
Dengue virus is transmitted to humans by the bite of a mosquito. This case is significant in that it is known to be the first locally acquired case of dengue virus in New York State. While Suffolk County had two confirmed cases of dengue virus in 2012 and three in 2011, those individuals are thought to have acquired the virus while traveling in dengue endemic regions of the world.
It is estimated that there are over 100 million cases of dengue worldwide each year. Southern Florida, southern Texas, and Hawaii are the only areas in the United States where locally acquired dengue fever transmission has routinely occurred. In the Western Hemisphere, the Aedes aegypti mosquito is the most important transmitter or vector of dengue viruses, although the Aedes albopictus, known locally as the Asian Tiger mosquito, can transmit disease.
“The exact route of transmission in this case is unknown,” said Dr. James Tomarken, Suffolk County Commissioner of Health Services. “However, we have determined that this individual acquired dengue virus locally, as he had not traveled outside of the local metropolitan area during the incubation period.”
This individual was likely infected locally with dengue virus when bitten by a mosquito that had previously bitten an infected traveler. Both state and local health officials say that despite this isolated finding of locally acquired dengue virus in New York, they do not expect that dengue virus will become widespread in the region, as the temperate climate in New York does not lend itself to sustained transmission of the virus.
"Given the recent introduction of Aedes albopictus into New York State and the high level of travel in New York to areas of the world endemic for dengue, it is not surprising that a locally acquired case of dengue has been found in the state," said State Health Commissioner, Nirav R. Shah, M.D., M.P.H. "This finding emphasizes the need for physicians to be aware of signs and symptoms of diseases common in tropical countries, but may occasionally present themselves in New York.”
The principal symptoms of dengue fever are high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, and mild bleeding or bruising. The more severe form of the disease, Dengue Hemorrhagic Fever (DHF), can be fatal, and most commonly occurs when someone is infected with dengue for the second time. There is no immunization for dengue virus, and there is no specific treatment for a dengue infection. Individuals with symptoms are advised to consult their health care providers.
The best preventive measure for mosquito-borne diseases is to reduce mosquito breeding areas around homes, primarily artificial containers that hold water. Proper application of mosquito repellents containing DEET, decreases the risk of being bitten by mosquitoes.
Although New York State is not thought to have mosquito populations endemic with dengue, Suffolk County maintains a long-term community-based plan to reduce mosquito populations and prevent other mosquito-borne diseases that are endemic to the region, including West Nile virus.
One locally acquired case of dengue in New York City – while surprising - serves more as a cautionary note than as an alarm bell.
It’s a not-so-subtle reminder that the barriers we erect against infectious diseases – like mosquito control programs, vaccinations, and public health departments – are as vital as they are tenuous, and can fail us if we do not maintain and support them.
Whether we are talking dengue or malaria, polio or measles, or diphtheria or yaws - the threats we’ve eradicated from the United States today still exist elsewhere in the world - and without constant vigilance, could someday return.
The old saying is true, `When public health works, nothing happens’.
