(Thu, 03 Mar 2011 11:27:00 +0000)
When it comes to mosquito activity in Florida, February is normally about as quiet as it gets. The weather is cool – or sometimes cold – and we’ve usually been in droughty conditions for a couple of months.
In fact, the latest Florida mosquito vector surveillance report, issued less than a week ago stated:
Week 8: February, 20 – February 26, 2011
During the period February 20, – February 26, 2011, the following arboviral activity was recorded in Florida:
- DENV activity: No new cases of dengue associated with Key West were reported this week.
- EEEV activity: No EEEV activity was reported this week.
- WNV activity: No WNV activity was reported this week.
- SLEV activity: No SLEV activity was reported this week.
- HJV activity: No HJV activity was reported this week.
Not much activity, although Miami-Dade County was listed as being under a mosquito-borne illness advisory.
So it comes as a bit of a surprise that yesterday the Miami-Dade County Health department issued a statement confirming their second locally acquired case of Dengue in the past 50 years.
March 2, 2011
(Miami, FL – March 2, 2011) – Miami-Dade County Health Department officials received confirmation of the second locally acquired case of Dengue Fever in Miami-Dade County.
The individual was diagnosed with Dengue Fever based on symptoms and confirmed by laboratory tests. The individual fully recovered from this illness.
Dengue Fever is a viral disease transmitted by a type of mosquito common to the southeastern United States and the tropics. It is not spread from person to person. The symptoms of Dengue Fever include, fever (over 101 degrees Fahrenheit), severe headache, severe pain behind the eyes, muscle, joint and bone pain, rash, loss of appetite, nausea and vomiting. There is no specific medication or vaccine for Dengue Fever. If you are experiencing symptoms consistent with Dengue Fever, please call your healthcare provider to see if you need to be seen.
Exactly when this individual was infected wasn’t disclosed, nor do we know which of the four serotypes of Dengue was involved.
All we are told is that the patient recovered.
Each year usually see a couple of hundred imported cases of Dengue and/or Malaria among travelers who had recently visited areas where those viruses are endemic.
Two years ago – for the first time in more than 50 years – we started to a small number of locally acquired Dengue cases showing up in Key West (see MMWR: Dengue Fever In Key West), and in 2010 they totaled 65 cases in Key West and 1 each in Broward and Miami-Dade County.
Through aggressive mosquito control efforts during the 1940s, Dengue and Malaria were both eliminated from Florida – and remained so for nearly a half century.
Since 1990 there have been a few scattered suspected (and confirmed) cases of locally acquired malaria in Florida, including one l reported on last December (see Florida: Locally Acquired Malaria Case Suspected).
But with millions of visitors arriving each year, many from regions where these diseases are endemic, it is basically only a matter of time before someone who is infected arrives – is bitten by a mosquito – and that mosquito manages to carry the virus on to someone else.
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.
In truth, it may take many such introductions of Dengue or Malaria 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 when it does, it can be very difficult to completely eradicate.
The explosive growth of Dengue around the world is well illustrated by the following graph from the World Health Organization.
What this graph doesn’t indicate is a doubling of dengue cases over the past 5 years.
For a fascinating podcast on the efforts of Florida’s mosquito control efforts, I would direct you to an episode of Vincent Racaniello’s TWiV taped last December with regulars Alan Dove & Rich Condit.
Joining them are Ed Fussell, Andrea Leal, and Amy Sargent of the Florida Keys Mosquito Control District at Florida Gulf Coast University (Ft. Myers) in a 105 minute show on Dengue in Florida and Mosquito control in the Florida Keys.
Although the overall risk of contracting a mosquito-borne illness in Florida remains very small, scattered cases of Dengue (along with West Nile, EEE, SLEV, and other rare arboviral threats) are why Florida health departments continue to urge people to remember to follow the `5 D’s’:
A few mosquito-disease centric posts from last year include:
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