1. Re-emergence of locally acquired Dengue Fever in Palm Beach County, Florida
Robert Parkes, MD; Sandra Warren, MPH, JoEllen Alvarez, RN, MPH, Barbara Johnson, RN, BSN, Epidemiology Unit, Palm Beach County Health Department; John Pellosie, JR.,D.O., MPH., FAOCOPM, Chair, Department of Preventive Medicine, Nova Southeastern University Alina Alonso, MD, Director, Palm Beach County Health Department

2. Dengue Virus Single-stranded RNA flavivirus
Arbovirus (Arthropod-Born) Vector = mosquitoes
Same virus family that causes West Nile fever, St. Louis encephalitis, yellow fever
Causes dengue and dengue hemorrhagic fever

3. Dengue Virus Four virus serotypes (DENV-1, 2, 3, 4)
Provides specific life-time immunity for that serotype only
Presence of a serotype may cause infection with a different serotype to be worse

4. Aedes aegypti and Aedes albopictus
Common Dengue Vectors
Aedes aegypti and Aedes albopictus
Primarily Aedes aegypti, but Aedes albopictus has been associated with outbreaks. Albopictus is less anthropophilic, making it a less efficient vector.
Aedes albopictus is found throughout Florida, Aedes aegypti is primarily in south and central Florida.
Transmitted from human to mosquito to human, unlike West Nile Virus where the primary cycle is between mosquitoes and birds and humans are considered incidental infections. In some areas of southeast Asia and western Africa, there is a monkey/mosquito reservoir cycle.

5. Incubation / Viremic Periods
Incubation period is 3-14 days
Fever lasts 2-7 days
Viremia begins just before fever and lasts until fever is gone
Source: CDC

6. Dengue Fever Often mild, non-specific Sudden onset of high fever
Severe headache
Pain behind the eyes
Body aches and joint pains
Nausea or vomiting
Rash
Often confused with other viral diseases, outbreaks are often identified slowly

7. Dengue Hemorrhagic Fever
Severe abdominal pain
Bleeding from the nose, mouth, and gums
Frequent vomiting with or without blood
Black stools
Excessive thirst
Pale, cold skin
Restlessness or sleepiness
Not fully understood why some people develop DHF, but a major risk factor is previous infection with another dengue serotype.

8. Dengue Epidemiology Re-emerging infectious diseases in the world
50 to 100 million cases annually
500,000 hospitalizations
22,000 deaths (mostly children)
Occurs in explosive epidemics

9. Dengue World Distribution in 2008
Estimated million cases per year worldwide, so even though DHF is rare, still hundreds of thousands of cases and tens of thousands of deaths.
Found in tropical and sub-tropical regions of the world, particularly in urban and semi-urban areas

10. Dengue in the Americas 1980 – 2009

11. Dengue in USA
During , no cases of dengue acquired in the continental United States were reported.
Since 1980, a few locally acquired U.S. cases have been confirmed along the Texas-Mexico border
Temporally associated with large outbreaks in neighboring Mexican cities

12. Dengue in Florida Dengue previously endemic Increase in imported cases
Warm climate, regular rainfall
Abundant vectors
Last outbreak in 1934
30 imported cases in 2008.

13. Imported Dengue in Florida
1986 – 2008:
Puerto Rico (41); Dominican Republic (21); Haiti (13)
2011:
Bahamas (9); Puerto Rico (7); Haiti (3), Colombia (3), Trinidad (3)

14. Vector Presence in Florida

15. Dengue Fever in Key West, 2009
September 1 - Monroe County Health Department notified of a New York resident diagnosed with dengue after travel to Key West
Issued a press release to the public and notified area physicians of potential for local transmission of dengue
Florida Keys Mosquito Control District implemented enhanced trapping and spraying of Aedes aegypti

16. Number of locally acquired dengue cases (N = 28), by week of illness onset and method of identification --- Key West, Florida,

17. Locally acquired Dengue in Florida Cumulative 2011 Data as of 3 am, Dec 14, 2011

18. Palm Beach County Dengue Cases 2005-2011
Acquired in FL
Acquired in US, not FL
Acquired outside of US
2005 3
2006
2007 5
2008 4
2009 1
2010 7
2011 2 9

19. Purpose
To present two cases of locally acquired dengue fever in Palm Beach County, Florida in 2011
To highlight the need for continued surveillance

20. Methods Case interviews and medical records review
Confirmatory testing using enzyme-linked immunosorbent (ELISA) and real time polymerase chain reaction (PCR)/reverse transcriptase PCR (RT-PCR)

21. Methods
Transmission from recent imported cases and travel companions was assessed.
Environmental evaluation
Classified using the Dengue Fever case definitions for reportable diseases in Florida (1)

22. Case Classification
Confirmed: a clinically compatible case that is laboratory confirmed
Test
Days post onset
Explanation
Interpretation
Real time PCR
≤ 5days
Patient viremic while febrile
Confirmatory
IgM (paired specimens, acute and convalescent)
≤ 5days for acute >5 days for convalescent
Negative IgM in acute followed by a positive IgM in convalescent specimen
IgG (paired specimens,acute and convalescent)
Must be a 4 fold increase in titer between acute and convalescent
IgM antibody in CSF
IgM antibodies demonstrated in cerebrospinal fluid

23. Case Classification
Probable: a clinically compatible case with supportive serologic findings
A positive IgM antibody test on a single acute (late)- or convalescent-phase serum specimen to one or more dengue virus

24. Case Classification
Suspect: a clinically compatible case with both epidemiologic linkage criteria
Travel to a dengue endemic country, OR
Presence at a location with an ongoing outbreak within previous two weeks of dengue-like illness, OR
Association in time and place with a confirmed or probable dengue case

25. Results
CASE 1:
On 9/30/2011, PBCHD received a positive lab for Dengue IgG
49 yr female, fever, sweating, fatigue
DENV-1 positive by PCR/RT-PCR in acute serum
IgG antibodies positive in acute and convalescent serum

26. Results
CASE 2:
On 10/3/2011, PBCHD received a positive lab for Dengue IgG
23 yr male, fever, chills, headache, fatigue and meningeal signs
IgM and IgG antibodies positive in acute and convalescent serum
Serological findings consistent with previous infection of dengue fever (3)

27. Results
Case 1 traveled to Haiti one month before onset of illness, outside incubation period (2)
None of case 1 travel companions were sick
Case 2 had no travel history outside Florida or the U.S.
Secondary transmission ruled out from recently imported cases

28. Results
Environmental investigation – Aedes albopictus for both cases.

29. Conclusion Case 1- confirmed dengue fever
Case 2- probable dengue fever
Both acquired locally in Palm Beach County, Florida
Both cases recovered

30. Control efforts implemented
County-wide mosquito advisory/alert were enacted
Information and updates were provided
Enhanced surveillance continued
No new cases have occurred

31. Conclusion
It is essential to continue surveillance for Dengue Fever in Florida.

32. References
1. Florida Department of Health Bureau of Epidemiology. Surveillance case definitions for Select reportable diseases in Florida. Retrieved February 15, 2012, from
2. Heymann,D.L., (Ed.). (2008). Control of communicable diseases manual. Washington: American Public Health Association.
3. Centers for Disease Control and Prevention. Dengue laboratory guidance and diagnostic testing. Retrieved February 15, 2012, from