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

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

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

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.

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

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

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.

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

Dengue World Distribution in 2008 Estimated 50-100 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

Dengue in the Americas 1980 – 2009

Dengue in USA During 1946--1980, 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

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.

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)

Vector Presence in Florida

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

Number of locally acquired dengue cases (N = 28), by week of illness onset and method of identification --- Key West, Florida, 2009--2010

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

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

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

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)

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)

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

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

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

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

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)

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

Results Environmental investigation – Aedes albopictus for both cases.

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

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

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

References 1. Florida Department of Health Bureau of Epidemiology. Surveillance case definitions for Select reportable diseases in Florida. Retrieved February 15, 2012, from http://www.doh.state.fl.us/disease_ctrl/epi/surv/CaseDefJan2010.pdf   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 http://www.cdc.gov/dengue/clinicalLab/laboratory.html