Wednesday, August 07, 2019

Miami-Dade DOH Issues Mosquito Advisory Following 2nd Dengue Case of 2019


Ten years ago this week (Aug. 11th, 2009), a woman in Rochester, New York - who had recently returned from the Florida Keys - visited her doctor complaining of headache, malaise, and chills.  
Although initially diagnosed and treated for a presumptive urinary tract infection, after her symptoms worsened an infectious disease specialist decided to test her for a disease not seen in the state of Florida in nearly 70 years; Dengue Fever. 
She became the first (of more than 2 dozen) Dengue patients identified in and around Key West in the fall of 2009 (see 2010 MMWR report Locally Acquired Dengue --- Key West, Florida, 2009--2010).

A year later, the CDC would issue a report indicating far more people were exposed in Key West, although most developed only mild symptoms (see CDC Press Release Report Suggests Nearly 5 Percent Exposed to Dengue Virus in Key West).
The virus returned in 2010 with even greater numbers; infecting 65 – mostly in the Florida Keys - but also 1 person in Broward County, and another in Miami-Dade County.
Since then we've seen a few brief flare-ups of Dengue, particularly along the Southern tip of Florida (see 2013's Florida: Dengue Forces Suspension Of Blood Donations In Two Counties), but no large epidemics. 
Last year,  Florida reported only one locally-acquired case. 
Late yesterday, the Miami-Dade County Health Department announced the 2nd locally acquired case of 2019 (the first was identified in March), and issued a mosquito advisory.

Contact: Communications Office 786-336-1276 
Miami, Fla.—The Florida Department of Health in Miami-Dade County (DOH-Miami-Dade) today confirmed a locally-acquired case of Dengue in the Miami-Dade County community. There is a heightened concern of additional residents becoming ill. DOH-Miami-Dade, Miami-Dade County Mosquito Control and Habitat Management Division will continue surveillance and prevention efforts.

DOH-Miami-Dade reminds residents and visitors to avoid being bitten by mosquitoes and to take basic precautions to help limit exposure. 

To protect yourself from mosquitoes, you should remember to “Drain and Cover”:

Although Zika, Chikungunya, and Dengue are not endemic in Florida, every year millions of people visit the state from all over the world.  And among those visitors are a handful who are recently infected with one of these viruses, and are capable of transmitting it - via mosquito bites - to others.
With Dengue reports up this year in places like the Philippines, Taiwan, and Honduras - the odds of seeing viremic passengers arrive in the United States are also increased.
As we saw in 2007, it only took a single infected traveler from India to introduce Chikungunya to Ravenna, Italy which ultimately spread to at least 290 other people. In late 2013, Chikungunya arrived in the Caribbean - likely carried in by a viremic tourist - and began to spread rapidly across all of Latin and South America (see MMWR: Chikungunya In the Caribbean & South America).
The State of Florida's most recent surveillance report already shows more imported Dengue cases by the end of July, than was reported in all of 2018.

Florida Arbovirus Surveillance

Week 31: July 28-August 3, 2019


International Travel-Associated Dengue Fever Cases: Seventy-five cases of dengue fever with onset in 2019 have been reported in individuals with travel history to a dengue endemic country in the two weeks prior to onset. Countries of origin were: Belize (2), Brazil (2), Central America/Mexico, Colombia, Colombia/Venezuela, Costa Rica, Cuba (46), Dominican Republic, El Salvador, Guatemala (2), Haiti, Honduras (2), India (2), Jamaica (6), Malaysia/Singapore, Mexico, Nicaragua, Thailand, and Venezuela (2).

Counties reporting cases were: Brevard, Broward (9), Hillsborough (5), Lake, Lee, Miami-Dade (41), Orange (6), Palm Beach (5), Pasco, Pinellas (2), Polk, Putnam, and St. Lucie. Four cases were reported in non-Florida residents. One case met the criteria for severe dengue (dengue shock syndrome [DSS] or dengue hemorrhagic fever [DHF]). Those at greater risk for DSS and DHF include persons with previous dengue infection, pregnant women, infants, the elderly, and those with co-morbidities. However, severe illness can also occur in those without any of these risk factors. In 2019, 63 cases of dengue reported in Florida have been serotyped by PCR. Additional serotyping and strain typing are being conducted.

In addition, Florida's DOH reports so far in 2019:
  • Five cases of imported Chikungunya fever 
  • 29 cases of imported Zika fever
  • Thirty-two cases of imported malaria

While we've seen small outbreaks of Dengue in South Florida and Southern Texas, none have managed to get a solid foothold and become endemic the way that West Nile Virus has across North America.
In 2003, a CDC EID study found that economics and lifestyle may have a lot to do to with our lack of locally transmitted Dengue (see Texas Lifestyle Limits Transmission of Dengue Virus).
But given the availability of two competent mosquito vectors (Aedes Aegypti & Aedes Albopictus), and repeated introductions of the virus from travelers coming from regions where the virus is endemic, our luck in this matter may not last forever.

The good news is that mosquito-borne illnesses (including WNV, Zika, CHKV, SLEV, EEE, etc.) are largely preventable. Florida’s Health department reminds everyone to always follow the `5 D’s’: