Nearly three years after Miami-Dade was plunged into a panic by an outbreak of Zika, the county’s stepped-up battle against mosquitoes has succeeded in limiting the spread of the deadly virus.
But as mosquito season again looms with the arrival of summer rains, county leaders on Tuesday cautioned that there are a lot more health threats to worry about than Zika — particularly in South Florida.
“Dengue is always a concern for us, and we are paying especially close attention to a spike in cases in Cuba and other Caribbean islands,’’ Miami-Dade Mayor Carlos Gimenez said, outlining the county’s mosquito-fighting strategies this year. “A lot of people travel to and from Cuba and other Caribbean and South American countries where dengue numbers are rising now and we need to stay on top of this disease.’’
The county poured millions into combating the primary carrier of disease, the Aedes aegypti mosquito, over the past two years. The effort helped reduce the spread of the Zika virus, which can lead to neurodevelopmental disorders in babies born to infected mothers. But that same mosquito species also transmits dengue, yellow fever, chikungunya and other tropical illnesses. The sharp increase in dengue fever cases in Cuba and other Caribbean nations cited by Gimenez is generating concern about what may happen when mosquito season heats up in Miami-Dade.
After Miami became ground zero for the first Zika outbreak in the continental United States in 2016, with 300 locally transmitted cases, more than 1,100 people infected in Florida and four babies born with the congenital Zika syndrome, the county boosted its mosquito control budget to more than $16 million from around $1.6 million. It tripled its staff to monitor and keep mosquito populations under control, implemented county-wide surveillance of breeding spots and partnered with the Florida Department of Health to monitor travel transmission.
Monitoring and mandatory reporting of travel cases are essential parts of Miami-Dade’s strategy to fight the mosquito, said zoologist Bill Petrie, who was hired in September 2017 to lead the county’s mosquito control efforts.
“I don’t like to use this term but dengue is exploding in Brazil this year, and we are seeing a significant increase in Cuba, so we are concerned,’’ Petrie said. “We can’t make predictions but we have a lot of people in Miami traveling to and from these countries. A person infected with dengue may arrive here and get bitten by a local mosquito, which will in turn be able to transmit the disease.’’
Dengue causes high fever, muscle and joint pain, pain behind the eyes, vomiting and fatigue, according to the Centers for Disease Control and Prevention. While the disease has been reported in Florida since the 1800s, the virus hasn’t been prevalent in the region. In Key West, however, there were outbreaks in 2009 and 2010 with a total of 88 locally acquired cases, according to the Florida Department of Health. In November, Florida health officials confirmed the state’s first case of dengue in 2018. The infection occurred in Miami-Dade but officials couldn’t trace the case to a specific area. There haven’t been any notifications of dengue cases so far this year.
Gimenez said the county is ready to respond to any increase in mosquito-borne diseases. Miami-Dade is using 186 traps to monitor mosquito populations and deploys weekly missions to apply larvicide where breeding occurs. Mosquito control technicians pay special attention to areas in Miami Beach and Wynwood, where local transmission was more active at the height of the outbreak in 2016.
This sense of control and efficiency is a far cry from 2016, when Miami-Dade came under fire for doing too little too late to deal with the outbreak of the virus that had already devastated areas in South America starting in 2015. The county had received several early warnings including predictions from a NASA-supported group of scientists that Miami would be the center for Zika transmission in the U.S. given the high number of Latin American visitors and the friendly environment for the Aedes aegypti mosquitoes to reproduce. Still, it proceeded with business as usual until soaring transmission numbers forced it to recognize the health threat and ask for more help.
Mosquito season was quiet last year, with no cases of locally transmitted Zika in Florida and just over 100 cases of travel cases. Across the U.S., the CDC reported no locally acquired infections in 2018 and 72 cases of travelers returning from infected areas.
The county didn’t need to deploy aerial spraying for nuisance black salt marsh mosquitoes last year, although it has an aerial spray contract in place with the Air Force Reserve in case spraying is necessary to reduce the population this season. That targets the black salt marsh mosquito, which bites but doesn’t transmit diseases.
Gimenez urged residents to be vigilant about stagnant water and other potential breeding grounds such as bromeliads, and reminded visitors to avoid getting bitten by using bug repellent and wearing pants and long-sleeve shirts when outdoors.