Orange County Mosquito Control has been busier than usual this summer.
That’s because hotter temperatures and longer periods of rain are creating ideal environments for mosquito breeding around the world. Locally, there’s also been an impact.
“What's happening here in Orange County, Florida, is a direct reflection of what we're seeing in other parts of the world,” said Steve Harrison, the manager of Orange County Mosquito Control.
Harrison said the agency responded to 60 different cases involving diseases that people within the county could transmit to somebody else through the bite of a mosquito — with most patients having traveled from outside Florida. Sixty is more than double the number of cases mosquito control responded to last year.
However, Harrison said Florida’s local mosquito breeding season has been pretty average.
He says the reason for the increase is travel.
The interconnectedness of global health
Nearly all of the cases in Orange County have involved a traveler to South American, Central American or a Caribbean country, where mosquito levels have reached historically unprecedented levels.
According to the Pan American Health Organization, there have already been over 11 million South American cases in 2024 – twice the amount throughout 2023. Most cases, about 9 million, were reported in Brazil.
The Florida Department of Health has reported 456 travel-related cases of dengue so far this year. The Department had expected around 215 for the year. Most cases, 173, have been from Cuba, followed by Brazil with 61 cases.
The travel cases are concerning to mosquito control, since dengue can only spread if a person who acquired it is bitten by a mosquito carrying the virus.
In August, two locally acquired cases of dengue were reported in Lockhart, in the northwest part of Orange County. They were the first two domestic cases in Orange since the 1930s.
But Ddengue isn’t the only vector disease (an illness disease transmitted to humans by animals such as mosquitos, ticks, or fleas) that’s popping up in Florida. Two travel-related cases of Oropouche fever, or sloth fever, have been detected in Orange County. Thirty cases have been found across the state, according to the state health department.
“The emergence of Oropouche virus, even though the cases are travel-related, is a cause for concern,” Harrison said in an Orange County press release. “It highlights the interconnectedness of global health and the potential for mosquito-borne diseases to spread in other parts of the world.”
Florida cases have involved patients with a travel history to Oropouche-endemic areas like Brazil, Cuba and Columbia.
A warming world means a buzzing breeding ground
What’s helping the mosquito population grow in these countries are rising temperatures and changing weather patterns, which are in turn growing the spread of vector-borne diseases, according to the World Health Organization.
The WHO reported the beginning of the 2024 summer as having above-average temperatures for North and South America. It predicted above-average temperatures would also be present throughout September.
But heat creating ideal mosquito-breeding grounds is only one factor, Harrison said. Hotter temperatures also allow mosquitoes to incubate, or develop, viruses at a quicker pace.
“You also have an extrinsic incubation period where a mosquito has to incubate viruses inside of them, and so the warmer it is, the faster they're able to do this,” he said.
Other factors have also probably led to more vector-borne diseases such as deforesting and urban spread into parts of the world that haven’t been treated for mosquitoes.
Harrison pointed out that Florida is also dealing with a hotter-than-normal summer but the reason Orange County hasn’t been reclaimed by the blood-sucking little flies is because of the public health infrastructure.
“Orange County put mosquito control up on a high level of importance, and so they fund us very well,” Harrison said. “In other countries, you may lack a public health pest control program. There are also cultural differences.”
Differences like not having window screening or air conditioning would stop more biting from happening.
Harrison said the best way residents can help reduce the odds of a vector disease from becoming endemic to the area is to tip or toss any containers that gather water.
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