Mosquitoes in Florida
By James | Last updated December 29, 2023
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If you are visiting Florida particularly during the summer, it pays to be aware of the potential dangers from mosquito bites. Whilst in some countries, mosquito bites are seen as a minor irritation, some Florida mosquitoes carry life threatening diseases.
There are around 80 species of mosquito to be found in Florida and around 13 of these can carry diseases harmful (and sometimes fatal) to humans.
Common symptoms of all these mosquito borne diseases include rashes, high fever, headaches, neck stiffness, pain behind the eyes and in the joints, nausea and vomiting and with Dengue Fever severe bleeding and shock. There are no preventative vaccines for these diseases.
The newest mosquito born virus to hit Florida is the Zika virus.
Eastern Equine Encephalitis Virus (EEEV)
Eastern Equine Encephalitis is carried by mosquitoes and is not just restricted to horses, humans can also be infected and it can be fatal. Other similar mosquito borne life threatening diseases found in Florida include West Nile Virus, St. Louis Encephalitis Virus and the rarer Highlands J Virus.
All of central Florida’s major theme parks have started offering free insect repellants to counter the threat of the mosquito borne viruses including the Zika virus.
Fatalities are rare but not unheard of so it sensible to take precautions (11 people died in the last major outbreak of St. Louis encephalitis in 1990).
In July 2019 Eastern Equine Encephalitis was detected in sentinel chickens in Orange County but there have been no reported cases of humans contracting the virus. On average there are around 6 to 7 cases a year in the whole of the United States.
In a lot of cases, the problems start when infected visitors come to Florida and are bitten by local indigenous mosquitoes that then transmit the disease to further victims.
In the south of Florida around Key West, several people have also contracted Dengue Fever, again carried by mosquitoes, the first cases reported since 1934. Dengue Fever is common in the Tropics but recently people have been contracting it whilst visiting southern Florida. It is carried by mosquitoes that bite during the day and typically those that have hatched locally. It is rarely fatal.
West Nile Virus (WNV)
West Nile Virus originated in Uganda in 1937. Most people exhibit no symptoms but about 1 in 5 people will contract mild symptoms. Less than 1% will develop severe symptoms such as meningitis and encephalitis.
Chikungunya Fever (CHIK)
This virus is usually picked up whilst abroad in the Caribbean, Africa and Asia but there have been a couple of cases where people have been infected in Florida itself. It was first identified in Tanzania in 1952.
The main symptom is terrible joint pains.
The Zika virus also originated in Uganda in 1947 and is spread by Aedes mosquitoes mostly active during the daytime. Both Aedes aegypti and Aedes albopictus mosquitoes are present in Florida.
In 2015 it hit the headlines as it spread to South America and a few isolated cases started to appear in Florida. To start with they were all people who had caught the illness whilst visiting South America.
However there were then a few cases in several areas of southern Florida. The first was in a one square mile district in the Miami area known as Wynwood where people have contracted the disease locally; i.e. the virus has been transmitted into local mosquitoes. Locally transmitted cases were subsequently identified in Miami-Dade, Palm Beach and Pinellas County.
Symptoms are generally similar to a mild form of Dengue fever but pregnant women can pass the virus onto their fetus which can result in brain damage to the unborn child. The virus can also be transmitted sexually.
As of September 2016, the virus had been eradicated in the Wynwood area but was still active around Miami Beach for a time. In 2017 it had all but died out in South Florida and in 2018/2019 there were no known cases in Florida.
Theme Parks and Mosquitoes
Most of Florida’s theme parks have large expanses of water which are a natural attraction to mosquitoes but you may notice that in most cases, the water is not stationary or stagnant.
This is because by keeping the water moving, it is less likely that mosquitoes will lay and successfully hatch their eggs. Parks also stock open expanses of water with fish that will eat the larvae.
Sensible Precautions against Mosquito Bites
If you staying in Florida, particularly during the summer months, then it makes sense to take precautions. If you are outdoors around dawn, dusk or during the evening then try to wear clothing that covers most of your skin.
You should also use a mosquito repellent that contains DEET (NN-diethyl-meta-toluamide) or a natural herbal alternative. Check the labels for the suggested protection time and dosage as these vary by product; some many only last a few minutes, others for several hours. Also make sure they are suitable for the age group you are trying to protect as some are not suitable for children.
You should also keep away from swampy and wooded areas if at all possible.
The Florida Department for Health has issued a set of precautions, the Five D’s:
- Drain/dump – get rid of stagnant water where mosquitoes can breed
- Dusk/dawn – time of day to remain indoors to avoid mosquitoes
- Dress – wear long sleeves and trousers (pants) when outside
- Defend – make sure all doors and windows have tight-fitting screens
- DEET – apply insect repellent with DEET active ingredient (children must be 2 or older)
The state of Florida regularly carries out both ground based and aerial spraying to kill mosquitoes.
Florida mosquitoes are classified as “standing water” species or “flood water” species.
Standing Water Mosquitoes
Standing water mosquitoes often lay their eggs in old tyres, shallow pools, tarpaulins, gutters, bird baths and other garden containers. Therefore if you have any of these types of containers near where you are staying, you are more vulnerable. Water in bird baths should be changed regularly, pool water chlorinated and all other standing water drained away.
These types of mosquitoes are dependent upon the level of rainfall so the mosquito breeding season typically coincides with Florida’s rainy season, i.e. May/June through October (also the hurricane season). In fact hurricanes and tropical storms often trigger a surge in mosquito numbers and many eggs hatch following the heavy rain associated with hurricanes and storms.
Flood Water Mosquitoes
Flood water species on the other hand lay their eggs in moist soil and the eggs actually have to dry out before they are ready to hatch. However, again, it is rain that triggers the hatching. Mosquito eggs can survive for a long time, they just need a shower of rain to cause them to hatch.
Anyone who is concerned about mosquitoes and in particular the Zika virus should talk to their doctor and/or visit the Centers for Disease Control and Prevention website.
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