FLORIDA MOSQUITO-BORNE VIRUSES AFFECTING MAN

Did you know that in the early 1800’s what is now Indian River County was part of a much larger “Mosquito County?” The prevalence of fresh water and coastal wetlands in Florida and the subtropical climate of much of the state were formidable obstacles to its colonization by Europeans. These same characteristics have made the human inhabitants particularly vulnerable to a variety of mosquito-transmitted pathogens, even today. Florida has historically suffered from repeated, large epidemics of serious mosquito-borne disease, including yellow fever, malaria, dengue, and encephalitis.

 

WNV transmission cycle

 

BIRDS AND MOSQUITOES AS THE PRIMARY HOST ANIMALS

West Nile, eastern equine encephalitis and St. Louis encephalitis are mosquito-transmitted viruses are of particular concern for residents of Indian River County because, unlike Zika, dengue and chikungunya viruses, they are considered to be endemic to the county (that is, present all of the time). These viruses are intimately associated with the natural wetlands and agricultural environment of the region. Humans are not a part of their natural life cycle and human infections are simply accidental “collateral damage.” As a group these are considered to be “encephalitis viruses” since encephalitis is the common severe manifestation of infection with any of these viruses. The kinds of mosquito that transmit these viruses bite at night, between dusk and dawn.

  

 

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HUMANS AND MOSQUITOES AS THE ONLY HOST ANIMALS 

Unlike other medically important viruses transmitted by mosquitoes, humans and two Florida mosquito species are the only host animals for dengue, chikungunya and Zika viruses. Besides being transmitted by the same two mosquitoes, these viruses have very similar symptoms, lack vaccines or medications to prevent infection and require the same mosquito control measures to reduce the potential of virus transmission. The mosquitoes that transmit these viruses bite primarily during daylight hours.