We provide education on vector-borne diseases transmitted by mosquitoes.
When a female mosquito bites her host, she uses her saliva to prevent the host’s blood from clotting. Mosquito saliva can cause severe skin irritation for some people through an allergic reaction. Mosquito saliva can also carry disease pathogens to humans and animals like protozoans (Malaria), nematodes (heartworm), and viruses (West Nile virus). The viruses that mosquitoes transmit are called arboviruses.
Multnomah County Health Department
Arbovirus: An arbovirus is a virus that is transmitted from a blood-sucking arthropod (i.e. insects and ticks) to humans or other animals. Arboviruses have complex transmission cycles that involve a primary vertebrate host (where the virus multiplies) and a primary arthropod vector (how the virus gets to one vertebrate host to another). Humans and domestic animals can develop clinical illness but are usually dead-end hosts, which means they do not contribute to the transmission cycle and cannot pass on the virus. Many people may not even know they are infected with an arbovirus. When symptoms do occur (2-15 days from the bite of an infected mosquito), they may include fever, headache, fatigue, dizziness, weakness, confusion, rashes, or muscle weakness. The most severe cases can lead to coma and death.
Mosquito-borne diseases
Chikungunya virus is transmitted by Aedes aegypti and Aedes albopictus mosquitoes, both of which are found in the United States. Transmission occurs when these mosquitoes bite a person infected with Chikungunya then bite a non-infected person. Outbreaks have occurred in North America, Africa, Asia, Europe, and the Indian and Pacific Oceans. There is a risk that the virus will be imported to new areas by infected travelers.
To learn more about Chikungunya:
Filariasis is caused by a nematode (roundworm) and transmitted by Culex and Anopheles mosquitoes. The Filariasis is still an epidemic in Africa and Asia. There are no recorded human cases in the USA and Florida , but dog heartworm (Dirofilaria immitis) is very common and can be a life-threatening disease for canines. Dogs and sometimes other animals such as cats, foxes and raccoons are infected with the worm through the mosquito bite. The major disease vector is the salt-marsh black mosquito, Ochlerotatus taeniorhynchus.
Please contact your local veterinarian or visit the Florida Department of Agriculture website to inquire more about heartworm.
St. Louis Encephalitis (SLE) is an important mosquito-borne disease in the United States. This disease is circulated in birds by certain mosquito species in the genus Culex. In Florida, the main mosquito vectors of the SLE virus are Culex quinquefasciatus and Culex nigripalpus. These mosquitoes usually feed on birds, which are the primary host of the SLE virus. A person can become infected with SLE when a vector mosquito of the SLE virus feeds on an infected bird, then bites a person. Humans are dead-end hosts of the SLE virus. A dead-end host is a host in which the virus cannot multiple enough of itself to make the host infectious. This means that dead-end hosts cannot infect anything else with the virus.
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West Nile virus (WNv) is the main arbovirus of concern in Florida and is transmitted by Culex quinquefaciatus and Culex nigripalpus. These mosquitoes circulate WNv in wild bird populations, which are the primary host of this virus. WNv can be transmitted to humans and horses when a vector mosquito of WNv bites an infected bird and then bites a human or horse. Humans and horses are dead-end hosts, so they cannot transmit WNv.
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Eastern Equine Encephalitis (EEE) is a disease that can be fatal to humans and horses. The primary host for the EEE virus is wild birds. The mosquito species Culiseta melanura is an important vector in maintaining the virus in nature because it almost exclusively on birds. The mosquito species Coquillettidia perturbans feed on birds as well as mammals. making it a bridge vector of EEE to humans. Transmission of the EEE virus occurs when a female Coquillettidia perturbans bites and infected bird, then bites a human or horse. Humans and horses are dead-end hosts so they cannot transmit the EEE virus.
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Yellow fever is a viral disease transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Both of these mosquito species can be found in the United States, however, there has not been a Yellow fever epidemic in Florida since 1905. Currently, Yellow fever occurs only in Africa and South America. Transmission of Yellow fever occurs when an Aedes aegypti or Aedes albopictus female bites an infected primate (human or non-human), and then bites a non-infected primate (human or non-human). A vaccine for Yellow fever is available when traveling to endemic countries.
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Dengue fever is caused by one of four closely related, but antigenically distinct, virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4) of the genus Flavivirus. Aedes aegypti and Aedes albopictus, both of which can be found in the United States,are the main vectors of Dengue virus. Transmission of the Dengue viruses occurs when an Aedes aegypti or Aedes albopictus female bites an infected person and then bites a non-infected person. These viruses can also be transferred from mother to fetus during pregnancy.
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Zika is a viral disease that can be spread in various ways but is mostly spread via the bite of an infected mosquito. The mosquito vectors of the Zika virus are Aedes aegypti and Aedes albopictus, both of which can be found in the United States. Transmission of the Zika virus occurs when an Aedes aegypti or Aedes albopictus female bites a person infected with the Zika virus, then bites a non-infected person.
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Keystone virus is a virus endemic to the southeastern United States. The Keystone virus is transmitted transstadially by the mosquito species Aedes atlanticus, which means that these mosquitoes can pass the virus to their offspring. There is evidence that Aedes atlanticus can vector the Keystone virus to mammals, but mammals’ role in the transmission cycle is largely unknown. There has only been one reported case of a person infected with the Keystone virus in the world. The person infected was a teenage boy in Gainesville Florida. Symptoms may include a rash, mild fever, and encephalitis, brain inflammation. More research is needed to thoroughly understand this virus.