What diseases do mosquitoes transmit?
Each year, over a million people die throughout the world as a result of mosquito-borne illnesses. Mosquitoes can transmit several viruses, parasites, and other diseases that humans, horses, dogs, birds, and other species are highly susceptible to. While many diseases are easy to spot and prevent, as well as to treat, others require more specialized care. Therefore, it’s important that you be aware of all of the diseases mosquitoes can transmit so that you can help protect yourself against contracting them.
Adult mosquito feeding on a person
West Nile Virus
West Nile Virus is transmitted to people, birds, and horses. It is incredibly common in the United States, and often presents no symptoms. Children and the elderly can have more pronounced symptoms. This disease is characterized by minor symptoms such as headache, fatigue, and a rash. In severe cases in which this disease is left untreated, it can also affect the nervous system.
West Nile Virus
La Crosse Encephalitis
This viral disease is transmitted by the Tree Hole mosquito and although rare, it can provoke serious illness in children and the immunocompromised. It tends to isolate itself within the Appalachian region and though not transmissible between humans, can b fatal in young children.
Jamestown Canyon Virus
This virus is transmitted through several types of mosquitoes, but rarely infects humans. It is closely related to the La Crosse virus, although it is more likely to affect health adults.
Western Equine Encephalitis
Also affecting humans, horses, and birds, this virus is spread through the same type of mosquitoes that spread West Nile Virus. While it was, at one time, rampant in many areas of the United States, outbreaks have thankfully become less frequent within the last couple of decades.
Eastern Equine Encephalitis
Eastern equine encephalitis (EEE) virus (Colourised transmission electron micrograph) on an affected salivary gland. Virus in red
This rare disease affects humans and horses, and very few people feel symptoms extreme enough to support. However, some cases have been extreme and caused their victims extreme suffering. It is more common in horses This is one of the most serious mosquito-borne illnesses, as it affects the central nervous system. It can cause severe symptoms and, in some cases, death.
The mosquito that carries this disease is found in hardwood swampland in Atlantic and Gulf Coast states, as well as in the Caribbean and Central and South America. The life cycle of this arbovirus is complex, requiring mosquitoes to feed on infected birds. These infected mosquitoes then feed on horses, humans, and other mammals. A human cannot spread the disease to another human, or a horse to another horse, because mammals are considered “dead-end hosts” who cannot pass the disease any further.
Eastern Equine Encephalitis causes severe symptoms if any present, such as flu-like complaints. Victims may experience fever and headache, and in extreme cases, seizures or coma. While the disease sometimes presents no symptoms, when it does, they are severe. Over half of those who contract this disease will die, but of those who survive, many will suffer permanent brain damage. Although a vaccine is available for horses, none is yet offered for humans.
St. Louis Encephalitis
St. Louis Encephalitis is transmitted from birds to mammals by infected mosquitoes, usually of the Culex genus. This is found throughout most of the United States, but typically in southern areas, such as the Gulf of Mexico. These outbreaks are usually re result of localized epidemics and tend to affect the elderly and very young. Just as with Eastern Equine Encephalitis, there is no vaccine. Symptoms are similar to Eastern Equine as well.
Chikungunya
Chikungunya is primarily found in Asia and Africa, but has been detected in rare bouts in the Western Hemisphere. It is more common in the Caribbean and has been reported in small amounts in Florida, Puerto Rico, and the U.S. Virgin Islands. This disease includes extreme joint pain, and while the disease is not fatal, it can produce such painful symptoms that its victims are debilitated for several weeks. There is no vaccination or treatment for this virus, besides pain medications. It is most commonly transmitted by the Asian Tiger Mosquito and tends to be more contained to urban areas. The mosquitoes that transmit this disease lay their eggs in containers, such as cans or old tires, making those living in close quarters more likely to contract the disease.
Foot of a person infested by the Chikungunya virus transmitted by the aedes mosquito. By Nsaa – Own work, CC BY-SA 3.0,
Dengue Fever
This tropical fever occurs rarely within the continental United States, although isolated outbreaks have occurred in southern, tropical-climate states such as Texas, Florida, and Hawaii. Dengue has a low mortality rate, but causes severely debilitating symptoms. Dengue is more common than other diseases because the mosquitoes that carry it, typically Aedes mosquitoes, prefer to lay their eggs in containers. These types of mosquitoes are usually not easily controlled by conventional spraying methods, either.
World dengue distribution map
Although this disease is rare in the continental United States, it has become more common within the last ten years. It has also become more deadly, requiring increased diligence to both control and prevent outbreaks.
Malaria
Unlike most of these diseases, which are caused by viruses, malaria is a disease caused by a parasite. This serious disease can be deadly, but there are various treatments and contraceptive methods available to help prevent it. While it is not found in the United States, it is very common in sub- Saharan Africa, South Asia, and Central America. It is not uncommon for American travelers to contract this disease while traveling abroad.
Malaria life cycle
Malaria was discovered thousands of years ago, and was originally thought to be caused by polluted winds from swamps and rivers. Today, about forty percent of the world’s population is at risk of contracting malaria as a result of climate change. In more temperate climates, malaria is rare, as it is controlled with DDT and other insecticides. However, if you plan on traveling to a tropical area, it’s important that you protect yourself against it. Anopheles mosquitoes are the primary vector of this parasite.
Yellow Fever
Yellow fever is easily preventable with a simple vaccination and, as a result, is rare in the United States. Having been discovered over four hundred years ago, it is mostly found in tropical areas of Africa and Central America. That being said, it is even rare for travelers to contract yellow fever, as most foreign countries have vaccination requirements that must be met before entry.
Zika
Zika is a new disease, discovered in 2015 for the first time in the United States. It originated in central Africa and has rapidly spread, now found in thirty-five countries in the Western Hemisphere. Zika is unique in that it can (rarely) be spread through sexual contact with another human. It presents profound symptoms, including joint pain, rash, and conjunctivitis. The most dangerous symptom of the disease presents when it is transmitted to a developing baby, who can develop microcephaly.
Zika virus suitable environment map. By Jkan997 – Own work, CC BY-SA 4.0,
Dog Heartworm
As the name suggests, this disease does not affect humans, but instead their pets. This illness is caused by a roundworm larvae and transmitted by a mosquito bite. These worms circulate in the bloodstream of a dog once it is bitten, and can remain for up to four months. While humans can initially be infected with this roundworm, they can’t survive inside a human host.
This disease can be prevented in dogs, as well as cats, with preventative pills and injections. This disease is painful for a pet, but rarely deadly. It has been reported in all fifty states.
More about mosquitoes
[catlist name=”mosquitoes”]