Mosquitoes are considered the world's deadliest animal because of the dangerous diseases they transmit. In the United States, the most well-known mosquito-borne virus, Malaria, was mostly eradicated in the 1950s. Today, West Nile Virus is the most commonly transmitted mosquito-borne illness within the U.S. With the Zika outbreak in 2015 and the impacts of climate change upon us, we should all be prepared, educated, and aware of the most common mosquito-borne illnesses.
How Does a Mosquito Pass on a Virus?
When a mosquito bites you, it injects a small amount of anticoagulant and saliva into your blood. Just as our immune systems attack viruses, mosquitoes also have immune systems. If the mosquito's immune system can't fight off the virus, that leaves a greater chance of the mosquito passing the virus to you. The virus must survive within the mosquito’s gut, then particles have to escape through the salivary gland. In areas where mosquitoes carry West Nile virus, about 1 out of 500 mosquitoes are infected. Furthermore, if bitten by an infected mosquito, the chance of a person developing the illness is roughly 1 in 300.
What Diseases Are Transmitted by Mosquitoes?
There are many different diseases people can contract from mosquitoes. Mosquito-borne illnesses caused by viruses and other microorganisms can easily spread to humans and pets. Because mosquito diseases can be deadly, it is vital for people to be aware of the danger they pose and take precautions to protect yourself and your loved ones. See below for the most common diseases transmitted by mosquitoes.
Malaria is by far the most common mosquito-borne illness affecting humans. According to the World Health Organization, nearly half of the world's population is at risk of Malaria. In 2015, there were roughly 212 million Malaria cases and an estimated 429,000 Malaria deaths. Many regions of Southeast Asia and Africa are extremely vulnerable to this mosquito population due to climate and geography. Mosquito Squad supports Malaria No More and has raised more than $450,000 to help fight Malaria in Africa.
West Nile Virus
Originating from the bird-biting mosquito Culex, West Nile Virus is the most common virus spread by mosquitoes in the continental United States. Since WNV is a virus, there is no vaccine or specific treatment for it. The WNV affects the brain, where it impedes the central nervous system and causes inflammation in the brain tissue, known as Encephalitis. However, according to the CDC, about 80 percent of those infected show no symptoms at all. About one out of 150 infected people develop a serious, sometimes fatal illness. In 2002, the WNV outbreak in North America was the largest outbreak ever recorded, with 4,156 people infected.
At its peak in 2017, there were 542 cases of Zika in the United States. Only seven of those cases were contracted locally, while the majority of individuals with the virus contracted it while traveling. Even if someone is infected from a mosquito bite, symptoms are usually mild and almost never fatal. The real danger is posed to pregnant women, who pass the virus onto the fetus, frequently resulting in microcephaly. This virus gets its name from the Zika Forest in Uganda, where researchers think it originated in 1947, transmitted by Aedes mosquitoes.
With more than one-third of the world’s population living in areas at risk for infection, Dengue virus is a leading cause of illness and death in the tropics and subtropics. Unlike other mosquito-borne viruses, Dengue has become more prevalent over the past decades. It is predominantly active in Southeast Asia and Latin America. In 2016, there were 3.34 million cases worldwide. As many as 400 million people are infected yearly.
Dengue is caused by any one of four related viruses transmitted by mosquitoes. There are not yet any vaccines to prevent infection with dengue virus and the most effective protective measures are those that prevent mosquito bites. When infected, early recognition and prompt supportive treatment can substantially lower the risk of medical complications and death.
Endemic to tropical areas of Africa and Central and South America, Yellow Fever has been eliminated in other parts of the world, thanks to a very effective vaccine. The World Health Organization launched its Eliminate Yellow Fever Epidemics (EYE) Strategy in 2017 to help put an end to this disease.
Yellow Fever virus causes headaches, muscle pain, nausea, and of course, fevers. This virus is usually transmitted by Aedes aegypti mosquitoes.
With symptoms of high fever and extreme joint pain, this mosquito-borne virus mostly occurs in Africa, Asia, and the Indian subcontinent. The first reports of Chikungunya in the United States occurred in 2013 when the virus emerged in the Caribbean. It then expanded rapidly to Central America, South America, and North America. This virus is usually carried by the Aedes mosquito, primarily Aedes aegypti.
What Can Dogs Catch From Mosquitoes?
You aren’t the only one in danger of mosquito-borne diseases. Diseases transmitted by mosquitoes can also affect your cats and dogs. Common mosquito-borne viruses that affect animals in the United States include:
- Eastern Equine Encephalitis (EEE): Unfortunately, this mosquito-borne virus is typically fatal for horses.
- Dog Heartworm (dirofilaria immitis): Mosquitoes can carry the larvae of roundworms and can transmit these larvae into dogs and cats (although dogs are much more susceptible to infection).
Let us help you fight the bite and fend off the world's deadliest animal. Contact your local Mosquito Squad today!
 State of Connecticut Mosquito Management Program. https://portal.ct.gov/Mosquito/Diseases/Mosquito-Transmitted-Diseases
 Sejvar, James J. MD. The Ochsner Journal, 2003. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3111838/