Mosquitoes are more than just annoying pests – they also pose serious health threats. Several dangerous diseases can be transmitted by mosquitoes, where a mosquito transfers the disease of an infected person to the next person(s) it bites. Hundreds of thousands of people contract mosquito-borne diseases each year and every year over one million people will die from diseases that they caught from a mosquito bite. Here’s a look at the 5 most dangerous diseases transmitted by mosquitoes. 

Malaria

Malaria is a parasite that is transmitted by mosquitoes, with symptoms beginning 10-15 days after the bite. The symptoms include fever, headache, vomiting and fatigue. Quinine and other anti-malarial drugs can help cure patients but, if not treated, the person can experience a recurrence of the disease months later. An estimated 300-600 million people suffer from Malaria each year, with most cases occurring in Sub-Saharan Africa. Over one million people die from malaria each year, most being children under five. 

Dengue Fever

Dengue fever is caused by a virus and spread by the Aedes mosquitoes in tropical and subtropical climates. Symptoms occur 4-13 days after being bitten include fever, headaches, joint pain, rashes and eye pain. For some, the disease develops into dengue hemorrhagic fever, a more dangerous form of the disease. There is no specific treatment for dengue fever and no vaccine. About 390 million people suffer from the disease each year. 

West Nile Virus

West Nile is a virus that is spread by Culex mosquitoes and the first large outbreak occurred in Romania in 1996. The virus is now spread in countries all around the globe, including the United States. About 80 percent of infections do not result in symptoms. Those who do experience symptoms get them between 2-15 days after the mosquito bite, with symptoms including fever, headache, muscle pain, nausea, vomiting, rash, and fatigue. In rare cases, the disease can also impact the central nervous system. There is a treatment procedure for West Nile but no vaccine. Since the first U.S. case in 1999, there have been 42,000 cases of West Nile in the United States. Of those cases, 19,000 experienced neurological disease and 1,700 died. 

Yellow Fever

Yellow fever is a virus spread by Aedes mosquitoes and people begin to feel symptoms 4-7 days after the bite. Symptoms include severe fever, headache and nausea, and 50 percent of those who are severely affected end up dying from the disease. While there is no specific treatment, there is an effective vaccine against yellow fever. The World Health Organization says that there are between 84,000 and 170,000 cases of yellow fever each year and up to 60,000 deaths caused by the disease.

Zika Virus

The Zika virus is a relatively new mosquito-transmitted disease. It was first discovered in 1947 with the first human cases detected in 1952. Since then there have been a few cases, but in 2015, there was an outbreak of Zika virus in Brazil. Eighty percent of people who are infected will not experience symptoms, but those that do experience minor symptoms like fever, joint pain, rash and red eyes. The Zika virus rarely causes death but it has gotten attention because of a potential link to microcephaly brain damage in babies born from mothers who contracted the disease during pregnancy. It is transmitted by the Aedes mosquito, which is widespread in tropical areas. However, this genus of mosquito is also found in the United States in Florida, Hawaii and along the Gulf Coast and, in hot weather, it has been found as far north as Washington, D.C.  There is no treatment and no vaccine. The World Health Organization has said that as many as four million people in the Americas could be infected by Zika by the end of the year. You can learn more about the Zika virus in our last blog post.

This list includes the most dangerous diseases transmitted by mosquitoes but there are several other mosquito-borne diseases including Chikungunya fever, Rift Valley fever, Murray Valley encephalitis, and Japanese Encephalitis. Mosquitoes can also transmit diseases to animals, including heartworm (a life-threatening disease for dogs) and Western equine encephalitis (which can impact humans and horses).

With mosquitoes posing serious health threats around the world and many diseases having no treatment or no vaccine, the best thing you can do is try to avoid mosquito bites. Although it will not fully prevent any of the above diseases, your best defense is using insect repellent that will keep the mosquitoes away and limit the number of bites you get.