Of the close to 3000 species of mosquitoes on the planet there are only about 100 types that can transmit mosquito borne diseases. Some affect only animals, like the parasite heartworm which can kill dogs that are not diagnosed and treated. Some mosquito borne diseases are a health crisis and concern in only parts of the world, and still others now have vaccinations or treatments available to quickly arrest symptoms.
Probably the most severe of the mosquito borne diseases is malaria, which annually sickens about three to five hundred million people. Due to lack of treatment, about a million people may die yearly from malaria. The condition is treatable, mainly through taking quinine, and there are some medications you can take to help prevent contracting the disease which occurs in the South Pacific, Africa, some areas of Eastern Europe, Central and South America, and parts of Asia. Travelers who visit areas with known malaria contagion still are not completely safe from contracting the disease, and there is no vaccine.
Some mosquitoes transmit various varieties of arboviral encephalitis. This is uncommon but tends to most affect horses, though it can also sicken people. The most fatal to horses are Western and Eastern encephalitis. Affected animals have a 33-50% chance of dying from brain inflammation.
A form that is potentially deadly to humans is West Nile Virus, which people may contract in summer and early fall in the US and other parts of the world. West Nile Virus can cause severe encephalitis, but this is also rare. Since it is a virus, there is no cure with antibiotics, so people with severe cases are at serious risk. Despite this risk in severe cases, it’s estimated that of all the people who contract West Nile Virus, only about 2 in 300 cases will result in severe infection. Most people have mild flulike symptoms and never have the condition diagnosed.
One of the dangerous mosquito borne diseases for which there is a vaccination is yellow fever. Again, the condition occurs rarely, though there have been some noted outbreaks in history that have devastated cities. Today, people who travel to areas where risk of yellow fever exists are usually vaccinated, in some cases are even required to be vaccinated before they can obtain leave to visit the area in question.
Another rare but sometimes very serious of the mosquito borne diseases is dengue fever, most commonly found in tropical areas. People may have minor flu symptoms as a result of this illness, or can have very serious and fatal blood infections as a result. This is rarely the case, but it is important to note that there is no vaccination for dengue fever. Dengue fever mosquitoes bite during the day, so all caution should be taken regarding wearing good strong insect repellent in tropical locations.