A mosquito doing what it does best on a person's arm

John Downer/Getty Images

The Most Deadly Animals: Mosquitoes

The most deadly ­animal in the world is the mosquito. It might seem impossible that something so miniscule can kill so many people, but it's true. Mosquito bites result in the deaths of more than 1 million people every year [source: WHO]. The majority of these deaths are due to malaria. The World Health Organization estimates that between 300 and 500 million cases of malaria occur each year -- and a child dies from malaria every 30 seconds [source: WHO].

It's not the mosquito itself that kills, but rather a parasite the mosquito carries. Not all mosquitoes carry the malaria parasite -- only females of the Anopheles genus. You'll find the Anopheles all over the world, with the exception of Antarctica. The mosquito transmits malaria after biting an infected person and then passes along the parasite to the next person it nibbles on. Malaria is a blood-transmitted disease, which means you can't contract it from casual contact with another person. Because it's transmitted through the blood, you can contract it from a contaminated transfusion or needle. But mosquitoes are primarily to blame for the spread of malaria infection.

­The United States no longer considers malaria a public health issue. The disease virtually disappeared in the 1950s when the National Malaria Eradication Program implemented a DDT (a synthetic pesticide) program to control the mosquito population [source: CDC]. However, this program saw limited success in the rest of the world. Nations with a temperate climate and seasonal mosquito issues were able to eradicate malaria. But in other countries, resistance to insecticides and drugs, cuts in funding and lack of participation made long-term eradication efforts impossible. The United States still reports a few hundred malaria cases per year. But most cases occur in travelers returning from a malaria-ridden country [source: CDC].

Today, the majority of malaria deaths occur in Africa, south of the Sahara, where the malaria parasite is very common. Anyone can contract malaria, but the people most likely to get seriously or fatally ill are those with little or no immunity -- young children, pregnant women or travelers who live in an area that has no malaria. People from poor communities with little access to health care and clean water sources -- standing water is a prime mosquito breeding ground -- are also at risk. Anti-malarial drugs exist, but there's currently no malaria vaccine.

Affected countries now turn to malaria control rather than eradication. The Centers for Disease Control and Prevention refers to these activities as vector control. Vector control means decreasing contact between humans and disease carriers on an area-by-area basis. The aim is to cut down on the mosquito parasite population using insecticide treated nets that drape over people's beds, indoor spraying and larval (egg) control. Insecticide treated bed nets in particular can cut mortality rates by 20 percent [source: CDC].

In addition to malaria, mosquitoes carry the West Nile virus and dengue fever. West Nile is a disease the insects pick up from infected birds. It affects the nervous system and, like malaria, can be very serious in people with lowered immune systems. The virus became prevalent for the first time in the eastern United States around 1999 [source: CDC]. As with malaria, the best way to avoid West Nile is to protect yourself from mosquitoes. Mosquitoes also carry dengue fever, which causes a rash and extreme muscle and joint pain. It can be fatal if not treated properly.

So, forget lions, tigers and bears -- turn your paranoia to the teeny mosquito buzzing near your ear. It's one scary little beast.