What’s the most dangerous creature on earth? Without question the answer is: the mosquito. Mosquitoes and the diseases they spread have been responsible for killing more people than all the wars in history. Even today, mosquitoes transmitting malaria kill 2 million to 3 million people and infect another 200 million or more every year. Tens of millions more are killed and debilitated by a host of other mosquito-borne diseases, including filariasis, yellow fever, dengue and encephalitis.

But for millions of Americans, malaria is something other people get somewhere else. The fact is that nearly half of the world’s population is at risk for malaria. Residents of the United States are not immune. Malaria has occurred in the United States, and still does on rare occasions. Mosquitoes capable of carrying and transmitting malaria still inhabit most parts of this country. And an influx of malaria-infected persons has produced localized malaria transmission in some areas of the United States.

Today, however, the threat of developing encephalitis from mosquitoes is far greater than the threat of malaria in the United States. Encephalitis, meningitis and other diseases can develop from the bites of mosquitoes infected with certain viruses. These include the viruses of West Nile, St. Louis encephalitis, LaCrosse (California) encephalitis, and Eastern equine and Western equine encephalitis.