West Nile Virus
West Nile Virus (WNV) was first detected in the United States in 1999. Most infected individuals do not know they are infected because there are no symptoms for the virus. However, symptoms may develop if the virus progresses into West Nile Fever or severe West Nile Disease. Symptoms may include fever, headache, fatigue and body aches. Occasionally a skin rash or swollen lymph glands will develop. WNV can also lead to serious complications of the liver or nervous system, inflammation of the brain (encephalitis) or paralysis. According to the Centers for Disease Control and Prevention (CDC), more than 15,000 Americans have been infected with WNV, with more than 500 cases resulting in death.

Eastern Equine Encephalitis
Eastern Equine Encephalitis occurs most often in the eastern United States. It takes four to 10 days after being bitten for individuals to develop symptoms of EEE, beginning with the sudden onset of fever, general muscle pain and headaches of increasing severity. Many individuals will progress to more severe symptoms, such as seizures and coma. Approximately one-third of all people with clinical encephalitis caused by EEE will die from the disease. Of those who recover, many will suffer permanent brain damage that requires institutional care.

St. Louis Encephalitis
St. Louis encephalitis can occur throughout most of the United States. Since 1964, there have been more than 4,000 reported human cases of St. Louis encephalitis, with an average of 128 cases reported each year. An infected mosquito of the Culex species transmits the virus during blood meals. Symptoms of the virus will appear approximately five to 15 days after being bit. Symptoms include headache, high fever, neck stiffness, disorientation, coma, tremors and occasional convulsions or spastic paralysis.

LaCrosse Encephalitis Virus
LaCrosse encephalitis is a rare viral disease that is spread by infected mosquitoes and usually affects children. Found mostly in the upper Midwestern United States and Appalachian regions, LaCrosse encephalitis affects the central nervous system and cause severe complications. Symptoms of the virus include mild illness with fever, headache, nausea and vomiting, and tiredness. More severe cases can produce seizures, coma, paralysis and even brain damage.

Dengue Hemoragic Fever Virus
Dengue Hemoragic Fever is a Flavivirus. The primary mosquito vector of this virus is Aedes aegypti; Ae. Albopictus, which breeds in urban areas in artificial and man made containers. The first case was in 1779 and it is primarily found in Asia, Africa, and South and Central America. There are approximately 10-15 million cases each year worldwide. The virus has been found increasingly in northern Mexico, and there are large numbers of Ae. Albopictus mosquitoes throughout the United States.

Malaria
Domestically generated malaria has been virtually eradicated in the United States since the 1950s, but the risk of infection has not. Two of the 10 species of Anopheles mosquito responsible for malaria transmission (Anopheles quadrimaculatus in the eastern states and An. freeborni in the west) are still widely prevalent in the continental United States. These vectors can become carriers by biting an infected human.

But what are the odds? In 2004, the Centers for Disease Control and Prevention (CDC) reported more than 1,300 U.S. malaria cases, most of which were acquired abroad. Americans are advised to practice caution; trendy vacation destinations such as Belize, Costa Rica, Dominican Republic, Southern Mexico and Great Exuma, Bahamas, are all listed as places with malaria risk by the CDC.

Rift Valley Fever
Malaria and WNV aren't the only vector-borne risks. Rift Valley Fever (RVF) is being watched closely since it first moved off Africa to Yemen and Saudi Arabia in 1999. With thousands of U.S. military personnel serving in the region, the potential for importing the disease to America has multiplied. RVF is carried by the Aedes species and Culex tritaeniorrhynchus. Symptoms range from weakness and fever to Ebola-like hemorrhaging. Victims are 10 times more likely to die from RVF than West Nile.