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Vector-Borne/Zoonotic Diseases

Vector-Borne Diseases

Diseases transmitted to humans or other animals by insects or other arthropods.
Usually mosquitoes or ticks.


Mosquito-borne virusesWest Nile virus (WNV) is one of several viruses in the US that can infect people. The virus exists in nature primarily through a transmission cycle involving certain species of mosquitoes and birds. La Crosse Encephalitis (LAC) is a viral infection that can cause inflammation of the brain.


Tick-borne illnessesRocky Mountain spotted fever (RMSF) is the most severe tick borne illness in the United States and is spread by the bite of infected ticks. The disease gets its name from the Rocky Mountain area where it was first identified.Ehrlichiosis is a disease caused by bacteria that are transmitted by the bite of an infected tick.

Zoonotic Diseases

Diseases that are transmitted between animals and humans.


Rabies is a viral disease of mammals most often transmitted through the bite of a rabid animal. The vast majority of rabies cases reported to the Centers for Disease Control and Prevention (CDC) each year occur in wild animals like raccoons, skunks, bats, foxes, and coyotes. The rabies virus infects the central nervous system (CNS), ultimately causing encephalitis and death.


Other important zoonotic diseases include potential bioterrorism agents or occupational illnesses such as anthrax, brucellosis, small pox, tularemia, Q fever, and psittacosis. A bioterrorism attack is the deliberate release of viruses, bacteria, or other germs (agents) used to cause illness or death in people, animals, or plants. These agents are typically found in nature, but it is possible that they could be changed to increase their ability to cause disease.


Infestations caused by pests such as bed bugs, fleas, and lice.


Bed bugs are small, flat, parasitic insects that feed solely on the blood of people and animals while they sleep. They are a problem worldwide, are resurging, causing property loss, expense, and inconvenience. The good news is that bed bugs do not transmit disease.


Brown recluse spiders are usually found in workplaces with secluded, dry, sheltered areas such as underneath structures logs, or in piles of rocks or leaves. If a brown recluse spider wanders indoors, they may be found in dark closets, shoes, or attics.

More Information

USGS Disease Map shows distribution of disease across US.
Summer safety tips tips for outdoor protection against VB diseases.
Tick information protect yourself against tick bites.
West Nile virus information (English) Fight the Bite.
Virus del Nilo Occidental (Español) ¡Luche Contra las Picaduras! 
La Crosse Encephalitis information (English) How you can prevent LAC 
Virus La Encefalitis La Crosse (Español) ¿Como Se Previene El virus La Encefalitis La Crosse?