Vector Related Diseases

What are Vector Related Diseases?

Disease that results from an infection transmitted to humans and other animals by blood-feeding anthropods, such as mosquitoes, ticks, and fleas.

Mosquito control is the main focus of this program with staff monitoring the county for West Nile virus activity by collecting animals that have died suspiciously and collecting live chicken blood for analysis for disease activity. To reduce the spread of West Nile virus and nuisance mosquitoes, staff provide integrated mosquito management by looking for physical, biological, and larvicide treatment solutions for property owners. Close collaboration with the State Public Health Biologist and the Nevada County Agriculture and Public Health Departments is essential to locate the source of a potential outbreak, provide surveillance, and conduct public outreach and education.

Zika Virus

The species of Aedes mosquitoes that are considered the vector for Zika virus have not been found in the County of Nevada. The Vector Control Program monitors for these and other mosquitoes seasonally. Please report 'Day Biting' mosquitoes to Vector Control at 530-265-1500. For more information, visit the California Department of Public Health - Zika.

Hantavirus Cardiopulmonary

Hantavirus Pulmonary Syndrome (HPS) is a severe, sometimes fatal, respiratory disease in humans caused by infection with hantaviruses. Anyone who comes into contact with rodents that carry hantaviruses is at risk of HPS. Rodent infestation in and around the home remains the primary risk for hantavirus exposure. Even healthy individuals are at risk for HPS infection if exposed to the virus. For more information, visit the State Vector-borne Disease Hantavirus Cardiopulmonary Syndrome Website (PDF).


Plague is a bacterial disease people can get if they are bitten by an infected rodent flea. Most persons with plague develop fever and swollen lymph nodes. Plague is treatable with antibiotics but can progress to severe and sometimes fatal illness if diagnosis and treatment are delayed. Squirrels, chipmunks, and other rodents in many areas of California can carry the plague. Persons visiting, hiking, or camping in these areas should avoid contact with rodents. For more information, visit the California Department of Public Health Plague Website.

Lyme Disease

Lyme disease is caused by a spirochete (a corkscrew-shaped bacteria) called Borrelia burgdorferi and is transmitted by the western black-legged tick. Lyme disease was first described in North America in the 1970s in Lyme, Connecticut, the town for which it was then named. This disease has since been reported from many areas of the country, including most counties in California. For more information, visit the California Department of Public Health Lyme Disease Website.

Head Lice

Head lice are small insects that live in people's hair and feed on their blood. Lice glue their eggs, or "nits," to hair so that the nits do not get brushed off. Lice die quickly (within two days) without feeding so they cannot live very long away from your child's head. Nits take six to nine days to hatch, and seven or more days for the lice to become egg-laying adults.

How do people get head lice? Children can give head lice to other children when they share combs, hats, clothing, barrettes, helmets, scarves, headphones, or other personal items. Head lice are a problem in homes, daycare centers, elementary, and preschools. Kids are much more likely to get lice from family members and playmates than from classmates at school. For more information, visit the California Department of Public Health Head Lice Website.

Tularemia Disease (Rabbit Fever, Deer-Fly Fever)

Tularemia is an infectious bacterial disease (Francisella tularensis). Tularemia is usually a disease of wild animals, but severe illness and death may also occur in humans. The bacterium that causes tularemia is common in various kinds of ticks and in small and medium-sized mammals, especially rabbits, hares, beavers, muskrats, and voles. In the United States, there are two main sources of infection for humans: 1) bites by ticks or biting flies, and 2) contact with infected animals or their carcasses, especially the cottontail rabbit. People may also become infected from eating improperly cooked rabbit or hare meat or from contact with contaminated water, dust, hay, mud, or animal bites. The disease is not spread from human-to-human.

To prevent infections, avoid exposure to bites by ticks and blood-feeding flies and avoid direct contact with wild animal tissues. When you enter areas infested with biting flies and ticks, wear protective clothing, tuck pants into socks, and apply insect repellents as directed by the manufacturer. Examine clothing and skin frequently for ticks. Remove attached ticks promptly. Hunters and trappers need to wear gloves, masks, and protective eye covers when handling animal carcasses. Animals that appear ill should not be skinned or dressed. Teach children to not handle any sick or dead animals. For more information, visit the California Department of Public Health Tularemia Disease Website.

Bed Bugs

Bed bugs are small parasitic insects that feed on the blood of mammals and birds. Bed bugs live in mattresses, linens, and headboards, as well as in the walls, flooring, and other furniture in areas where people sleep in homes, hotels, and other dwellings. Because bed bugs usually feed at night when people are sleeping, most people do not realize they were bitten. The only evidence that a person was bitten may be itchy welts that appear a few days later. Bed bugs do not transmit disease, but are a nuisance and infestations should be controlled by a licensed pest control operator. For more information, visit the California Department of Public Health Bed Bug Website.