Diseases and surveillance

Bottled dog heartworm

Canine Heartworm

Canine Heartworm Disease impacts around 250,000 dogs every year. This disease is caused by a bite of an infected Western treehole mosquito (Aedes sierrensis).

Culex pipien taking a blood meal

West Nile virus

West Nile virus (WNV) is a mosquito-borne disease that was first detected in the West Nile District of Uganda. Transmitted by mosquito bites, WNV affects humans, horses, some birds, and squirrels.

A close-up image of a tick on a green leaf

Tick surveillance

Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of infected blacklegged ticks.

A close-up image of a mosquito on a person's thumb

Western equine encephalitis

Western equine encephalitis is a disease that is spread to horses and humans by infected mosquitos.

Norway rat

Arenavirus in California

Arenavirus infections are generally spread by rodents.

picture of a mouse

Hantavirus pulmonary syndrome

Hantaviruses are a family of viruses named for the Hantaan River in Korea, where the first strain was discovered decades ago.

Image of pigs and piglets on a farm


Leptospirosis is a bacterial disease that affects humans and animals.

A close-up image of roundworms

Raccoon Roundworm

Raccoon roundworm eggs are passed in the feces of infected raccoons. Raccoons defecate in communal sites, called latrines. Raccoon latrines are often found at bases of trees, unsealed attics, or on flat surfaces such as logs, tree stumps, rocks, decks, and rooftops.

Flea on human skin

Flea-borne Typhus

Flea-borne typhus is a bacterial disease that is spread by fleas. Infected fleas shed Rickettsia typhi in their feces, which is left on a person's skin after the flea bites. Flea bites are very itchy, so if a person scratches the flea bite, Rickettsia typhi can enter the person's bloodstream and they become infected with flea-borne typhus.