Tickborne Relapsing Fever

Tickborne relapsing fever (TBRF) is a bacterial disease transmitted to people by soft ticks in the genus Ornithodoros. TBRF is a rare disease in California with between 1 and 8 cases reported per year, generally during the summer months. People are at risk of contracting TBRF when they sleep in rustic mountain cabins that are infested with wild rodents. The soft ticks that transmit TBRF feed rapidly; most people who contract TBRF have no recollection of a tick bite.

Tickborne Diseases

Ticks are the vectors of a large number of disease-causing agents in California. While Lyme disease is by far the most common tickborne disease of people in the United States and California, ticks also transmit the organisms that cause tickborne relapsing fever, Rocky Mountain spotted fever, tularemia, anaplasmosis, human ehrlichiosis, and babesiosis.  In addition, people and domestic animals can develop tick paralysis following a tick bite.

Malaria Outbreaks in California Since 1945

Malaria is not endemic to California. But on occasion, imported malaria resulted in local outbreaks. The map below illustrates those transmissions where 10 or more cases resulted.

Last 28 Days Positive Samples in California

As part of California's vector control efforts, samples from a variety of sources are regularly tested for the presence of West Nile virus, St. Louis encephalitis and Western equine encephalomyelitis. The map below is provided to illustrate the ongoing efforts to detect and control the these diseases. Use the layer checkboxes below the map to enable or disable the various layers.

Terms Associated with Human Malaria Cases

  • Autochthonous malaria:

    --- Indigenous. Mosquitoborne transmission of malaria in a geographic area where malaria occurs regularly.
    --- Introduced. Mosquitoborne transmission of malaria from an imported case in an area where malaria does not occur regularly.