Flea-borne Typhus
What is Flea-borne Typhus?
Flea-borne typhus is a bacterial disease that is spread (or vectored) by fleas and is caused by the bacteria Rickettsia typhi. Flea-borne typhus used to be known as murine typhus, as in rodent-related typhus, because people sometimes developed the disease after close contact with rats. However, research has revealed that other animals (like feral cats, squirrels, opossums, etc.) can also act as hosts to the flea. The name was changed to better signify the vector of the disease.
Flea-borne typhus occurs worldwide, but mainly in tropical and coastal areas. Infections are more common in people who live in poverty or who have close contact with wild animals. In the United States, there are about 300 human cases every year, with higher concentrations in Southern Texas, Southern California, and Hawaii. Flea-borne typhus is considered endemic in Los Angeles and Orange counties.
To date, there has been one travel-related case of flea-borne typhus in Santa Clara County, meaning the individual lives in the county but became infected elsewhere. Otherwise, flea-borne typhus has not been found in our county.
How it Spreads
Fleas become infected when they bite infected animals, and stay infected until they die. 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.
Signs and Symptoms
Symptoms of flea-borne typhus typically appear between 6 to 14 days after being infected, but it is possible to have no symptoms at all. Symptoms are similar to many other diseases, but can include:
- Fever
- Chills
- Headache and body aches
- Rash
- Muscle pain
- Cough
If you have had recent contact with fleas or animals that might have fleas, consult your doctor. There are currently no vaccines for flea-borne typhus. The best prevention is to avoid contact with fleas.
Monitoring Flea-borne Typhus
Unhoused encampments can create conditions that attract rodents. Rodents harbor fleas and other ectoparasites which pose health risks for both the unhoused population and surrounding communities. We have a flea-borne typhus surveillance program that focuses on collecting rodents and their associated ectoparasites from unhouse encampments. The primary focus is fleas. Risk of human exposure to flea-borne typhus is determined through our surveillance program. Targeted action-based mitigation plans are developed based on risk to exposure.
Process
- We live-trap rodents in unhoused encampments around the county, collect the ectoparasites found on the rodents, and test them for disease.
- Live-trapping rodents consists of setting metal cage traps.
- We use a mixture of peanut butter and cat food to attract rodents into the cages.
- Traps are left out overnight and collected the following day.
- We follow the American Veterinary Medical Association guidelines and place the trapped rats inside a carbon dioxide gas chamber.
- Rats are then sprayed with a pesticide to kill the ectoparasites on them.
- We use a fine-bristled toothbrush to comb the ectoparasites off the rats.
- We then count the ectoparasites and sort them by species.
- We test the fleas for disease using a laboratory technique called polymerase chain reaction (PCR).
The PCR process involves placing the fleas into small containers (vials) and placing a few tiny beads into the vial. A machine shakes up the vial at high speeds to help the tiny beads break down the flea bodies. We do this a few times until the fleas become a liquid mixture. The liquid mixture is then tested with the PCR machine to know if the disease was present in the collected fleas.
Our goal is to monitor the changes in ectoparasite species and numbers and presence of disease, to detect any potential disease outbreaks before they spread.
Reports