Q: I read there was an outbreak of typhus in California. Is this real? I thought this only existed in developing countries.

A: Typhus may be caused by several types of the bacteria, leading to several different typhus diseases; scrub typhus, murine typhus, epidemic typhus, as well as other subtypes.

Scrub typhus is due to the bacteria Orientia tsutsugamushi and is transmitted to humans by a bite from an infected chigger (a type of mite that lives in certain vegetation). It is endemic in areas of the Asian-Pacific Region (such as Korea, China, Taiwan, Japan, Pakistan, India, Thailand, Laos, Malaysia, Sri Lanka and Australia), and is not typically found in the United States. Overall scrub typhus is pretty common, estimated to infect more than a million people per year.

The symptoms of scrub typhus (an eschar at the site of the bite(s), fever, chills, headache, muscle aches, swollen lymph glands, rash and/or altered mental status) usually begin about a week after exposure. Other complications, such as low platelet count, may also occur.

The diagnosis of scrub typhus is made based on the physical exam and a risk for exposure, and may be confirmed by indirect immunofluorescence assay (IFA a specialized type of blood test), although other blood tests (such as testing for antibodies to the causal bacterium) are also helpful. Appropriate antibiotic treatment should be started when there is clinical suspicion of this condition.

Murine typhus is caused by the bacteria Rickettsia typhi, and occurs worldwide, including in the U.S. (most commonly in California, Texas and Hawaii). Murine typhus is transmitted to humans through the bite of an infected flea (which can live and thrive on rats, dogs, cats, opossums and even other animals, often without making the animal sick). Murine typhus is not very common, although there are still many tens of thousands of cases worldwide each year, and several dozen (usually fewer than 100) in the U.S. per year (with many of these in returning travelers).

The symptoms of murine typhus include fatigue, nausea, abdominal pain, loss of appetite, headaches, confusion and/or a rash (which begins on the body then spreads to the arms and legs, typically sparing the palms and soles), and usually begin a week or two after exposure.

Similar to scrub typhus, the diagnosis is suspected based on the symptoms and the potential for exposure, and similar to scrub typhus may be confirmed with specialized blood testing. The treatment of murine typhus is the same type of antibiotics used to treat scrub typhus.

Epidemic typhus is caused by the bacteria Rickettsia prowazekii, and occurs in Burundi, Rwanda, Ethiopia and in the rural highlands of South America, Asia and Algeria, as well as in the U.S. (most commonly in California, with cases recorded in several other states). Epidemic typhus is transmitted by a different type of flea than murine typhus. Today there are tens of thousands of cases of infection worldwide per year (although there are still occasional outbreaks where many more people may be affected, but not as badly as in the early 1900s where millions of people were infected, such as the outbreak in Russia which affected 25 million people between 1917 to 1925). Epidemic typhus outbreaks still occasionally occur in the U.S., sometimes affecting dozens to even several hundred people. The fleas responsible for the outbreaks in the U.S. typically live on flying squirrels.

Symptoms of epidemic typhus typically begin within several days after exposure, and may include fever, headache, malaise, cough, abdominal pain, nausea, diarrhea, joint aches, and/or rash (as with murine typhus the rash starts on the trunk and spreads to the arms and legs, sparing the palms and soles).

Similar to the other types of typhus, the diagnosis of epidemic typhus is usually suspected based on the symptoms and the potential for exposure, and may be confirmed with specialized blood tests. As with the other types of typhus, epidemic typhus is treated with antibiotics. Epidemic typhus is a pretty severe disease, and without treatment about 10 to 50 percent of patients may die from this infection.

Years after the initial infection of epidemic typhus, a recrudescence of the disease can occur (called Brill-Zinsser disease). Although the symptoms may be similar to the initial infection (including fever, chills, headache, malaise, confusion, breathing problems, rash, and/or other symptoms), this recurrence of symptoms is typically much milder than the initial infection.

The best way to prevent any of the forms of typhus is to avoid exposure to the transmitting vector (whether chigger or flea). During an outbreak, antibiotics may be given to individuals at high risk of exposure to prevent the patient becoming infected. There are presently no vaccines available to prevent typhus.
