SCRUB TYPHUS

Picture of typhus

CAUSES

Cause of typhus

Typhus is not transmitted from person to person like a cold or the flu. There are three different types of typhus, and each type is caused by a different type of bacterium and transmitted by a different type of arthropod.

Epidemic/louse-borne typhus

This type is caused by Rickettsia prowazekii and carried by the body louse, and possibly by ticks as well. It can be found around the world, including in the United States, but is typically found in areas of high population and poor sanitation, where conditions promote lice infestation.

Endemic typhus

Alternatively known as murine typhus, this type is caused by Rickettsia typhi and is carried by the rat flea or cat flea. Endemic typhus can be found worldwide. It may be found among people in close contact with rats. It isn’t commonly found in the United States, but cases have been reported in some areas, primarily Texas and southern California.

Scrub typhus

This type is caused by Orientia tsutsugamushi and carried by mites in their larval stage when they are chiggers. This type of typhus is more commonly found in Asia, Australia, Papua New Guinea, and the Pacific Islands. It’s also called tsutsugamushi disease.

The louse, flea, tick, or mite becomes a carrier of the bacteria when they feed on the blood of an infected person (epidemic typhus) or an infected rodent (any of the three typhus forms mentioned above).

If you come in contact with these bacterium-carrying arthropods (for example, by sleeping on bed sheets infested with lice), you can become infected in a couple ways. The bacteria, in addition to being transmitted through your skin by their bites, can also be transmitted through their feces. If you scratch the skin over an area where lice or mites have been feeding, the bacteria in their feces can enter your bloodstream through the tiny wounds on your skin.

Symptoms of typhus

Symptoms vary slightly by the type of typhus, but there are symptoms that are associated with all three types of typhus, such as:

• headache
• fever
• chills
• rash

Symptoms of epidemic typhus usually appear suddenly and include:

• severe headache
• high fever (above 102.2°F)
• rash that begins on the back or chest and spreads
• confusion
• stupor and seeming out of touch with reality
• low blood pressure (hypotension)
• eye sensitivity to bright lights
• severe muscle pain

The symptoms of endemic typhus last for 10 to 12 days and are very similar to the symptoms of epidemic typhus but are usually less severe. They include:

• dry cough
• nausea and vomiting
• diarrhea

Symptoms seen in people with scrub typhus include:

• swollen lymph nodes
• tiredness
• red lesion or sore on the skin at the site of the bite
• cough
• rash

The incubation period for the disease is five to 14 days, on average. This means that symptoms won’t usually appear for up to five to 14 days after you are bitten. Travelers who get typhus while traveling abroad may not experience symptoms until they are back home. This is why it is important to tell your doctor about any recent trips if you have any of the above symptoms.

DIAGNOSIS

Diagnosing typhus

If you suspect that you have typhus, your doctor will ask about your symptoms and your medical history. To help with the diagnosis, tell your doctor if you:

• are living in a crowded environment
• know of a typhus outbreak in your community
• have traveled abroad recently

Diagnosis is difficult because symptoms are common to other infectious diseases, including:

• dengue, also known as breakbone fever
• malaria, an infectious disease spread by mosquitos
• brucellosis, an infectious disease caused by Brucella bacterial species

Diagnostic tests for the presence of typhus include:

• skin biopsy: a sample of the skin from your rash will be tested in a lab
• Western blot: a test to identify the presence of typhus
• immunofluorescence test: uses fluorescent dyes to detect typhus antigen in samples of serum taken from the bloodstream
• other blood tests: results can indicate the presence of infection

Treatment for typhus

Antibiotics most commonly used to treat typhus include:

• doxycycline (Doryx, Vibramycin): the preferred treatment
• chloramphenicol: an option for those not pregnant or breastfeeding
• ciprofloxacin (Cipro): used for adults who are unable to take doxycycline

Complications of typhus

Some complications of typhus include:

• hepatitis, which is inflammation of the liver
• gastrointestinal hemorrhage, which is bleeding inside the intestines
• hypovolemia, which is a decrease in blood fluid volume

Outlook for typhus

Early treatment with antibiotics is very effective, and relapses aren’t common if you take the full course of antibiotics. Delayed treatment and misdiagnosis can lead to a more severe case of typhus.

Epidemics of typhus are more common in poor, unsanitary, and crowded areas. People who are most at risk of dying are generally those who are unable to afford quick treatments. The overall mortality rate for untreated typhus depends on the type of typhus and other factors, such as age and overall health status.

The highest rates are seen in the older adults and those who are malnourished. Children usually recover from typhus. People with underlying diseases (such as diabetes mellitus, alcoholism, or chronic renal disorders) also have a higher risk of mortality. Mortality for epidemic typhus that goes untreated can range from 10 to 60 percent, and mortality from untreated scrub typhus can range up to 30 percent.

Endemic/murine typhus is rarely deadly, even without treatment. Death occurs in no more than 4 percent of cases, according to an article in Clinical Infectious Diseases.

Preventing typhus

During World War II, a vaccine was created to prevent epidemic typhus. However, the shrinking number of cases has stopped the manufacture of the vaccine. The easiest way to prevent typhus is by avoiding the pests that spread it.

Suggestions for prevention include:

• maintaining adequate personal hygiene (helps guard against lice carrying the disease)
• controlling the rodent population (rodents are known to carry arthropods)
• avoiding travel to regions where typhus exposure has occurred, or to countries that are high risk due to lack of sanitation
• chemoprophylaxis with doxycycline (used as a preventive only in those at high risk, such as those on humanitarian campaigns in areas with extreme poverty and little or no sanitation)

Use tick, mite, and insect repellant. Perform routine examinations for ticks, and wear protective clothing if you’re traveling near an area where there have been typhus outbreaks.