Epidemic typhus

Japanese: 発疹チフス - ほっしんチフス（英語表記）Epidemic typhus

What kind of infection is it?

It is an acute febrile infectious disease caused by Rickettsia typhus. The Rickettsia multiplies in the intestines of body lice that have sucked the patient's blood and are excreted in the feces. If you scratch your skin due to the itching caused by the louse bites, the skin wounds and Bite ( Shiko ) Lice are transmitted by rubbing into the area, or by inhaling dust contaminated with lice faeces.

There have been no cases in Japan since 1957. Overseas, there are localized epidemics in high altitude areas such as Africa, Mexico, and the Andes region of South America. In a November 2003 revision to the Infectious Diseases Control Law, it was classified as a new Category 4 infectious disease that requires animal control. It is designated as a disease requiring international surveillance, and outbreaks are reported to the WHO.

How symptoms manifest

The incubation period is 1 to 2 weeks. Symptoms include chills, headache, back pain, and muscle pain in the limbs. A high fever develops suddenly and continues. In severe cases, the patient may suffer from severe headaches and loss of consciousness. coma ( Today ) This leads to:

A rash appears on the trunk about 4 days after the onset of fever, and spreads to the whole body except the face. Millet ( Dragon ) They range in size from large to the size of a red bean, and rarely merge. At first, they are pale pink and disappear with acupressure, but eventually they turn dark red and do not disappear with acupressure.

The fever subsides rapidly in about two weeks, but after the initial infection, the rickettsiae remain dormant in the body and the infection may recur several years later.

Testing and diagnosis

If your fever lasts for more than three days or you experience severe headache or muscle pain, please see a doctor.

It would be certain if Rickettsia could be identified from the blood of a patient during the fever phase, but since isolating Rickettsia requires a laboratory with a safety level of 3 or higher, diagnosis is mainly based on antibodies. It is necessary to distinguish from typhus, typhoid fever, paratyphoid fever, scrub typhus, etc.

Treatment methods

Tetracycline antibiotics are effective, and fever usually subsides within 3 days of starting administration. The drug should be taken for at least 1 week. If appropriate antibiotics are used, death will not occur, but if antibiotics are not used, the fatality rate is 10-60%.

Prevention

Generally, lice do not infect people directly, so the first step in prevention is to get rid of them. Clothes and bedding should be disinfected with heat. Generally, lice will die if exposed to 70°C heat for 30 minutes.

The vaccine is not commercially available in Japan, but inactivated and live vaccines are available.

Yuko Sagara

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

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