What is Epidemic Typhus?

Epidemic typhus is a disease which is bacterial in origin which has been documented in human populations for over 1,000 years. Untreated, typhus can be deadly, and despite control measures, periodic outbreaks of typhus do occur in various regions of the world. Epidemic typhus is most commonly seen during periods of stress, crowding, and deprivation, such as during wartime and in refugee camps, where it can spread quickly between people with weakened immune systems.

There are a number of alternate names for typhus, many of which reference the conditions in which it thrives, such as famine fever, ship fever, jail fever, camp fever, or hospital fever. This disease is also known as petechial fever, a nod to the distinctive rash associated with epidemic typhus, and putrid fever.

This disease is caused by the bacterium Rickettsia prowazekii. The bacterium is ingested by lice which in turn feed on people, leaving feces behind. When people scratch the louse bites or touch a bite and then handle the mucus membranes around their eyes, the bacterium enters the body. Someone who carries the bacterium can pass it to other people as lice feed on the original patient's body and spread the organism to new victims. In unclean conditions, typhus can move easily from person to person.

It can take one to two weeks for epidemic typhus to incubate in the body. Once the disease breaks out, it is characterized by a very high fever and a state of stupor; the term “typhus” is derived from the Greek word for “mist” or “fog,” referencing the state of confusion and fogginess which patients enter. Patients also develop a rash, muscle pains, chills, and headaches. They are often sensitive to light and fall into a delirium.

Epidemic typhus is preventable with vaccines and it can also be treated with antibiotic medications. Furthermore, control measures which limit louse populations can also reduce the risk of spreading typhus. If animals like rats and squirrels which can sustain a population of lice are kept away from human habitation, this also limits the chance that epidemic typhus will gain a foothold.

Typhus is a condition which can recrudesce, meaning that it will recur in a patient after an extended period of reasonably good health. Typhus returns because organisms can linger in the body and when the patient's immune system declines, they can start breeding again. When typhus recurs, it is known as Brill-Zinsser disease.