Several different illnesses are called typhus; all of them are caused by one of the bacteria in the family Rickettsiae. Each illness occurs when the bacteria is passed to a human through contact with an infected insect.
The first known description of typhus (probably epidemic typhus) occurred in the late 1480s and early 1490s while Spanish soldiers were fighting during the siege of Granada. Fever, rash, red spots (on their arms, back and chest), delirium, gangrenous sores, and decaying flesh were some of the common symptoms of typhus during this conflict. At the time, it was called disease gaol or jail fever. In 1760, the English government first called it typhus, from the Greek word “typhos”. Meaning smoky or hazy, it described the state of mind of those people with the disease. Typhus continued to be a major problem in Europe over the next several centuries, most often due to the crowded and unsanitary living conditions commonly present. In the nineteenth century, many outbreaks occurred around the world. In the 1810s, large numbers of French troops under Napoleon died from typhus, and in the 1830s, hundreds of thousands of Americans and Irish died in several epidemics in the United States and Ireland.
By the early twentieth century, the cause of epidemic typhus was identified. In 1916 Brazilian physician Henrique da Rocha Lima (1879–1956) discovered its cause while performing typhus research in Germany. Millions of deaths were attributed to typhus in World War I (1914–1918) and World War II (1939–1945). After the second world war, the insecticide dichlorodiphenyltrichloroethane (DDT) was used to kill lice, which reduced the number of epidemics and limited their locations to Africa, the Middle East, Eastern Europe, and Asia.
The four main types of typhus are:
These four diseases are somewhat similar, but they vary in terms of severity. The specific type of Rickettsia that causes the disease varies, as does the specific insect that carries the bacteria.
Epidemic typhus, sometimes called jail fever or louse-borne typhus, is caused by Rickettsia prowazekü, which is carried by body lice. When lice feed on a human, they may simultaneously defecate. When a person scratches the bite, the feces that carries the bacteria are scratched into the wound. Body lice are common in areas where there is overcrowding, poor sanitation, and poor hygiene. As a result, this form of typhus occurs simultaneously in large numbers of individuals living within the same community; that is, in epidemics. Epidemic typhus occurs when cold weather, poverty, war, and other disasters result in close living conditions that encourage the maintenance of a population of lice living among humans. Some medical historians have reported that the Great Plague of Athens in 430 B.C. may have been epidemic typhus. Epidemic typhus is now found in the mountainous regions of Africa, South America, and Asia.
Brill-Zinsser disease is a reactivation of an earlier infection with epidemic typhus. It affects people years after they have completely recovered from epidemic typhus. A weakening of a person's immune system (from aging, surgery, or illness) can cause the bacteria to gain hold again, causing illness. This disease tends to be extremely mild.
Endemic typhus is carried by fleas. When a flea lands on a human, it may defecate as it feeds. When a person scratches the itchy spot where the flea was feeding, the bacteria-laden feces are scratched into the skin causing infection. The causative bacteria is called Rickettsia typhi. Endemic typhus occurs most commonly in warm, coastal regions. In the United States, southern Texas and southern California have the largest number of cases.
Scrub typhus is caused by Rickettsia tsutsugamushi. Mites or chiggers carry the bacteria. As the mites feed on humans, they deposit the bacteria. Scrub typhus occurs commonly in the southwest Pacific, Southeast Asia, and Japan. It is a very common cause of illness in people living in or visiting these areas. It occurs more commonly during the wet season.
The risk factors for getting typhus include living in or visiting areas where it is endemic, such as coastal cities where rodent and insect (such as lice, mites, fleas, and ticks) populations are high and in close contact with people, and areas where hygiene is degraded such as within poverty-stricken regions, disaster zones, homeless camps, and other similar places. Typhus is most often contracted during the spring and summer months.
The International Association for Medical Assistance to Travellers identified the following countries as having increased risks for typhus: Bolivia, Burundi, Colombia, Eritrea, Ethiopia, Guatemala, Kenya, Mexico, Peru, Rwanda, and Somalia.
Since World War II, large outbreaks of typhus have occurred primarily in three African countries: Burundi, Ethiopia and Rwanda. In Ethiopia, the number of cases reported annually has ranged between 7,000 and 17,000. In 1996, for example, Burundi reported 3,500 cases and that number increased to 20,000 for the period from January to March 1997. In the first two decades of the twenty-first century, the World Health Organization (WHO) reported that typhus kills about 0.2 people per million per year.
The four varieties of typhus cause similar types of illnesses, though they vary in severity.
Brill-Zinsser disease is quite mild, resulting in about a week-long fever and a light rash similar to that of the original illness.
Endemic typhus causes about 12 days of high fever, with chills and headache. A light rash may occur.
Scrub typhus causes a wide variety of effects. The main symptoms include fever, headache, muscle aches and pains, cough, abdominal pain, nausea and vomiting, and diarrhea. Some patients experience only these symptoms, while others also develop a rash that can be flat or bumpy. The individual spots develop crusty black scabs. Other patients develop a more serious disease, in which encephalitis, pneumonia, and swelling of the liver and spleen (hepatosplenomegaly) occur.
Numerous tests exist to determine the reactions of a patient's antibodies (immune cells in the blood) to the presence of certain viral and bacterial markers. For instance, a complete blood count (CBC) may show anemia and low platelets. Blood tests for typhus may show: low level of albumin, high level of typhus antibodies, low sodium level, moderately high liver enzymes, and mild kidney failure. When the antibodies react in a particular way, it suggests the presence of a rickettsial infection. Many tests require time for processing, so practitioners frequently begin treatment without completing tests, simply on the basis of a patient's symptoms.
The antibiotics tetracycline or chloramphenicol are used for treatment of each of the forms of typhus. Other antibiotics used for typhus include azithromycin and doxycycline. Tetracycline is taken orally. It is usually not prescribed for children because it can permanently stain their teeth. Besides antibiotics, patients with epidemic typhus may also require oxygen and intravenous fluids. Prompt treatment with one of these antibiotics usually will cure most cases of typhus. Without treatment, typhus can be fatal. The death rate for untreated epidemic typhus varies from 10% for younger people to 40% for older ones.
Outbreaks of typhus are limited in developed countries like the United States but the disease has the potential to re-emerge. In undeveloped and developing countries, the disease is still responsible for major outbreaks. Typhus killed approximately 100,000 people during the civil war in Burundi, which lasted from 1993 to 2005.
WHO published the report Outbreak Surveillance and Response in Humanitarian Emergencies in 2012. The report notes that humanitarian crises that result in large populations of displaced people gathering in one location where there are infrastructure issues (refugee camps) are cause for increased spread of infectious diseases. Diseases that may remain contained under normal circumstances will spread and early rapid detection and prevention is necessary. WHO reports that scrub typhus is one of the most common vectorborne diseases that can occur in humanitarian emergency settings.
The relatively high death rate from untreated typhus is one reason there is some concern that its causative organisms might be used in the future as agents of bioterrorism.
Prevention for each of these forms of typhus includes avoidance of the insects that carry the causative bacteria. Other preventive measures include good hygiene and the use of insect repellents.
See also Endemic ; Epidemiology ; Traveler's health .
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Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, 30333, (800) 232-4636, email@example.com, http://www.cdc.gov/ .
National Institute of Allergy and Infectious Diseases, 1301 Pennsylvania Ave., NW, Ste. 800, Washington, D.C., 20004, (202) 785-3355, Fax: (202) 452-1805, http://www.niaid.nih.gov .
World Health Organization, Avenue Appia 20, Geneva, Switzerland, 1211 27, 41 22 791-2111, Fax: 41 22 791-3111, http://www.who.int/en .
Rosalyn Carson-DeWitt, MD
Rebecca J. Frey, PhD
Revised by William A. Atkins, BB, BS, MBA