Throughout history, battles and wars have been lost due to typhus epidemics that spread among soldiers fighting in unsanitary conditions. After World WarI, 25 million people in the Soviet Union alone were infected with the disease. People forced to live in crowded, filthy, rodent-infested neighborhoods also suffered untimely deaths from the disease.

Howard Taylor Ricketts, an American pathologist born in Findlay, Ohio in 1871, is credited with discovering the genus Rickettsia, the cause of the disease, during his studies of Rocky Mountain spotted fever, which he noticed resembled typhus. In 1910, Ricketts traveled to Mexico City to study typhus, whichhe found was transmitted by a body louse. But his research had tragic results. Before he could return to the United States where he had accepted a position at the University of Pennsylvania, Ricketts died of typhus, the very disease he was studying.

At the same time, the curiosity of French physician Charles-Jean-Henri Nicolle's (1866-1936) was aroused by the contagious aspects of typhus, which he hadwitnessed while working at the Pasteur Institute in Tunis, Tunisia. Outsidethe hospital, the disease was caught on contact. Hospital admission employeesalso caught it, but once inside the hospital, the patient no longer seemed contagious.

He began to suspect body lice as the carriers when he realized the patients were stripped and scrubbed down when they entered the hospital. His work withanimals proved his suspicions. Nicolle won the 1928 Nobel Prize in physiologyor medicine for his work on typhus. Nicolle, the son of a Rouen physician, was born in 1866 and practiced medicine in Paris and Rouen until deafness began to interfere with his effectiveness in treating patients. In 1903, he movedto Tunis where he remained until his death in 1936.

Epidemic typhus is carried by lice. This disease, caused by R. prowazekii, was responsible for millions of deaths in eastern Europe and the Balkancountries after World War I and World War II. It devastated military troops during World War I, but during World War II, DDT was used to kill the lice carrying the disease. R. prowazekii also causes recrudescent epidemic typhus, a disease which is reactivated years after an initial bout of epidemic typhus.

After an incubation period of about one week, a person infected with typhus develops a headache, chills, prostration, and fever up to 104° F. Other symptoms include a rash, conjunctivitis (inflammation of the mucous membrane that lines the inner surface of the eyelids and covers the forepart of the eyeball), and a dry cough. In severe cases, there is renal failure and mental confusion. Death occurs in 10 to 50 percent of the cases, and the mortality rateincreases if the victim is over 60 years old. However, under medical supervision, drug therapy can be very effective.

Murine endemic typhus is caused by R. typhi, a microorganism carried by a rat flea. It occurs worldwide and was once common in the southeastern United States. When the rat flea cannot find a natural host, it feeds on humans.During the feeding, it drops infected feces which, when rubbed into a breakin the skin, give rise to the disease.

The incubation period of murine endemic typhus is one to two weeks. The infected person initially develops a headache, malaise, backache, and chills. Later, typhus causes shaking, chills, fever up to 103° F, severe headache, vomiting, and nausea. Eventually a rash appears in the armpits and inner surface of the upper arms and moves to the trunk, thighs and lower arms. After therash disappears, a dry cough develops. Murine endemic typhus is fairly mild compared to other diseases caused by rickettsia. It can be treated withtetracyclines, but even untreated, death rarely results.

The typhus vaccine, developed by Hans Zinsser in 1932, is based on dead microorganisms which stimulate the body's immune system to produce antibodies to the antigens carried on the surfaces of the dead cells. The immune system alsoproduces "memory cells" which remain in the body to trigger a rapid responsein the event of reinfection. Since the vaccine uses dead organisms, the reaction is mild and there is no risk of the patient contracting the disease. Inoculation, antibiotics and control of rats and lice have combined to greatly reduce the incidence of typhus throughout the world.

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