epidemic typhus

Typhus

[tahy-fuhs]

Typhus is any of several similar diseases caused by louse-borne bacteria. The name comes from the Greek typhos, meaning smoky or lazy, describing the state of mind of those affected with typhus. The causative organism Rickettsia is an obligate parasite and cannot live long outside living cells. Rickettsia is endemic in rodent hosts, including mice and rats, and spreads to humans through mites, fleas and body lice. The arthropod vector flourishes under conditions of poor hygiene, such as those found in prisons, concentration camps, or refugee camps, amongst the homeless, or until the middle of the 20th century, in armies in the field. In developed countries, typhus is primarily transmitted by common fleas. In tropical countries, typhus is often mistaken for dengue fever.

Most rickettsial diseases include the word "typhus" in their description, however related diseases include Rocky Mountain spotted fever and "spotted fevers" endemic in Colombia and Brazil.

Types of typhus

Epidemic typhus

Epidemic typhus (also called "Camp Fever", "Jail Fever", "Hospital Fever", "Ship Fever", "Famine Fever", "Petechial Fever", and "louse-borne typhus") is so named because the disease often causes epidemics following wars and natural disasters. The causative organism is Rickettsia prowazekii, transmitted by the human body louse (Pediculus humanus corporis). Feeding on a human who carries the bacillus infects the louse. R. prowazekii grows in the louse's gut and is excreted in its feces. The disease is then transmitted to an uninfected human who scratches the louse bite (which itches) and rubs the feces into the wound. The incubation period is one to two weeks. R. prowazekii can remain viable and virulent in the dried louse feces for many days. Typhus will eventually kill the louse, though the disease will remain viable for many weeks in the dead louse.

Symptoms include severe headache, a sustained high fever, cough, rash, severe muscle pain, chills, falling blood pressure, stupor, sensitivity to light, and delirium. A rash begins on the chest about five days after the fever appears, and spreads to the trunk and extremities but does not reach the face, palms and soles. A symptom common to all forms of typhus is a fever which may reach 39°C (102°F).

The infection is treated with antibiotics. Intravenous fluids and oxygen may be needed to stabilize the patient. The mortality rate is 10% to 60%, but is vastly lower if antibiotics such as tetracycline are used early. Infection can also be prevented via vaccination. Brill-Zinsser disease, first described by Nathan Brill in 1913 at Mount Sinai Hospital in New York City, is a mild form of epidemic typhus which recurs in someone after a long period of latency (similar to the relationship between chickenpox and shingles). This type of recurrence can also occur in immunosuppressed patients.

Epidemic typhus is found most frequently during times of war and privation. For example, typhus killed many thousands of prisoners in Nazi Germany concentration camps during World War II. The abysmally low standards of hygiene enforced in camps such as Theresienstadt and Bergen-Belsen created conditions where diseases such as typhus flourished. A possible scenario for typhus epidemics in the 21st Century would be in refugee camps during a major famine or natural disaster.

Endemic typhus

Endemic typhus (also called "flea-borne typhus" and "murine typhus" or "rat flea typhus") is caused by the bacteria Rickettsia typhi, and is transmitted by the fleas that infest rats. Less often, endemic typhus is caused by Rickettsia felis and transmitted by fleas carried by cats or opossums. Symptoms of endemic typhus include headache, fever, chills, myalgia, nausea, vomiting, and cough. Endemic typhus is highly treatable with antibiotics. Most people recover fully, but death may occur in the elderly, severely disabled or patients with a depressed immune system. Symptoms may resemble those of measles, rubella, or possibly Rocky Mountain spotted fever.

Scrub typhus

Scrub typhus (also called "chigger-borne typhus") is caused by Orientia tsutsugamushi and transmitted by chiggers, which are found in areas of heavy scrub vegetation. This variety of typhus was known in Japan as tsutsugamushi disease, hence the formal name, and was also prevalent in Malaysia and Australia. According to J. R. Audy, severe epidemics of the disease occurred among troops in what was then known as Burma and Ceylon during World War II. Symptoms include fever, headache, muscle pain, cough, and gastrointestinal symptoms. More virulent strains of O. tsutsugamushi can cause hemorrhaging and intravascular coagulation. Contact with species related to the chigger mite, found in many parts of the world, can also cause an intense irritation of the human skin.

Vaccine

The first major step in the development of the vaccine was Charles Nicolle's 1909 discovery that lice were the vectors for epidemic typhus. This made it possible to isolate the bacteria causing the disease and develop a vaccine; he was awarded the 1928 Nobel Prize in Physiology or Medicine for this work. Nicolle attempted a vaccine but was not successful in making one that worked on a large enough scale.

Henrique da Rocha Lima in 1916 then proved that the bacteria Rickettsia prowazekii was the agent responsible for typhus; he named bacteria after H. T. Ricketts and Stanislaus von Prowazek, two zoologists who died investigating a typhus epidemic in a prison camp in 1915. Once these crucial facts were recognized, Rudolf Weigl in 1930 was able to fashion a practical and effective vaccine production method by grinding up the insides of infected lice that had been drinking blood. It was, however, very dangerous to produce, and carried a high likelihood of infection to those who were working on it.

A safer mass-production-ready method using egg yolks was developed by Herald R. Cox in 1938. This vaccine was widely available and used extensively by 1943.

History

The first description of typhus was probably given in 1083 at a convent near Salerno, Italy. In 1546, Girolamo Fracastoro, a Florentine physician, described typhus in his famous treatise on viruses and contagion, De Contagione et Contagiosis Morbis.

Before a vaccine was developed in World War II, typhus was a devastating disease for humans and has been responsible for a number of epidemics throughout history. These epidemics tend to follow wars, famine, and other conditions that result in mass casualties.

During the second year of the Peloponnesian War (430 BC), the city-state of Athens in ancient Greece was hit by a devastating epidemic, known as the Plague of Athens, which killed, among others, Pericles and his two elder sons. The plague returned twice more, in 429 BC and in the winter of 427/6 BC. Epidemic typhus is a strong candidate for the cause of this disease outbreak, supported by both medical and scholarly opinions.

Typhus also arrived in Europe with soldiers who had been fighting on Cyprus. The first reliable description of the disease appears during the Spanish siege of Moorish Granada in 1489. These accounts include descriptions of fever and red spots over arms, back and chest, progressing to delirium, gangrenous sores, and the stink of rotting flesh. During the siege, the Spaniards lost 3,000 men to enemy action but an additional 17,000 died of typhus.

Typhus was also common in prisons (and in crowded conditions where lice spread easily), where it was known as Gaol fever or Jail fever. Gaol fever often occurs when prisoners are frequently huddled together in dark, filthy rooms. Imprisonment until the next term of court was often equivalent to a death sentence. It was so infectious that prisoners brought before the court sometimes infected the court itself. Following the Assize held at Oxford in 1577, later deemed the Black Assize, over 300 died from Epidemic typhus, including Sir Robert Bell Lord Chief Baron of the Exchequer. The outbreak that followed, between 1577 to 1579, killed about 10% of the English population. During the Lent Assize Court held at Taunton (1730) typhus caused the death of the Lord Chief Baron, as well as the High Sheriff, the sergeant, and hundreds of others. During a time when there were 241 capital offenses--more prisoners died from 'gaol fever' than were put to death by all the public executioners in the realm. In 1759 an English authority estimated that each year a quarter of the prisoners had died from Gaol fever. In London, typhus frequently broke out among the ill-kept prisoners of Newgate Gaol and then moved into the general city population.

Epidemics occurred throughout Europe from the 16th to the 19th centuries, and occurred during the English Civil War, the Thirty Years' War and the Napoleonic Wars. During Napoleon's retreat from Moscow in 1812, more French soldiers died of typhus than were killed by the Russians. A major epidemic occurred in Ireland between 1816-19, and again in the late 1830s, and yet another major typhus epidemic occurred during the Great Irish Famine between 1846 and 1849. The Irish typhus spread to England, where it was sometimes called "Irish fever" and was noted for its virulence. It killed people of all social classes, since lice were endemic and inescapable, but it hit particularly hard in the lower or "unwashed" social strata.

In America, a typhus epidemic killed the son of Franklin Pierce in Concord, New Hampshire in 1843 and struck in Philadelphia in 1837. Several epidemics occurred in Baltimore, Memphis and Washington DC between 1865 and 1873. Typhus fever was also a significant killer during the US Civil War, although typhoid fever was the more prevalent cause of US Civil War "camp fever". Typhoid is a completely different disease from typhus.

During World War I typhus caused three million deaths in Russia and more in Poland and Romania. De-lousing stations were established for troops on the Western front but the disease ravaged the armies of the Eastern front, with over 150,000 dying in Serbia alone. Fatalities were generally between 10 to 40 percent of those infected, and the disease was a major cause of death for those nursing the sick. Between 1918 and 1922 typhus caused at least 3 million deaths out of 20–30 million cases. In Russia after World War I, during a civil war between the White and Red armies, typhus killed three million, largely civilians. Even larger epidemics in the post-war chaos of Europe were only averted by the widespread use of the newly discovered DDT to kill the lice on millions of refugees and displaced persons.

During World War II typhus struck the German army as it invaded Russia in 1941. In 1942 and 1943 typhus hit French North Africa, Egypt and Iran particularly hard. Typhus epidemics killed inmates in the Nazi Germany concentration camps; infamous pictures of typhus victims' mass graves can be seen in footage shot at Bergen-Belsen concentration camp. Thousands of prisoners held in appalling conditions in Nazi concentration camps such Theresienstadt and Bergen-Belsen also died of typhus during World War II, including Anne Frank at the age of 15 and her sister Margot.

Following the development of a vaccine during World War II, epidemics have usually occurred in Eastern Europe, the Middle East and parts of Africa.

Literary references

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References

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