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Key Diagnostic Tests.

• Agglutination test (acute- and convalescent-phase serum antibody titers are needed to confirm diagnosis);
• Immunoassay;
• Culture (This is difficult as it requires animal cells cultured in an antibiotic-free media, embryonated eggs, or susceptible animals.)

Symptoms and effects.

Epidemic typhus is contracted by exposure to contaminated feces or larvae. It has an incubation period of 6-15 days develops rapidly. It is characterized by severe headaches, chills, a sustained high fever (38.8-40°C or 102-104°F in adults, up to 41.1° C or 106° in children) that can last for two weeks, general pain, and a skin rash. The rash, which appears as irregular pink macular patches can become extensive or even confluent, usually appears about five days after the fever begins. The disease can affect both the circulatory and neurological systems. Neurological effects in clide spasticity, agitation, stupor and coma. Circulatory problems include tachycardia (slow heart rate), low blood pressure, high levels of blood nitrogen, thrombosis and cutaneous gangrene.

Endemic typhus is not as severe a disease as epidemic typhus. It is contracted through the bite of infected rats or fleas, and exposure to contaminated feces or larvae. The incubation period is about the same as that for epidemic typhus (6-14 days), but the onset is not as fast and the symptoms not as severe.

Vaccination (Immunoprophylaxis).

Effective protective vaccines that lower the risk of infection, modify the course of the disease, and lower mortality are available, but the duration of the protection is uncertain. Immunization should be repeated every four months as long as there is a danger of typhus.

Antibiotics. Epidemic typhus can be effectively treated with tetracyclines or chloramphenicol. This shortens the course of the disease and reduces the severity of the symptoms.

Supportive care

Symptoms (pain, rash) need to be treated and precautions must be taken against secondary infection of the weakened patient. Although rare today, stupor or delirium may be seen and the patient may need sedation.

Ticks must be removed. The disease can affect many organs, so a wide range of supportive measures measures, e.g. analgesics, maintenance of blood pressure, supporting of breathing, must be kept ready. Intravenous prednisolone and cold-sponging of patients with high fevers (>40°C, 104°F) are often used in the treatment of rickettsial disease.

Patients should be thoroughly cleaned and treated for lice infection. If the area where the infection originated from can be identified, it should be treated with pesticides and public health lice control procedures should be invoked.

Decontamination

The microorganisms can be killed by heat (112°F (45°C)) for 15-30 minutes and surfaces can be decontaminated with 0.1% formalin, glutaraldehyde or 0.5% phenol disinfectants.

Treat the affected area for tick infestation. The patient and his medical and nursing staff may also need to be treated with malathion or DDT to prevent reinfection.

Agent Properties and Potential Uses

Epidemic typhus is highly infective and often fatal in untreated cases. It cannot be communicated man-to-man but only through a tick vector. It is not particularly stable in storage and an unlikely biological agent.

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Terrorist Acquisition and Attempted Use.

• In 1976, a number of letters supposedly containing ticks (a typhus vector) were mailed to businessmen in a number of US cities.

The History and Natural History of Typhus.

Rickettsia live in rodent hosts such as mice, rats, and the flying squirrel Glaucomys volans in the case of typhus, without causing them any harm and are spread to humans by fleas and lice (including head, body, and pubic lice) that flourish under conditions of poor hygiene including prison or refugee camps, amongst the homeless, or until the middle of the 20th Century, in armies in the field.

Typhus appears to be a relatively new disease with the first reliable description is from the Spanish siege of Moorish Granada in 1489. The disease gave rise to sores that could become gangrenous and the victims stank of rotting flesh and became delirious and stupefied. While the Spaniards lost 3,000 men to enemy action during the siege, they lost 17,000 to typhus. The disease ravaged Europe for four centuries and even artillery surrendered its crown as queen of the battlefield to typhus. More than any other disease, it may have served as a model for the use of biological weapons to harry an enemy in the field. It affected the course of every war from the liberation of Spain to Napoleon's failure in Russia. It even killed half of the army he raised after escaping from Elba. In World War I, it still ravaged the armies of the Eastern front.

Not only armies were affected. In London, typhus frequently broke out amongst the ill-kept prisoners of Newgate Gaol and went from there through the courts to the general population, killing at least one Lord Mayor of London. In the aftermath of World War I and during the civil war between the White (Royalist) and Red (Communist) armies that followed the Bolshevik Revolution, typhus killed three million in a devastated and anarchic Soviet Union. It came closer to toppling Lenin than the White Army ever did.