|Communicable Disease Control in Emergencies - A Field Manual (WHO - OMS, 2003, 223 p.)|
|CHAPTER 5: DISEASE PREVENTION AND CONTROL|
· Typhus is a rickettsial disease caused by the pathogen Rickettsia prowazeki.
· It is transmitted by the human body louse, which is infected by feeding on the blood of a patient with acute typhus. Infected lice excrete rickettsiae in their faeces, and humans are infected by rubbing faeces or crushed lice into the bite
· The disease is endemic in the highlands and cold areas of Africa, Asia and South America. Cases occurred in the past in the Balkans and parts of the former USSR, and cases of Brill-Zinsser disease (recrudescent typhus) are still reported from these regions.
· Refugees and displaced persons in affected areas are at a high risk of epidemics if there is overcrowding, poor washing facilities and body lice.
· Large outbreaks have been reported among refugees in Burundi, Ethiopia and Rwanda.
· The crude mortality rate ranges from 10% to 40% without treatment, and can rise to 50% in the elderly.
· The crude mortality rate is around 70% among those who develop complications.
· The incubation period is 1-2 weeks, commonly 12 days.
· There is a sudden onset of fever, chills, headache and generalized pain.
· A macular rash spreads over the trunk and limbs after 5-6 days of the illness.
· In severe cases, complications such as vascular collapse, gangrene, acute respiratory distress syndrome and coma can occur.
· Typhus has a non-specific clinical presentation, so laboratory testing is usually needed to confirm the diagnosis for the first cases in a suspected epidemic.
· Serological techniques are used, the most common being the Indirect fluorescent antibody test.
· Other tests are the enzyme-linked immunosorbent assay and complement fixation.
· Only initial cases should be confirmed; after confirmation of an epidemic the diagnosis should be clinical.
· In areas where typhus is known to present a risk, all newly arrived refugees or internally displaced persons in a camp or community should be screened and, if body lice are found, mass delousing should be carried out.
· Prompt treatment of patients with antimicrobials is essential.
· The treatment of first choice is a single oral dose of doxycycline (5 mg/kg body weight).
· Typhus can also be treated with tetracycline or chloramphenicol orally with a loading dose of 2-3 g (in children, tetracycline at 25-50 mg/kg body weight, chloramphenicol 50 mg/kg body weight) followed by daily doses of 1-2g/day in four divided doses at 6-hour intervals until the patient becomes afebrile (usually 3-7 days) plus one day.
· In severe cases, patients should be admitted to hospital and given intravenous tetracycline or chloramphenicol.
Prevention and control measures
· Once an epidemic is confirmed, all patients and contacts should be deloused using permethrin powder 0.5%. Permethrin is applied to all clothes and bedding using a shaker-top container or a special hand-held powder duster. The powder is blown into the clothing through the neck openings, up the sleeves, up the legs and from all sides of the loosened waist. If this is not available a 25% solution of benzyl benzoate (found in all essential drug kits) can be applied and washed off 24 hours later.
· Clothing and bedding that has not been used should also be treated. One easy method is to place all clothing and bedclothes in a blanket, add dusting powder and shake. Alternatively, such items can be impregnated with permethrin by the same methods that are used for impregnating mosquito nets. Clothing thus treated will retain its insecticidal properties for several washes and will resist re-infestation by lice.