Epidemic typhus (additionally known as “camp fever”, “jail fever”, “hospital fever”, “ship fever”, “famine fever”, “putrid fever”, “petechial fever”, “Epidemic louse-borne typhus,” and “louse-borne typhus”) is a type of typhus so named as a result of the illness typically causes epidemics following wars and pure disasters. The causative organism is Rickettsia prowazekii, transmitted by the human physique louse (Pediculus humanus humanus). Feeding on a human who carries the bacterium infects the louse. R. prowazekii grows within the louse’s intestine and is excreted in its feces. The illness is then transmitted to an uninfected human who scratches the louse chew (which itches) and rubs the feces into the wound. The incubation interval is one to 2 weeks. R. prowazekii can stay viable and virulent within the dried louse feces for a lot of days. Typhus will ultimately kill the louse, although the illness will stay viable for a lot of weeks within the useless louse.
After an incubation interval of seven to 14 days, fever, headache, and prostration immediately happen. Temperature reaches 40° C in a number of days and stays excessive, with slight morning remission, for about 2 wk. Headache is generalized and intense. Small, pink macules, which seem on the 4th to sixth day, quickly cowl the physique, normally within the axillae and on the higher trunk and never on the palms, soles, and face. Later, the rash turns into darkish and maculopapular. In extreme instances, the rash turns into petechial and hemorrhagic.
Splenomegaly typically happens. Hypotension happens in most significantly unwell sufferers. Vascular collapse, renal insufficiency, encephalitic indicators, ecchymosis with gangrene, and pneumonia are poor prognostic indicators.
Transmission of Epidemic Typhus
- Rickettsia prowazekii is transmitted from human to human by the physique louse Pediculus humanus humanus. The head louse (Pediculus humanus capitis) and crab louse (Phthirus pubis) can transmit R. prowazekii experimentally however identified epidemics are linked to the physique louse.
- Rickettsiae could stay viable and infectious within the useless louse for weeks and in louse faeces for as much as 100 days.
- When feeding on an contaminated human, the physique louse ingests R. prowazekii which multiplies within the epithelial cells of the midgut. When these burst, the pathogens are excreted with the faeces of the physique louse. R. prowazekii has an impression on the longevity of the physique louse and may kill it.
- On common a mature physique louse will reside for 20–30 days. Body lice multiply quickly and their inhabitants can enhance by 11% per day.
- Overcrowding results in shut private contact and unfold of arthropod vectors (notably lice) amongst people. Humans grow to be contaminated by contamination of the chew website with contaminated faeces or by means of contamination of the conjunctivae or mucous membranes with lice faeces. Presumed an infection by means of aerosols of faeces-infected mud has been reported.
- Rickettsia prowazekii is taken into account a bioterrorism agent because of particular organic options (notably on the subject of environmental stability and doable aerosol transmission).
- While uncovered in refugee camps and different settings characterised by crowding and poor hygiene, humanitarian aid staff and army personnel are probably at increased threat in illness foci than the overall inhabitants. In basic, the danger for travellers could be very low as they’re making use of measures that scale back publicity to physique lice throughout journey.
Treatment for Epidemic Typhus
The an infection is handled with antibiotics. Intravenous fluids and oxygen could also be wanted to stabilize the affected person. The mortality charge is 10% to 60%, however is vastly decrease (near zero) if intracellular antibiotics similar to tetracycline are used earlier than eight days. Chloramphenicol can be used. Infection can be prevented by vaccination.
Immunization and louse management are extremely efficient for prevention. However, vaccines should not obtainable within the US. Lice could also be eradicated by dusting infested individuals with malathion or lindane.