Rickettsiosis
Overview
A disease caused by infection with rickettsial bacteria which are transmitted by arthropods such as ticks, mites and lice. Different rickettsial bacteria can cause different types of infections such as typhus, spotted fever and trench fever. Symptoms can vary somewhat between the different types.
Symptoms
Headache Chills Fever Stupor Skin rash
Causes
Rickettsiosis/rickettsioses are a group of diseases generally caused by species of Rickettsia, a genus of obligate intracellular bacteria. Most of the Rickettsioses are transmitted by ticks, but they can also be transmitted by fleas, lice and mites. Although they are widely distributed throughout the world, the species and associated human clinical diseases vary depending on the geographical locations.
Prevention
Epidemic typhus: Delousing (e.g. 1% permethrin or 1% malathion puffs in/on clothing, heat sterilisation of clothing), treat cases, improve general hygiene. Endemic typhus: Rodent control Scrub typhus: Preventive antibiotics, rodent control. In endemic areas vegetation must be cleared. RMSF: Protective clothing, tick repellents in infested areas. Manual removal of ticks Fièvre boutonneuse: as for RMSF
Diagnosis
The diagnosis can be confirmed at a late stage by serology. Seroconverson however does not occur so fast. A 4-fold increase in titre between acute and convalescent sera must be detected. Rickettsiae have some antigens in common with Proteus vulgaris strains OX19, OX2 and OXK. On this basis, a flocculation test was developed: the Weil-Felix test [1916, Edmund Weil and Arthur Felix, Hungarian doctors]. The test is aspecific. Q fever tests negative in it. Scrub typhus only produces a positive result in 50% of cases. There are now many better tests but often they are not available under field conditions. Treatment must be started early without waiting for laboratory confirmation.