Prognosis

Prognosis with timely diagnosis and appropriate antibiotic treatment is excellent.

Rickettsial infections can be due to rickettsiae of low virulence (e.g., Rickettsia felis, causing cat-flea rickettsiosis; R africae, causing African tick-bite fever), where there are rarely any severe complications during the acute illness. However, infection with rickettsiae of inherently high virulence (e.g., Orientia tsutsugamushi, causing scrub typhus; R rickettsii, causing Rocky Mountain spotted fever; R prowazekii, causing epidemic louse-borne typhus) can cause a range of serious complications during the acute illness. These include infarction of digits, leading to the need for amputation; severe pneumonia; life-threatening meningo-encephalitis and other neurological conditions; cardiac abnormalities (myocarditis or pericarditis); renal impairment; hearing loss; necrotic skin rash; and multi-organ dysfunction. However, if the patient survives the acute rickettsial infection, as most do, there are usually no long-term complications, although some patients have described a long period of lethargy after recovery.[38]

The course of illness is typically mild in African tick-bite fever, while Mediterranean spotted fever can lead to severe or fatal infection, with a case-fatality of 21% reported among hospitalised adults in Portugal.[22][39]

Systematic reviews of scrub typhus have reported a mortality rate of 6% in untreated infection and 1.4% in treated infection, with significant heterogeneity between studies.[5][40] The case fatality rate in children was 1.1%, with the most common complications being hepatitis, shock, pneumonia, acute kidney injury, and meningitis/meningo-encephalitis.​[41]

If the patient has recovered naturally, without the use of antibiotics, there is the risk of relapse/recurrence in some rickettsial infections: for example, epidemic typhus (leading to Brill-Zinsser disease) or scrub typhus, which can occur many years after the initial infection.[42]

Use of this content is subject to our disclaimer