Imported rickettsial infections to the United Kingdom, 2015-2020

Abstract

Objective: The burden of imported rickettsial infection in the UK is not previously described. This retrospective review identifies rickettsial cases diagnosed at the national reference laboratory between 2015 and 2022.

Methods: Samples testing positive for spotted fever group, typhus group, and scrub typhus IgG/IgM on acute and convalescent blood samples, and/or PCR on tissue/blood were categorized as suspected, confirmed or past infection.

Results: 220 patients had rickettsioses, and the commonest import was acute spotted fever group infection (61%, 125/205), 54% (62/114) from South Africa. In acute typhus group cases, 60% (40/67) were from Southeast Asia. One patient with Rickettsia typhi bacteremia died. Scrub typhus group infections (5%, 10/205) were exclusively from Asia and the Western Pacific regions. Overall, 43% of confirmed cases (39/91) had not received doxycycline prior to results.

Conclusions: Rickettsial infections are important and under-recognized causes of imported fever in the UK. Thorough history, examination, and timely treatment with doxycycline should be considered if there is suspicion of Rickettsia infection before testing.

Keywords: Eschar; Fever; Murine typhus; Rickettsia; Scrub typhus; Spotted fever; Tick.