Rickettsial Infections and Fever, Vientiane, Laos

TLDR

Rickettsial diseases had not been previously reported in Laos, yet a prospective study found that acute rickettsial infection caused fever in 27 % of 427 adults with negative blood cultures admitted to Mahosot Hospital in Vientiane. Serology identified Orientia tsutsugamushi (14.8 %), Rickettsia typhi (9.6 %) and spotted‑fever group rickettsiae (2.6 %) as the etiologic agents, with murine typhus patients showing markedly less peripheral lymphadenopathy than scrub‑typhus cases, underscoring that rickettsioses are an underrecognized cause of undifferentiated fever in Laos and warrant consideration in empiric therapy.

Abstract

Abstract Rickettsial diseases have not been described previously from Laos, but in a prospective study, acute rickettsial infection was identified as the cause of fever in 115 (27%) of 427 adults with negative blood cultures admitted to Mahosot Hospital in Vientiane, Laos. The organisms identified by serologic analysis were Orientia tsutsugamushi (14.8%), Rickettsia typhi (9.6%), and spotted fever group rickettsia (2.6% [8 R. helvetica, 1 R. felis, 1 R. conorii subsp. indica, and 1 Rickettsia "AT1"]). Patients with murine typhus had a lower frequency of peripheral lymphadenopathy than those with scrub typhus (3% vs. 46%, p<0.001). Rickettsioses are an underrecognized cause of undifferentiated febrile illnesses among adults in Laos. This finding has implications for the local empiric treatment of fever.