Rickettsial diseases, caused by Orientia tsutsugamushi (scrub typhus), Rickettsia typhi (murine typhus) and members of the spotted fever group (SFG), are important causes of fever in southeast Asia especially in rural communities where agriculture is a dominant activity. World Health Organization has noted that “Scrub typhus is probably one of the most under-diagnosed and under-reported febrile illnesses requiring hospitalisation in the region”.

Rickettsial studies at MORU concentrate on determining the epidemiology and incidence of the disease using hospital-based fever studies at centres in northern and north-eastern Thailand as well as Laos. From these studies we have examined and compared the antigenic and genetic composition of strains that cause infection.

Improved acute diagnosis of rickettsial illness has also been a major theme at MORU. We have developed molecular approaches such as real time PCR and Loop-mediated Isothermal Amplification (LAMP) for the diagnosis of scrub typhus and murine typhus.

We have also evaluated commercial rapid tests for the diagnosis of acute typhus in Thai and Lao clinical settings and have raised issues regarding the lack of consistency in the application of gold-standard assays and diagnostic criteria for scrub typhus infection.

MORU also has ongoing studies to determine the pathophysiological mechanisms of scrub typhus infection.