Epidemiological, Clinical and Laboratory Characteristics of 19 Serologically Confirmed Rickettsial Disease in Singapore

MIC Chen, JKT Chua, CC Lee, YS Leo, G Kumarasinghe
Correspondence: Dr Lee Cheng Chuan, lee_cheng_chuan@ttsh.com.sg

ABSTRACT
Aim To identify epidemiological, clinical and laboratory features of serologically-proven typhus in the local setting.
Method & Results Retrospective study looking at rickettsial serologies done over a six-month period and collection of the epidemological, clinical, laboratory and treatment response data from the case notes of the patients with an ordered rickettsial serology. Twenty of the 35 cases had a positive serology. Of these 20 patients, 18 were already clinically diagnosed as having murine typhus. All except one were males and all were migrant workers. Majority of the patients were construction workers staying in containers where rats abound. The most consistent clinical features were high fever (100%) for a median period of seven days, headache (94%) and cough (47%). The white cell count was usually normal (74%) but thrombocytopenia was common (68%). Transaminitis was also common (90%) with the AST component higher than the ALT in half of the cases. Response to doxycycline therapy was rapid and most (88%) were afebrile by 72 hours.
Conclusion Typhus (notably murine type) can be confidently diagnosed from consistent clinical features supported by epidemiological and laboratory clues. Early recognition with the prompt treatment response will result in shorter hospital stay with decreased cost. Serological testing may only prove useful in difficult situations when the clinical diagnosis is less clear.

Keywords: rickettsial, typhus, murine, scrub
Singapore Med J 2001; 42(12): 553-558