Prevalence of rickettsial infections in acute coronary syndromes in Sri Lanka: a case control study

Abstract

Background: Place of infection in atherosclerosis and or coronary heart disease has recently drawn interest. Rickettsiae are a group of obligate intracellular pathogens who invade vascular endothelial cells leading to vasculopathy. A study conducted in Thaiwan, scrub typhus was found to increase the risk of acute coronary syndromes (ACS) by 37% compared to general population after adjusting for age, sex and other known independent risk factors. Objective: To assess the prevalence of Rickettsial infections in patients with ACS residing in Western province, Sri Lanka. Methods: Patients admitted with ACS to Professorial-Medical-unit, were studied for serological prevalence of Rickettsial infections and were compared with a matched control group; who had no fever or ACS. 2ml serum samples were obtained at enrolment and 2weeks after and were assessed for IFA-IgG antibody titres against Orientiatsutsugamushi (OT) and Spotted-fever-group-rickettsioses (SFG). An IgG titre>1:128 or a rising/declining titre were considered positive for acute rickettsioses. A static titre was considered to be due to previous exposure to rickettsioses. Results: 46 ACS patients (males-23.9%, mean age 61.1 [SD=13.1] years) and 52 controls (male-50%, mean age 56.0[SD=13.6] years) were studied. None had evidence of acute Rickettsiel infection. Sero-prevalence of IgG-OT was 6.4% and IgG-SFG was 15.2% among ACS patients. Same for control group were 3.8% and 11.5% respectively. There was no significant difference in sero-prevalence of OT [OR =0.74; CI: 0.28-10.93; p=0.66] or SFG [OR=1.376; CI:0.43-4.44; p=0.59] in patients with ACS compared to controls. Conclusions: No significant difference was observed in sero-prevalence of rickettsioses in patients with acute coronary syndromes compared to controls in this study.