Serological evidence indicates widespread distribution of rickettsioses in Myanmar

Philip N D Elders ,Htet Naing Lin,Ni Ni Zaw,Myo Maung Maung Swe,Ampai Tanganuchitcharnchai,Thin Thin Nwe,Ni Ni Tun,Wei Yan Aung Htay,Aung Pyae Phyo,Stuart D Blacksell,Frank Smithuis ,Alistair R D Mclean ,Thel K Hla ,Yin Yin Htwe ,Myat Myat Moe ,Htun Linn ,Win May Thein ,Kyaw Soe ,Wai Mon Kyaw ,Elizabeth A Ashley

doi:10.1016/j.ijid.2020.12.013

Abstract

BackgroundLittle research has been published on the prevalence of rickettsial infections in Myanmar. This study determined the seroprevalence of immunoglobulin G (IgG) antibodies to rickettsial species in different regions of Myanmar. MethodsSeven hundred leftover blood samples from patients of all ages in primary care clinics and hospitals in seven regions of Myanmar were collected. Samples were screened for scrub typhus group (STG), typhus group (TG) and spotted fever group (SFG) IgG antibodies using enzyme-linked immunosorbent assays (ELISA). Immunofluorescence assays were performed for the same rickettsial groups to confirm seropositivity if ELISA optical density ≥0.5. ResultsOverall IgG seroprevalence was 19% [95% confidence interval (CI) 16–22%] for STG, 5% (95% CI 3–7%) for TG and 3% (95% CI: 2–5%) for SFG. The seroprevalence of STG was particularly high in northern and central Myanmar (59% and 19–33%, respectively). Increasing age was associated with higher odds of STG and TG seropositivity [per 10-year increase, adjusted odds ratio estimate 1.68 (p < 0.01) and 1.24 (p = 0.03), respectively]. ConclusionRickettsial infections are widespread in Myanmar, with particularly high seroprevalence of STG IgG antibodies in central and northern regions. Healthcare workers should consider rickettsial infections as common causes of fever in Myanmar.

Highlights

Rickettsial infections are among the most important causes of non-malarial fever in Southeast Asia (Acestor et al, 2012; Wangdi tsutsugamushi and the recently described Candidatus Orientia chuto and Candidatus Orientia chiloensis (Abarca et al, 2020; Izzard et al, 2010)
All participants were screened with enzyme-linked immunosorbent assays (ELISA) for scrub typhus group (STG), typhus group (TG) and spotted fever group (SFG) immunoglobulin G (IgG) antibodies
This study aimed to determine the seroprevalence of previous rickettsial infections in different regions of Myanmar

Summary

Introduction

Rickettsial infections are among the most important causes of non-malarial fever in Southeast Asia (Acestor et al, 2012; Wangdi tsutsugamushi and the recently described Candidatus Orientia chuto and Candidatus Orientia chiloensis (Abarca et al, 2020; Izzard et al, 2010). Overall mortality of rickettsial infections differs by species and can be as low as 0.4% for murine typhus, but has been reported to be approximately 6% for scrub typhus if left untreated, and higher if patients develop complications such as meningitis or meningoencephalitis (Bonell et al, 2017; Doppler and Newton, 2020; Taylor et al, 2015). These types of central nervous system infections have been found to be caused by rickettsial infections in a significant proportion of patients in Laos (Dittrich et al, 2015). Conclusion: Rickettsial infections are widespread in Myanmar, with high seroprevalence of STG IgG antibodies in central and northern regions.

Objectives

Methods

Results

Conclusion