Serological evidence indicates widespread distribution of rickettsioses in Myanmar

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

doi:10.1016/j.ijid.2020.12.013

Cited by 9 publications

(8 citation statements)

References 49 publications

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“…Being older age was detected as one of the potential risk factors for scrub typhus exposure among hill tribe people in Thailand. This coincides with studies in India [ 37 – 39 ] and Myanmar [ 34 ], which reported that the risk of exposure was strongly associated with increasing age. Studies conducted in Japan and South Korea confirmed that older participants were more susceptible to scrub typhus infection than younger participants [ 10 ].…”

Section: Discussionsupporting

confidence: 91%

“…Several studies conducted in countries in Tsutsugamushi Triangle areas also reported prevalence rates of 10.0% in China [ 29 ], 35.2% in Korea [ 30 ], and 34.7–40.0% in India [ 31 , 32 ]. Interestingly, studies from Laos and Myanmar reported lower prevalence than that among the hill tribes in Thailand, at 20.3% and 19.0% [ 33 , 34 ], respectively. Several studies conducted in other regions of Thailand reported a lower prevalence than that among hill tribe people, with rates of 31.8% in the central region [ 35 ] and 4.2% [ 36 ] in the northeastern region of Thailand.…”

Section: Discussionmentioning

confidence: 99%

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Prevalence of and factors associated with scrub typhus exposure among the hill tribe population living in high incidence areas in Thailand: a cross-sectional study

Tasak,

Apidechkul,

Law

et al. 2023

BMC Public Health

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Background Scrub typhus is a significant tropical disease, occurring in rural settings and therefore usually afflicting remote agricultural populations who have lower socioeconomic status and limited access to medical care. A large proportion of the hill tribe people in Thailand are financially poor, have limited education, and do not have adequate health care access. This study aimed to estimate the prevalence of and determine factors associated with scrub typhus exposure among the hill tribe population living in high-incidence areas in northern Thailand. Methods A cross-sectional study design was used to gather information from hill tribe people aged 18 years and over living in ten hill tribe villages in Mae Fah Luang, Chiang Rai Province, Thailand. Participants who met the inclusion criteria were invited to participate in the study. A validated questionnaire was used as the research instrument, and 5 mL blood samples were taken. Orientia tsutsugamushi IgM and IgG antibodies were detected by enzyme-linked immunosorbent assay (ELISA) and then confirmed by immunofluorescence assay (IFA). Logistic regression was used to detect associations between variables at a significance level of α = 0.05. Results A total of 485 hill tribe people participated in the study; 57.1% were female, 29.9% were over 60 years of age, 46.4% were from the Akha tribe, and 74.2% had never attended school. The overall prevalence of scrub typhus exposure was 48.0%. In the multivariate model, five variables were found to be associated with scrub typhus exposure. Participants aged over 60 years had a 4.31-fold increased risk (95% CI = 1.73–10.72) of scrub typhus exposure compared to those who were younger than 30 years. Those who were illiterate had a 3.46-fold increased risk (95% CI = 1.93–6.21) of scrub typhus exposure than those who had at least a primary education level. Participants from the Akha tribe had a 2.20-fold increased risk (95% CI = 1.31–3.72) of scrub typhus exposure than those from the Lahu tribe. Subjects who had a history of cutting grass had a 1.85-fold increased risk (95% CI = 1.20–2.84) of scrub typhus exposure. Those who never wore gloves for farming had a 2.12-fold increased risk (95% CI = 1.28–3.49) of scrub typhus exposure than those who wore gloves daily. Conclusions There is a high prevalence of scrub typhus exposure among the hill tribe in Thailand. Effective public health interventions to promote scrub typhus awareness and prevention are urgently needed in these populations.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Prevalence of and factors associated with scrub typhus exposure among the hill tribe population living in high incidence areas in Thailand: a cross-sectional study

Tasak,

Apidechkul,

Law

et al. 2023

BMC Public Health

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“…Diagnosis of these pathogens relies on molecular techniques such as PCR-based amplification to demonstrate the presence of the infectious agent, as well as serological methods as a surrogate including enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assays (IFA) [ 23 ]. Serological investigations allow epidemiologists to investigate the history of rickettsial exposure and estimation of seroprevalence by detecting the occurrence of preexisting levels of antibodies in a population [ 24 – 26 ]. IFA detection of IgM and/or IgG is recognized as a gold standard for rickettsial serological diagnosis, particularly for STG, however there remains uncertainty as to the most suitable diagnostic cut-off for each geographic location [ 23 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Risk factors analysis for neglected human rickettsioses in rural communities in Nan province, Thailand: A community-based observational study along a landscape gradient

et al. 2022

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In this study, we estimated exposure for Scrub typhus (STG), Typhus (TG) and Spotted fever groups (SFG) rickettsia using serology at a fine scale (a whole sub-district administration level) of local communities in Nan Province, Thailand. Geographical characteristics of the sub-district were divided into two landscape types: lowland agricultural area in an urbanized setting (lowland-urbanized area) and upland agricultural area located close to a protected area of National Park (upland-forested area). This provided an ideal contrast between the two landscapes with low and high levels of human-altered habitats to study in differences in disease ecology. In total, 824 serum samples of participants residing in the eight villages were tested by screening IgG ELISA, and subsequently confirmed by the gold standard IgG Immunofluorescent Assay (IFA). STG and TG IgG positivity were highest with seroprevalence of 9.8% and 9.0%, respectively; whereas SFG positivity was lower at 6.9%. Inhabitants from the villages located in upland-forested area demonstrated significantly higher STG exposure, compared to those villages in the lowland-urbanized area (chi-square = 51.97, p < 0.0001). In contrast, TG exposure was significantly higher in those villagers living in lowland-urbanized area (chi-square = 28.26, p < 0.0001). In addition to the effect of landscape types, generalized linear model (GLM) analysis identified socio-demographic parameters, i.e., gender, occupation, age, educational level, domestic animal ownership (dog, cattle and poultry) as influential factors to explain the level of rickettsial exposure (antibody titers) in the communities. Our findings raise the public health awareness of rickettsiosis as a cause of undiagnosed febrile illness in the communities.

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“…Orientia tsutsugamushi has been detected in small mammal species across Southeast Asia (reviewed in [ 40 ]), and detection was usually based on bacteria isolation or serology [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ]. However, more recent efforts focused on PCR assays targeting the TSA47 gene for O. tsutsugamushi detection as they are more sensitive and the products can be sequenced to provide genetic information [ 49 , 50 , 51 , 52 ].…”

Section: Discussionmentioning

confidence: 99%

Molecular Surveillance for Vector-Borne Bacteria in Rodents and Tree Shrews of Peninsular Malaysia Oil Palm Plantations

et al. 2023

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Many human clinical cases attributed to vector-borne pathogens are underreported in Malaysia, especially in rural localities where healthcare infrastructures are lacking. Here, 217 small mammals, consisting of rodents and tree shrews, were trapped in oil palm plantations in the Peninsular Malaysia states of Johor and Perak. Species identification was performed using morphological and DNA barcoding analyses, and 203 small mammals were included in the detection of selected vector-borne bacteria. The DNA extracted from the spleens was examined for Orientia tsutsugamushi, Borrelia spp., Bartonella spp. and Rickettsia spp. using established PCR assays. The small mammals collected in this study included Rattus tanezumi R3 mitotype (n = 113), Rattus argentiventer (n = 24), Rattus tiomanicus (n = 22), Rattus exulans (n = 17), Rattus tanezumi sensu stricto (n = 1) and Tupaia glis (n = 40). Orientia tsutsugamushi, Borrelia spp. and Bartonella phoceensis were detected in the small mammals with the respective detection rates of 12.3%, 5.9% and 4.9%. Rickettsia spp., however, was not detected. This study encountered the presence of both Lyme disease and relapsing fever-related borreliae in small mammals collected from the oil palm plantation study sites. All three microorganisms (Orientia tsutsugamushi, Borrelia spp. and Bartonella phoceensis) were detected in the R. tanezumi R3 mitotype, suggesting that the species is a competent host for multiple microorganisms. Further investigations are warranted to elucidate the relationships between the ectoparasites, the small mammals and the respective pathogens.

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Serological evidence indicates widespread distribution of rickettsioses in Myanmar

Cited by 9 publications

References 49 publications

Prevalence of and factors associated with scrub typhus exposure among the hill tribe population living in high incidence areas in Thailand: a cross-sectional study

Prevalence of and factors associated with scrub typhus exposure among the hill tribe population living in high incidence areas in Thailand: a cross-sectional study

Risk factors analysis for neglected human rickettsioses in rural communities in Nan province, Thailand: A community-based observational study along a landscape gradient

Molecular Surveillance for Vector-Borne Bacteria in Rodents and Tree Shrews of Peninsular Malaysia Oil Palm Plantations

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