“…This present study shows that Karp-like and Gilliam-like strains were the most prevailing types. Karp-like strains also predominated in a recent study in the north east of India (Bora et al, 2018). Gilliam-types were the second most common type in our study.…”
Section: Discussionsupporting
confidence: 77%
“…There are more than 20 prototype strains of Orientia tsutsugamushi documented to date (Kelly et al, 2009). From India, there have been a few studies conducted on the genetic diversity of circulating strains (Varghese et al, 2013;Bora et al, 2018). These studies were predominantly from the north, south and extreme north-east of India.…”
“…This present study shows that Karp-like and Gilliam-like strains were the most prevailing types. Karp-like strains also predominated in a recent study in the north east of India (Bora et al, 2018). Gilliam-types were the second most common type in our study.…”
Section: Discussionsupporting
confidence: 77%
“…There are more than 20 prototype strains of Orientia tsutsugamushi documented to date (Kelly et al, 2009). From India, there have been a few studies conducted on the genetic diversity of circulating strains (Varghese et al, 2013;Bora et al, 2018). These studies were predominantly from the north, south and extreme north-east of India.…”
“…In the present study in north-central Bangladesh, the genetically defined detection rate of O. tsutsugamushi was 17.2% among suspected cases of rickettsial illness. A prevalence of O. tsutsugamushi among febrile patients comparable to our study has been reported in eastern Taiwan (16%) [12], northern Thailand (21%) [13] and northeast India (Assam) (16%, IgM-positive cases) [14]. Accordingly, north-central Bangladesh is also considered to be an endemic area of scrub typhus in South Asia.…”
Scrub typhus is a mite-borne rickettsial disease caused by Orientia tsutsugamushi, which is endemic in Asia Pacific region. In this study, infection rate and molecular epidemiologic traits of O. tsutsugamushi was investigated in Mymensingh, located in north-central Bangladesh. Among the blood samples from 453 febrile patients who visited Mymensingh medical college hospital in 2018, the 47 kDa protein gene of O. tsutsugamushi was detected in 78 samples (17.2%) by nested PCR. Phylogenetic analysis of the O. tsutsugamushi 56 kDa protein gene (18 samples) revealed a predominance of Karp-related genotype (89%), while the remaining belonged to Gilliam genotype. Samples of the Karp-related genotype mostly clustered with those of China, Taiwan, Thailand and India, etc., in emergent subgroups clades 2 and 4, which were distinct from clade 1, including prototype Karp strains. Among the 18 samples, three variable domains (VD) of 56 kDa type-specific antigen had different types of sequence diversity; VDI contained two or three repeats of eight amino acid units, while VDII and VDIII had amino acid substitution, deletion or insertion. The present study documented a potentially high prevalence of genetically diverse O. tsutsugamushi in north-central Bangladesh.
“…A direct method of diagnosis involves isolation and culturing of bacteria in cell lines like L929 (normal fibroblast cell line of the mouse), HeLa (cancer cell line), BHK21 (baby hamster kidney fibroblast cell lines), Vero lineage (isolated from kidney epithelial cells extracted from an African green monkey) and their DNA-based diagnosis using different genetic markers by PCR. Indirect methods of diagnosis include serological assays such as Weil–Felix test, immunofluorescence assay (IFA), enzyme-linked immunosorbent assay (ELISA) and rapid diagnostic assays (Bora et al 2018 ; Lijuan et al 2011 ; Koraluru et al 2015 ; Zhang et al 2011 ). Fig.…”
Section: Diagnosis Of Scrub Typhusmentioning
confidence: 99%
“…PCR-based detection methods are highly specific and sensitive for disease diagnosis and can detect bacterial infection even in early stages, unlike serological methods. PCR based detection methods utilize genetic markers such as 56 kDa tsa , GroEL , 16s RNA and 47 kDa HtrA to detect specifically the target organism, i.e., Orientia tsutsugamushi (Bora et al 2018 ; Jiang et al 2004 ; Sonthayanon et al 2009 ; Paris et al 2009 ). The 56 kDa tsa gene is mostly used for the characterization of the O. tsutsugamushi strains.…”
Scrub typhus is a mite-borne, acute febrile illness caused by the bacterium Orientia tsutsugamushi. It is a re-emerging infectious disease of the tsutsugamushi triangle. Scrub typhus is transmitted through bites of contaminated chiggers (larval stage). Diagnosis of scrub typhus is challenging as its symptoms mimic with other acute febrile illnesses. Several methods are effectual for diagnosis of scrub typhus that includes enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), immunochromatographic test (ICT), Weil-Felix, polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP). Weil-Felix test was initially used for the diagnosis of scrub typhus in underdeveloped countries but not preferred due to a lack of both specificity and sensitivity. Other immuno-based methods like IFA and ELISA are most outrank for detection of scrub typhus due to their higher sensitivity and specificity, but not vigorous to lay bare the infection at early stages and need the convalescent sampling for verification of positive samples. On another deed, PCR based methods becoming acceptable over era due to its dexterity of early-stage diagnosis with higher specificity and sensitivity but lack its applicability in circumstances of scrub typhus due to the variegated genetic makeup of Orientia tsutsugamushi among its serotypes. The present review focused on various detection methods along with their advantages and disadvantages used in the diagnosis of scrub typhus. A comparison between available methods of diagnosis with challenges in the detection of scrub typhus is also summarized.
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