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From July 2015 to December 2016, the presence of rickettsial pathogens was investigated for 414 patients with unknown fever in eight places in all the divisions of Bangladesh. Rickettsia felis was identified in blood samples from all the regions (overall detection rate, 19.6%), suggesting nationwide prevalence of R. felis infections. [ABSTRACT FROM AUTHOR]

In Bangladesh, coronavirus disease 2019 (COVID-19) has been highly prevalent during late 2020, with nearly 500 000 confirmed cases. In the present study, the spike (S) protein of severe acute respiratory coronavirus 2 (SARS-CoV-2) circulating in Bangladesh was genetically investigated to elucidate the diversity of mutations and their prevalence. The nucleotide sequence of the S protein gene was determined for 15 SARS-CoV-2 samples collected from eight divisions in Bangladesh, and analysed for mutations compared with the reference strain (hCoV-19/Wuhan/WIV04/2019). All the SARS-CoV-2 S genes were assigned to B.1 lineage in G clade, and individual S proteins had 1–25 mutations causing amino acid substitution/deletion. A total of 133 mutations were detected in 15 samples, with D614G being present in all the samples; 53 were novel mutations as of January 2021. On the receptor-binding domain, 21 substitutions including ten novel mutations were identified. Other novel mutations were located on the N-terminal domain (S1 subunit) and dispersed sites in the S2 subunit, including two substitutions that remove potential N-glycosylation sites. A P681R substitution adjacent to the furin cleavage site was detected in one sample. All the mutations detected were located on positions that are functionally linked to host transition, antigenic drift, host surface receptor binding or antibody recognition sites, and viral oligomerization interfaces, which presumably related to viral transmission and pathogenic capacity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]