BACKGROUND AND PURPOSE: Scrub typhus is an endemic zoonosis caused by Orientia tsutsugamushi, presenting with a range of neurologic manifestations. Despite its high prevalence in endemic areas and clinical relevance, systematic descriptions of the neuroimaging patterns are sparse. This study emphasi

For long-term stable residence within host cells, endosymbionts must evolve mechanisms to ensure their segregation into both daughter cells during cell division, and to coordinate their division with the host cell cycle. This regulation was also a prerequisite for the evolution of mitochondria, enabling their transition from free-living bacteria to an organelle. Here, we examine Orientia tsutsugamushi and Rickettsia rhipicephali, two obligate intracellular Rickettsiales that replicate directly in the host cytoplasm, during host mitosis. Using cell cycle synchronisation and immunofluorescence microscopy, we demonstrate that O. tsutsugamushi frequently localise near the spindle poles during mitosis, and are distributed between daughter cells in a manner dependent on its surface protein ScaC, that drives dynein-dependent motility of the bacterium along microtubules. In contrast, R. rhipicephali, which does not interact with microtubules, largely inhibits host mitosis and is randomly distributed in the few cells that divide. Overall, our findings reveal distinct strategies for mitotic adaptation among these two Rickettsiales and suggest that associations with the hosts cytoskeletal elements may be critical for near-equal distribution into daughter cells.

For long-term stable residence within host cells, endosymbionts must evolve mechanisms to ensure their segregation into both daughter cells during cell division, and to coordinate their division with the host cell cycle. This regulation was also a prerequisite for the evolution of mitochondria, enabling their transition from free-living bacteria to an organelle. Here, we examine Orientia tsutsugamushi and Rickettsia rhipicephali, two obligate intracellular Rickettsiales that replicate directly in the host cytoplasm, during host mitosis. Using cell cycle synchronisation and immunofluorescence microscopy, we demonstrate that O. tsutsugamushi frequently localise near the spindle poles during mitosis, and are distributed between daughter cells in a manner dependent on its surface protein ScaC, that drives dynein-dependent motility of the bacterium along microtubules. In contrast, R. rhipicephali, which does not interact with microtubules, largely inhibits host mitosis and is randomly distributed in the few cells that divide. Overall, our findings reveal distinct strategies for mitotic adaptation among these two Rickettsiales and suggest that associations with the hosts cytoskeletal elements may be critical for near-equal distribution into daughter cells.

Scrub typhus is an acute zoonotic disease caused by Orientia tsutsugamushi. There are limited reports on scrub typhus in pregnancy, and the misdiagnosis rate is relatively high, potentially leading...

Orientia tsutsugamushi is the causative agent of scrub typhus infection in humans. This pathogen is transmitted into mammalian hosts including humans through Leptotrombidium mites. Till date, detection of O. tsutsugamushi in human was performed using PCR assay with 56kDa type specific antigen (TSA56), 47kDa outer membrane protein (47kDa-OMP) and groEL chaperonin gene. To understand the efficiency of different genes for the detection of O. tsutsugamushi in Leptotrombidium mites, we performed a comparative PCR assay with various universal primers targeting different genes including TSA56, 47kDa-OMP and groEL gene. We have collected 500 Leptotrombidium mites from Vellore, Tamil Nadu and, the mites were segregated into 50 pools with 10 mites in each pool were used for DNA extraction. The molecular detection of O. tsutsugamushi was performed using PCR assays (including conventional, nested and duplex PCR). The comparative PCR analysis showed nested PCR of groEL gene has high efficiency in detecting the presence of O. tsutsugamushi in chigger samples compared to other genes. Interestingly, groEL target demonstrated high efficiency for detection of O. tsutsugamushi in chigger samples and, when used with nested primers, can facilitate differentiation of O. tsutsugamushi from other rickettsial pathogens. Thus, we conclude groEL gene nested PCR assay can be used routinely to detect O. tsutsugamushi in trombiculid mites.

Orientia tsutsugamushi is the causative agent of scrub typhus infection in humans. This pathogen is transmitted into mammalian hosts including humans through Leptotrombidium mites. Till date, detection of O. tsutsugamushi in human was performed using PCR assay with 56kDa type specific antigen (TSA56), 47kDa outer membrane protein (47kDa-OMP) and groEL chaperonin gene. To understand the efficiency of different genes for the detection of O. tsutsugamushi in Leptotrombidium mites, we performed a comparative PCR assay with various universal primers targeting different genes including TSA56, 47kDa-OMP and groEL gene. We have collected 500 Leptotrombidium mites from Vellore, Tamil Nadu and, the mites were segregated into 50 pools with 10 mites in each pool were used for DNA extraction. The molecular detection of O. tsutsugamushi was performed using PCR assays (including conventional, nested and duplex PCR). The comparative PCR analysis showed nested PCR of groEL gene has high efficiency in detecting the presence of O. tsutsugamushi in chigger samples compared to other genes. Interestingly, groEL target demonstrated high efficiency for detection of O. tsutsugamushi in chigger samples and, when used with nested primers, can facilitate differentiation of O. tsutsugamushi from other rickettsial pathogens. Thus, we conclude groEL gene nested PCR assay can be used routinely to detect O. tsutsugamushi in trombiculid mites.

Scrub typhus, a vector-borne zoonotic disease, remains a growing public health concern in India, particularly in the Western Ghats. We conducted a sero-prevalence and ectoparasite survey during 202...

Scrub typhus is a miteborne infectious disease caused by Orientia tsutsugamushi bacteria. In Japan, most cases occur in spring and autumn and are transmitted by Leptotrombidium pallidum and L. scutellare mites; summer scrub typhus, transmitted by L. akamushi mites, is rarely reported. In August 2024, a pregnant woman had scrub typhus develop after attending a fireworks event in Niigata Prefecture, Japan, resulting in fetal death. A Vietnam-related Karp-like O. tsutsugamushi genotype, distinct from the Kato type usually associated with L. akamushi mites, was detected from patient samples. Field investigations at the site of the fireworks event revealed seasonal predominance of L. akamushi mites in summer. We detected O. tsutsugamushi sequences identical to the patient’s strain in 3 L. akamushi mite larvae and 1 field mouse, suggesting that L. akamushi mites were the source of human infection. Our findings suggest reemergence of summer scrub typhus associated with infected L. akamushi mites carrying a locally novel genotype.

Scrub typhus is a miteborne infectious disease caused by Orientia tsutsugamushi bacteria. In Japan, most cases occur in spring and autumn and are transmitted by Leptotrombidium pallidum and L. scut...

Scrub typhus, a re-emerging zoonosis caused by Orientia tsutsugamushi, can present with severe, life-threatening complications, including multi-organ dysfunction and hemolytic anemia. This report d...

AbstractIn a serologically diagnosed Nepalese scrub typhus cohort (n = 77), gastrointestinal symptoms were common. We assessed Orientia tsutsugamushi DNA in serum and performed TSA56 genotyping. Orientia DNA was detected in 10 of 77 samples (12%). TSA56 sequencing identified 4 genotypes. Polymerase chain reaction positivity was associated with diarrhea, groin lymphadenopathy, and stronger Th1-type cytokine responses.

Around 10,000 people contracted scrub typhus, while 8,262 people have tested positive for dengue so far this year.