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Mites
Published in Jerome Goddard, Public Health Entomology, 2022
Infestation with trombiculid larvae is called trombiculosis, or sometimes trombidiosis. Larval chiggers crawl up on blades of grass or leaves and subsequently get on passing vertebrate hosts. On humans, they attach to the skin anywhere (Figure 18.4), but particularly where clothing fits snugly or where flesh is tender, such as ankles, groin, or waistline. Chiggers then attach to the skin with their mouthparts, inject saliva into the wound (which dissolves tissue), and then suck up this semidigested material. They do not actually burrow in human skin; only the chelicerae penetrate the skin of the host. Feeding is aided by formation of a stylostome, or feeding tube, created by interaction of the saliva and surrounding skin tissue. Scrub typhus, a zoonotic rickettsial infection caused by Orientia tsutsugamushi, is mite-borne and occurs over much of Southeast Asia, India, Sri Lanka, Pakistan, islands of the southwest Pacific, and coastal Australia (Queensland) (Figure 18.5). Chiggers are the vectors, so the name chigger-borne ricketsiosis might be more appropriate for the disease. Scrub typhus occurs in nature in small, but intense foci of infected host animals. These “mite islands” or “typhus islands” occur where the appropriate combination of rickettsiae, vectors, and suitable animal hosts occurs.4,5 Epidemics occur when susceptible individuals come into contact with these areas. Historically, military operations have often been severely affected by scrub typhus.6
Spinal Cord Disease
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
There have been single case reports in the literature involving: Campylobacter jejuni.Tropheryma whippeli (Whipple's disease).Orientia tsutsugamushi (scrub typhus).
Infectious Disease and Foreign Travel Emergencies
Published in Anthony FT Brown, Michael D Cadogan, Emergency Medicine, 2020
Anthony FT Brown, Michael D Cadogan
Scrub typhus is one of the spotted fevers, and is caused by an acute bacterial infection by Orientia tsutsugamushi, transmitted by trombiculid mites (‘chiggers’). Foci of scrub typhus occur in South-East Asia, northern Japan and northern Australia. Other tick-borne spotted fevers include Queensland tick typhus, Rocky Mountain and Mediterranean.
Detection of co-infection with Orientia tsutsugamushand and hemorrhagic fever with renal syndrome by next-generation sequencing
Published in International Journal of Neuroscience, 2023
Qianhui Xu, Wenyi Zhang, Qian Wang, Xuejun Fu, Jing Han, Ying Huang
Orientia tsutsugamushi (O. tsutsugamushi) is an obligate intracellular bacterium belonging to the subspecies of Proteobacteria, family Rickettsiaceae, and is responsible for scrub typhus. O. tsutsugamushi is transmitted to humans through the bites of larval trombiculid mites. The bacterium is still a major cause of undifferentiated fever in Asia. The prognosis varies among patients, ranging from asymptomatic infection to death. Co-infection with O. tsutsugamushi and other pathogens such as dengue virus [1] Leptospira [1,2] has been reported in Southeast Asia. To our knowledge, the present patient, who is an original resident of Zijin County, Heyuan, Guangdong, is the first case of co-infection with O. tsutsugamushi and Hantaan virus. Serological testing and next-generation sequencing confirmed co-infection in the patient. Lack of knowledge of co-infection may jeopardize the health of affected patients. Our study serves as a reminder of potential co-infection and provides clues for its detection.
Scrub Typhus Presenting as Unilateral Abducens Nerve Palsy
Published in Neuro-Ophthalmology, 2022
Ritwik Ghosh, Subhrajyoti Biswas, Arnab Mandal, Kaustav De, Srijit Bandyopadhyay, Sona Singh Sardar, Arpan Mandal, Julian Benito-León
Routine blood tests were normal, except for raised erythrocyte sedimentation rate (56 mm/hr) and mild elevations of transaminases without hyperbilirubinaemia. Anti-nuclear antibody (ANA) screening using HEp-2 cells, ANA profile, antiphospholipid antibodies, anti-neutrophil cytoplasmic antibodies (cANCA and pANCA) were negative. Anti-acetylcholine receptor and anti-muscle-specific tyrosine kinase antibodies as well as anti-thyroid peroxidase and anti-thyroglobulin antibodies were also negative. Electrophysiological testing, including repetitive nerve stimulation and single fibre electromyography, was normal. Brain magnetic resonance imaging (MRI) with gadolinium revealed mild thickening and enhancement along the lateral walls of both cavernous sinuses (left more than right), basal cistern and posterior inter-hemispheric fissure, suggestive of meningitis (Figure 1). Cerebrospinal fluid (CSF) analysis revealed a mononuclear pleocytosis (20 cells/µl, all lymphocytes), normal glucose (45 mg/dL), and elevated protein content (102 mg/dL). Other CSF studies, including cytology examination, and cultures for relevant bacteria were negative, except for the presence of IgM antibodies against Orientia tsutsugamushi in both serum and CSF. Subsequently, a polymerase chain reaction confirmed the presence of Orientia tsutsugamushi in the CSF.
Scrub typhus and antibiotic-resistant Orientia tsutsugamushi
Published in Expert Review of Anti-infective Therapy, 2021
Chin-Te Lu, Lih-Shinn Wang, Po-Ren Hsueh
Direct methods of diagnosis involve bacterial culture and isolation or detection of O. tsutsugamushi DNA using PCR [51]. Similar to all human pathogens, culturing of Orientia spp. in vitro or in vivo carries the intrinsic hazard of infection of laboratory and ancillary staff (known as laboratory-acquired infections [LAIs]). Scrub typhus LAIs were documented in 25 individuals, from 1931 to 2000, with eight (32%) reported deaths during the pre-antibiotic era [52]. There are safety concerns regarding isolating O. tsutsugamushi in biosafety level (BSL) 2 facilities within a biological safety cabinet, and its isolation should be performed in high-containment BSL 3 laboratories [52]. Cells are typically cultured on cell monolayers, with a median time to positivity of 27 days [53]. Mouse inoculation is even more laborious and resource-intensive. These methods of isolation are primarily used for research purposes and are not appropriate for the routine diagnosis of scrub typhus because of the marked delay in obtaining results.