Scrub typhus ecology: a systematic review of Orientia in vectors and hosts

Abstract Scrub typhus, caused by Orientia tsutsugamushi, is an important and neglected vector-borne zoonotic disease with an expanding known distribution. The ecology of the disease is complex and poorly understood, impairing discussion of public health interventions. To highlight what we know and the themes of our ignorance, we conducted a systematic review of all studies investigating the pathogen in vectors and non-human hosts. A total of 276 articles in 7 languages were included, with 793 study sites across 30 countries. There was no time restriction for article inclusion, with the oldest published in 1924. Seventy-six potential vector species and 234 vertebrate host species were tested, accounting for over one million trombiculid mites (‘chiggers’) and 83,000 vertebrates. The proportion of O. tsutsugamushi positivity was recorded for different categories of laboratory test and host species. Vector and host collection sites were geocoded and mapped. Ecological data associated with these sites were summarised. A further 145 articles encompassing general themes of scrub typhus ecology were reviewed. These topics range from the life-cycle to transmission, habitats, seasonality and human risks. Important gaps in our understanding are highlighted together with possible tools to begin to unravel these. Many of the data reported are highly variable and inconsistent and minimum data reporting standards are proposed. With more recent reports of human Orientia sp. infection in the Middle East and South America and enormous advances in research technology over recent decades, this comprehensive review provides a detailed summary of work investigating this pathogen in vectors and non-human hosts and updates current understanding of the complex ecology of scrub typhus. A better understanding of scrub typhus ecology has important relevance to ongoing research into improving diagnostics, developing vaccines and identifying useful public health interventions to reduce the burden of the disease.</jats:p

Surface antigen expressed in hematopoietic cells derived from fv-4r mouse strains.

ABSTRACT-Fv-4 locus controls the susceptibility of mice to ecotropic murine leukemia virus (MuLV). Antiserum against Fv_4 r / s mice with BALB/c background was raised in inbred BALB/c mice. In the com-plement-dependent cytotoxicity test, the antiserum killed the hemato-poietic cells derived from Fv-4 r /- mice but not those from Fv_4 s / s mice, and the genetic cross experiments located the locus controlling the expression of the target molecule of the antibody in the close vicinity of Fv-4. In addition, the antigenic expression of the exogenously infecting MuLV suppressed the expression of the target molecule of the antiserum. The expressions of these two antigens appear to com-pete with each other on the cell surface. JNCI 1982; 68: 1005-1009. The presence of Fv-4 locus was indicated by the isolation of a mouse strain from a ddY mouse colony in Shizuoka, Japan, which was resistant to N-, B-, or NB-tropic ecotropic MuLV (1). The resistance allele (Fv-4r) was dominant ove

Ages of Silurian radiolarians from the Kurosegawa terrane, southwest Japan constrained by U/Pb SHRIMP data

Radiolarians are abundant in mid-Paleozoic tuffs of the Kurosegawa terrane of southwest Japan. Well preserved Silurian radiolarian faunas recovered from several localities are described herein and include four new species: Ceratoikiscum kurosegum n. sp., Fusalfanus? konomoriensis n. sp., Futobari? jingamoriensis n. sp., and Futobari? tosaensis n. sp. The absence, within the same strata, of fossils belonging to other taxonomic groups has presented difficulties in determining the precise ages of the Kurosegawa radiolarian faunas. U/Pb SHRIMP ages of pyroclastic zircons from tuff units within the succession indicate Wenlockian [427.2 ± 7.6] and Pridolian [408.9 ± 7.6] ages and remove ambiguity regarding the Silurian age of tuffaceous rocks in the Kurosegawa sequence