Parasitology

Abstract Background Rickettsia spp. are human pathogens that cause a number of diseases and are transmitted by arthropods, such as ixodid ticks. Estonia is one of few regions where the distribution area of two medically important tick species, Ixodes persulcatus and I. ricinus, overlaps. The nidicolous rodent-associated Ixodestrianguliceps has also recently been shown to be present in Estonia. Although no data are available on human disease(s) caused by tick-borne Rickettsia spp. in Estonia, the presence of three Rickettsia species in non-nidicolous ticks has been previously reported. The aim of this study was to detect, identify and partially characterize Rickettsia species in nidicolous and non-nidicolous ticks attached to rodents in Estonia. Results Larvae and nymphs of I.ricinus (n = 1004), I. persulcatus (n = 75) and I.trianguliceps (n = 117), all removed from rodents and shrews caught in different parts of Estonia, were studied for the presence of Rickettsia spp. by nested PCR. Ticks were collected from 314 small animals of five species [Myodes glareolus (bank voles), Apodemus flavicollis (yellow necked mice), A.agrarius (striped field mice), Microtus subterranius (pine voles) and Sorex araneus (common shrews)]. Rickettsial DNA was detected in 8.7% (103/1186) of the studied ticks. In addition to identifying R.helvetica, which had been previously found in questing ticks, we report here the first time that the recently described I.trianguliceps-associated Candidatus Rickettsia uralica has been identified west of the Ural Mountains. Graphical Abstract

A 59-year-old female living in Rayong Province, eastern Thailand, presented with painless, right upper eyelid nodule for 3 months. Upon removal of the eyelid mass, a well-circumscribed, firm globular mass with diameter about 1 cm was found. Histopathological examination revealed an immature female dirofilarial worm reminiscent of Dirofilaria repens, characterized by prominent sharp longitudinal ridges at external surface of the cuticle. Analysis of the mitochondrial 12S rRNA sequence showed that the worm belongs to Candidatus Dirofilaria hongkongensis. It is likely that some infections previously reported as D. repens based on histological examination may have actually been due to Candidatus D. hongkongensis.

Abstract Culicoides biting midges (Diptera: Ceratopogonidae) are vectors responsible for the transmission of several viruses of veterinary importance. Previous screens of Culicoides have described the presence of the endosymbiont Candidatus Cardinium hertigii (Bacteroidetes). However, any impacts of this microbe on vectorial capacity, akin to those conferred by Wolbachia in mosquitoes, are yet to be uncovered and await a suitable system to study Cardinium ‐midge interactions. To identify potential candidate species to investigate these interactions, accurate knowledge of the distribution of the endosymbiont within Culicoides populations is needed. We used conventional and nested PCR assays to screen Cardinium infection in 337 individuals of 25 Culicoides species from both Palearctic and Afrotropical regions. Infections were observed in several vector species including C. imicola and the Pulicaris complex ( C. pulicaris , C. bysta , C. newsteadi and C. punctatus ) with varying prevalence. Phylogenetic analysis based on the Gyrase B gene grouped all new isolates within ‘group C’ of the genus, a clade that has to date been exclusively described in Culicoides . Through a comparison of our results with previous screens, we suggest C. imicola and C. sonorensis represent good candidates for onward study of Cardinium‐ midge interactions.

Abstract.We tried to determine the epidemiology and species of human dirofilariasis observed at two tertiary care hospitals in Kerala. We searched the hospital database to identify cases of dirofilariosis from January 2005 to March 2020. Along with human isolates, one dog Dirofilaria isolate was also subjected to PCR and sequencing of pan filarial primers cytochrome oxidase subunits 1 and 12S rDNA. We documented 78 cases of human dirofilariosis. The orbit, eyelid, and conjunctiva were the most commonly affected sites. Molecular characterization identified one dog and five human isolates as Candidatus Dirofilaria Hongkongensis. A rare case of subconjunctival infestation by B. malayi was also documented. Human dirofilariosis is a public health problem in the state of Kerala in India, and it is mostly caused by Candidatus Dirofilaria Hongkongensis. We propose that all diroifilaria isolates are subjected to sequencing for identification.

AbstractThe fast development of molecular taxonomy is impacting our knowledge of the world parasite diversity at an unprecedented level. A number of operational taxonomic units have been uncovered and new species described. However, it is not always that new parasite species are being described in compliance with the International Code of Zoological Nomenclature. This is the case of “Candidatus Dirofilaria hongkongensis”, a nematode found in dogs, jackals and humans in Hong Kong and parts of India. This name has been proposed without a formal description and without the designation of a holotype, and therefore is an unavailable name. Finally, we argue that using the provisional status Candidatus in zoological nomenclature is inappropriate, considering this term is not considered in the International Code of Zoological Nomenclature.