Evaluation of the efficacy of permethrin- and cypermethrin-based textile against taiga tick, Ixodes persulcatus.

A comparison of the efficacy of permethrin- and cypermethrin-based textile against taiga ticks (Ixodes persulcatus) was carried out in a tick-borne viral encephalitis hotspot in the Irkutsk Region (Russia) using model samples of impregnated textiles. We demonstrated that permethrin- and cypermethrin-treated model samples have similar protective parameters in terms of maximum height reached by the tick when climbing up the treated textile (20.9-38.7 cm for cypermethrin, 27.6-39.3 cm for permethrin, depending on concentration) and knockdown time (i.e., the time until a female tick falls off the treated textile; 3.52-4.31 min for cypermethrin, 5.02-8.25 min for permethrin, depending on concentration). In contrast, when evaluating the 'biting speed' index (which is the ratio of the average attaching time of ticks contacting untreated textiles and ticks contacting treated textiles), it has been shown that permethrin-treated textiles accelerate biting. So, using permethrin-treated protective clothing against the taiga tick could be risky because it increases the likelihood of being bitten and thus getting infected. In contrast, cypermethrin-treated textiles appear to block the ability of ticks to attack warm-blooded animals and humans - after contact with cypermethrin-treated textiles none of the ticks attached to a rabbit. So cypermethrin-based textiles could be an alternative to permethrin for tick-bite protection clothing production if there is no toxic effect on humans of textile materials based on it.

Multilocus genetic analysis indicates taxonomic status of "Candidatus Rickettsia mendelii" as a separate basal group.

To date, the phylogeny of Rickettsia spp. from basal groups is based on the small number of identified species. Thus, the finding of "Candidatus Rickettsia mendelii" in 2016 is of great interest. In this study, "Ca. R. mendelii" was first identified in the Asian region in a new carrier, Ixodes pavlovskyi. "Candidatus R. mendelii", along with "Candidatus Rickettsia tarasevichiae", were found in Ixodes ticks collected on Russky Island (the Far East), where I. pavlovskyi coexists with I. persulcatus. To establish the taxonomic position of "Ca. R. mendelii", a detailed genetic study was carried out. "Candidatus R. mendelii" was genotyped by five genetic fragments (16S rRNA, gltA, and ompB genes, groESL operon, and 23S-5S IGS region); among them, the ompB gene, groESL operon and 23S-5S IGS region were sequenced for the first time. In addition, "Ca. R. tarasevichiae" was genetically characterized by eight genetic loci (16S rRNA, gltA, ompA, ompB, sca4, htrA genes, groESL operon, and 23S-5S IGS region), of which the sca4 gene was first determined. Phylogenetic analysis indicated that regardless of analyzed genetic loci, "Ca. R. mendelii" formed a separate well-supported cluster on each phylogenetic tree. Phylogenetic analysis based on concatenated sequences of gltA, ompB, and groEL gene fragments (total length of 3191 bp) demonstrated that "Ca. R. mendelii", like Rickettsia bellii, is a basal group of Rickettsia.