Synthetic pyrethroid resistance in Rhipicephalus (Boophilus) microplus ticks from north-western Himalayas, India.

In the present study, adult immersion test (AIT) was used for evaluation of resistance against synthetic pyrethroids (deltamethrin and cypermethrin) in Rhipicephalus (Boophilus) microplus ticks collected from nine districts of three agro-climatic zones of north-western Himalayan region of India. Resistance factors (RFs) were calculated between 0.94 to 50.71 for deltamethrin and 0.32 to 13.18 for cypermethrin. Resistance to deltamethrin was detected at level I in two, level II in four, level III and level IV in one isolate each while one isolate was susceptible. Against cypermethrin, resistance at levels I and II was detected in three isolates each while three isolates were found susceptible. The low altitude sub-tropical zone revealed higher density of resistant ticks where intensive animal husbandry practices were followed and the synthetic pyrethroid usage was common. Data generated on pyrethroid resistance status of ticks in north-western Himalayan region will provide new insights in acaricidal resistance particularly from remote areas of this region and will help in formulating suitable control measures.

Molecular Detection and Genotyping of Theileria spp. in Deer (Cervidae) in Korea.

Major clinical symptoms of Theileria infection include fever, anemia, anorexia, jaundice, and decreased milk production. Although several studies have been conducted on tick-borne pathogens, including Theileria in Korea, only a few have focused on Theileria infection in deer, including the Korean water deer. Blood samples from 160 deer were collected and subjected to DNA extraction and polymerase chain reaction (PCR). Next, PCR-positive samples were sequenced and analyzed by constructing a phylogenetic tree. The results showed that the overall infection rate of Theileria was 8.1% (13/160). Infection rates of 100% were observed in the northern and southern regions. However, the study's limitation was its small sample size, wherein five and one samples were analyzed from the northern and southern regions, respectively. The central region exhibited the lowest infection rate of 2.9% (4/140). Infection rates also differed based on seasons, with the highest (18.4%, 9/49) being observed in spring, followed by that in summer (8.9%, 4/45). However, no infection was observed during autumn and winter. A phylogenetic analysis indicated that the PCR-positive samples contained Theileria luwenshuni, which usually infects small ruminants, such as goats and sheep.

Status of ivermectin resistance in Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) populations from north-western Himalayas, India.

Status of ivermectin resistance was studied in 16 isolates of Rhipicephalus (Boophilus) microplus ticks collected from north-western Himalayan region of India using larval immersion test (LIT). Regression graphs of probit mortality of larval ticks plotted against log values of concentrations of ivermectin were utilized for the determination of slope of mortality, lethal concentrations (LC50 and LC95) and resistance ratios (RRs). Out of 16 isolates examined, 15 were found resistant against ivermectin. Level II resistance was detected in eleven isolates (RR50 ranged from 5.72 to 7.62), whereas four isolates exhibited level I resistance (RR50 ranged from 1.58 to 2.77). Only one isolate was found susceptible (RR50: 1.23). Higher RR values were observed in tick isolates from low altitude areas where intensive animal husbandry activities are practiced as compared to tick isolates of high altitudes accredit the fact that managemental practices, availability of drug and its frequency of application play an important role in development of resistance.