Acaricide resistance in Rhipicephalus microplus collected from selected districts of Madhya Pradesh, Uttar Pradesh and Punjab states of India.

The isolates of Rhipicephalus microplus collected from Madhya Pradesh (MP), Punjab (PJB) and Uttar Pradesh (UP) states of India were characterized using laboratory standardized adult immersion test (AIT) against macrocyclic lactone (ivermectin), synthetic pyrethroids (cypermethrin and deltamethrin), organophosphates (coumaphos and diazinon) and phenylpyrazole compounds (fipronil). Out of the six isolates tested, five isolates except MTH were resistant to deltamethrin and cypermethrin at level II with RF ranging from 16.4 to 24.02 and 7.05 to 13.2, respectively. In case of organophosphates, coumaphos was less effective showing resistance level II (RF 8.52-11.2) in all the six populations compared with diazinon to which three isolates (MHW, RWA and AGS) were resistant at level II. Except MTH, other five isolates were categorized at level I with RF ranging from 1.53 to 3.02 against ivermectin. The phenylpyrazole compound however was found effective, and none of the isolates could survive at a discriminating concentration. The possible strategy for the management of multi-acaricide-resistant ticks in the surveyed districts was discussed in the present study.

Covert stroke after non-cardiac surgery: a prospective cohort study.

BACKGROUND: Overt stroke after non-cardiac surgery has a substantial impact on the duration and quality of life. Covert stroke in the non-surgical setting is much more common than overt stroke and is associated with an increased risk of cognitive decline and dementia. Little is known about covert stroke after non-cardiac, non-carotid artery surgery. METHODS: We undertook a prospective, international cohort study to determine the incidence of covert stroke after non-cardiac, non-carotid artery surgery. Eligible patients were ≥65 yr of age and were admitted to hospital for at least three nights after non-cardiac, non-carotid artery surgery. Patients underwent a brain magnetic resonance study between postoperative days 3 and 10. The main outcome was the incidence of perioperative covert stroke. RESULTS: We enrolled a total of 100 patients from six centres in four countries. The incidence of perioperative covert stroke was 10.0% (10/100 patients, 95% confidence interval 5.5-17.4%). Five of the six centres that enrolled patients reported an incident covert stroke, and covert stroke was found in patients undergoing major general (3/27), major orthopaedic (3/41), major urological or gynaecological (3/22), and low-risk surgery (1/12). CONCLUSIONS: This international multicentre study suggests that 1 in 10 patients ≥65 yr of age experiences a perioperative covert stroke. A larger study is required to determine the impact of perioperative covert stroke on patient-important outcomes. CLINICAL TRIAL REGISTRATION: NCT01369537.

Determination and validation of discriminating concentration of ivermectin against Rhipicephalus microplus.

Rhipicephalus microplus, the major cattle tick species of India is prevalent all over the country and causes huge economic loss directly or indirectly to the dairy industries. Chemical acaricides are playing an important role in managing tick infestations on livestock for many years and consequently, resistance to commonly used organophosphate (OP) and synthetic pyrethroid (SP) compounds has been reported. Subsequently, ivermectin (IVM) has been emerged as an alternative to manage OP and SP resistant ticks. However, with the increase of use during the last 5-8 years, there is a possibility of development of resistance and thus there is an urgent need to develop a robust resistance monitoring tool to safeguard the drug. Lethal concentrations for 50 and 95% mortality of treated ticks were determined to work out discriminating concentration (DC) in order to diagnose resistance in the field situation. The DC (2 x LC95) was determined as 93.54 ppm using an established reference susceptible IVRI-1 line of R. microplus adopting adult immersion test. For validation of DC, the resistance status was checked in seven tick isolates of R. microplus collected from northern and eastern regions of India. The RR50 and RR95 values of the field isolates against ivermectin were determined and were in the range of 1.56-8.25 and 1.93-27.58, respectively. All the collected isolates were found to have higher lethal concentration and resistance ratio in comparison to reference susceptible IVRI-1 tick line (LC50 = 21.68, LC95 = 46.77 ppm, RR = 1.0). Amongst the field isolates, the isolate collected from Fatehgarh Sahib district (FTG) of Punjab state showed highest RR50 of 8.25 indicating high level of resistance to IVM. The generated DC will be used for IVM resistance characterization of ticks infesting cattle in different parts of the country.