Multiple Insecticide Resistance: An Impediment to Insecticide-Based Malaria Vector Control Program

BACKGROUND: Indoor Residual Spraying (IRS), insecticide-treated nets (ITNs) and long-lasting insecticidal nets (LLINs) are key components in malaria prevention and control strategy. However, the development of resistance by mosquitoes to insecticides recommended for IRS and/or ITNs/LLINs would affect insecticide-based malaria vector control. We assessed the susceptibility levels of Anopheles arabiensis to insecticides used in malaria control, characterized basic mechanisms underlying resistance, and evaluated the role of public health use of insecticides in resistance selection. METHODOLOGY/PRINCIPAL FINDINGS: Susceptibility status of An. arabiensis was assessed using WHO bioassay tests to DDT, permethrin, deltamethrin, malathion and propoxur in Ethiopia from August to September 2009. Mosquito specimens were screened for knockdown resistance (kdr) and insensitive acetylcholinesterase (ace-1(R)) mutations using AS-PCR and PCR-RFLP, respectively. DDT residues level in soil from human dwellings and the surrounding environment were determined by Gas Chromatography with Electron Capture Detector. An. arabiensis was resistant to DDT, permethrin, deltamethrin and malathion, but susceptible to propoxur. The West African kdr allele was found in 280 specimens out of 284 with a frequency ranged from 95% to 100%. Ace-1(R) mutation was not detected in all specimens scored for the allele. Moreover, DDT residues were found in soil samples from human dwellings but not in the surrounding environment. CONCLUSION: The observed multiple-resistance coupled with the occurrence of high kdr frequency in populations of An. arabiensis could profoundly affect the malaria vector control programme in Ethiopia. This needs an urgent call for implementing rational resistance management strategies and integrated vector control intervention

Altered arterial function in migraine of recent onset

OBJECTIVE: Migraine is associated with cardiovascular disorders but the underlying mechanisms are unknown. Arterial structure and function are important determinants of cardiovascular morbidity and mortality. The aim of the present study was to assess arterial properties in patients with migraine of recent onset. METHODS: In a cross-sectional study, structural and functional arterial properties were assessed using ultrasound and applanation tonometry in 50 patients with a history of migraine >1 and <6 years during a headache-free interval and 50 age- and gender-matched subjects without a history of migraine. RESULTS: Brachial artery diameter (4.82 +/- 0.93 mm vs 5.39 +/- 0.89 mm, p = 0.01) and compliance (0.30 +/- 0.17 mm(2)/kPa vs 0.37 +/- 0.19 mm(2)/kPa, p = 0.02) were decreased in migraine patients compared with controls. Femoral artery compliance was decreased in migraine patients (1.19 +/- 0.55 mm(2)/kPa vs 1.42 +/- 0.59 mm(2)/kPa, p = 0.04). Carotid arterial wall properties were similar between groups. Aortic augmentation index was increased in migraine patients (4 +/- 10% vs -1 +/- 10%, adjusted p = 0.04). Flow-mediated vasodilation of the brachial artery (normalized to peak shear rate) was decreased in patients with migraine (29 +/- 15 vs 37 +/- 15 10(-3)%. sec, p = 0.006). CONCLUSION: Functional arterial properties are altered in patients with migraine of recent onset.status: publishe