Mosquito nets used to cover beds may be treated with a solution of permethrin. This increases the effectiveness of the bed net by killing parasitic insects before they are able to find gaps or holes in the net. Personnel working in malaria-endemic areas may be instructed to treat their clothing with permethrin as well. Permethrin is the most commonly used insecticide worldwide for the protection of wool from keratinophagous insects such as Tineola bisselliella.To better protect soldiers from the risk and annoyance of biting insects, the British and US armies are treating all new uniforms with permethrin.Permethrin (as well as other long-term pyrethroids) is effective over several months, in particular when used indoors. International studies report that permethrin can be detected in house dust, in fine dust, and on indoor surfaces even years after the application. Its degradation rate under indoor conditions is approximately 10% after 3 months. Resistance
Contrary to the most common mechanism of insecticide resistance evolution – selection for preexisting, low-frequency alleles – in Aedes aegypti permethrin resistance has arisen through the mechanism common to pyrethroids and DDT known as "knockdown resistance" (kdr) mutations. García et al 2009 found that a kdr allele has rapidly spread throughout Mexico and recently become dominant there. Side effects
Permethrin application can cause mild skin irritation and burning. Permethrin has little systemic absorption, and is considered safe for topical use in adults and children over the age of two months. The FDA has assigned it as pregnancy category B.
Polymorphous light eruption (PLE), sometimes also called polymorphic light eruption (PMLE), is a non-life-threatening and potentially distressing skin condition that is triggered by sunlight and artificial UV exposure in a genetically susceptible person, particularly in temperate climates during the spring and early summer. Due to its many clinical appearances, it is named polymorphic or polymorphous and the terms are used interchangeably. The resulting itch can cause significant suffering.PLE is also defined as an idiopathic primary photodermatosis, in which the photosensitizer is unknown.Treatments include prevention with sun avoidance and supervised light therapy, and symptom control with topical steroids. Signs and symptoms
Typically, the first episode develops in the spring following the first exposure to intense sun. Further episodes of the irritable rash occur several hours to days following subsequent sun exposure.PLE appears on areas of the skin newly exposed to sunlight such as the visible part of the neckline, backs of hands, arms and legs, and feet, but less commonly the face. At these areas, there may be feelings of burning and severe itching. Smooth red-topped small papules which merge into plaques, small fluid-filled blisters (papulovesicles) and less commonly target-shaped lesions which look like erythema multiforme may be visible.