![]() Once a mutation occurs it can spread very fast, as it can be observed in the case of Aedes aegypti for which there are reports of populations where the frequency of the mutant allele 1534Cys is above 95%, and there is also evidence of slow reversal in the absence of insecticide pressure. ![]() In Aedes aegypti, these kdr genes have been mainly identified, although there is some controversy as to the question of single or multiple genes being necessary for resistance development. a genetic mutation also known as Knock-Down Resistance-kdr. Specifically, in the case of pyrethroid-based insecticides the mechanism for resistance is target-site alteration, i.e. In all cases, resistance is likely to be genetically mediated, and due to mutations in one or more genes. There are several mechanisms that might lead to development of insecticide resistance, which broadly fall in four categories: metabolic, target-site alteration, behavioural, and penetration resistance. Insecticide resistance might undermine a number of control programs that exist worldwide, and therefore has received considerable attention by regional and worldwide health organizations: a number of protocols were developed by these agencies to identify and manage such behaviour. Īrthropod vectors are becoming increasingly more resistant to those insecticides probably due to their intensive, and sometimes indiscriminate, use. ![]() However, not only are pyrethroid-derived insecticides extensively used in agriculture, but they are also found in many commercial products available on store shelves, such as household insecticides, pet sprays and shampoos, lice treatments, mosquito repellents and impregnated bed nets, as mentioned in. Many of the pyrethroid insecticides are applied by public health officials and trained personnel as an ultra low-volume (ULV) spray, which stays in the air and kills adult mosquitoes on contact. Organophosphorus and carbamate insecticides affect nerve synapses through the neuro-transmitter acetylcholinesterase, while the organochlorines (DDT) and pyrethroids aim the sodium channels of the nerve sheath, producing an effect similar to a knockdown. In this scenario, control of the vector population is possibly the best alternative available to health authorities for disease prevention, and lack of such an adequate control might lead to periodical occurrence of epidemics-cf.Ĭontrol of these arthropod vectors is particularly important in areas where they are widespread, and to a large extent is achieved by use of chemical insecticides that target them at a particular stage of their life-cycle, such as larvicides or adulticides. In addition, there is no licensed vaccine available for them, even though several candidate vaccines are currently being evaluated in clinical studies. įor a considerable number of diseases associated to arboviruses, there is neither aetiological treatment nor chemoprophylaxis. However, even typically more innocuous diseases seem to be undergoing transformations and are evolving towards more severe forms. ![]() Recurring epidemics of these vector-borne diseases are likely to cause a large burden to national health systems, even if these diseases were solely benign. severe dengue is a leading cause of serious illness and death among children in Asian and Latin American countries. Vector-borne diseases can have a wide spectrum of morbidity varying from mainly benign to lethal, and also have a large impact on child mortality-e.g. Mário Santos Braga, Niterói, RJ, BrasilĪrthropods vectors are at the crossroads of current human development as health authorities are observing a global re-emergence of many vector-borne diseases such as malaria, dengue and chikungunya disease, probably due to the fast spread of some of the associated vectors in many areas of the world. Affiliation: Programa de Computação Científica, Fundação Oswaldo Cruz, Rio de Janeiro, RJ, BrasilĪffiliation: Departamento de Matemática Aplicada, Universidade Federal Fluminense, R. ![]()
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