@article {96403, title = {Pyrethroid-linked resistance allelic mutations by molecular analysis in wild human head louse (Phthiraptera: Pediculidae) populations from schoolgirls of South Iran}, journal = {Parasite Epidemiology and Control}, volume = {18}, year = {2022}, month = {Aug-01-2022}, pages = {7 pp}, abstract = {

Background: Human head louse, Pediculus humanus capitis De Geer, 1767 (Anoplura: Pediculidae), is one of the most frequent ectoparasites infesting Homo sapiens worldwide. Reduced sensitivity to treatment due to genetic mutations, in particular knockdown resistance (kdr) (or target site insensitivity) allele, has led to this infestation prevalence. Molecular characterization of this resistance has a crucial impact on selecting appropriate treatment protocol. The aim of this study was to investigate kdr gene mutations on voltage-sensitive sodium channel (VSSC) among wild head lice samples from Fars province, southern Iran.

Methods: Head lice were collected using plastic detection combs on girls enrolled in public schools from 10 counties in Fars province. The specimens were screened in 10 pools (each pool per county containing 35 specimens), with three pools (30\%) being positive. Following species identification with valid entomological keys, 350 (68\%) out of 514 randomly collected adult head lice were analyzed after their somatic genomic DNA extraction using Sinaclon kit. Samples were investigated by polymerase chain reactions (PCR), and the amplicon was subsequently sequenced.

Results: Sequence analysis showed that the sodium channel genes in the pooled ectoparasites had two intron and three exon regions. Single (L840F), double (I836L, E837K), and triple novel point mutations (V875L, Q876P, S879V); the last involving two concomitant allelic substitutions; were discovered in the second and third exon regions of head louse DNA on chromosome II from three (30\%) counties. Other exon or intron regions remained non-mutated from the remaining seven counties.

Conclusions: The detection of six amino acid substitutions from 30\% of examined head lice among infested schoolgirls reveal that mutants are minutely developing. These findings provide further incentive to recapitulate the legitimacy of current control measures and resolve dynamics of resistance in human head louse populations.

}, keywords = {Amino acid substitution, genome, insect, Kdr gene, Node of Ranvier, Pediculosis, Permethrin Resistance, Voltage-sensitive sodium channel}, issn = {2405-6731}, doi = {10.1016/j.parepi.2022.e00252}, url = {https://www.sciencedirect.com/science/article/pii/S2405673122000162}, author = {Jalal Mohammadi and Hamzeh Alipour and Kourosh Azizi and Marzieh Shahriari-Namadi and Mohsen Kalantari and Saeedeh Ebrahimi and Mohammad Djaefar Moemenbellah-Fard} } @article {96105, title = {Frequency of pyrethroid resistance in human head louse treatment: systematic review and meta-analysis}, journal = {Parasite}, volume = {28}, year = {2021}, month = {Jan-01-2021}, pages = {10 pp}, abstract = {

Head lice (Pediculus humanus capitis) are one of the most common insects causing infestations in humans worldwide, and infestation is associated with adverse socio-economic and public health effects. The development of genetic insensitivity (e.g., target site insensitivity\ =\ knockdown resistance or kdr) to topical insecticides has impaired effective treatment. Therefore, this study was undertaken to review and meta-analyze the frequency of pyrethroid resistance in treated head louse populations from the beginning of 2000 to the end of June 2021 worldwide. In order to accomplish this, all English language articles published over this period were extracted and reviewed. Statistical analyses of data were performed using fixed and random effect model tests in meta-analysis, Cochrane, meta-regression and I2 index. A total of 24 articles from an initial sample size of 5033 were accepted into this systematic review. The mean frequency of pyrethroid resistance was estimated to be 76.9\%. In collected resistant lice, 64.4\% were homozygote and 30.3\% were heterozygote resistant. Globally, four countries (Australia, England, Israel, and Turkey) have 100\% kdr gene frequencies, likely resulting in the ineffectiveness of pyrethrin- and pyrethroid-based pediculicides. The highest resistance recorded in these studies was against permethrin. This study shows that pyrethroid resistance is found at relatively high frequencies in many countries. As a result, treatment with current insecticides may not be effective and is likely the cause of increased levels of infestations. It is recommended that resistance status be evaluated prior to insecticide treatment, to increase efficacy.

R\ésum\é

Les poux de t\ête (Pediculus humanus capitis) sont l\’un des insectes les plus courants \à l\’origine d\’infestations chez l\’homme dans le monde, et l\’infestation est associ\ée \à des effets socio-\économiques et de sant\é publique n\éfastes. Le d\éveloppement d\’une insensibilit\é g\én\étique (par exemple, l\’insensibilit\é au site cible = r\ésistance knockdown ou kdr) aux insecticides topiques a alt\ér\é l\’efficacit\é de leur traitement. Par cons\équent, cette \étude a \ét\é entreprise pour examiner et m\éta-analyser la fr\équence de la r\ésistance aux pyr\éthro\ïdes dans les populations de poux de t\ête \étudi\ées du d\ébut 2000 \à la fin juin 2021 dans le monde. Pour ce faire, tous les articles en anglais publi\és au cours de cette p\ériode ont \ét\é extraits et examin\és. Les analyses statistiques des donn\ées ont \ét\é effectu\ées \à l\’aide de tests de mod\èles \à effets fixes et al\éatoires dans la m\éta-analyse, Cochrane, m\éta-r\égression et indice I2. Un total de 24 articles provenant d\’un \échantillon initial de 5033 ont \ét\é accept\és dans cette revue syst\ématique. La fr\équence moyenne de la r\ésistance aux pyr\éthro\ïdes a \ét\é estim\ée \à 76,9 \%. Chez les poux r\ésistants collect\és, 64,4 \% \étaient homozygotes r\ésistants et 30,3 \% \étaient h\ét\érozygotes r\ésistants. \À l\’\échelle mondiale, quatre pays (Australie, Angleterre, Isra\ël et Turquie) ont des fr\équences de g\ène kdr de 100 \%, ce qui entra\îne probablement une inefficacit\é des p\édiculicides \à base de pyr\éthrine et de pyr\éthrino\ïde. La r\ésistance la plus \élev\ée enregistr\ée dans ces \études \était celle contre la perm\éthrine. Cette \étude montre que la r\ésistance aux pyr\éthro\ïdes est trouv\ée \à des fr\équences relativement \élev\ées dans de nombreux pays. En cons\équence, le traitement avec les insecticides actuels peut ne pas \être efficace et est probablement la cause d\’une augmentation des niveaux d\’infestation. Il est recommand\é d\’\évaluer le statut de r\ésistance avant le traitement insecticide, pour augmenter son efficacit\é.

}, keywords = {Allele, Control, ectoparasite, Kdr genes, Pyrethrum, therapy}, issn = {1776-1042}, doi = {10.1051/parasite/2021083}, url = {https://www.parasite-journal.org/articles/parasite/full_html/2021/01/parasite210144/parasite210144.html}, author = {Jalal Mohammadi and Kourosh Azizi and Hamzeh Alipour and Mohsen Kalantari and Masoumeh Bagheri and Marzieh Shahriari-Namadi and Saeedeh Ebrahimi and Mohammad Djaefar Moemenbellah-Fard} } @article {95977, title = {Permethrin-associated kdr Mutations through Molecular Analysis of Human Head Lice (Phthiraptera: Pediculidae) Populations in School Children in the South of Iran}, journal = {Journal Health Sciences and Surveillance System }, volume = {9}, year = {2022}, month = {Oct 2021}, pages = {257-264}, abstract = {

Abstract

Background:Human head lice is one of the most invincible neglected skin diseases. The use of pyrethroid insecticides is a standard method of treating the disease, which leads to lice population resistance in the long run. The main aim of the current survey was to screen the biomarkers of permethrin-associated kdr (knockdown resistance) point mutations through molecular analysis of the human head lice populations in primary school children in the south of Iran.

Methods: In an experimental study, Field-collected head lice from infested students were fixed in ethanol, identified using valid taxonomic keys, and processed by PCR for kdr mutant studies. Sequencing partial voltage-sensitive sodium channel gene in different head lice populations was subsequently implemented and compared with the permethrin-resistant diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) as the gold standard.

Results:Human head lice appeared to reflect kdr point mutations in specimens from the city of Shiraz. At least three amino acid mutations at designated sites of D820E, L840F, and N874G, corresponding to replacements of aspartic acid to glutamic acid, leucine to phenylalanine, and asparagine to glycine, are clear in this representative population, respectively. At the same time, only L840F is reported as a new mutant in this survey.

Conclusion: The ongoing treatment of head lice infested in school children harboring kdr-mutated or permethrin-resistant mutants in Shiraz is risky, illogical, and contrary to the One Health initiative of the World Health Organization. Health executives should thus immediately take the indispensable steps to prohibit further procurement of permethrin

}, keywords = {insecticide, Iran, Permethrin, Voltage-sensitive sodium channel}, doi = {10.30476/jhsss.2021.91764.1222}, url = {https://jhsss.sums.ac.ir/article_47895.html}, author = {Saeedeh Ebrahimi and Marzieh Shahriari-Namadi and Saeed Shahabi and Mohammad Djaefar Moemenbellah-Fard and Hamzeh Alipour} }