A comprehensive survey of permethrin resistance in human head louse populations from northwest Iran: ex vivo and molecular monitoring of knockdown resistance alleles
Abstract Background Head louse infestation is an important public health problem, and expanding resistance to permethrin is a major challenge to its control. The mapping and detection of pyrethroid resistance are essential to the development of appropriate treatments and ensure the effectiveness of...
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| Format: | Article |
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BMC
2023-02-01
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| Series: | Parasites & Vectors |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s13071-023-05652-0 |
| _version_ | 1811166083405578240 |
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| author | Mohammad Bagher Ghavami Sanaz Panahi Seyede Maede Nabati Maryam Ghanbari Behrooz Taghiloo |
| author_facet | Mohammad Bagher Ghavami Sanaz Panahi Seyede Maede Nabati Maryam Ghanbari Behrooz Taghiloo |
| author_sort | Mohammad Bagher Ghavami |
| collection | DOAJ |
| description | Abstract Background Head louse infestation is an important public health problem, and expanding resistance to permethrin is a major challenge to its control. The mapping and detection of pyrethroid resistance are essential to the development of appropriate treatments and ensure the effectiveness of current measures. The aim of this study was to present the phenotypic and genotypic basis of permethrin resistance and identify knockdown resistance (kdr) mutations in head louse populations in northwestern Iran. Methods Adult head lice were collected from 1059 infested girls in Ardebil, East Azerbaijan, West Azerbaijan and Zanjan Provinces, northwestern Iran. The toxicity of permethrin and the possible synergistic effect of piperonyl butoxide (PBO) on this toxicity were assessed using bioassays. Fragments of voltage-sensitive sodium channels (vssc) and cytochrome b (cytb) genes were amplified and analyzed for the detection of knockdown resistance (kdr) mutations and mitochondrial groups. Moreover, genotypes of the two hot spot regions of the vssc gene were determined by melting curve analysis of amplicons. Results A total of 1450 adult head lice were collected during 2016–2021. Live lice were exposed to a dose of 1% permethrin for 12 h, and the median lethal time (LT50) and time to achieve 90% mortality (LT90) were determined to be 6 and 14.8 h, respectively. Topical application of 2 and 16 ng permethrin per louse resulted in 25% and 42.11% mortality, respectively. Pre-exposure of samples to 3% piperonyl butoxide had no synergistic effect on the effects of permethrin. Analysis of the 774-bp vssc gene fragment showed the presence of the M815I, T917I and L920F mutations, wild-type and T917I mutation, in 91.6%, 4.2% and 4.2% of samples, respectively. Investigation of the mitochondrial cytb gene demonstrated the predominance of clade B. The frequency of domain II segment 4 (S4)-S5 kdr genotypes in mitochondrial groups was identical, and heterozygotes were present in 93.5% of samples. A significant difference was detected in the frequency of domain IIS1-S3 kdr genotypes, and the frequency of resistant alleles and heterozygotes was higher in clade B than in clade A. Conclusions The presence of kdr mutations in the vssc gene and the non-synergist effect of PBO indicate that pyrethroid target site insensitivity is the main resistance mechanism. This phenomenon and the high frequency of resistant alleles necessitate that new pediculosis management programs be developed. Further studies need to be conducted to identify all factors contributing this resistance and to develop alternative pediculicides. Graphical Abstract |
| first_indexed | 2024-04-10T15:46:47Z |
| format | Article |
| id | doaj.art-c8eb8ac7db77406f862808bf4a2ef9da |
| institution | Directory Open Access Journal |
| issn | 1756-3305 |
| language | English |
| last_indexed | 2024-04-10T15:46:47Z |
| publishDate | 2023-02-01 |
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| series | Parasites & Vectors |
| spelling | doaj.art-c8eb8ac7db77406f862808bf4a2ef9da2023-02-12T12:05:48ZengBMCParasites & Vectors1756-33052023-02-0116111510.1186/s13071-023-05652-0A comprehensive survey of permethrin resistance in human head louse populations from northwest Iran: ex vivo and molecular monitoring of knockdown resistance allelesMohammad Bagher Ghavami0Sanaz Panahi1Seyede Maede Nabati2Maryam Ghanbari3Behrooz Taghiloo4Department of Medical Entomology and Vector Control, School of Medicine, Zanjan University of Medical SciencesDepartment of Medical Entomology and Vector Control, School of Medicine, Zanjan University of Medical SciencesDepartment of Medical Entomology and Vector Control, School of Medicine, Zanjan University of Medical SciencesDepartment of Medical Entomology and Vector Control, School of Medicine, Zanjan University of Medical SciencesDepartment of Medical Entomology and Vector Control, School of Medicine, Zanjan University of Medical SciencesAbstract Background Head louse infestation is an important public health problem, and expanding resistance to permethrin is a major challenge to its control. The mapping and detection of pyrethroid resistance are essential to the development of appropriate treatments and ensure the effectiveness of current measures. The aim of this study was to present the phenotypic and genotypic basis of permethrin resistance and identify knockdown resistance (kdr) mutations in head louse populations in northwestern Iran. Methods Adult head lice were collected from 1059 infested girls in Ardebil, East Azerbaijan, West Azerbaijan and Zanjan Provinces, northwestern Iran. The toxicity of permethrin and the possible synergistic effect of piperonyl butoxide (PBO) on this toxicity were assessed using bioassays. Fragments of voltage-sensitive sodium channels (vssc) and cytochrome b (cytb) genes were amplified and analyzed for the detection of knockdown resistance (kdr) mutations and mitochondrial groups. Moreover, genotypes of the two hot spot regions of the vssc gene were determined by melting curve analysis of amplicons. Results A total of 1450 adult head lice were collected during 2016–2021. Live lice were exposed to a dose of 1% permethrin for 12 h, and the median lethal time (LT50) and time to achieve 90% mortality (LT90) were determined to be 6 and 14.8 h, respectively. Topical application of 2 and 16 ng permethrin per louse resulted in 25% and 42.11% mortality, respectively. Pre-exposure of samples to 3% piperonyl butoxide had no synergistic effect on the effects of permethrin. Analysis of the 774-bp vssc gene fragment showed the presence of the M815I, T917I and L920F mutations, wild-type and T917I mutation, in 91.6%, 4.2% and 4.2% of samples, respectively. Investigation of the mitochondrial cytb gene demonstrated the predominance of clade B. The frequency of domain II segment 4 (S4)-S5 kdr genotypes in mitochondrial groups was identical, and heterozygotes were present in 93.5% of samples. A significant difference was detected in the frequency of domain IIS1-S3 kdr genotypes, and the frequency of resistant alleles and heterozygotes was higher in clade B than in clade A. Conclusions The presence of kdr mutations in the vssc gene and the non-synergist effect of PBO indicate that pyrethroid target site insensitivity is the main resistance mechanism. This phenomenon and the high frequency of resistant alleles necessitate that new pediculosis management programs be developed. Further studies need to be conducted to identify all factors contributing this resistance and to develop alternative pediculicides. Graphical Abstracthttps://doi.org/10.1186/s13071-023-05652-0Pediculus humanus capitisHead louseBiological assayPyrethroid resistanceVoltage-sensitive sodium channel mutationsMitochondrial cytochrome b groups |
| spellingShingle | Mohammad Bagher Ghavami Sanaz Panahi Seyede Maede Nabati Maryam Ghanbari Behrooz Taghiloo A comprehensive survey of permethrin resistance in human head louse populations from northwest Iran: ex vivo and molecular monitoring of knockdown resistance alleles Parasites & Vectors Pediculus humanus capitis Head louse Biological assay Pyrethroid resistance Voltage-sensitive sodium channel mutations Mitochondrial cytochrome b groups |
| title | A comprehensive survey of permethrin resistance in human head louse populations from northwest Iran: ex vivo and molecular monitoring of knockdown resistance alleles |
| title_full | A comprehensive survey of permethrin resistance in human head louse populations from northwest Iran: ex vivo and molecular monitoring of knockdown resistance alleles |
| title_fullStr | A comprehensive survey of permethrin resistance in human head louse populations from northwest Iran: ex vivo and molecular monitoring of knockdown resistance alleles |
| title_full_unstemmed | A comprehensive survey of permethrin resistance in human head louse populations from northwest Iran: ex vivo and molecular monitoring of knockdown resistance alleles |
| title_short | A comprehensive survey of permethrin resistance in human head louse populations from northwest Iran: ex vivo and molecular monitoring of knockdown resistance alleles |
| title_sort | comprehensive survey of permethrin resistance in human head louse populations from northwest iran ex vivo and molecular monitoring of knockdown resistance alleles |
| topic | Pediculus humanus capitis Head louse Biological assay Pyrethroid resistance Voltage-sensitive sodium channel mutations Mitochondrial cytochrome b groups |
| url | https://doi.org/10.1186/s13071-023-05652-0 |
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