Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Vector Biology and Vector Borne Disease Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
PLoS One. 2021 Sep 7;16(9):e0257024. doi: 10.1371/journal.pone.0257024. eCollection 2021.
Pediculus humanus capitis or head louse is an obligate ectoparasite and its infestation remains a major public health issue worldwide. Molecular analysis divides head lice into six clades and intra-clade genetic differences have been identified. Several hypotheses have been formulated to elucidate the discrepancies of the variety of head lice among different regions of the world. It is currently concluded that head lice distribution might be associated with human migration history. This study aims to investigate genetic data of human head lice in Thailand. We believe that the analysis could help establish the correlation between local and global head lice populations.
We investigated mitochondrial cytochrome b (cytb) gene of the collected 214 head lice to evaluate genetic diversity from 15 provinces among 6 regions of Thailand. The head lice genes were added to the global pool for the phylogenetic tree, Bayesian tree, Skyline plot, and median joining network construction. The biodiversity, neutrality tests, and population genetic differentiation among the 6 Thailand geographic regions were analyzed by DNAsp version 6.
The phylogenetic tree analysis of 214 collected head lice are of clade A and clade C accounting for roughly 65% and 35% respectively. The Bayesian tree revealed a correlation of clade diversification and ancient human dispersal timeline. In Thailand, clade A is widespread in the country. Clade C is confined to only the Central, Southern, and Northeastern regions. We identified 50 novel haplotypes. Statistical analysis showed congruent results between genetic differentiation and population migration especially with South Asia.
Pediculosis remains problematic among children in the rural areas in Thailand. Cytb gene analysis of human head lice illustrated clade distribution and intra-clade diversity of different areas. Our study reported novel haplotypes of head lice in Thailand. Moreover, the statistic calculation provided a better understanding of their relationship with human, as an obligate human parasite and might help provide a better insight into the history of human population migration. Determination of the correlation between phylogenetic data and pediculicide resistance gene as well as residing bacteria are of interest for future studies.
人虱或头虱是一种专性外寄生虫，其感染仍然是全球主要的公共卫生问题。分子分析将头虱分为六个进化枝，并且已经确定了种内遗传差异。已经提出了几种假设来阐明世界不同地区头虱种类的差异。目前的结论是，头虱的分布可能与人类的迁移历史有关。本研究旨在调查泰国的人体头虱的遗传数据。我们相信，分析可以帮助建立当地和全球头虱种群之间的相关性。
我们调查了从泰国 6 个地区的 15 个省收集的 214 个头虱的线粒体细胞色素 b（cytb）基因，以评估遗传多样性。将头虱基因添加到全球池中，构建系统发育树、贝叶斯树、天际图和中位数连接网络。使用 DNAsp 版本 6 分析 6 个泰国地理区域的生物多样性、中性检验和种群遗传分化。
对 214 个头虱的系统发育树分析表明，A 进化枝和 C 进化枝分别占大约 65%和 35%。贝叶斯树揭示了进化枝多样化与古代人类扩散时间线的相关性。在泰国，A 进化枝广泛分布于全国各地。C 进化枝仅局限于中部、南部和东北部地区。我们鉴定了 50 个新的单倍型。统计分析显示遗传分化与人口迁移之间存在一致的结果，特别是与南亚的关系。
在泰国的农村地区，头虱仍然是一个问题。人体头虱 cytb 基因分析说明了不同地区的进化枝分布和种内多样性。我们报告了泰国头虱的新单倍型。此外，统计计算提供了对头虱作为一种专性人体寄生虫与其人类宿主关系的更好理解，这可能有助于更好地了解人类人口迁移的历史。未来的研究将关注种系数据与除虱剂抗性基因以及寄生细菌之间的相关性。
