In vitro experiments of Pediculus humanus capitis (Phthiraptera: Pediculidae) resistance to permethrin and 6-paradol in East Jakarta: Detoxification enzyme activity and electron microscopic changes in lice

Background and Aim: Pediculus humanus capitis, the human head louse, remains a global health problem. This study evaluated the resistance of head lice to permethrin and 6-paradol mediated by in vitro detoxification enzyme activity experiments and to describe physical changes in the lice using scanning electron microscopy (SEM). Materials and Methods: The adult stages of P. h. capitis were collected from patients exposed to 1% permethrin and three different concentrations of 6-paradol (0.00005%, 0.0001%, and 0.00015%) using a filter paper diffusion bioassay. Healthy P. h. capitis adults served as the control. The in vitro bioassays were conducted after 10, 20, 30, and 60 min of exposure. The activities of acetylcholinesterase (AChE), glutathione S-transferase (GST), and oxidase were analyzed. Physical changes in the lice were analyzed using SEM. Results: Permethrin and 6-paradol exhibited low toxicity against the lice. At 60 min, 1% permethrin had killed 36.7% of the lice present, while 6-paradol had killed 66.7-86.7%. Permethrin induced significantly elevated AChE, GST, and oxidase activity; 6-paradol also caused significantly elevated AChE, GST, and oxidase activity. Permethrin did not cause any ultrastructural morphological changes on the lice, while 6-paradol severely damaged the head, thorax, respiratory spiracles, and abdomen of the dead lice. Conclusion: This in vitro experimental of P. h. capitis is the first study to report P. h. capitis in East Jakarta shows complete resistance to permethrin and 6-paradol, and to describe the associated increase in AChE, GST, and oxidase activity. It was observed that 6-paradol severely damaged the head, thorax, respiratory spiracles, and abdomen of the dead lice.

Pediculus humanus capitis: a study of the male genitalia using a combined stereoscopic, confocal laser scanning, and scanning electron microscopy approach

Background The male genital structures of arthropods are key features in the taxonomic and phylogenetic study of these organisms. The male genitalia of the head louse Pediculus humanus capitis are complex organs which are partly composed of structures that dynamically extrude during copulation. Methods Here, we describe the morphology of the genitalia of P. humanus capitis at the copulation stage, and at rest, by using stereoscopic microscopy, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM). Results CLSM and SEM images revealed that the vesica is composed of two distinct anatomical parts, the proximal lobe and the distal lobe. Both lobes have short and narrow spines, as well as long and wide scales with either sharp or rounded tips. The rounded scales vary in size and have a wavy base and rounded tips, and thus resemble a tongue in appearance. We identified a gland-like area on the penis with 11 shallow circular depressions, and a flat area with 14–16 exit orifices. The apical end of the penis has a foliaceous trifurcation and serves to expel the contents of the ejaculatory duct. These characteristics were recorded for all the specimens analyzed, indicating that these structures are highly conserved; to our knowledge, they have not been previously reported for any suborder of lice. Conclusions To the best of our knowledge, our results reveal for the first time the morphological details, and complexity, of the male genitalia of the head louse P. humanus capitis at different stages of copulation. The new approach described here provided information that should be taken into consideration in future research on the genitalia of lice. Application of this approach will also impact the taxonomic and phylogenetic study of other insect taxa. Graphical Abstract

Archaeoparasitology — a new source of reconstruction of migrations of ancient populations: opportunities, results, and prospects

The resilience of intestinal parasite ova to harsh environmental conditions and possibility of identification of many of them down to genus/species with the aid of conventional visual light microscopy make parasites an im-portant source of information on different aspects of life of ancient populations. Of special interest is the study of the phenomenon of parasitoidism aimed at reconstruction of ancient human migrations. Ectoparasites (the head louse) and a range of intestinal parasites of such groups as the helminths, tapeworms, and trematodes can be used as a marker of contacts and/or migration of people. Finding helminth ova in ancient samples collected in territories outside the endemic pockets can be direct evidence of contacts and/or migrations of the ancient popu-lation. An example of reconstruction of such migrations is given by, for instance, finding ova of the ascarids and whipworm on the territories of the Far North, mountainous Altai, deserts of the Central Asia etc. A remarkable example of migrations, according to the archaeoparasitology data, is the use of the helminths as a marker of an-cient human migrations, with the example of population of the American continent. It is noteworthy that almost a century old archaeoparasitology data find confirmation in the results of modern paleogenetic studies. In the recent decades, there have been review publications concerned with the finds of ova of various parasitic organisms in archaeological sites, many of which consolidated archaeoparasitology materials dealing with specific intestinal parasites, the impact of the parasites on the human evolution and their (viz., parasites and human) coevolution, and spread of the parasitic diseases as a result of climate changes both in ancient and modern times. All the works, without exception, emphasize the importance of archaeoparasitology data for the deeper understanding of these processes. However, although the first works on the reconstruction of migrations from parasitological data were published back in the beginning of the last century, the research works substantiating this approach and demonstrating its viability appeared only early in this century and elucidated biological pre-requisites for the re-construction of migrations. Therefore, new broad consolidation of the materials on the reconstruction of migrations from the data of archaeoparasitology is motivated not only by the need of reconsideration of already existing and new data, but also by the need of examination and verification of the archaeoparasitology facts in the context of the genetic data, archaeology, anthropology etc.

Characterization of nit sheath protein functions and transglutaminase-mediated cross-linking in the human head louse, Pediculus humanus capitis

Background Head louse females secrete liquid glue during oviposition, which is solidified to form the nit sheath over the egg. Recently, two homologous proteins, named louse nit sheath protein (LNSP) 1 and LNSP 2, were identified as adhesive proteins but the precise mechanism of nit sheath solidification is unknown. Methods We determined the temporal transcriptome profiles of the head louse accessory glands plus oviduct, from which putative major structural proteins and those with functional importance were deduced. A series of RNA interference (RNAi) experiments and treatment of an inhibitor were conducted to elucidate the function and action mechanism of each component. Results By transcriptome profiling of genes expressed in the louse accessory glands plus uterus, the LNSP1 and LNSP2 along with two hypothetical proteins were confirmed to be the major structural proteins. In addition, several proteins with functional importance, including transglutaminase (TG), defensin 1 and defensin 2, were identified. When LNSP1 was knocked down via RNA interference, most eggs became nonviable via desiccation, suggesting its role in desiccation resistance. Knockdown of LNSP2, however, resulted in oviposition failure, which suggests that LNSP2 may serve as the basic platform to form the nit sheath and may have an additional function of lubrication. Knockdown of TG also impaired egg hatching, demonstrating its role in the cross-linking of nit sheath proteins. The role of TG in cross-linking was further confirmed by injecting or hair coating of GGsTop, a TG inhibitor. Conclusions Both LNSP1 and LNSP2 are essential for maintaining egg viability besides their function as glue. The TG-mediated cross-linking plays critical roles in water preservation that are essential for ensuring normal embryogenesis. TG-mediated cross-linking mechanism can be employed as a therapeutic target to control human louse eggs, and any topically applied TG inhibitors can be exploited as potential ovicidal agents. Graphical abstract

A Rare Case of Coexisting Pediculosis Capitis and Tinea Capitis in a Healthy Adult Female

Pediculosis capitis is a common condition caused by infestation with the human head louse, <i>Pediculus humanus capitis</i>, and primarily affects children in the age-group of 6–12 years. The most prominent symptom is intense scalp itching, yet moving lice or nonmoving nits may be seen on the scalp and hair. Tinea capitis, also known as scalp ringworm, is a superficial fungal infection caused by keratinophilic fungi termed dermatophytes. Tinea capitis is rare in adults, and its symptoms include hair loss, dry scaly areas, redness, and itching. We here report a case of a rare coexistence between pediculosis capitis and tinea capitis in an otherwise healthy adult female, motivating the search for a possible cause of this rare coexistence and alarming dermatologists to be aware of the modified clinical appearance of this coexistence which could be mistaken with other conditions such as cutaneous lupus erythematosus or lichen planopilaris.

Molecular Monitoring of Knockdown Resistance in Head Louse (Phthiraptera: Pediculidae) Populations in Iran

Knockdown resistance (kdr) is a common mechanism of insecticide resistance in head lice to the conventionally used pyrethroid pediculosis and can be the result of various amino acid substitutions within the voltage-sensitive sodium channel (VSSC). In this study, 54 sequences from varied specimens were investigated to monitor well-known resistance mutations and probable new mutations. The Pediculus humanus capitis de Geer specimens were collected from 13 provinces in Iran. The specimens were stored in 70% ethanol until DNA extraction and PCR amplification of ~900-bp fragment of VSSC. The sequences were analyzed using different bioinformatics software for the detection of well-known kdr substitutions and additional mutations potentially associated with kdr resistance in head lice. There were six new and an old (haplotype I) kdr haplotypes within the Iranian head louse population. K794E, F815I, and N818D amino acid substitutions were reported for the first time. The P813H mutation was the most prevalent amino acid substitution in eight provinces. Among 53 sequences, 26 (49%) were homozygous susceptible, and 27 (51%) were heterozygotes. Thus, 51% of the head lice collected in Iran harbored only the P813H allele. The exact test for the Hardy–Weinberg (H–W) equilibrium showed that genotype frequencies differed significantly from the expectation in East-Azerbaijan and Tehran provinces. Moreover, these populations had an inbreeding coefficient (Fis) &lt;0, indicating the excess of heterozygotes. This observation suggests that the populations of head lice from Iran are currently under active selective pressure. For the rest of the populations, H–W equilibrium and the expectations were significantly in harmony. The results of the current study highlight molecular techniques in the accurate detection of resistance genotypes before their establishment within the head louse population. Accurate detection of resistant genotypes seems to be helpful in decision-making on lice control programs and resistance monitoring and management.

Impact of a Health Educational Interventional Program on Reducing the Head Lice Infestation Among Pupils in an Elementary School of a Sub-Tropical Region

Background: Pediculosis is an important social challenge that can be caused by human head louse, Pediculus humanus capitis. This infestation is cosmopolitan, especially in countries with low hygiene and sanitation. Regular health education classes for students and their parents are required to reducing this infestation in schools and families. This study aimed to evaluate the impact of a health education intervention program on reducing of head lice among pupils of an elementary school.Methods: In a pre-post study, a total of 594 pupils, a girl elementary school, were screened for pediculosis (2017-2018). The prevalence of pediculosis estimated before and after two month interventional education program. Visual inspection was applied for initial diagnosis of infection. The suspected cases were confirmed by wood lamp examination and potassium hydroxide (KOH) microscopic wet‐mount examination. An elementary school in the same area was selected as the control group, with no interference. The prevalence of contamination by the same method was obtained in the study group.Results: At the beginning of study, pre-intervention prevalence of pediculosis among pupils was 8.4% (49/594). The mean age in all pupils was 9.86±1.83 years old and the most infestation was showed in fourth-grade students with 10 years old. Analysis of statistics demonstrated a significance difference between having infestation and the number of members in the families. Post-intervention phase led to a decreased prevalence of pediculosis in pupils to 3% (8/594) (p-value < 0.05) and significant increase of parental knowledge on prevention program of pediculosis (p-value < 0.001), Conclusion: The prevalence of pediculosis was significantly reduced following the interventions in the school. The applied interventions may be implemented in other residual centers to get rid of this important infestation.

Impact of a health educational interventional program on reducing the head lice infestation among pupils in an elementary school of a sub-tropical region

Background Pediculosis is an important social challenge that can be caused by human head louse, Pediculus humanus capitis. This infestation is cosmopolitan, especially in countries with low hygiene and sanitation. Regular health education classes for students and their parents are required to reducing this infestation in schools and families. This study aimed to evaluate the impact of a health education intervention program on reducing of head lice among pupils of an elementary school. Methods In a case-control study, a total of 594 pupils, a girl elementary school, were screened for pediculosis (2015–2016). Interventions were applied in two steps, pediculosis cases eradication and training-oriented prevention program. Visual inspection was applied for initial diagnosis of infection. The suspected cases were confirmed by wood lamp examination and potassium hydroxide (KOH) microscopic wet-mount examination. An elementary school in the same area was selected as the control group, with no interference. The prevalence of contamination by the same method was obtained in the study group. Results At the beginning of study, the overall prevalence of pediculosis among pupils was 8.4% (49/594). The mean age in all pupils was 9.86 ± 1.83 years old and the most infestation was showed in fourth-grade students with 10 years old. Analysis of statistics demonstrated a significance difference between having infestation and the number of members in the families. The interventions led to a significant increase of parenting knowledge on prevention program of pediculosis (p-value < 0.001), and a decreased prevalence of pediculosis in pupils to 3% (8/594) (p-value < 0.05). Conclusions The prevalence of pediculosis was significantly reduced following the interventions in the school. The applied interventions may be implemented in other residual centers to get rid of this important infestation.

Molecular Characterization and Genetic Diversity of Haplogroup E Human Lice in Guinea, West Africa

Pediculus humanus capitis, the head louse, is an obligate blood-sucking ectoparasite that occurs in six divergent mitochondrial clades (A, D, B, F, C and E). Several studies reported the presence of different pathogenic agents in head lice specimens collected worldwide. These findings suggest that head louse could be a dangerous vector and a serious public health problem. Herein, we aimed to study the mitochondrial genetic diversity, the PHUM540560 gene polymorphisms profile of head lice collected in Guinea, as well as to screen for their associated pathogens. In 2018, a total of 155 head lice were collected from 49 individuals at the Medicals Centers of rural (Maférinyah village) and urban (Kindia city) areas, in Guinea. Specimens were subjected to a genetic analysis and pathogens screening using molecular tools. Results showed that all head lice belonged to eight haplotypes in the E haplogroup, with six newly identified for the first time. The study of the PHUM540560 gene polymorphisms of our clade E-head lice revealed that 82.5% exhibited the same polymorphism profile as the previously reported clade A-body lice. Screening for targeted pathogens revealed the presence of Acinetobacter spp., while sequencing highlighted the presence of several species, including Acinetobacter baumannii, Acinetobacter nosocomialis, Acinetobacter variabilis, Acinetobacter towneri and for the first time Acinetobacter haemolyticus. Our study is the first to report the existence of the Guinean haplogroup E, the PHUM540560 gene polymorphism profile as well as the presence of Acinetobacter species in head lice collected from Guinea.