Pediculosis capitis among school-age students worldwide as an emerging public health concern: a systematic review and meta-analysis of past five decades

Exploring the lived experiences of adolescent girls affected by head lice infestation: a qualitative descriptive study

BACKGROUND

Head lice infestation is a prevalent dermatological condition among adolescent girls, which has wide-ranging adverse physical, psychological, and emotional effects on their lives. However, these experiences have been sparsely documented. This study aimed to investigate the lived experiences of Iranian adolescent girls regarding head lice infestation.

METHODS

In this phenomenological study, a purposive sampling technique was employed to select 15 adolescent girls who were experiencing head lice infestation. Collaboration was established with local schools to identify and recruit the participants. Subsequently, the purpose and nature of the study were explained to the identified participants and their guardians. Semi-structured in-depth interviews were conducted to gather the necessary data. The collected data underwent analysis using Colaizzi's seven-step method. To enhance the credibility of the findings, Lincoln and Guba's (2004) criteria were applied. The management of the data was facilitated through the utilization of MAXQDA software version 0.9.5.

RESULTS

The average age of the participants, aged 12 to 17, was 14.5 (standard deviation = 1.7). In terms of education, the majority of them had completed upper secondary education (n = 8, 53.3%), followed by lower secondary education (n = 4, 26.6%). The participants' experiences were categorized into four main themes and 15 sub-themes. The main themes included living in the shadow of fear, torment of infestation, "struggling with head lice, and disturbing ramifications. The sub-themes encompassed social fear, fear of harm, fear of beauty decline, stigma, bullying behavior, self-blame, adversity, challenging struggle, effective coping, nonconforming behavior, family disruption, academic disruption, health threats, and confused mental state.

CONCLUSION

During head lice infestation, adolescent girls endured negative experiences and extensive fears, considering it a significant ordeal. They encountered multiple challenges while dealing with lice and utilized both adaptive and maladaptive strategies to cope with the infestation. It is recommended to enhance public awareness regarding head lice infestation, and healthcare providers should offer emotional support and counseling services to affected girls and their families.

Prevalence and associated factors of head lice infestation among primary school children in low- and middle-income countries: systematic review and meta-analysis

INTRODUCTION

Head lice infestation remains a persistent public health concern among primary school children in resource-limited settings, affecting their well-being and academic performance. Despite previous studies, there is no consistent evidence on the prevalence and factors associated with head lice infestation. This study aimed to determine the prevalence and factors related to head lice infestation among primary school children in low and middle-income countries.

METHODS

This review was conducted by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Relevant electronic databases, including PubMed, Cochrane Library, Web of Science, Science Direct, AJOL, and Google Scholar, were used to retrieve articles. The study included only published articles written in English languages between December 01, 2014 to January 31, 2024 for studies reporting the prevalence of head lice infestation or associated factors among primary school children in low- and middle-income countries. This review has been registered on PROSPERO with Prospero registration number CRD42024506959. The heterogeneity of the data was evaluated using the I2 statistic. A meta-analysis was conducted using STATA 17 software, with a 95% confidence interval. Publication bias was evaluated using funnel plots and statistical tests, such as Egger's and Beggs's tests, to identify publication biases in the included studies. Meta-regression was also carried out to assess the source of publication of publication bias.

RESULTS

The review included 39 studies involving 105,383 primary school children. The pooled prevalence of head lice infestation among primary school children in low- and middle-income countries was 19.96% (95% CI; 13.97, 25.95). This review also found out that being a girl was 3.71 times (AOR = 3.71; 95% CI: 1.22-11.26) more likely to have head lice infestation as compared to boys, while children with a previous history of infestation were 4.51 times (AOR = 4.51; 95% CI: 2.31-8.83) more likely to have head lice infestation as compared to their counterparts.

CONCLUSION

The overall prevalence of head lice infestation among primary school children in low- and middle-income countries was found to be high. Female gender, children who had a previous history of infestation, and family size were significant predictors of head lice infestation. As a result, policymakers and program administrators should focus on the identified determinants.

Toxicity of 6-gingerol and Cymbopogon citratus against Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae): Mortality, detoxifying enzymes, and morphological ultrastructure alterations in lice

Pediculus humanus capitis (head louse), which causes pediculosis capitis, remains a global health concern. Plant products are efficient alternative pediculicides for treating the human ectoparasite P. h. capitis which is resistant to permethrin. The study evaluates the toxicity and mechanisms of 6-gingerol and Cymbopogon citratus leaf extract on P. h. capitis. Pediculus humanus capitis adult stages were exposed to three different dosages of 6-gingerol and C. citratus crude leaf extract on filter sheets for 5, 10, and 30 min, respectively. The biochemical approach was used to assess the activity of detoxifying enzymes including acetylcholinesterase (AChE), glutathione S-transferase (GST), and oxidase. Scanning electron microscope (SEM) was used to investigate the ultrastructure of the morphological body of lice. After 30 min, 6-gingerol and C. citratus leaf extract killed P. h. capitis completely. Bioassay periods significantly affected lice mortality (P < 0.05). The LC50 values for 6-gingerol and C. citratus extract were 1.79 μg/cm2 and 25.0 μg/cm2, respectively. 6-Gingerol and C. citratus leaf extract significantly lower AChE and GST activity (P < 0.05). Cymbopogon citratus also caused morphological ultrastructure changes in P. h. capitis, including an irregularly formed head, thorax, abdominal respiratory spiracles, and belly. 6-Gingerol and C. citratus leaf extracts could be used as an alternate pediculicide to decrease P. h. capitis populations.

High mitochondrial gene diversity of Pediculus humanus capitis among children in northern Iran

BACKGROUND

The head louse, Pediculus humanus capitis, is an obligate ectoparasite and its infestation remains a major public health issue worldwide. Determining the genetic characteristics of the existing clades is essential to identify the population structure and to develop head lice-control programs. Hence, we aimed to investigate the genetic diversity of head lice among infested individuals in northern Iran.

METHODS

Adult head lice were collected from 100 infested individuals referring to the health centers throughout five geographical regions in Mazandaran Province, Iran. Partial fragments of the mitochondrial cytb gene were amplified by PCR, then consequently sequenced.

RESULTS

The results of the phylogenetic tree of collected head lice confirmed the existence of two clades, A and B, in the studied areas. Thirteen haplotypes were detected in the studied populations, of which 11 were novel haplotypes. Clade A was the dominant form and accounted for 75% of samples, while clade B included the rest. Haplotype and nucleotide diversity were 0.999 and 0.0411, respectively.

CONCLUSIONS

Clade A and B of Pediculus humanus capitis exist among the human populations of northern Iran. We observed high genotypic diversity of this head lice.

COVID-19 pandemic and the consumption of self-care products for pediculosis capitis in Portugal: an interrupted time-series analysis

This study aims to assess the effect of the COVID-19 pandemic on the consumption of self-care products for pediculosis capitis management, in Portugal. A segmented regression analysis of interrupted time series (March 2020) was performed from January 2017 to August 2023 to analyze the short- and long-term impact of the COVID-19 pandemic on the consumption of pediculicides and related products. Monthly rates of absolute consumption were estimated by community pharmacies' dispensing records. Portuguese municipalities were organized into quintiles according to their purchasing power index and percentage of youth, to study the association of these social and demographic variables on the sale of these products. COVID-19 pandemic significantly reduced the sales of products indicated for pediculosis. Since the start of the pandemic, an absolute decrease of 21.0 thousand packages was observed in the monthly average consumption (p < 0.0001) compared to the pre-pandemic period. After this reduction, the average monthly trend increased in the pandemic period in comparison with the previous period, although not significant (267.0 packages per month, p = 0.1102). Regions with higher disposable income and more young people were associated with higher sales of these products. The outbreak of the COVID-19 pandemic has had a notable impact on the sales of self-care products for pediculosis capitis in Portugal, in the short term. The lockdowns and other isolation measures implemented to control the spread of the virus may have led to a decrease in the number of head lice cases, consequently resulting in a reduction in sales of products.

Effectiveness and chemical insights: Exploring interactions between nanomicelles and monoterpenoids for head lice treatment

This study evaluates the pediculicidal activity of nanoformulations containing different binary essential oil component mixtures (eugenol:linalool, 1,8 -cineole:linalool, and eugenol:thymol) using immersion bioassays. These have allowed us to evaluate the knockdown time affecting 50% of the individuals (KT50). In addition, the type of interaction between the components in each mixture was established in terms of the combination index (IC). The KT50 values were 6.07; 8.83; 7.17 and 27.23 h for linalool, 1,8 -cineole, eugenol, and thymol, respectively. For the eugenol:linalool mixtures, the efficacy was lower or equal to that obtained for the nanoformulations of the pure compounds, with values of KT50 about 13.33, 8.16 and 6.71 h for mixtures with ratios 3:1, 1:1 and 1:3, respectively. These mixtures present IC > 1, evidencing antagonistic interaction, which is enhanced with eugenol content. In the case of the binary mixtures of 1,8 -cineole: linalool, KT50 values were similar to those obtained for eugenol:linalool mixtures with similar ratios. In this case, IC assumes values close to unity, suggesting additive interactions independently of the mixture composition. On the other side, mixtures of eugenol:thymol with 1:1 and 1:3 ratios showed values of 9.40 and 32.93 h, while the mixture with a 3:1 ratio showed the greatest effectiveness (KT50 of 4.42 h). Eugenol:thymol mixtures show synergistic interaction (IC < 1) for combinations 3:1 and 1:1, while no interaction was observed for 1:3 combination. This indicates that eugenol enhances thymol activity. These results must be considered an important step forward to the development of effective pediculicidal nanoformulations based on botanical compounds.

Body lice: a vector for re-emerging disease outbreak in a rehabilitation camp in Northwestern Iran

OBJECTIVE

The report of the outbreak of body louse in northwestern Iran after three decades reminds us again of the danger of the re-emerging of previous epidemics.

RESULTS

The results of the study that nearly 70% of the patients in a rehabilitation Centre were infected with body louse. In this study, scientific measures were taken to prevent the spread of body lice to healthy people, including isolation of the patients, washing the clothes of those infected at high temperatures, and spraying the rest area, beddings, and blankets. This is a more recent report on an outbreak of body louse in Iran in 2023.

Comparative efficacy of chemical and botanical pediculicides in Thailand and 4% dimeticone against head louse, Pediculus humanus capitis

Head louse infestations remain a global public-health concern due to increased resistance of lice to artificial pediculicides. In Thailand, there is a lack of comparative data on the current efficacy of pediculicides for treating head lice. In this study, we explored the status of botanical and toxic synthetic pediculicides with that of 4% dimeticone liquid gel for treating head lice in Thailand. The ex-vivo pediculicidal activity of various pediculicidal shampoos available at drugstores in Thailand was assessed and compared with that of 4% dimeticone liquid gel. The shampoos chosen were based on active ingredients toxic to lice (1% permethrin, 0.6% carbaryl, 0.15% Stemona root crude extract, or mixed plant extracts), whereas dimeticone acts physically on lice. We found that exposure to 4% dimeticone liquid gel following the manufacturer's instructions completely killed 100% of head lice in 15 min, whereas other pediculicide products failed to kill the great majority of head lice, whether treatment was for 10 min (resulting in 0% to 50.0% mortality) or 30 min (resulting in 17.0% to 60.0% mortality). We also extended a clinical assessment to confirm the efficacy of 1% permethrin for treating head lice in infested schoolchildren. In this clinical assessment, none of the 26 children treated with 1% permethrin shampoo achieved a cure after two applications. These results highlight that 4% dimeticone demonstrated a higher ex-vivo pediculicidal efficacy compared to both chemical and botanical pediculicides in Thailand. Conversely, 1% permethrin showed low efficacy in both laboratory and clinical assessments. Given its physical mode of action, 4% dimeticone merits consideration as an alternative treatment option for lice in Thailand, particularly in cases where treatment with toxic pediculicides has proven ineffective.

Pediculosis humanus capitis in 6-7 years old schoolchildren in Valencia, Spain

OBJECTIVES

Pediculosis humanus capitis is a worldwide public health concern that affects mostly school-aged children. The aim of this study is to determine the rate of pediculosis and to determine possible risk factors in a group of primary school children in Valencia, Spain; 227 children, 6-7 years old, were selected from 7 schools.

METHODS

A self-reported questionnaire completed by the parents/guardians about the presence of pediculosis in their children and their knowledge about pediculosis. The results recorded in the questionnaire were analysed by SPSS® software.

RESULTS

30.4% of the children had pediculosis. The results showed significant variation (p < 0.05) in prevalence depending on the following factors: sex, hair length, level of parental education, family size, presence of affected family member in the home, and frequency of hair washing. Less than half of parents/guardians showed an appropriate level of knowledge on pediculosis. Pediculosis remains a health problem in Valencian schoolchildren. The family size and existence of another member with pediculosis were shown to be the main potentiating factors.

CONCLUSIONS

Parents are not sufficiently informed about pediculosis and adopt inappropriate practices. There is a need to promote studies with the objective of determining risk factors for pediculosis as well as the need for actions to increase the knowledge of parents and healthcare professionals on this parasitosis to prevent outbreaks in the community, assure correct treatment and maintain effective epidemiological surveillance.

Head Lice Infestation in Pre-High School Girls, Lak Hok Suburban Area, Pathum Thani Province, in Central Thailand

This is a cross-sectional descriptive survey to determine the prevalence of lice infestation in a pre-high school, Lak Hok subdistrict, Pathum Thani Province, in central part of Thailand. The knowledge, attitudes, and practices of parents/guardians toward head lice in female children during February-April 2020 were evaluated. A total of 83 out of 111 parents (74.8%) agreed to complete consent forms and questionnaires. The prevalence of pediculosis found in this study was 68.7%. The infestation was found in the primary school level (87.5%), which was significantly higher than pre-primary school (29.6%; p < 0.05). Itching scalp was revealed in 93.0% of pediculosis. The results showed that occupation, religion, education, and income showed no significant difference between lice infested and non-infested students (p > 0.05). There was no significant association between sex, occupation, religion, education, income, status of parents, and family size among lice infested and non-infested students (p > 0.05). The parents/guardians showed the middle level of knowledge concerning with pediculosis capitis (66.8%). The lack of knowledge leading, first, to the belief that pediculosis does not need any treatment (89.2%), followed by boys getting head lice more frequently than girls (85.5%), and the belief that sharing infested combs, brushes, or hair ribbons does not result in lice transmission (79.9%). More than 75% of the parents/guardians had experienced infestation of head lice and showed themselves willing and able to diagnose and treat their family. However, 50.6% of them did not feel shame when their children were infested with head lice. Children washing their hair by themselves were found to be a significant factor in infestation (88.5%). High rate of pediculosis in this suburban school needs more intensive care by parents/guardians and teachers. Furthermore, improvement strategies to prevent and control lice in the school need to be more specifically planned and scheduled by teachers and health administrators.

Pyrethroid-linked resistance allelic mutations by molecular analysis in wild human head louse (Phthiraptera: Pediculidae) populations from schoolgirls of South Iran

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.

Human pediculosis, a global public health problem

BACKGROUND

Human pediculosis is caused by hematophagous lice, which are transmitted between individuals via direct and/or indirect contact. Despite the public health importance of louse infestation, information concerning the global burden of pediculosis and the epidemiological landscape of louse-borne diseases is limited. The aim of this review was to summarize the biology, epidemiology, diagnosis, and control of lice infestation in humans. We also discussed the latest advances in molecular taxonomy and molecular genetics of lice.

METHODS

We searched five electronic bibliographic databases (PubMed, ScienceDirect, CNKI, VIP Chinese Journal Database, and Wanfang Data) and followed a standard approach for conducting scoping reviews to identify studies on various aspects of human lice. Relevant information reported in the identified studies were collated, categorized, and summarized.

RESULTS

A total of 282 studies were eligible for the final review. Human pediculosis remains a public health issue affecting millions of people worldwide. Emerging evidence suggests that head lice and body lice should be considered conspecific, with different genotypes and ecotypes. Phylogenetic analysis based on mitochondrial (mt) cytb gene sequences identified six distinct clades of lice worldwide. In addition to the direct effect on human health, lice can serve as vectors of disease-causing pathogens. The use of insecticides plays a crucial role in the treatment and prevention of louse infestation. Genome sequencing has advanced our knowledge of the genetic structure and evolutionary biology of human lice.

CONCLUSIONS

Human pediculosis is a public health problem affecting millions of people worldwide, particularly in developing countries. More progress can be made if emphasis is placed on the use of emerging omics technologies to elucidate the mechanisms that underpin the physiological, ecological, and evolutionary aspects of lice.

Head Lice Infestation in Schoolchildren, in Poland-Is There a Chance for Change?

Pediculosis capitis is a current and neglected health issue worldwide. The lack of screening programs contributes to the marginalization of the problem and delays therapeutic measures. Our study aimed to analyze the occurrence of this parasitosis in primary schools in Poland and to determine factors contributing to the persistence of its foci. The research tools were two questionnaires: one for primary school children and the other for school managers. While children answered questions about the epidemiology of pediculosis capitis and expressed their opinion on the hygienic condition of infested persons, the school directors were asked about the occurrence of head lice in schools, preventive measures, and institutions supporting schools in combating the infestation. The survey covered the period 2014–2018. Pediculosis capitis was reported in 87.5% of the schools. The greatest number of cases was reported in the group of 6–9 year-olds (68%). Among 4970 children, 16.7% had no knowledge of head lice; however, 57.1% wanted to increase their awareness of the problem. Campaigns on lice were conducted mainly as a result of emerging pediculosis capitis cases, and most schools could not rely on institutional support. Screening programs and preventive educational campaigns should be part of pediculosis capitis control in Poland.

Frequency of pyrethroid resistance in human head louse treatment: systematic review and meta-analysis

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.

Effects of the Covid-19 pandemic on head lice and scabies infestation dynamics: a population based study in France

BACKGROUND

Lockdowns and physical distancing have dramatically limited the circulation of SARS-CoV-2 and other common communicable infections. However, little is known about their impact on head lice and scabies.

OBJECTIVES

To assess the impact of the 2020 French National lockdowns (March 17^th -May 11^th , and Oct 30^th -Dec 15^th ) and physical distancing recommendations (from February 2020) on the head lice and scabies infestation dynamics.

METHODS

The weekly sales of topical head lice treatments, topical scabies treatments, and oral ivermectin were extracted from the IQVIA database (60% of all French retail pharmacies) and analysed over a 5-year period (March 2016 - December 2020). A periodic regression model was fit to drug sales before the COVID-19 period (i.e. 2016-2019) and extrapolated afterwards in order to compare the sales observed in 2020 to the expected sales.

RESULTS

A decrease of the sales of tracer topical treatments for head lice and scabies was observed from March 2020, synchronously with the first French national lockdown. For the period March 2020-December 2020, the mean reduction in observed versus expected sales were 44% and 14% for head lice and scabies topical treatments, respectively. On the other hand, the observed decrease of oral ivermectin sales after March 2020 was much lower (4%), probably because of studies reporting the potential positive effects of this drug on the Covid-19 infection.

CONCLUSION

COVID-19 lockdown and physical distancing reduce circulation of head lice and scabies in France. Further studies are needed to assess long term impact of these social behaviour changes.

Epidemiologic evolution of common cutaneous infestations and arthropod bites: A Google Trends analysis

Background

Common cutaneous infestations and arthropod bites are not reportable conditions in most countries. Their worldwide epidemiologic evolution and distribution are mostly unknown.

Objective

To explore the evolution and geographic distribution of common cutaneous infestations and arthropod bites through an analysis of Google Trends.

Methods

Search trends from 2004 through March 2021 for common cutaneous infestations and arthropod bites were extracted from Google Trends, quantified, and analyzed.

Results

Time series decomposition showed that total search term volume for pubic lice decreased worldwide over the study period, while the interest for ticks, pediculosis, insect bites, scabies, lice, and bed bugs increased (in increasing order). The interest for bed bugs was more pronounced in the former Union of Soviet Socialist Republics countries, interest for lice in Near East and Middle East countries, and interest for pubic lice in South American countries. Internet searches for bed bugs, insect bites, and ticks exhibited the highest seasonal patterns.

Limitations

Retrospective analysis limits interpretation.

Conclusion

Surveillance systems based on Google Trends may enhance the timeliness of traditional surveillance systems and suggest that, while most cutaneous infestations increase worldwide, pubic lice may be globally declining.

State-of-the-Art Techniques for Diagnosis of Medical Parasites and Arthropods

Conventional methods such as microscopy have been used to diagnose parasitic diseases and medical conditions related to arthropods for many years. Some techniques are considered gold standard methods. However, their limited sensitivity, specificity, and accuracy, and the need for costly reagents and high-skilled technicians are critical problems. New tools are therefore continually being developed to reduce pitfalls. Recently, three state-of-the-art techniques have emerged: DNA barcoding, geometric morphometrics, and artificial intelligence. Here, data related to the three approaches are reviewed. DNA barcoding involves an analysis of a barcode sequence. It was used to diagnose medical parasites and arthropods with 95.0% accuracy. However, this technique still requires costly reagents and equipment. Geometric morphometric analysis is the statistical analysis of the patterns of shape change of an anatomical structure. Its accuracy is approximately 94.0-100.0%, and unlike DNA barcoding, costly reagents and equipment are not required. Artificial intelligence technology involves the analysis of pictures using well-trained algorithms. It showed 98.8-99.0% precision. All three approaches use computer programs instead of human interpretation. They also have the potential to be high-throughput technologies since many samples can be analyzed at once. However, the limitation of using these techniques in real settings is species coverage.

Common pediatric infestations: update on diagnosis and treatment of scabies, head lice, and bed bugs

PURPOSE OF THE REVIEW

This review will update pediatric providers on the recent data regarding the epidemiology, diagnosis, and treatment of common skin infestations affecting children and adolescents.

RECENT FINDINGS

Standard superficial skin biopsy for scabies and the vacuum method for head lice can increase diagnostic accuracy and efficiency. There is growing resistance to some of the traditional treatments for scabies and head lice, and progress has been made in finding newer and potentially more effective treatments, such as oral moxidectin for scabies and abametapir for head lice. Recent studies have established the safety of traditional treatments, such as permethrin and oral ivermectin in infants and small children.

SUMMARY

Permethrin and ivermectin are both considered safe and effective for children and adolescents with scabies. Permethrin is generally considered safe in infants less than two months of age. Proper application of permethrin is critical, and providers should emphasize proper application technique. Treatment of head lice should only be initiated with active infestations. Resistance to permethrin continues to increase and other options are now available, including an over-the-counter topical ivermectin formulation. Identification and eradication of bed bug infestations are crucial in preventing bedbug bites.

Comparative efficacy and safety of interventions for treating head lice: a protocol for systematic review and network meta-analysis

Background

Head lice infestation is a major public health problem around the globe. Its treatment is challenging due to product failures resulting from rapidly emerging resistance to existing treatments, incorrect treatment applications and misdiagnosis. Various head lice treatments with different mechanism of action have been developed and explored over the years, with limited report on systematic assessments of their efficacy and safety. This work aims to present a robust evidence summarising the interventions used in head lice.

Method

This is a systematic review and network meta-analysis which will be reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement for network meta-analyses. Selected databases, including PubMed, Embase, MEDLINE, Web of Science, CINAHL and Cochrane Central Register of Controlled Trials will be systematically searched for randomised controlled trials exploring head lice treatments. Searches will be limited to trials published in English from database inception till 2021. Grey literature will be identified through Open Grey, AHRQ, Grey Literature Report, Grey Matters, ClinicalTrials.gov, WHO International Clinical Trials Registry and International Standard Randomised Controlled Trials Number registry. Additional studies will be sought from reference lists of included studies. Study screening, selection, data extraction and assessment of methodological quality will be undertaken by two independent reviewers, with disagreements resolved via a third reviewer. The primary outcome measure is the relative risk of cure at 7 and 14 days postinitial treatment. Secondary outcome measures may include adverse drug events, ovicidal activity, treatment compliance and acceptability, and reinfestation. Information from direct and indirect evidence will be used to generate the effect sizes (relative risk) to compare the efficacy and safety of individual head lice treatments against a common comparator (placebo and/or permethrin). Risk of bias assessment will be undertaken by two independent reviewers using the Cochrane Risk of Bias tool and the certainty of evidence assessed using the Grading of Recommendations, Assessment, Development and Evaluations guideline for network meta-analysis. All quantitative analyses will be conducted using STATA V.16.

Discussion

The evidence generated from this systematic review and meta-analysis is intended for use in evidence-driven treatment of head lice infestations and will be instrumental in informing health professionals, public health practitioners and policy-makers.

PROSPERO registration number

CRD42017073375.

Phylogeography and demographic history of Thai Pediculus humanus capitis (Phthiraptera: Pediculidae) revealed by mitochondrial DNA sequences

Pediculus humanus (human louse) is a hematophagous insect that feeds on human blood. It is distributed worldwide. Understanding phylogeography and population-genetic structure of the human louse will illuminate the evolution of this insect and the dynamics of how resistance alleles might spread in the landscape. In this work, we used mitochondrial (cox1 and cytb genes) sequences of the human louse to investigate genetic diversity, population-genetic structure and demographic history of the louse in Thailand. Human lice in Thailand belonged to mitochondrial clades A and C. Most genetic variation was attributed to intra-region 65.71% within provinces for clade A and 68.92% for clade C, while inter-region level was 34.40% among provinces within regions for clade A and 20.09% for clade C. Neutrality and other indices suggested that louse populations from clades A and C in Thailand have experienced a population expansion. But head lice from Khon Kaen Province in clade C demonstrated a significant recent population bottleneck or natural selective pressure with constant population size. Head lice in Thailand showed varying degrees of low to high genetic differentiation at the level of province with many populations being genetically distinct from each other among regions and within the same region. Knowledge of the clades present in Thailand and that gene flow occurs between regions will assist in developing appropriate strategies for management of head lice at the local level in the country.

Head lice were also affected by COVID-19: a decrease on Pediculosis infestation during lockdown in Buenos Aires

Pediculosis is a worldwide disease affecting school-aged children produced by the presence of the head louse, Pediculus humanus capitis De Geer, an obligate ectoparasite on the human scalp feeding exclusively on blood. Transmission occurs primarily through direct physical head-to-head contact. In March 2020, the World Health Organization (WHO) declared the COVID-19 outbreak as a pandemic. COVID-19 is caused by SARS-CoV-2, a variant of the coronavirus. Therefore, on March 18, 2020, the Argentinean government established mandatory isolation for an indefinite period. This obligatory isolation interrupted regular classes avoiding direct contact between children, thus affecting the dispersal route of individuals and the evolution of head louse populations. In this study, we evaluated through an online survey how confinement affected the prevalence of lice during lockdown compared to the situation prior to confinement. The survey allowed to discriminate the different control strategies, the number of treatments, and the amount of insects recorded by parents. Data of 1118 children obtained from 627 surveys were analyzed. As the main result, it was observed that prevalence of lice decreased significantly from before (69.6%) to during (43.9%) COVID-19 lockdown. Moreover, head lice infestation was more effectively controlled in households with up to 2 children in comparison to households with 3 or more children. This is the first study that analyzed the prevalence of head lice during COVID-19 pandemic. In addition, this work demonstrated the impact of social distance in the population dynamics of head lice and how it could affect the control strategies in the future.