Head lice infestations in rural Honduras: the need for an integrated approach to control neglected tropical diseases

Impact factors and genetic characteristics of head lice infestation in schoolchildren: a cross-sectional study from 2018 to 2023 in central China

BACKGROUND

Head lice (Pediculus humanus capitis) infestation is a worldwide public health concern, especially in school-aged children. However, its main impact factors and genetic characteristics remain poorly understood in China. Hence, the purpose of the study was to explore the precise association between multiple impact factors and head lice infestation, characterize the genetic variation of the head lice, and develop a sensitive and specific mitochondrial (mt) DNA duplex polymerase chain reaction (PCR) for accurately distinguishing clades A and B.

METHODS

A cross-sectional study was conducted in Hunan Province, central China from January 2018 to July 2023. A total of 9254 schoolchildren from 48 primary schools in each administrative region were examined for head lice. Impact factors for infestation were analyzed using the data collected by a questionnaire. The mt cytb gene sequences of head lice collected in the current study were used for sequence analysis, then were added to the global pool to conduct the phylogenetic analyses. Primers designed on the basis of this gene sequence were used in duplex PCR to diagnose head lice clades A and B by amplicon size.

RESULTS

Head lice infestation was found in 93.8% (45/48) of the primary schools included in the study. Overall, 6.8% (630/9254) of the examined schoolchildren harbored head lice, with 94.6% (596/630) being girls. A total of 2132 adult head lice were collected from 630 infested cases. The impact factors for head lice infestation included gender, school location, family situation, per capita income, study mode, and hair washing per week (p < 0.01). However, season and age were not considered as impact factors for head lice prevalence (p > 0.05). Phylogenetic analysis based on mt cytb gene sequences showed that head lice are classified into two clades (A and B), with clade B being more dominant in Hunan Province, central China. The newly developed duplex PCR was able to differentiate clades A from B in China with 100% sensitivity and specificity.

CONCLUSIONS

Our findings revealed that head lice infestation is mostly associated with poverty and poor hygiene in Hunan Province, central China. It is crucial to consider the simultaneous surveillance of head lice infestation in schoolchildren in regions with low level of socioeconomic status; however, datasets from other provinces are warranted to confirm the findings. It further showed that clades A and B are common in central China and that the latter has emerged and become the dominant one.

Collateral benefits of ivermectin mass drug administration designed for malaria against headlice in Mopeia, Mozambique: a cluster randomised controlled trial

BACKGROUND

Headlice are prevalent worldwide, with a higher burden in rural, lower-middle income settings. They can cause intense itchiness, discomfort, and secondary bacterial infections with potentially serious consequences. Ivermectin is efficacious against headlice, and is also being evaluated as a malaria vector control tool. In this study, we explored risk factors for headlice, and assessed the efficacy of ivermectin mass drug administration (MDA) designed for malaria against headlice.

METHODS

We conducted an open-label, assessor-blind, cluster-randomized controlled trial in Mopeia, Mozambique. A single dose of ivermectin was given monthly to eligible humans or humans and livestock (humans: 400 μg/kg, livestock: 1% injectable 200 μg/kg) in 3 consecutive months during the rainy season. The control group received albendazole (humans only). Thirty-nine clusters (13 per arm) were randomly selected for the nested assessment of headlice prevalence. 1341 treated participants were followed up at least once, 1, 2 and 3 months and 382 untreated (ineligible) participants at 3 and 6 months after the first MDA round. Headlice diagnosis was determined by scalp examination. Logistic regression was used to identify risk factors for headlice at baseline, and to estimate the treatment effect at each time point.

RESULTS

A total of 1309 participants were included in the main analysis assessing ivermectin MDA efficacy, and 1332 in the risk factor analysis. The baseline headlice prevalence was 11%. Risk factors included living with a household member with head itch [adjusted odds ratio (aOR) = 48.63, 95% confidence interval (CI): 28.7-82.3, P-value < 0.0001], being female (aOR = 2.25, 95% CI: 1.33-3.80, P-value < 0.01), and using surface water as the main water (aOR = 2.37, 95% CI: 1.12-5.33, P-value = 0.04). The treated population receiving ivermectin had significantly lower odds of having headlice at 3 months compared to those receiving albendazole (aOR = 0.19, 95% CI: 0.04-0.91, P-value = 0.04). There was no indirect effect on headlice among children ineligible for treatment.

CONCLUSIONS

In a highly endemic setting, mass drug administration with ivermectin significantly reduces headlice infestation prevalence among those who receive the drug for three sequential months. The lack of effect among untreated, ineligible children implies that additional interventions would be needed to interrupt local transmission.

TRIAL REGISTRATION

This study is registered with ClinicalTrials.gov (NCT04966702).

Systematic review of the evidence for treatment and management of common skin conditions in resource-limited settings: An update

INTRODUCTION

The skin is the largest and most visible organ of the human body. As such, skin infections can have a significant impact on overall health, social wellbeing and self-image. In 2019, we published a systematic review of the treatment, prevention and public health control of skin infections including impetigo, scabies, crusted scabies and tinea in resource-limited settings where skin infections are endemic. This current review serves as an update to assess the evidence for treatment of these conditions as well as atopic dermatitis, molluscum contagiosum and head lice in endemic settings. The data from this systematic review have supported an update to the Australian National Healthy Skin guidelines.

METHODS

A systematic review was conducted using two separate searches in MEDLINE, PubMed, Embase, CINAHL, Cochrane and Web of Science. The first search was an update of the 2018 systematic review using the same search strategy for the same skin conditions to identify emerging literature from 2018 to 2022. The second search strategy used the same key terms but with the addition of atopic dermatitis, head lice and molluscum contagiosum from 1960 to 2022. Eligible studies included Indigenous peoples and populations in resource-limited settings with a diagnosis of impetigo, scabies, crusted scabies, tinea capitis, atopic dermatitis, molluscum contagiosum or who presented with head lice. Studies conducted in high-income countries were excluded. Articles were screened for inclusion independently by one author with a second group of reviewers independently double screening. Data extraction and an in-depth quality assessment conducted by one author and checked by two others.

RESULTS

Of 1466 original articles identified, 68 studies were included and key findings outlined for impetigo, scabies, crusted scabies, atopic dermatitis, head lice and molluscum contagiosum. Recommendations for each condition based on the available evidence are provided.

CONCLUSION

The importance of assessing literature relevant to the populations with heavy burden of skin infections is outlined in this systematic review. We have summarised updates to this literature, which may benefit in developing guidelines for skin infection management similar to the National Healthy Skin Guidelines for Australia.

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.

Molecular detection of hemotropic Mycoplasma and Bartonella species in lice from sheep and goats of Mexico

The knowledge of lice associated with small ruminants, especially sheep and goats, is scarce. In Mexico, there are historical reports of six species of chewing and sucking lice associated with Capra hircus and Ovis canadensis. However, the reports did not analyze the ecology of the infestations or the presence of potentially pathogenic bacteria. For this reason, the objectives of this study were i) to identify the species of lice associated with sheep and goats in three states of the Mexican Republic, ii) to characterize the infestations, and iii) to identify the presence of bacterial pathogens. From October 2019 to August 2021, six ranches with sheep and goats were sampled in the states of Hidalgo and Veracruz. Hosts were visually inspected, and lice were retrieved with forceps. The specimens were sexed and identified using morphological taxonomic keys. DNA extraction was performed individually, and a fragment of the cytochrome oxidase subunit 1 gene (COI) was amplified for the molecular identification of the specimens. Subsequently, Anaplasma, Bartonella, Ehrlichia, Mycoplasma, and Rickettsia were molecularly detected. Additionally, the infestations were characterized by calculating the prevalence and mean abundances. We collected 563 specimens of three species, Bovicola caprae, Bovicola ovis, and Linognathus africanus. The highest infestation levels were recorded for B. ovis (66.7%; 4.4) from Veracruz. Additionally, two Bartonella species were detected: Bartonella mellophagi in B. ovis and Bartonella capreoli in L. africanus. In contrast, Mycoplasma ovis was detected exclusively in one pool of B. ovis. This study provides new bacterial-ectoparasite associations and highlights the possible role of these neglected ectoparasites as vectors in the populations of sheep and goats from Mexico.

First Detection of Acinetobacter baumannii in Pediculus humanus capitis from Latin America

Several studies have documented the presence of Acinetobacter baumannii, a known multi-drug-resistant pathogen, in the human head louse, Pediculus humanus capitis. Since no reports from countries in Latin America have been published, the aim of the present study was to determine whether A. baumannii was present in head lice specimens collected in this geographic region. Head lice specimens from Argentina, Colombia, and Honduras were analyzed. PCR assays were performed to confirm the specimens' species and to investigate whether the DNA of A. baumannii was present. The products of the latter were sequenced to confirm bacterial identity. Altogether, 122 pools of head lice were analyzed, of which two (1.64%) were positive for A. baumannii's DNA. The positive head lice had been collected at the poorest study site in Honduras. The remaining specimens were negative. This study is the first to report the presence of A. baumannii in human head lice from Latin America. Further investigations are required to elucidate whether these ectoparasites can serve as natural reservoirs or even effectively transmit A. baumannii to humans.

First exploratory study of bacterial pathogens and endosymbionts in head lice from a Mayan community in southern Mexico

Lice represent one of the most neglected group of vectors worldwide, particularly in Latin America. Records of bacterial agents related to head lice are non-existent in this region of the continent. Many of these communities often do not have adequate access to public services and/or health protection. The normalization of this condition prevents them from manifesting discomfort, such as bites and itching, which further aggravates the situation, as they can be vectors of important diseases. For this reason, the aim of this work was to identify the richness of bacterial pathogens (Acinetobacter, Bartonella, and Rickettsia) and endosymbionts (Wolbachia) in head lice of paediatric patients from the indigenous municipality of Hoctun, Yucatan, Mexico. DNA extraction was performed using the QIAamp DNA Mini Kit. For the detection of bacterial pathogens, fragments of the gltA, rpoB, and 16S rDNA genes were amplified. For the detection of Wolbachia, the wsp gene was amplified. Of the 28 lice analysed, the presence of two genera of bacterial pathogens was detected Acinetobacter (42.9% = 12/28) and Bartonella (7.14% = 2/28). We also detected the endosymbiont Wolbachia (71.42% = 20/28). Our results showed that DNA from three bacteria species (Acinetobacter baumannii, Bartonella quintana, and Wolbachia pipientis) was present with frequencies ranging from 3.57% to 71.42%. This work represents the first exploratory study of the diversity of agents associated with head lice (Pediculus humanus capitis) in Mexico and Latin America. Due to the findings generated in the present study, it is important to perform surveillance of head lice populations to identify the degree of spread of these pathogens and their impact on populations in the region.

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.

Head Lice at School: Traditional Medicine and Community Engagement

Purpose: The prevalence of head lice in poor rural communities and urban slums is estimated to be between 28% and 43% in Brazil, respectively. Children are among the most affected, often in clusters within schools. We launched a program intending to tackle the social stigma associated with head lice using scientific information and a local traditional remedy as a way to lower the prevalence of head lice in a low-resource community. Methods: A program involving the entire school community and the teachers addressed how to treat head lice and avoid new infestations. An affordable solution widely used in traditional Brazilian medicine was provided for the ones infested. Evaluation of the outcome was based on direct observation and was designed as a satisfaction survey. The study complied with the criteria for Standards for Reporting Qualitative Research (SRQR). Results: Two hundred and eighty participants, including parents and siblings of the school children, took part in the program. Among them, 24% (N=67) had head lice, with girls representing 85% of cases; 74.7% of participants infested with head lice were between 4 and 10 years old; 55.2% (N=37) of participants infested showed no signs of nits or adult lice after the program. Conclusions: This experience suggests that the use of playful activities associated with a well-known and accessible local product to treat head lice in low-income families gathered a high degree of community adherence and may be an important tool in overcoming health inequalities.

First evidence of the mutations associated with pyrethroid resistance in head lice (Phthiraptera: Pediculidae) from Honduras

Background

The human head louse, Pediculus humanus capitis, is a cosmopolitan blood-sucking ectoparasite affecting mostly schoolchildren in both developed and developing countries. In Honduras, chemical pediculicides are the first line of treatment, with permethrin as their main active ingredient. Despite the extended use of these products, there is currently no research investigating insecticide resistance in Honduran head lice. In head lice, the most common mechanism is knockdown resistance (kdr), which is the result of two point mutations and the associated amino acid substitutions, T917I and L920F, within the voltage-sensitive sodium channel (VSSC).

Methods

Genomic DNA was extracted from 83 head lice collected in the localities of San Buenaventura and La Hicaca, Honduras. Polymerase chain reaction (PCR) was used to amplify a 332-bp fragment of the VSSC gene that contains a site affected by C/T mutation which results in a T917I amino acid substitution on each human head louse genomic DNA fragments.

Results

The C/T non-synonymous mutation which results in the T917I kdr amino acid substitution was detected in both head lice populations at frequencies ranging between 0.45–0.5. Globally, the frequency of this substitution was 0.47. Of these, 5 (6.1%) were homozygous susceptible and 78 (93.9%) were heterozygotes. The kdr-resistant homozygote (RR) was not detected in the studied populations. Thus, 93.9% of the head lice collected in Honduras harbored only one T917I allele. Exact test for the Hardy-Weinberg equilibrium for both localities showed that genotype frequencies differed significantly from expectation. In addition, San Buenaventura and La Hicaca populations had an inbreeding coefficient (F_is) < 0, suggesting an excess of heterozygotes.

Conclusions

To our knowledge, this is the first study showing the presence of the C/T mutation responsible of the T917I kdr allele associated with pyrethroid resistance in P. h. capitis from Honduras. The PCR-restriction fragment length polymorphism (RFLP) employed here has demonstrated to be a reliable, economic, and reproducible assay that can be used to accurately genotype individual head lice for the mutation encoding the resistance-conferring T917I amino acid substitution. This highlights the necessity of proactive resistance management programmes designed to detect pyrethroid mutations before they become established within populations of head lice.

Assessing the link between head lice infestation and selected cognitive-behavioral factors in a sample of Iranian female adolescents

Background

Head lice infestation is a serious health issue among adolescents in Iran. The primary purpose of the study was to determine the association of head lice infestation with cognitive-behavioral factors in female adolescents.

Methods

The study was cross-sectional, took place between September and October of 2017 in Sarab, East Azerbaijan province, Iran. Using a multi-stage sampling to recruit the study's 226 female adolescents, five of the Sarab's 13 schools were selected through simple random sampling. In the second step, the students were randomly selected using the systematic random sampling method. A survey questionnaire was used to collect the data.

Findings

The prevalence rate of head lice was calculated 20.4%, and the subjects with head lice infestation had lower levels of severity, benefits, self-efficacy, and preventive behaviors. Those without head lice infestation reported adhering to preventive behaviors. The perceived severity and self-efficacy were the statistically significant predictors of head lice infestation and use of preventive behaviors.

Conclusion

Public health authorities, with feedback from the community, must design and implement prevention programs, focusing on mothers and their school-aged children, school principals, and managers of public places as potential change agents. In addition to, perceived severity and self-efficacy should be considered as the key categories when developing these prevention programs.