Head lice infestations: A clinical update

The association between knockdown resistance and treatment outcome of 1% permethrin lotion in head lice infestations in Nonthaburi province, Thailand

Head lice infestations significantly impact schoolchildren, with permethrin being the primary treatment. The escalation in the prevalence of the knockdown resistance (kdr) mutation, potentially affecting treatment efficacy, is highly concerning. This study examined head lice infestation prevalence, the efficacy of 1% permethrin lotion, kdr mutation frequency, and the association between kdr genotype and permethrin treatment outcomes in schoolchildren in Nonthaburi province, Thailand. Participants and lice samples were collected from six primary schools using cluster sampling. Clinical outcomes and adverse events were assessed on days 7 and 14 post-treatment. Kdr mutations (T917I) in head lice samples were analyzed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Head lice infestation prevalence was 6.1%, with a kdr mutation frequency of 63.2% and a permethrin cure rate of approximately 50%. Multivariate regression analysis revealed the association between kdr genotype and clinical response to permethrin treatment (Odds Ratio (OR) = 13.15, p = 0.005). The presence of resistance genes hinders the cure rate (presence 35.9% versus absence 85.7%). These findings highlight the importance of the kdr genotype in predicting permethrin treatment responses in head lice infestations. Furthermore, in regions with documented reduced permethrin efficacy and a high prevalence of kdr mutations, alternative non-pyrethroid-based pediculicides should be considered. This research could help improve the control of head lice infestations, especially in problematic areas of Thailand.

Prevalence of head louse infestation among primary schoolchildren in the Republic of Korea: nationwide observation of trends in 2011-2019

Head louse infestation is a significant public health problem across the world, particularly among preschool and primary schoolchildren. This study investigated the trends of head louse infestation in the Republic of Korea over a 9-year period (2011-2019), targeting primary schoolchildren in 3 areas of Seoul, 4 other large cities, and 9 provinces. A survey was administered annually by the health staff of each regional office (n= 16) of the Korea Association of Health Promotion (KAHP). The branch offices of KAHP examined a total of 51,508 primary schoolchildren, comprising 26,532 boys and 24,976 girls. Over the 9-year survey, a total of 1,107 (2.1%) schoolchildren tested positive for adults and/or nits of Pediculus humanus capitis. The prevalence was 2.8% (133/4,727) in 2011-2012 and gradually decreased to 0.8% (49/6,461) in 2019 (P< 0.05). Head lice were found more frequently in girls (3.0%; 746/24,976) than in boys (1.4%; 361/26,532) (P< 0.05). In terms of geographic localities, the highest infestation rate, 4.7% (average prevalence over 9 years), was observed in southern Seoul (Gangnam branch of KAHP), whereas the lowest infestation rate, 0.7%, was seen in Gyeongsang (north and south provinces) and western Seoul. Although the prevalence decreased significantly during the 9-year period, head louse infestation remains a health and hygiene issue among primary schoolchildren in the Republic of Korea. Regular surveys along with health education are needed to further improve children's hair hygiene.

Head Lice

Head lice infestation is associated with limited morbidity but causes a high level of anxiety among caregivers of school-aged children and adolescents. Since the 2015 clinical report on head lice was published by the American Academy of Pediatrics, new medications have been approved, and an algorithm for management of affected patients is included. This revised clinical report clarifies current diagnosis and treatment protocols.

A Rare Case of Anemia Secondary to Lice Infestation

Lice are parasitic infections that can infect humans and survive by consuming host blood. They are most commonly associated with a lack of hygiene and occur most commonly in school-age children, homeless populations, and densely populated areas. Lice infections can potentially lead to vector-containing illness and are rarely complicated by acute blood loss anemia. These side effects, while exceedingly rare, are often very significant and potentially life-threatening. Here we present a rare case of severe anemia found in a patient with chronic lice colonization. We hope our findings will broaden the differential for acute anemias and raise awareness of lice infection as a possible cause of acute anemia.

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.

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.

Children’s Perception Scale of Head Lice Infestation (CPS-HLI): Design and Psychometrics

Background: Pediculosis is a common ectoparasitic infestation that involves especially the skin of children worldwide. Studying the children’s perception of the disease’s risk factors, the effectiveness of personal preventive measures, and its implications for their health could be a major leap forward in health promotion activities. Objectives: This study aimed to develop and evaluate the psychometric properties of the Children’s Perception Scale of Head Lice Infestation (CPS-HLI) and its initial feasibility assessment for use on Iranian and possibly other elementary school children. Methods: The scale’s items were retained based on an extensive literature search and classified into the underlying constructs of the extended health belief model (EHBM). An expert panel endorsed the qualitative content and face validity of the preliminary draft, and 47 items remained for quantitative validity testing on a sample of 362 elementary school students in the city of Paveh, West of Iran. Explanatory and confirmatory factor analyses (EFA and CFA) were employed to test the content and structural validity of the constructed instrument. Cronbach's alpha and intra-class correlation coefficients were calculated to assess the internal consistency and reliability of the scale. Results: The values of Lawshe's content validity index (0.90) and content validity ratio (0.77), the subscales’ Cronbach's alpha (0.59), and intra-class correlation (0.72) coefficients confirmed plausible internal consistency of the scale. The values of root mean square error of approximation (RMSEA) (< 0.08 with χ2 < 0.05), Tucker-Lewis index (TLI), and comparative fit index (CFI) > 0.9 approved the applied statistical model’s goodness of fit. The ranges of Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy for the underlying subscales (0.49 - 0.74) and the statistically significant result of Bartlett’s test of sphericity (P < 0.001) confirmed the patterned relationship among the constructed scale’s items. The principal component analysis that was performed using STATA favored the 11-factor solution. Conclusions: The study findings support the construct validity of CPS-HLI for use in studies on children’s perception of head lice infestation risk factors, the effectiveness of personal preventive measures, and the disease implications for their health and well-being. Further cross-cultural and cross-national validation studies are recommended for using the instrument in a wider range of populations and settings.

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.

[Parasitoses in childhood]

Parasitoses are a frequent occurrence in pediatric consultations in both hospitals and private practices. Responsible for this are parasites that permanently infest human skin, such as Sarcoptes scabiei hominis and Pediculus humanus capitis (persistent parasites) as well as those that only attack the skin for feeding, such as Pulex irritans, Cimex lectularius und Neotrombicula autumnalis (transient parasites). The main symptom of parasitoses is pruritus, which is caused by a delayed allergic reaction to proteins in the saliva of the parasites. In some parasitoses, such as scabies, the pruritus is typical, occurs particularly at night and is associated with a considerable impairment in the quality of life due to the resulting lack of sleep, whereas the pruritus is often absent in the case of pediculosis capitis. In this article persistent and transient parasitoses are characterized based on the patient history, morphology and symptoms.

Presence of the knockdown resistance (kdr) mutations in the head lice (Pediculus humanus capitis) collected from primary school children of Thailand

Human head lice are blood-sucking insects causing an infestation in humans called pediculosis capitis. The infestation is more prevalent in the school-aged population. Scalp itching, a common presenting symptom, results in scratching and sleep disturbance. The condition can lead to social stigmatization which can lead to loss of self-esteem. Currently, the mainstay of treatment for pediculosis is chemical insecticides such as permethrin. The extended use of permethrin worldwide leads to growing pediculicide resistance. The aim of this study is to demonstrate the presence of the knockdown resistance (kdr) mutation in head lice populations from six different localities of Thailand. A total of 260 head lice samples in this study were collected from 15 provinces in the 6 regions of Thailand. Polymerase chain reaction (PCR) was used to amplify the α subunit of voltage-sensitive sodium channel (VSSC) gene, kdr mutation (C→T substitution). Restriction fragment length polymorphism (RFLP) patterns and sequencing were used to identify the kdr T917I mutation and demonstrated three genotypic forms including homozygous susceptible (SS), heterozygous genotype (RS), and homozygous resistant (RR). Of 260 samples from this study, 156 (60.00%) were SS, 58 (22.31%) were RS, and 46 (17.69%) were RR. The overall frequency of the kdr T917I mutation was 0.31. Genotypes frequencies determination using the exact test of Hardy-Weinberg equilibrium found that northern, central, northeastern, southern, and western region of Thailand differed from expectation. The five aforementioned localities had positive inbreeding coefficient value (F_is > 0) which indicated an excess of homozygotes. The nucleotide and amino acid sequences of RS and RR showed T917I and L920F point mutations. In conclusion, this is the first study detecting permethrin resistance among human head lice from Thailand. PCR-RFLP is an easy technique to demonstrate the kdr mutation in head louse. The data obtained from this study would increase awareness of increasing of the kdr mutation in head louse in Thailand.

Head louse infestation is still a common health problem worldwide. Permethrin is the first line treatment of choice for pediculosis. However, the increase of recurrent cases and treatment failure of pediculosis raises public health concerns about the growing resistance of permethrin among head lice populations. Early determination of the permethrin resistance status is crucial in order to choose the pediculicide of choice appropriately. Our study demonstrated that the PCR-RFLP is a beneficial technique for knockdown resistance detection of T917I point mutation in head lice because it was inexpensive, accurate, and reproducible. Ultimately, our study emphasized that prompt investigation for permethrin resistance should be taken into account in the context of recurrent or treatment failure cases of pediculosis and the alternative chemical pediculicides based on different mechanism of action should be considered under those particular circumstances.

Economic Burden Associated with Head Louse (Pediculus humanus capitis) Infestation in Iran

Background

The head louse infestation is a public health issue in the world especially, affecting most people who live in camps, school-aged children and their families. Head lice treatment has economic ramifications that often under calculated. The aim of this study was evaluation of economic burden associated with head louse infestation in Iran.

Methods

In a cross-sectional study, 500,002 infestations were diagnosed among suspected head lice infested people who referred to health care system in all provinces of Iran during 2017. Direct and indirect costs related to paid by patients and government systems were extracted by referring to accounting documents and interviews with patients and experts and were recorded in researcher-made forms. Microsoft Excel 2010 software was used for economic burden calculation.

Results

The incidence rate of head lice infestation in Iran was 500,002/79,926,270 (625.5 per 100,000 populations). Economic burden of head lice in the country was calculated at 5,790,143$. Direct and indirect costs, governmental cost, out of pocket and total costs of head lice were included 3.14$, 2.84$, 5.98$, 5.60$ and 11.58$ per case respectively.

Conclusion

The direct and indirect costs associated with treatment of infestations were relatively high. Therefore, the creation of medical facilities such as availability of diagnostic and treatment strategies can be effective in the control of infestation. The adoption of infestation prevention methods, such as health education to people at risk of infestation, reduces the incidence of head lice and imposition of related treatment costs on governmental health care system and head lice cases.

Multi-region assessment of pharmaceutical exposures and predicted effects in USA wadeable urban-gradient streams

Human-use pharmaceuticals in urban streams link aquatic-ecosystem health to human health. Pharmaceutical mixtures have been widely reported in larger streams due to historical emphasis on wastewater-treatment plant (WWTP) sources, with limited investigation of pharmaceutical exposures and potential effects in smaller headwater streams. In 2014-2017, the United States Geological Survey measured 111 pharmaceutical compounds in 308 headwater streams (261 urban-gradient sites sampled 3-5 times, 47 putative low-impact sites sampled once) in 4 regions across the US. Simultaneous exposures to multiple pharmaceutical compounds (pharmaceutical mixtures) were observed in 91% of streams (248 urban-gradient, 32 low-impact), with 88 analytes detected across all sites and cumulative maximum concentrations up to 36,142 ng/L per site. Cumulative detections and concentrations correlated to urban land use and presence/absence of permitted WWTP discharges, but pharmaceutical mixtures also were common in the 75% of sampled streams without WWTP. Cumulative exposure-activity ratios (EAR) indicated widespread transient exposures with high probability of molecular effects to vertebrates. Considering the potential individual and interactive effects of the detected pharmaceuticals and the recognized analytical underestimation of the pharmaceutical-contaminant (unassessed parent compounds, metabolites, degradates) space, these results demonstrate a nation-wide environmental concern and the need for watershed-scale mitigation of in-stream pharmaceutical contamination.

Deterministic approaches for head lice infestations and treatments

Pediculus humanus capitis are human ectoparasites which cause infestations, mostly in children, worldwide. Understanding the life cycle of head lice is an important step in knowing how to treat lice infestations, as the parasite behavior depends considerably on its age and gender. In this work we propose a mathematical model for head lice population dynamics in hosts who could be or not quarantined and treated. Considering a lice population structured by age and gender we formulate the model as a system of hyperbolic PDEs, which can be reduced to compartmental systems of delay or ordinary differential equations. Besides studying fundamental properties of the model, such as existence, uniqueness and nonnegativity of solutions, we show the existence of (in certain cases multiple) equilibria at which the infestation persists on the host’s head. Aiming to assess the performance of treatments against head lice infestations, by mean of computer experiments and numerical simulations we investigate four possible treatment strategies. Our main results can be summarized as follows: (i) early detection is crucial for quick and efficient eradication of lice infestations; (ii) dimeticone-based products applied every 4 days effectively remove lice in at most three applications even in case of severe infestations and (iii) minimization of the reinfection risk, e.g. by mean of synchronized treatments in families/classrooms is recommended.

Medical and Social Factors of Pediculosis

Pediculosis is a global problem in public health. An important factor in the efficient eradication of lice is ensuring adequate recognition and treatment of the disease by the population. In the present study, awareness of the population about the physiological properties of head lice, the ways of infestation with head lice, and the methods of treatment and prevention were studied. Perception of the disease by the people who had had head pediculosis and other people around them was identified.

Prevalence and Alternative Treatment of Head-Lice Infestation in Rural Thailand: A Community-Based Study

Head-lice infestation, pediculosis capitis, remains a public-health burden in many countries. The widely used first-line pediculicides and alternative treatments are often too costly for use in poor socio-economic settings. Ivermectin has been considered an alternate treatment for field practice. This study was composed of 2 parts, a cross-sectional survey and an intervention study. The main objectives were to determine the prevalence and potential factors associated with head-lice infestation, and to evaluate the effectiveness and safety of oral ivermectin administration. A community-based cross-sectional survey was conducted among 890 villagers in rural areas along Thai-Myanmar border. Females with infestations were eligible for the intervention study, and 181 participated in the intervention study. A post-treatment survey was conducted to assess acceptance of ivermectin as a treatment choice. Data analysis used descriptive statistics and a generalized-estimation-equation model adjusted for cluster effect. The study revealed the prevalence of head-lice infestation was 50% among females and only 3% among males. Age stratification showed a high prevalence among females aged <20 years, and among 50% of female school-children. The prevalence was persistent among those with a history of infestation. The major risk factors were residing in a setting with other infected cases, and sharing a hair comb. The study also confirmed that ivermectin was safe and effective for field-based practice. It was considered a preferable treatment option. In conclusion, behavior-change communication should be implemented to reduce the observed high prevalence of headlice infestation. Ivermectin may be an alternative choice for head-lice treatment, especially in remote areas.

Effective treatments for head lice

Head lice is a parasitic infestation common in children. Proper management is essential to treat lice in a safe, convenient, cost-effective, and efficacious manner. School lice policies are often antiquated and can stigmatize the child and family. Evidence-based care guidelines may significantly help families minimize the stress of lice.

Tubule Nanoclay-Organic Heterostructures for Biomedical Applications

Natural halloysite nanotubes (HNTs) show unique hollow structure, high aspect ratio and adsorption ability, good biocompatibility, and low toxicity, which allow for various biomedical applications in the diagnosis and treatment of diseases. Here, advances in self-assembly of halloysite for cell capturing and bacterial proliferation, coating on biological surfaces and related drug delivery, bone regeneration, bioscaffolds, and cell labeling are summarized. The in vivo toxicity of these clay nanotubes is discussed. Halloysite allows for 10-20% drug loading and can extend the delivery time to 10-100 h. These drug-loaded nanotubes are doped into the polymer scaffolds to release the loaded drugs. The rough surfaces fabricated by self-assembly of the clay nanotubes enhance the interactions with tumor cells, and the cell capture efficacy is significantly improved. Since halloysite has no toxicity toward microorganisms, the bacteria composed within these nanotubes can be explored in oil/water emulsion for petroleum spilling bioremediation. Coating of living cells with halloysite can control the cell growth and is not harmful to their viability. Quantum dots immobilized on halloysite were employed for cell labeling and imaging. The concluding academic results combined with the abundant availability of these natural nanotubes promise halloysite applications in personal healthcare and environmental remediation.