Overdiagnosis and consequent mismanagement of head louse infestations in North America

Embryonic Development of Pediculus humanus capitis: Morphological Update and Proposal of New External Markers for the Differentiation Between Early, Medium, and Late Eggs

BACKGROUND AND OBJECTIVES

The head louse Pediculus humanus capitis is a cosmopolitan ectoparasite that causes pediculosis. In the study of human lice, little research focuses on embryonic development. Currently, external markers of embryonic development represent a new approach in the evaluation of ovicidal drugs. The objective of this work was to update the morphology of embryonic development and propose novel external markers to differentiate between early, medium, or late P. h. capitis eggs.

METHODS

Using stereoscopic light microscopy, we describe the morphological characteristics of P. h. capitis eggs with a special focus on embryonic development.

RESULTS

The morphological analysis of the eggs revealed the presence of an operculum with ten aeropyles, although no micropyles were observed. For the first time, the presence of defective eggs that were non-viable due to the apparent absence of yolk granules was documented. The early eggs presented yolk granules and developing germ bands, while the medium eggs presented an embryonic rudiment and the outlines of the eyes and limbs. In late eggs, the head with eyes and antennae, the thorax with three pairs of legs, and the abdomen with six pairs of spiracles were observed as formed structures. At the end of this stage, the embryos acquired the morphology of the nymph I stage.

CONCLUSION

We propose novel biomarkers (e.g., the presence of spiracles and antennae, the proportion of the egg occupied by the embryo) to facilitate the differentiation between the developmental stages. The updated morphological characteristics of P. h. capitis eggs facilitate the standardization of toxicological tests in the quest for ovicidal drugs.

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.

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.

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.

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.

International recommendations for an effective control of head louse infestations

Head louse infestations continue to be a concern of public health in most countries, including the most developed ones. The present recommendations are intended to inform and stress the role and impact of the different authorities, institutions, industry, and the public in the control of head lice in order to reduce the prevalence of this parasite. We encourage health authorities to pursue more effective methods to correctly identify such infestations, and evaluate existing and new pediculicides, medical devices, louse repellents, and louse- and nit-removal remedies. Pediculicides and medical devices must have verifiable claims in the instructions for use and should be tested periodically to document current levels of resistance by lice to the active ingredients and to the formulated products. Where the prevalence of lice is claimed to be epidemic, children should be periodically evaluated objectively to document the actual level of prevalence. Continuing education for health providers and the general population promises to correct misinformation regarding the biology, prevention, and management of lice. Parents should regularly inspect their children for head lice and treat as necessary. Health authorities are encouraged to eliminate policies and practices that rely upon school exclusion as a means to reduce incidence and prevalence, e.g., the 'no-nit' policy which lacks scientific justification, and are counterproductive to the health and welfare of children.

A Cosmetically Acceptable Dye Product to Improve Detection of Head Louse Eggs and Nits

Removing head louse eggshells and nits after a successful pediculicide treatment is often made more difficult because it is not easy to see them all amongst the hairs. Therefore, a treatment that makes louse eggs more visible potentially makes the task of removal easier and reduces the risk that children would be sent home from school or over-treated. This project involved the development of a hair treatment gel concept that was easy to apply, wash out, and that stained louse eggs and nits but without staining the hair and skin. A series of food-grade dyes were evaluated for their ability to stain the eggshells, and various copolymer-based rheology modifiers were tested for dye compatibility and stability. Several dyes were rejected because either they failed to stain louse eggshells or else stained skin too easily. Two dyes, Patent Blue and Ponceau 4R, were eventually selected for different product developments, one specifically for post-treatment nit removal and the other for pre-treatment diagnosis. In clinical field studies, both were found to make the treated eggshells contrast sufficiently with the hair to enable identification of persistent nits. Use of a nit stain product can enable easier detection of louse eggs and nits, thus facilitating the removal process and reducing the risk that persistent eggshells could be mistaken for signs of a continuing infestation.

Vaccuuming method as a successful strategy in the diagnosis of active infestation by Pediculus humanus capitis

Most human epidemiological and clinical studies use visual inspection of the hair and scalp to diagnose Pediculus humanus capitis , however this method has low sensitivity to diagnose active infestations (presence of nymphs and adult lice). Vacuuming the hair and scalp has been used as a diagnostic method, but there are no previous data comparing its effectiveness with visual inspection. The aim of this study was to determine the prevalence of overall infestation (nits and trophic stages), of active infestation by Pediculus humanus capitis , and to evaluate the effectiveness of vacuuming in comparison with the visual inspection. Visual inspection was performed by three examiners and vacuuming of the scalp by one investigator, with an adapted vacuum cleaner. A total of 166 children aged 4 to 10 years old were randomly selected from public schools in Southern Brazil. Considering the positive results obtained by both methods, the prevalence of overall infestation was 63.3%, whereas active infestation was 18.7%. The visual inspection was more effective on diagnosing overall infestation, however, its effectiveness to detect active infestation was lower, ranging from 0.6% (RR=3%, p<0.001) to 6.6% (RR=35%, p=0.001), depending on the number of examiners. The effectiveness of vacuuming to diagnose active infestation was higher than the one of visual inspection, with a prevalence rate of 16.3% (RR=87%, p=0.332). As presented in our study, the vacuuming method was 2.74 to 7.87 times most likely to detect active infestation, thus it could be adopted as a more accurate method to diagnose active pediculosis.

Stigma resulting from head lice infestation: A concept analysis and implications for public health

AIM

The aim of this concept analysis was to examine stigma in the context of head lice, illuminating its components and providing insights for the development of appropriate nursing interventions.

BACKGROUND

Stigma associated with the phenomenon of head lice management is pervasive, promulgating fear and influencing policy and treatment practices. Few studies have examined stigma in this context.

METHOD

The method followed was the Rodgers's evolutionary method.

DATA SOURCES

Health, education, and social sciences databases were searched and yielded 20 articles spanning 1996-2018 used to create a relevant literature review.

RESULTS

Stigma arising from head lice infestation is preceded by an actual or perceived case of head lice, negative perceptions of lice, negative perception of groups or persons with head lice, or being associated with a group or person of lesser status believed to be a carrier of head lice. Defining attributes include marks of infestation, negative and unfair beliefs, and shame. Consequences of stigma are economic costs, social costs, mistreatment, and overtreatment with pediculicides.

CONCLUSION

The concept of stigma in the context of head lice management is multifaceted. Further research is required to understand the magnitude of stigma as well as other factors associated with optimal treatment of children with head lice.

Lice Update: Management and Treatment in the Home

Lice infestation is a common health issue affecting 6 to 12 million school-age children in the United States each year, impacting all members of the household. The home care nurse can be a valuable resource in the management of lice in the home and can assist the family in understanding the various myths and misconceptions about lice. This article provides an overview of lice management, including identification and treatment of a lice infestation as well as recommendations for environmental control strategies in the home. It includes an overview of the various over-the-counter and prescription treatment options and highlights the social stigma that is often associated with a lice infestation.

Head lice infestations: A clinical update

Head lice (Pediculus humanus capitis) infestations are not a primary health hazard or a vector for disease, but they are a societal problem with substantial costs. Diagnosis of head lice infestation requires the detection of a living louse. Although pyrethrins and permethrin remain first-line treatments in Canada, isopropyl myristate/ST-cyclomethicone solution and dimeticone can be considered as second-line therapies when there is evidence of treatment failure.

No-Nit Policies in Schools: Time for Change

No-nit policies that exist in many schools throughout the United States were established years ago based on fear and misinformation, rather than scientific evidence. Children who are found to have live lice are no more infectious on the day of diagnosis than they had been prior to the discovery. Transmission of head lice requires close personal contact, which is not common in the school setting. To date, no scientific literature exists to support the exclusion of children from school due to head lice infestation. Therefore, there is a need to develop updated school policies using research-based evidence to determine the best method of treating infestations while allowing children to remain in school.

Head Lice

BACKGROUND

Conflicting information about the proper treatment of head lice has given rise to uncertainty among patients and treating personnel. For example, the reported efficacy of permethrin fell from 97% in the 1990s to 30% in 2010.

METHODS

Review of the literature based on a selective search of PubMed.

RESULTS

In Germany, outbreaks of head lice mainly occur among 5- to 13-year-olds returning to school after the summer vacation. Nymphs hatch from eggs after an average of 8 days and become sexually mature lice over the ensuing 9 days. The main route of transmission is direct head-to-head contact; transmission via inanimate objects is of no relevance. Symptoms arise 4-6 weeks after an initial infestation; many affected persons have no symptoms at all. Wet combing is the most sensitive method of establishing the diagnosis and monitoring treatment. Resistance to neurotoxic pediculocidal drugs is increasing around the world. Dimethicones are the treatment of choice, with 97% efficacy. Outbreaks must be managed with the synchronous treatment of all infested persons to break the chain of infestation. If the agent used is not ovicidal, the treatment must be repeated in 8-10 days and sometimes in a further 7 days as well.

CONCLUSION

Outbreaks of head lice can be successfully terminated by synchronous treatment with ovicidal dimethicones.

Head lice

Head lice infestation is associated with limited morbidity but causes a high level of anxiety among parents of school-aged children. Since the 2010 clinical report on head lice was published by the American Academy of Pediatrics, newer medications have been approved for the treatment of head lice. This revised clinical report clarifies current diagnosis and treatment protocols and provides guidance for the management of children with head lice in the school setting.

Socioeconomic status, family background and other key factors influence the management of head lice in Norway

How head lice infestations are managed by households is an important but generally neglected issue in head lice research. In the present study, we investigate actions taken against head lice by Norwegian households in association with socioeconomic status, family background, school-related variables and other key factors. Repeat questionnaires distributed to caretakers of the same elementary school children during a 2-year period enabled us to study both previous head lice management and any changes in this management through time. Households from 12 schools spanning the main socioeconomic variation found in Norway participated in the study. All students with active head lice infestation were treated in the four investigated periods. Most caretakers used a thorough head lice checking technique and informed others of own infestation. Checking frequency was low as most children were inspected less than monthly. The best determinant of increased checking frequency and thoroughness was personal experience with head lice. The increased awareness, however, seemed to be somewhat short-lived, as there was a decrease in checking frequency and thoroughness within 1 year after infestation. Personal experience with head lice also increased general knowledge related to the parasite. Parents born in developing countries checked their children for head lice more frequently, although less thoroughly, informed fewer contacts when infested, used pediculicides preventively more often and knew less about head lice than parents born in developed countries. Households with highly educated mothers had a lower checking frequency, but their knowledge and willingness to inform others was high. Single parents were more concerned about economic costs and kept children home from school longer while infested than other parents. As head lice management varied among socioeconomic groups and with parental background, differentiated advice should be considered in the control of head lice. The biannual focus on head lice during the 2 years of investigation increased checking thoroughness, while checking frequency remained unchanged. Based on the results, we suggest new head lice management guidelines for health authorities.

Knowledge, attitudes, and practices of parents/guardians regarding pediculosis in the Umm el-Jimal district of Jordan

The aim of this study is to assess the prevalence of pediculosis capitis in one district in Jordan, and to determine the knowledge, attitudes and practices of parents/guardians regarding head lice. The study was performed in Jordan’s Umm el-Jimal district from February 2010 to May 2010, and involved the surveying of 105 randomly selected households containing a total of 213 children. The households’ parents were interviewed for their knowledge, attitudes and practices regarding pediculosis, and afterward their children’s hair was checked for head lice via a 5-min visual scalp examination. Chi-square testing was used to analyse the data, with statistical significance assumed at p < 0.05. The prevalence rate of pediculosis among the 213 children was found to be 14.6%. Parental knowledge of head lice was found to be very limited; only 35.2% of the parents/guardians correctly answered 10 of the 20 questions (50%), and only 17.1% correctly answered 14 questions (70%). More than 94% of the parents reported feeling shame upon learning that their children were infested with pediculosis, and nearly 90% felt too ashamed to ask for help from a healthcare provider. Many parents used traditional/local techniques that they believed to be effective in managing pediculosis; 61% of the parents applied kerosene to the scalps of infested individuals, 39.9% used medical shampoo and 37.6% used special combs. There is a clear deficiency in Jordanian parents’ knowledge of, and practices concerning, pediculosis capitis. It is recommended that the Jordanian Ministry of Health and local health departments work together to ensure the dissemination of accurate and consistent head lice information to families.

Prevalence of Pediculus humanus capitis infestation among kindergarten children in Bahía Blanca city, Argentina

The human head louse, Pediculus humanus capitis De Geer (Anoplura: Pediculidae), is a worldwide public health concern. This human obligate ectoparasite usually infests school age children. The aim of this work was to investigate the prevalence of head lice in kindergarten children from Bahia Blanca. In addition, the influence of risk factors for pediculosis infestation, such as gender, hair characteristics, and socioeconomic class, was studied in relation to the prevalence of this ectoparasite. From a total of 220 pupils examined (125 girls and 95 boys), 94 showed pediculosis. The overall prevalence of head lice infestation was 42.7 %. Pediculosis was more frequent in girls (53.6 %) than in boys (28.4 %) and in medium, long, and very long hairs. No differences were found between socioeconomic classes. This indicated that head lice are relatively common in kindergarten children from Bahía Blanca.

Pediculosis capitis: new insights into epidemiology, diagnosis and treatment

Pediculosis capitis is a ubiquitous parasitic skin disease caused by Pediculus humanus capitis. Head lice are highly specialised parasites which can propagate only on human scalp and hair. Transmission occurs by direct head-to-head contact. Head lice are vectors of important bacterial pathogens. Pediculosis capitis usually occurs in small epidemics in play groups, kindergartens and schools. Population-based studies in European countries show highly diverging prevalences, ranging from 1% to 20%. The diagnosis of head lice infestation is made through the visual inspection of hair and scalp or dry/wet combing. The optimal method for the diagnosis of active head lice infestation is dry/wet combing. Topical application of a pediculicide is the most common treatment. Compounds with a neurotoxic mode of action are widely used but are becoming less effective due to resistant parasite populations. Besides, their use is restricted by safety concerns. Dimeticones, silicone oils with a low surface tension and the propensity to perfectly coat surfaces, have a purely physical mode of action. This group of compounds is highly effective and safe, and there is no risk that head lice become resistant. The control of epidemics requires active contact tracing and synchronised treatment with an effective and safe pediculicide.

Head lice in Norwegian households: actions taken, costs and knowledge

INTRODUCTION

Head lice infestations cause distress in many families. A well-founded strategy to reduce head lice prevalence must shorten the infectious period of individual hosts. To develop such a strategy, information about the actions taken (inspection, treatment and informing others about own infestations), level of knowledge and costs is needed. The present study is the first to consider all these elements combined.

MATERIALS AND METHODS

A questionnaire was answered by 6203 households from five geographically separated municipalities in Norway.

RESULTS

94% of the households treated members with pediculicides when head lice were discovered. Nearly half of the households checked biannually or not at all. Previous occurrence of head lice and multiple children in a household improved both checking frequency and method. More than 90% of the households informed close contacts about their own pediculosis. Direct costs of pediculosis were low (less than €6.25 yearly) for 70% of the households, but the ability to pay for pediculicides decreased with the number of head lice infestations experienced. One in three households kept children from school because of pediculosis. Other widespread misconceptions, such as that excessive cleaning is necessary to fight head lice, may also add unnecessary burden to households. School affiliation had a significant effect on checking frequency and method, knowledge and willingness to inform others about own pediculosis.

CONCLUSIONS

Increased checking frequencies appear to be the most important element to reduce head lice prevalence in Norway and should be a primary focus of future strategies. National campaigns directed through schools to individual households, might be an important tool to achieve this goal. In addition to improving actions taken, such campaigns should also provide accurate information to reduce costs and enhance the level of knowledge about head lice in households.

Hats off to success: changing head lice policy

Pediculosis at school is an emotional and contentious issue. Many school nurses do not feel prepared to take on the task of changing long-standing school policy, even in the light of solid evidence to do so. This article explores one school nurse's experience in changing lice policy for her district.

Head lice

Head lice infestation is associated with limited morbidity but causes a high level of anxiety among parents of school-aged children. Since the 2002 clinical report on head lice was published by the American Academy of Pediatrics, patterns of resistance to products available over-the-counter and by prescription have changed, and additional mechanical means of removing head lice have been explored. This revised clinical report clarifies current diagnosis and treatment protocols and provides guidance for the management of children with head lice in the school setting.

The mode of action of dimeticone 4% lotion against head lice, Pediculus capitis

Background

Treatment of head lice using physically acting preparations based on silicones is currently replacing insecticide use due to widespread resistance to neurotoxic agents. It has been postulated that some products act by asphyxiation, although the limited experimental evidence and the anatomy of the louse respiratory system suggest this is unlikely.

Results

Observation over several hours of lice treated using 4% high molecular weight dimeticone in a volatile silicone base showed that, although rapidly immobilised initially, the insects still exhibited small movements of extremities and death was delayed. One common effect of treatment is inhibition of the louse's ability to excrete water by transpiration through the spiracles. Inability to excrete water that is ingested as part of the louse blood meal appears to subject the louse gut to osmotic stress resulting in rupture. Scanning electron microscopy coupled with X-ray microanalysis to detect silicon showed dimeticone lotion is deposited in the spiracles and distal region of the tracheae of lice and in some cases blocks the lumen or opening entirely.

Conclusion

This work raises doubts that lice treated using dimeticone preparations die from anoxia despite blockage of the outer respiratory tract because movements can be observed for hours after exposure. However, the blockage inhibits water excretion, which causes physiological stress that leads to death either through prolonged immobilisation or, in some cases, disruption of internal organs such as the gut.

Head lice treatments and school policies in the US in an era of emerging resistance: a cost-effectiveness analysis

BACKGROUND

Head lice are a common infection in school-age children worldwide. Several authorities in the US have recommended different treatments and school policies in order to control this disease. Recent concerns of emerging lice resistance worldwide raise the necessity to reassess the current recommendations.

OBJECTIVES

To perform a cost-effectiveness analysis (from the US caregiver perspective) of three head lice treatments commonly used in the US, permethrin 1%, malathion 0.5% and the lice comb, in order to evaluate the cost effectiveness of different treatments in the current era, and to explore the effect of different factors in this analysis.

METHODS

We used a decision-tree model to represent the costs and effectiveness of the different treatment strategies. A patient/caregiver perspective was applied, with a time horizon of 2 weeks. Probabilities of treatment success or failure of the three treatments were based on the literature. Effectiveness was measured as the successful eradication of head lice, and costs - including the costs of the treatment, the physician co-pay and the costs of days out of school - were calculated. One-way and multi-way analyses were performed using decision analysis software (Treeage Pro Healthcare 2008).

RESULTS

Combing was dominated by permethrin 1%. The incremental cost-effectiveness ratio of malathion 0.5% versus permethrin 1% was $US161.75 per cure. For caregivers whose willingness to pay is <$US161.75 per cure, permethrin 1% is the most cost-effective option. For those with a willingness to pay of > or =$US161.75 per cure malathion 1% may offer the highest net monetary benefit. Twenty percent of the uncertainty in the model is due to variation in permethrin 1% resistance, and approximately 73% of the total variability of the model is attributed to the number of days the student has to be out of school because of the school's policy.

CONCLUSIONS

Our study suggests that permethrin 1% was the most cost-effective treatment for those with a willingness to pay of <$US162 per cure. Sensitivity of lice to permethrin and the specific school head lice policy had major effects on the model. Thus, informing communities in a given geographical area about the degree of head lice resistance and sensitivity is necessary in order for the public to make a rational decision regarding treatment. Schools' head lice policies have a major effect on the cost of head lice treatments.

Plastic detection comb better than visual screening for diagnosis of head louse infestation

Finding lice can be difficult in head louse infestation. We compared a new louse detection comb with visual inspection. All children in two rural Turkish schools were screened by the two methods. Those with lice were offered treatment and the results monitored by detection combing. Children with nits only were re-screened to identify latent infestations. Using visual inspection we found 214/461 children (46%) with nits but only 30 (6.5%) with live lice. In contrast detection combing found 96 (21%) with live lice, of whom 20 had no nits. Detection combing was 3.84 times more effective than visual inspection for finding live lice. Only 10/138 (7.2%) children with nits and no lice were found to have active infestation by day 16. We found that the detection comb is significantly (P<0.001) more effective than visual screening for diagnosis; that nits are not a good indicator of active infestation; and that treatment with 1% permethrin was 89.6% effective.

Shared vulnerability: a theory of caring for children with persistent head lice

Head lice infestation is a worldwide phenomenon that affects persons of all ages. For reasons that are not entirely clear, a number of children experience persistent head lice infestations lasting weeks, months, or years. Little is known about the impact of caring for children with persistent head lice on parents/caregivers. The purpose of this grounded theory study is to explore how parents and caregivers manage caring for children with persistent head lice. Data were obtained through participant observation and in-depth interviews with a purposive sample of 20 parents/caregivers of school-age children with persistent head lice. The researcher identified a 4-stage process of shared vulnerability used by parents/caregivers to manage caregiver strain associated with caring for children with persistent head lice. The four stages included (a) being ostracized, (b) losing integrity of the self, (c) struggling with persistence, and (d) managing strain.

Therapy for head lice based on life cycle, resistance, and safety considerations

The timing of head lice maturation most favorable to their survival in the presence of anti-lice agents is the maximum time as an ovum (12 days) and the shortest possible time of maturing from newly hatched nymph to egg-laying adult (8.5 days). Pediculicides that are not reliably ovicidal (pyrethroids and lindane) require 2 to 3 treatment cycles to eradicate lice. Ovicidal therapies (malathion) require 1 to 2 treatments. Treatment with an agent to which there is genetic resistance is unproductive. In the United States, lice have become increasingly resistant to pyrethroids and lindane but not to malathion. Treatment with malathion has favorable efficacy and safety profiles and enables the immediate, safe return to school. Nit combing can be performed adjunctively. No-nit policies should be rendered obsolete.

Efficacy of neem seed extract shampoo on head lice of naturally infected humans in Egypt

Sixty heavily lice-infested male and female children (4-15 years) were selected and subjected to the treatment with a neem seed extract shampoo. Twenty to thirty milliliter of the shampoo were thoroughly mixed with completely wet hair and rubbed in to reach the skin of the scalp. After 5, 10, 15 and 30 min, the shampoo was washed out and the hair basically combed. Head lice were collected and examined. The neem seed extract shampoo proved to be highly effective against all stages of head lice. No obvious differences regarding the efficacy of the shampoo were observed between an exposure time of 10, 15 or 30 min. No side effects, such as skin irritation, burning sensations, or red spots on the scalp, forehead or neck, respectively, were observed.

Head louse infestations: the "no nit" policy and its consequences

Health authorities in the USA, Canada and Australia recommend a "no nit" policy, i.e. the immediate dismissal of all children who have head lice, eggs and/or nits on their hair from school, camp or child-care settings. These children would be readmitted to the institution only when all head lice, eggs and nits have been removed. The "no nit" policy assumes that all nits seen when examining the scalp are viable and therefore the infested individual should be treated for lice, and all nits must be removed from the scalp. However, it has been repeatedly shown that only a small number of children who have nits on their scalp are also infested with living lice. Accordingly, in the USA alone 4-8 million children are treated unnecessarily for head lice annually, which amounts to 64% of all lice treatments. In addition, 12-24 million school days are lost annually. The annual economic loss owing to missed workdays by parents who have to stay home with their children adds US$4-8 billion to the country's economy. The policy also results in serious psychological problems for children and their parents. Therefore, the "no nit" policy should be abandoned and alternative ways of examination and treatment for head lice should be found.

Pediculus capitis infestation according to sex and social factors in Argentina

OBJECTIVE

To determine the intensity of Pediculus capitis infestation (abundance) among Argentinean schoolchildren. Children's sex and social stratum were analyzed as modifiers of the general prevalence and degree of parasitism.

METHODS

The study included 1,370 schoolchildren (692 girls, 678 boys) from 26 schools of the province of La Rioja (21 public schools, five private schools). Classic prevalence was obtained as the percentage of children with nits and/or lice. Moreover, five degrees of parasitism were classified: 0) children with no signs of pediculosis; 0+) children with evidence of past infestation; 1) children with a recent infestation and low probability of active parasitism; 2) children with a recent infestation and high probability of active parasitism; 3) children with mobile lice (active pediculosis).

RESULTS

The general prevalence was 61.4% (girls: 79%; boys: 44%, p<0.001). Private schools showed lower prevalence than public schools (p=0.02), especially due to the low prevalence in boys. Fifty percent of children were classified in classes 0 and 0+, 22% in class 1; and 28% in grades 2 and 3. The proportion of children in grade 3 was higher in public schools than in private schools. There were significant sexual differences in the intensity of parasitism for grades 2 and 3, where girls' rates exceeded twice those of boys'.

CONCLUSIONS

Sex and social stratum are important modifiers of P. capitis general prevalence and degree of infestation. The classification of children by intensity of infestation allowed a more precise delimitation of this condition, which is especially important for disease surveillance and application of control measures.

Home remedies to control head lice: assessment of home remedies to control the human head louse, Pediculus humanus capitis (Anoplura: Pediculidae)

As the frequency and level of pediculicide resistance increases throughout the world, the need for novel solutions to control pediculosis has intensified. The development and registration of new pesticides has become so costly that many chemical companies are unwilling to pursue it and health-care providers now face a serious lack of new commercial pediculicides. Many infested people resort to using "home-remedy" approaches that have not been scientifically tested. In this article, we examined the potential value of six purportedly effective "home remedies" (vinegar, isopropyl alcohol, olive oil, mayonnaise, melted butter, and petroleum jelly) to treat head louse infestations and the likelihood of drowning lice by water submersion. Results indicated that only the application of petroleum jelly caused significant louse mortality but no treatment prevented lice from laying eggs. Most home remedy products did little to kill eggs, despite prolonged exposure. Petroleum jelly caused the greatest egg mortality, allowing only 6% to hatch. It was extremely difficult to drown lice, despite extended periods (i.e., 8 hr) of water submersion, suggesting that killing lice by depriving them of oxygen is inefficient. None of the home remedy products we surveyed was an effective means of louse control. This suggests that when treatment failure occurs, an increased amount of time and effort should be focused on alternative chemical pediculicides and/or manual louse removal (i.e., combing) rather than using any of these products.

Economic considerations associated with Pediculus humanus capitis infestation

An estimated 6 to 12 million head lice infestations occur in the United States annually, with children ages 3 to 12 most likely to be affected. There are significant direct costs associated with treatment and indirect costs due to lost time from school. Anecdotal reports suggest that direct costs of treatment are in the hundreds of millions of dollars annually. Indirect costs are also substantial but more difficult to quantify. Examples of indirect costs include missed days from schools that use a "no nit" policy, lost wages for parents who must stay home with children, and costs of daycare for parents who cannot miss work. Contributors to the expense of treating head lice include misdiagnosis, and, consequently unneeded treatment; treatment failure due to misuse of pediculicides or other agents; and developing resistance, particularly to over-the-counter pyrethroid agents. An overview of direct and indirect costs of infestation are included in this review, along with a discussion of factors that lead to misuse and overuse of pediculicides. More accurate diagnosis of head lice infestation may provide the most effective means of controlling the costs of care and ensuring proper use of pediculicides.

Pediculosis

The 3 major lice that infest humans are Pediculus humanus capitis (head louse), Pthirus pubis (crab louse), and Pediculus humanus humanus (body louse). Patients with louse infestation present with scalp pruritus, excoriations, cervical lymphadenopathy, and conjunctivitis. A hypersensitivity rash, or pediculid, may mimic a viral exanthem. Head lice infestation crosses all economic and social boundaries, whereas body lice infestation preferentially affects the homeless and displaced. Body lice are major vectors of diseases such as typhus, trench fever, and relapsing fever. Pubic lice infestation often is acquired as a sexually transmitted disease and may be a marker to screen for other sexually transmitted diseases. Treatment of louse infestation can be challenging. Mechanical measures, such as combing, are helpful as adjunctive measures, but most studies suggest they are not as effective as chemical agents. Resistance to chemical agents is a growing problem. Major types of resistance include knock-down resistance, glutathione-S-transferase-based resistance, and monooxygenase-based resistance. Research is needed to identify new effective treatments.

Human lice and their control

Current research on human louse biology has focused on the long-standing debate about speciation of head and body lice but using new tools of DNA and enzyme analysis. These studies have indicated that head and body lice from the same geographical zone may be more closely allied than insects inhabiting the same ecological niche in other regions. However, the majority of research over the past decade has involved clinical aspects including transmission, treatment, and the appearance and identification of resistant strains within populations of lice. Despite advances, there is a need for a better understanding of louse biology, as existing therapies fail and lice remain potential vectors of disease for millions of people.

Managing head lice in an era of increasing resistance to insecticides

Head lice are present in all age groups, however, the peak age for infestation is 7-8 years and the incidence varies throughout the year with higher incidence during the winter. Different insecticides have been used over the past 60 years to manage this condition. There is now strong evidence of insecticide resistance established in many countries to such an extent that some of these chemicals have become obsolete. Resistance to some pediculicides can vary from country to country and region to region within a country. The lack of a local monitoring system of resistance patterns means that parents and pupils are hampered in making an informed decision regarding how to treat head lice. One should no longer assume that treatment failure is due to poor treatment compliance or re-infestation. Clear treatment guidelines drawn up by healthcare professionals with an interest in head lice and taking into account regional/national resistance patterns should be implemented. These guidelines should combine chemical and non-chemical approaches to treatment and be coordinated and regularly reviewed by local public health departments. Drug companies should be made to provide up-to-date efficacy of their products.

Review of common therapeutic options in the United States for the treatment of pediculosis capitis

Numerous therapies are available in both over-the-counter and prescription formulations for the treatment of head lice infestation. We summarize treatment recommendations from published literature and from a recent meta-analysis from the Cochrane Database of Systematic Reviews that describe the efficacy, safety, and resistance patterns of monotherapies available in the United States. If treatment with pyrethrin or permethrin fails to eradicate the infestation, the treatment of choice is malathion. However, because of malathion's flammability, it should be a second-line therapy. Orally administered ivermectin has been reported to be efficacious, but it is not currently a US Food and Drug Administration-approved pediculicide. Alternative therapies are also discussed, in addition to indications for prophylaxis, resistance reporting, and the social impact of infestation.

Issues in public health entomology

Public health entomology focuses on the population biology of vector-borne infections, seeking to understand how such pathogens perpetuate over time and attempting to devise methods for reducing the burden that they impose on human health. As public health entomology passes its centennial, a series of pervasive research themes and spirited debates characterize the discipline, many reflecting a tension between field and laboratory research. In particular, institutional support for population-based research and training programs has fallen behind that for those using modern lab-based approaches. Discussion of modes of intervention against vector-borne infections (such as deployment of genetically modified vectors, the role of DDT in malaria control, host-targeted acaricides for Lyme disease risk reduction, and truck-mounted aerosol spraying against West Nile virus transmission) illustrates the discipline's need for strengthening population-based research programs. Even with the advent of molecular methods for describing population structure, the basis for anophelism without malaria (or its eastern North American counterpart, ixodism without borreliosis) remains elusive. Such methods have not yet been extensively used to examine the phylogeography and geographical origins of zoonoses such as Lyme disease. Basic ecological questions remain poorly explored: What regulates vector populations? How may mixtures of pathogens be maintained by a single vector? What factors might limit the invasion of Asian mosquitoes into North American sites? Putative effects of "global warming" remain speculative given our relative inability to answer such questions. Finally, policy and administrative issues such as the "no-nits" dictum in American schools, the Roll Back Malaria program, and legal liability for risk due to vector-borne infections serve to demonstrate further the nature of the crossroads that the discipline of public health entomology faces at the start of the 21st Century.

An observer-blinded study of 1% permethrin creme rinse with and without adjunctive combing in patients with head lice

OBJECTIVES

To determine if NIX (Warner Lambert Healthcare, Morris Plains, NJ) 1% Permethrin Creme Rinse Lice Treatment (1% PLT) without combing will effectively treat >/=95% of patients on day 2 or on day 15; to determine whether combing influences efficacy.

STUDY DESIGN

A randomized, observer-blinded study enrolled 95 infested adults and children. All patients were treated with 1% PLT on day 1 and, if still infested, on day 8. One third of households were randomized to the combing group and two thirds to the no-combing group. Efficacy was assessed by: (1) visual inspection on days 1, 2, 8, 9, and 15 and, (2) shampooing/straining on days 2, 9, and 15. The target efficacy was 95%.

RESULTS

In the no-combing group, the lice-free rate was 83.1% on day 2 (95% CI, 71.0-91.6), 45.8% on day 8 (before second treatment) (95% CI, 32.7-59.2), 77.6% on day 9 (95% CI, 64.7-87.5), and 78.3% on day 15 (95% CI, 65.8-87.9). Adjunctive combing did not improve efficacy on any day.

CONCLUSIONS

In this population, 1% PLT was significantly less than 95% effective and suggests resistance to 1% PLT. The failure of nit removal combing by nonprofessional caregivers to improve efficacy demonstrates the unreliability of combing as adjunctive treatment in this setting.

Wet combing for head lice: feasibility in mass screening, treatment preference and outcome

There is no scientific consensus on the best way to control head louse infestation in schoolchildren. A study was conducted to test the feasibility and acceptability of a screening campaign by wet combing and a community approach to head-louse control with home visits, and to explore parents' treatment preferences and treatment outcomes. A non-controlled intervention (advice on treatment options offered to all positive children) was nested within an epidemiological prevalence study. All children in three primary schools in Ghent, Belgium, were invited to take part in screening by wet combing (n=677, 3-11 years). Positive children were offered structural treatment advice, a home visit on day 7, and a check by wet combing on day 14. 83% of the children were screened. The prevalence of active infestation (living moving lice) was 13.0% in school 1 and 19.5% in school 3. In school 2, prevalence of signs of active and past infestation was 40.7%. A home visit was made to 58% of the positive children. 85% of the positive children were screened again on day 14. Wet combing was the most widely used treatment, followed by chemical treatment and a combination of the two. In school 1 and 3 51% were cured, and in school 2 24% became nit-free. A wet combing screening campaign and a community-oriented approach to head-louse control is feasible though resource-intensive. The prevalence of head lice was high and the cure rate was low, with either topical treatments or wet combing.

Wet Combing for Head Lice: Feasibility in Mass Screening, Treatment Preference and Outcome

There is no scientific consensus on the best way to control head louse infestation in schoolchildren. A study was conducted to test the feasibility and acceptability of a screening campaign by wet combing and a community approach to head-louse control with home visits, and to explore parents’ treatment preferences and treatment outcomes. A non-controlled intervention (advice on treatment options offered to all positive children) was nested within an epidemiological prevalence study. All children in three primary schools in Ghent, Belgium, were invited to take part in screening by wet combing (n=677, 3–11 years). Positive children were offered structural treatment advice, a home visit on day 7, and a check by wet combing on day 14.

83% of the children were screened. The prevalence of active infestation (living moving lice) was 13.0% in school 1 and 19.5% in school 3. In school 2, prevalence of signs of active and past infestation was 40.7%. A home visit was made to 58% of the positive children. 85% of the positive children were screened again on day 14. Wet combing was the most widely used treatment, followed by chemical treatment and a combination of the two. In school 1 and 3 51% were cured, and in school 2 24% became nit-free. A wet combing screening campaign and a community-oriented approach to head-louse control is feasible though resource-intensive. The prevalence of head lice was high and the cure rate was low, with either topical treatments or wet combing.