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

INTRODUCTION: Head lice infestation remains a persistent public health concern among primary school children in resource-limited settings, affecting their well-being and academic performance. Despite previous studies, there is no consistent evidence on the prevalence and factors associated with head lice infestation. This study aimed to determine the prevalence and factors related to head lice infestation among primary school children in low and middle-income countries. METHODS: This review was conducted by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Relevant electronic databases, including PubMed, Cochrane Library, Web of Science, Science Direct, AJOL, and Google Scholar, were used to retrieve articles. The study included only published articles written in English languages between December 01, 2014 to January 31, 2024 for studies reporting the prevalence of head lice infestation or associated factors among primary school children in low- and middle-income countries. This review has been registered on PROSPERO with Prospero registration number CRD42024506959. The heterogeneity of the data was evaluated using the I2 statistic. A meta-analysis was conducted using STATA 17 software, with a 95% confidence interval. Publication bias was evaluated using funnel plots and statistical tests, such as Egger's and Beggs's tests, to identify publication biases in the included studies. Meta-regression was also carried out to assess the source of publication of publication bias. RESULTS: The review included 39 studies involving 105,383 primary school children. The pooled prevalence of head lice infestation among primary school children in low- and middle-income countries was 19.96% (95% CI; 13.97, 25.95). This review also found out that being a girl was 3.71 times (AOR = 3.71; 95% CI: 1.22-11.26) more likely to have head lice infestation as compared to boys, while children with a previous history of infestation were 4.51 times (AOR = 4.51; 95% CI: 2.31-8.83) more likely to have head lice infestation as compared to their counterparts. CONCLUSION: The overall prevalence of head lice infestation among primary school children in low- and middle-income countries was found to be high. Female gender, children who had a previous history of infestation, and family size were significant predictors of head lice infestation. As a result, policymakers and program administrators should focus on the identified determinants.

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

BACKGROUND: The head louse, Pediculus humanus capitis, is an obligate ectoparasite and its infestation remains a major public health issue worldwide. Determining the genetic characteristics of the existing clades is essential to identify the population structure and to develop head lice-control programs. Hence, we aimed to investigate the genetic diversity of head lice among infested individuals in northern Iran. METHODS: Adult head lice were collected from 100 infested individuals referring to the health centers throughout five geographical regions in Mazandaran Province, Iran. Partial fragments of the mitochondrial cytb gene were amplified by PCR, then consequently sequenced. RESULTS: The results of the phylogenetic tree of collected head lice confirmed the existence of two clades, A and B, in the studied areas. Thirteen haplotypes were detected in the studied populations, of which 11 were novel haplotypes. Clade A was the dominant form and accounted for 75% of samples, while clade B included the rest. Haplotype and nucleotide diversity were 0.999 and 0.0411, respectively. CONCLUSIONS: Clade A and B of Pediculus humanus capitis exist among the human populations of northern Iran. We observed high genotypic diversity of this head lice.

Current challenges in diagnosing and treating infectious skin diseases - a case series. / Choroby zakazne skóry jako wciaz aktualny problem diagnostyczny i terapeutyczny ­ przeglad nietypowych przypadków klinicznych.

Infectious skin diseases constitute a significant public health problem. Despite the systematic development of many modern diagnostic and therapeutic tools, they still pose a serious challenge for clinicians. Due to their prevalence and mild course in most cases, they are often marginalized, which can delay their diagnosis and treatment initiation. Such an approach in more clinically advanced cases can have serious consequences, sometimes leading to tragic outcomes. This work presents a series of four cases of common infectious skin diseases with an unusually atypical clinical picture: the history of a 49-year-old female patient with recurrent erysipelas of the right lower leg co-occurring with a SARS-CoV-2 infection, a 75-year-old male patient with a generalized form of herpes zoster, a 38-year-old female patient with a complicated severe course of head lice, and a 34-year-old male patient with a severe form of post-steroid mycosis. In each of these cases, difficulties in making the correct diagnosis were highlighted, even though they represent some of the most common bacterial, viral, parasitic, and fungal dermatoses. The paper discusses the risk factors for these diseases, the pathophysiology of their atypical course, the effects and challenges in the therapeutic approach conducted. Infectious skin dermatoses require aggressive treatment and should never be underestimated.

Measuring local genetic variation in permethrin-resistant head lice (Phthiraptera: Pediculidae) from Buenos Aires, Argentina.

The cosmopolitan ectoparasite human head louse, Pediculus humanus capitis (De Geer)(Phthiraptera:Pediculidae), affects mostly school-aged children, with infestations reported every year mainly due to louse resistance to pyrethroids. One of the main resistance mechanisms of pyrethroids is the target site insensitivity (kdr), which is caused by single-nucleotide point mutations (SNPs) located in the voltage-sensitive sodium channel gene. In this study, we analyzed individual head lice toxicologically via the description of their susceptibility profile to permethrin and genetically through the genotypification of their kdr alleles as well as nuclear microsatellite loci. Lice were collected from 4 schools in the city of Buenos Aires, Argentina. The resistance ratios varied from 33.3% to 71.4%, with a frequency of the T917I kdr mutation of 87.31% and with 83.6% of the head lice being homozygous resistant to pyrethroids. Microsatellite data indicated that all the louse school populations had genotype proportions that deviated from Hardy-Weinberg expectations, with FIS > 0 reflecting a deficit of heterozygotes. Bottleneck analysis suggested that all louse school populations underwent a recent reduction in population sizes, while 3 of the 4 schools had gene flow values around 1, indicating ongoing gene flow among those schools. Our study suggests that school louse populations in the city of Buenos Aires may form a metapopulation, where each school represents a small population that undergoes extinction and recolonization processes under strong permethrin selection. This is the first multilevel analysis integrating toxicological, kdr-genotyping, and microsatellite data in human louse populations.

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

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

Cuticular extracts induce aggregation in head lice.

The human head lice Pediculus humanus capitis (De Geer) (Phthiraptera: Pediculidae) are strict, obligate human ectoparasites that spends their entire life cycle in the host and cause skin irritation and derived infections. Despite the health-related importance, few studies have evaluated the chemical communication among these insects. Here, we evaluate the response of lice of both sexes to cuticular extracts using two solvents of different polarity (hexane and methanol). Cuticular extracts that elicited an attraction response towards head lice were analysed by gas chromatography-mass spectrometry (GC-MS) to determine the cuticular lipid profile. Both lice sexes were attracted to the hexane extracts but not the methanol extracts, suggesting the non-polarity of the compounds present in the cuticle. Chemical analyses of hexane extracts from males and females showed high similarity in major compounds. This study provides the first evidence that lice respond to cuticle extracts, which may be important to understand aggregation behaviour.

Parasites in ancient Egypt and Nubia: Malaria, schistosomiasis and the pharaohs.

The civilizations of ancient Egypt and Nubia played a key role in the cultural development of Africa, the Near East, and the Mediterranean world. This study explores how their location along the River Nile, agricultural practices, the climate, endemic insects and aquatic snails impacted the type of parasites that were most successful in their populations. A meta-analysis approach finds that up to 65% of mummies were positive for schistosomiasis, 40% for headlice, 22% for falciparum malaria, and 10% for visceral leishmaniasis. Such a disease burden must have had major consequences upon the physical stamina and productivity of a large proportion of the workforce. In contrast, the virtual absence of evidence for whipworm and roundworm (so common in adjacent civilizations in the Near East and Europe) may have been a result of the yearly Nile floods fertilising the agricultural land, so that farmers did not have to fertilise their crops with human faeces.

Head lice infestation and the role of some cognitive-behavioral factors in its spread and prevention among adolescent girls: A cross-sectional study in Northwest Iran.

Background and Aims: Head lice is a public health problem of worldwide distribution, particularly among school children and girls. Head lice infestation (HLI) can lead to negative social and psychological outcomes such as distress and anxiety in children and their families. Hence, the present study aimed to investigate the role of cognitive-behavioral factors in its spread and prevention among adolescent girls. Methods: The cross-sectional study was conducted among 276 school-aged adolescent girls from September 2022 to January 2023 in Herris, a city located in Northwest Iran. A multistage cluster random sample was used to recruit adolescent girls in secondary schools. Two schools were randomly selected from five secondary schools. Then, students in each school were randomly selected from a school list. Data were collected using a valid and reliable questionnaire. Results: The high protective behaviors were significantly associated with the number of family members (ß = 0.158; p value = 0.012). An additional 21.8% of the variation in preventive behaviors was explained by cognitive factors as predictor variables (p value > 0.05). Perceived collective family efficacy, perceived barriers, perceived self-efficacy, and response efficacy were predictors of head lice preventive behaviors, respectively. Among all variables, perceived collective family efficacy was the strongest predictor. Conclusions: The findings of current research support the determinants of the cognitive-behavioral factors in the spread and prevention of HLI. It is better to involve these factors in school-based educational programs by policymakers and healthcare providers.

POPULATION STRUCTURE AND BARTONELLA QUINTANA IN HEAD AND BODY LICE IN POKHARA, NEPAL (ANOPLURA: PEDICULIDAE).

This study examined the population structure of head and body lice infesting a random sample of people in Pokhara, Nepal during 2003, 2004, and 2005. A total of 106 participants (6 to 72 yr old, median = 12) volunteered to have lice collected from their heads and clothing. Most participants (70%) harbored only head lice, some (15%) had only body lice, and some (15%) had concurrent infestations of head and body lice (dual infestations). A total of 1,472 lice was collected. Significantly more nymphs were collected than adult lice. Louse populations were generally small (geometric mean = 8.8 lice per person) but a few participants harbored larger louse populations (maximum = 65 lice). People with dual infestations harbored significantly more lice than people with single infestations; however, there was no difference in the infestation intensities between people infested with head lice only vs. those infested with body lice only. Male participants harbored significantly more lice than did females. There were no significant differences in infestation intensity due to participant age or their socioeconomic level. The sex ratio of adult lice was increasingly female biased with increasing adult louse density. Infection of lice with Bartonella quintana was low (ca. 1.5%). Pediculosis is a common problem in urban Nepal.

Prevalence of permethrin-resistant kdr mutation in head lice (Pediculus humanus capitis) from elementary school students in Jeddah, Saudi Arabia.

Head lice (Pediculus humanus capitis) are a major global concern, and there is growing evidence of an increase in head lice prevalence among Saudi schoolchildren. The purpose of this study is to investigate the prevalence of an insecticidal resistance mutation in head lice collected from schoolchildren. A polymerase chain reaction (PCR) was used to amplify a segment of the voltage-gated sodium channel gene subunit to assess the prevalence and distribution of the kdr T917I mutation in head lice. Subsequently, the restriction fragment length polymorphism (RFLP) patterns revealed two genotypic forms: homozygous-susceptible (SS) and homozygous-resistant (RR). The results showed that 17 (37.80%) of the 45 samples were SS, whereas 28 (62.2%) were RR and T917I and L920F point mutations were found in the nucleotide and amino acid sequences of RR. Compared to other nations, the frequency of permethrin resistance mutation in the head louse population in Saudi Arabia was low. This study provides the first evidence of permethrin resistance mutation in human head lice in Saudi Arabia. The findings of this study will highlight the rising incidence of the kdr mutation in head lice in Saudi Arabia.

Ovicidal and Pediculicidal Activity of Indigofera suffruticosa Mill. Leaf Oil on Pediculus humanus capitis Egg to Adult Stages.

PURPOSE: Pediculosis capitis, commonly known as head lice infestation, represents a significant health 26 problem for school children worldwide. Repeated and long-term usages of highly toxic pediculicides have resulted in the development of increased levels of resistance and do not kill louse eggs. Alternative pediculicides, such as herbal products, have recently been proposed for the treatment of head lice infestation, thereby decreasing toxicity. METHODS: This study analyzed the chemical composition of I. suffruticosa leaf extracts using GC-MS and evaluated the effects of Indigofera suffruticosa Mill. (I. suffruticosa) leaf extract on the mortality of head lice and their eggs. RESULTS: The major five components of the tested oils identified were as follows: n-hexadecanoic acid, hexadecanoic acid, ethyl ester, oleic acid, (E)-9-octadecenoic acid ethyl ester, and linoleic acid ethyl ester. The effective pediculicide of the I. suffruticosa leaf extracts affected head lice in all stages (egg, nymph, and adults). The concentrations of I. suffruticosa leaf extracts at 500 mg/mL produced the highest effective ovicidal on egg with 96.6% unhatching and pediculicide on nymphs and adults with 96.7 ± 5.7% and 86.7 ± 5.7% mortality, respectively, at 60 min (LT50 value < 10 min). The analysis of the external structure of the adult-stage head lice by SEM examination revealed that dead lice exposed to I. suffruticosa leaf extract displayed damage to the outer smooth architecture and obstructed the respiratory spiracles. CONCLUSION: We may conclude that the application of I. suffruticosa leaf extract produces an effective herbal pediculicide capable of affecting all stages of head lice.

Treatment Modalities of Pediculosis Capitis: A Narrative Review.

The review has been done to find out the best-suited treatment modality for pediculosis capitis. Pediatric patients frequently experience pediculosis capitis, a head louse infestation brought on by the Pediculus humanus var. capitis. The primary sign of head lice infestation is a scratchy scalp, and the presence of living nits confirms this diagnosis. When a doctor diagnoses pediculosis as a primary bacterial infection, a bacterial impetignization and secondary infection, and cervical and occipital lymphadenopathy might make the clinical diagnosis more difficult. A proper therapy of pediculosis requires screening and treatment of all close contacts. The careful use of topical pediculicidal treatments, especially permethrin lotion and wet combing with a fine tooth comb, is required for the medical treatment of a head louse infestation. We've tried to outline the key points of treating head lice infestations. There are several treatment alternatives suggested, including over-the-counter permethrin and pyrethrin as well as prescription medications including malathion, lindane, benzyl alcohol, and spinosad.

Head lice as vectors of pathogenic microorganisms.

Body lice and head lice are the most common ectoparasites of humans. Head lice (Pediculus humanus capitis) occur worldwide in children and their caretakers, irrespective of their social status. In contrast, body lice (Pediculus humanus corporis) are confined to marginalized population groups in countries of the Global South, homeless people, and refugees. Body lice are known to transmit an array of bacterial pathogens, such as R. prowazekii, R. rickettsii, C. burneti, B. quintana, B. recurrentis, and Y. pestis. The vector capacity of head lice is still a matter of debate. The objective of the review was to scrutinize the existing evidence on the vector capacity of head lice for the transmission of bacterial pathogens. The PUBMED database was searched using a combination of the terms "pediculus humanus" OR "body lice" OR "head lice" AND "pathogen" OR "Rickettsia prowazekii" OR "Bartonella quintana" OR "Borrelia recurrentis" OR "Coxiella burneti" without a time limit. Data from epidemiological studies as well as historical observations demonstrate that body lice and head lice can carry the same array of pathogens. Since the presence of a bacterial pathogen in an arthropod is not sufficient to state that it can be transmitted to humans, and since experimental models are lacking, as yet one cannot conclude with certainty that head lice serve as vectors, although this review presents circumstantial evidence that they do. Adequately designed experimental and epidemiological studies are needed to ascertain the exact transmission potential of head lice.

Head lice: impact of COVID-19 and slow recovery of prevalence in Cambridgeshire, UK.

Following school closures and changes in contact behavior of children and adults a reduced head louse prevalence has been reported from across the globe. In parallel, sales of treatments were observed to fall, partly because of supply problems of some products following the pandemic, but this did not appear to result in more cases of infestation. Surveys of schools in and around Cambridge, UK, found that infestation rates were significantly reduced particularly in city schools compared with similar surveys conducted before the COVID-19 pandemic. Contrary to expectation the number of cases in schools has only risen slowly since schools returned to normal full time working in 2022-2023.

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.

The Impact of the COVID-19 Pandemic on the Prevalence of Head Lice Infestation among Children Attending Schools and Kindergartens in Poland.

Pediculosis capitis predominantly affects child populations. During the COVID-19 pandemic, various types of social limitations such as social isolation and limitations on educational facilities' functionalities were introduced worldwide, including in Poland. The impact of these pandemic restrictions on the prevalence of pediculosis capitis has not been extensively investigated so far. Existing data on this topic are limited mainly to indirect evaluation methods, such as online surveys or Internet analysis. In this study, we directly examined a cohort of over five thousand children to assess the influence of COVID-19 pandemic restrictions on the prevalence of head lice infestation among school and kindergarten attendees in Poland. Our findings demonstrate that the restrictions imposed during the COVID-19 pandemic led to a decrease in the number of children infested with head lice compared to pre-pandemic data. These results confirm that head lice infestations remain an ongoing epidemiological concern and warrant continued monitoring.

Evaluation of resistance of human head lice to pyrethroid insecticides: A meta-analysis study.

Introduction: Pediculosis is one of the most common annoying infections caused by parasitic lice in humans. Pyrethroids are one of the main insecticides used to treat this infection. But recently, due to the Resistance of lice to this group of insecticides, its insecticidal effects have been affected. The present study was conducted through a meta-analysis to investigate the prevalence of pyrethroid resistance against these insecticides worldwide. Methods: This study was conducted as a meta-analysis of the prevalence of treatment resistance in human head lice against pyrethroid insecticides worldwide. Based on this, all articles published without a time limit until the end of June 2022 in PubMed/MEDLINE, Web of Science (ISI), Scopus, and Google Scholar databases were extracted and using random-effects meta-analysis model statistical methods in the meta-analysis, Cochrane, Index I2, and funnel plot were analyzed by STATA software. Results: Twenty studies were included in the meta-analysis process. According to this, the prevalence of pyrethroid resistance insecticides in human head lice was estimated at 59% (CI95%: 50%-68%). Among pyrethroid insecticides, the highest prevalence of pyrethroid resistance against permethrin insecticide was 65%. Regarding the prevalence of Resistance by year, the prevalence before 2004 was estimated at 33%, but after 2015, this rate reached 82%. Also, the majority of pyrethroid resistance was estimated at 68% using genetic diagnosis methods and 43% using clinical diagnosis methods. Conclusion: More than half of human head lice pyrethroid resistance insecticides. Based on this, it is recommended that before using this treatment method to treat human head lice Infestation, it should investigate the prevalence of pyrethroid resistance in that area, and if the majority of Resistance is high, alternative or combined treatment methods should be used.

Case report: Head lice in the eyelashes.

Purpose: Head lice infection of the eyelashes and adjacent eyelids is extremely rare. In this case report we present a child with head lice infection of the eyelashes. Observations: A 3-year-old boy presented to the ophthalmology department with a chief complaint of itching and visible abnormal secretions of the upper eyelashes in the right eye for more than 1 week. On ocular examination, a large number of nits and brown secretions were tightly adhered to the root of the upper eyelashes of the right eye, and translucent parasites crept slowly along the eyelashes, without impairment of vision. A few of the parasites and nits were further viewed with a microscope and were identified as head lice. Conclusions and Importance: This case suggests that ophthalmologists should not only consider common inflammation and allergies, but also be alert to parasitic infections when treating patients with ocular itching and abnormal secretions.