Ectoparasites

Trichomoniasis and Other Sexually Transmitted Parasitic Diseases in Women

Parasitic sexually transmitted infections are spread through sexual contact (vaginal, oral, and/or anal sex). The majority of parasitic STIs involve protozoan pathogens (ie, Trichomonas vaginalis, Entamoeba histolytica, and Giardia duodenalis); however, ectoparasitic infections (Pthirus pubis and Sarcoptes scabiei) are also included in this group. The purpose of this review is to provide a comprehensive summary of the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of parasitic sexually transmitted infections, with a particular focus on their impact on women.

Comparative Efficacy of Commercial Antilice Shampoos Against Head Lice in a High-Prevalence Primary School in Thailand

This is a cross-sectional study that is aimed at evaluating the efficacy of antilice shampoo against head lice infestation in primary schoolgirls at level 3-6 (aged between 9 and 12 years) with a high prevalence of infestation in Pathum Thani Province and which also reported a current prevalence of lice infestation in this school. The study was conducted during January-March 2023. A total of 356 schoolchildren were screened for lice infestation. The prevalence rate of lice infestation was found in 78 students (21.9%) from all schoolchildren. Girls (50.3%) showed a higher rate of lice infestation than boys (0.5%) with a significant difference (p < 0.05). Most lice-infested girls (100%) reported itching. Seventy-two of 77 infested girls (93.5%) agreed to use shampoos for lice treatment. Two types of commercial shampoos were considered for lice treatment: (1) chemical (permethrin 0.5% W/V) antilice shampoo and (2) herbal antilice shampoo, since it is cheap and available in the market. The results of chemical (permethrin 0.5% W/V) antilice shampoo showed similar efficacy for lice treatment as herbal antilice shampoo with no significant difference in statistics (p > 0.05). Using the antilice shampoos consecutively 3 times demonstrated the highest efficacy of treatment (73.0%), followed by 2 times (34.3%), and the lowest efficacy of treatment was a single application (5.6%). No serious side effects from both shampoos in participants: 2 cases of itching and 1 case of the burning sensation. This indicated that in the area of the high prevalence of lice infestation, herbal antilice shampoo might be an alternative choice for lice treatment. However, we recommended using it once a week 3 times consecutively to reach the highest efficacy for treatment. In addition, this treatment should be extended to family members with lice infestation.

The Role of Parental and Institutional Approaches in the Persistence of Pediculosis Capitis in Early Childhood Education Settings: A General Survey

Pediculus humanus capitis infestation is one of the most underestimated parasitoses still constituting a current epidemiological and social problem. Haematophagous insects, the etiological factor of pediculosis capitis, spread most easily in preschool children, which is determined by social and behavioural aspects. The study aimed to search for factors contributing to pediculosis capitis persistence in kindergartens located in south-eastern Poland. For this purpose, anonymous surveys among the management staff of preschool institutions were conducted. Head lice infestations were reported in 87.0% of the 561 surveyed facilities. A positive correlation was confirmed between the prevalence of head lice and a higher number of children in these facilities. Additionally, in 69.3% of the facilities where cases of pediculosis capitis were reported, it was noted that the infestation was associated with the child's attendance at preschool. Familial and occupational transmission was observed in 78.5% and 25.2% of the facilities, respectively. In contrast, in 93.2% of preschools where no cases of infestation were reported, all parents consented to periodic head inspections. Parents' attitudes and their perception of head lice as a health issue, rather than an embarrassing problem, appear to be key factors in effectively limiting the spread of head lice in the studied kindergartens.

Presence of the knockdown resistance (kdr) mutations in the head lice (Pediculus humanus capitis) population in the North of Iran

Head lice infestation continues to be a major health problem worldwide. In order to solve this problem, frequent use of pediculocides has caused growing resistance among head lice population. This study aims to investigate the presence of the knockdown resistance (kdr) mutation in the head lice population in northern Iran. Adult head lice were collected from 115 infested individuals referring to the health centers in different parts of Mazandaran province, northern Iran. 38 samples were randomly selected, and Polymerase chain reaction (PCR) was used to amplify a 332-bp and ⁓ 900-bp fragment of the α-subunit of the voltage-sensitive sodium channel (VSSC) gene. According to the analysis of a 332-bp fragment of the VSSC gene, the frequency of kdr T917I mutation including homozygous susceptible (SS), heterozygous resistant (RS), and homozygous resistant (RR) were 45.83%, 12.5%, and 41.66%, respectively. The total frequency of the resistance allele was 54.16%. The results of the 900-bp fragment of the VSSC gene showed two new mutations in the IIS1-2 extracellular loop (H813P) and IIS2 (S825R) and old well-known kdr mutations (M815I-T917I-L920F). The results of Hardy-Weinberg's exact equilibrium test showed that the frequency of genotypes in the studied areas is different from expectations. Moreover, a positive inbreeding coefficient value (F is >0) was found in studied areas which indicated an excess of homozygotes. Overall, the results showed a high frequency of resistant alleles in the northern region of the country. Therefore, it is necessary to develop appropriate control programs for the treatment of pediculosis.

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.

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.

Scabies, Bedbug, and Body Lice Infestations: A Review

Importance

Scabies, bedbug, and body lice infestations are caused by organisms that live on or in the skin, on clothing, or in the environment and commonly cause pruritus and rash. In 2021, approximately 622 million incident cases of scabies occurred globally. Data on bedbug infestations are limited. Body lice prevalence ranges from 4.1% to 35% among persons experiencing homelessness worldwide.

Observations

Scabies is caused by mites (Sarcoptes scabiei) that burrow into the epidermis. Transmission primarily occurs from prolonged skin-to-skin contact with an individual who has an infestation. Common scabies is characterized by excoriated pruritic papules, plaques, and pathognomonic burrows on finger/toe web spaces, volar wrists, ankles, axillae, buttocks, male genitalia, and areolae. Permethrin cream and oral ivermectin are first-line treatments for adults, with similar clearance rates by week 2 (74% with permethrin vs 68% with ivermectin; relative risk, 0.91; 95% CI, 0.76-1.08). Treatment failure can occur with oral ivermectin (11.8%; 95% CI, 8.4%-15.4%) and topical permethrin (10.8%; 95% CI, 7.5%-14.5%). Bedbugs (Cimex lectularius, Cimex hemipterus) are insects that live on mattresses and furniture and feed on blood nocturnally, causing linear pruritic erythematous papules. New skin lesions on waking, cohabitants with similar symptoms, and recently residing in a high-occupancy setting should raise suspicion. Treatment requires eradication with pest management. Body lice (Pediculus humanus humanus) are insects found on clothing that travel to the skin for blood meals. Body lice bites cause pruritic excoriated macules/papules and hyperpigmentation in areas where clothing seams contact skin. Treatment and prevention require at least once-weekly bathing and laundering of clothing and bedding.

Conclusions and Relevance

Scabies, bedbug, and body lice infestations are common. Accurate diagnosis requires taking a history, including social drivers of health (eg, housing status, living environment), and physical examination. First-line treatments include scabicides for patients with common scabies and their close contacts. Scabies, bedbug, and body lice infestations should be treated with decontamination measures.

State-of-the-Art Review: Evaluation and Management of Delusional Infestation

Delusional infestation is a condition encountered frequently by healthcare professionals across a variety of specialties in which patients have a fixed, false belief that they are infested with living creatures, such as bugs, parasites, worms, or mites, or nonliving objects, such as fibers. Delusional infestation can be debilitating for patients, who not only present with intense psychological distress and physical discomfort but are also at risk of developing numerous dermatological and psychiatric complications. This condition poses unique diagnostic challenges, as these symptoms can occur secondary to many metabolic or infectious causes, as well as unique treatment challenges, with patients frequently refusing psychiatric care and consequently seeking evaluation by other healthcare professionals. In this review, we aim to use existing literature to provide clinicians in infectious diseases or other specialties with sufficient clinical context and treatment guidance for the appropriate management of delusional infestation.

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

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

Secondary Bacterial Infections in Patients with Atopic Dermatitis or Other Common Dermatoses

Secondary bacterial infections of common dermatoses such as atopic dermatitis, ectoparasitosis, and varicella zoster virus infections are frequent, with Staphylococcus aureus and Streptococcus pyogenes being the bacteria most involved. There are also Gram-negative infections secondary to common dermatoses such as foot dyshidrotic eczema and tinea pedis. Factors favoring secondary bacterial infections in atopic dermatitis, ectoparasitosis, and varicella zoster virus infections mainly include an epidermal barrier alteration as well as itch. Mite-bacteria interaction is also involved in scabies and some environmental factors can promote Gram-negative bacterial infections of the feet. Furthermore, the bacterial ecology of these superinfections may depend on the geographical origin of the patients, especially in ectoparasitosis. Bacterial superinfections can also have different clinical aspects depending on the underlying dermatoses. Subsequently, the choice of class, course, and duration of antibiotic treatment depends on the severity of the infection and the suspected bacteria, primarily targeting S. aureus. Prevention of these secondary bacterial infections depends first and foremost on the management of the underlying skin disorder. At the same time, educating the patient on maintaining good skin hygiene and reporting changes in the primary lesions is crucial. In the case of recurrent secondary infections, decolonization of S. aureus is deemed necessary, particularly in atopic dermatitis.

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

OBJECTIVE

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

RESULTS

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

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.

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

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

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

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

Cost-Effective PCR-Based Identification of Tunga penetrans (Siphonaptera) Larvae Extracted from Soil Samples Containing PCR Inhibitor-Rich Material

Tungiasis is a neglected tropical disease caused by skin-penetrating female Tunga penetrans fleas. Although tungiasis causes severe health problems, its ecology is poorly understood and morphological descriptions of the larvae are unavailable. To identify T. penetrans immature stages and sites where they develop, diagnostic PCRs are required. However, flea larvae feed on soil organic matter rich in PCR inhibitors. Here, three DNA preparation methods, including a soil DNA kit that removes inhibitors, a simple ammonium acetate precipitation approach (AmAcet) and a crude lysate of larvae (CL), were combined with amplification by the highly processive FIREPol^® Taq or the inhibitor-resistant Phusion^® polymerase. Independent of the polymerase used, the frequency of successful amplification, C_q values and PCR efficacies for the low-cost CL and AmAcet methods were superior to the commercial kit for amplification of a 278 bp partial internal transcribed spacer-2 (ITS-2) and a 730 bp pan-Siphonaptera cytochrome oxidase II PCR. For the CL method combined with Phusion^® polymerase, the costs were approximately 20-fold lower than for the methods based on the soil DNA kit, which is a considerable advantage in resource-poor settings. The ITS-2 PCR did not amplify Ctenocephalides felis genomic or Tunga trimammilata ITS-2 plasmid DNA, meaning it can be used to specifically identify T. penetrans.

Lice and lice-borne diseases in humans in Africa: a narrative review

Lice are host-specific insects. Human lice include Pediculus humanus humanus (body lice) which are known to be vectors of serious human bacterial infectious diseases including epidemic typhus, relapsing fever, trench fever and plague; Pediculus humanus capitis (head lice) that frequently affect children; and Pthirus pubis, commonly known as crab lice. In Africa, human infections transmitted by lice remained poorly known and therefore, underestimated, perhaps due to the lack of diagnostic tools and professional knowledge. In this paper we review current knowledge of the microorganisms identified in human lice in the continent of Africa, in order to alert health professionals to the importance of recognising the risk of lice-related diseases.

Human pediculosis, a global public health problem

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Broadening the range of use cases for ivermectin - a review of the evidence

Ivermectin is a broad-spectrum antiparasitic agent that interferes with glutamate-gated chloride channels found in invertebrates but not in vertebrate species. Mass drug administration (MDA) with ivermectin-based regimes has been a mainstay of elimination efforts targeting onchocerciasis and lymphatic filariasis for more than 3 decades. More recently, interest in the use of ivermectin to control other neglected tropical diseases (NTDs) such as soil-transmitted helminths and scabies has grown. Interest has been further stimulated by the fact that ivermectin displays endectocidal efficacy against various Anopheles species capable of transmitting malaria. Therefore there is growing interest in using ivermectin MDA as a tool that might aid in the control of both malaria and several NTDs. In this review we outline the evidence base to date on these emerging indications for ivermectin MDA with reference to clinical and public health data and discuss the rationale for evaluating the range of impacts of a malaria ivermectin MDA on other NTDs.

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.

Understanding Dermatologic Concerns Among Persons Experiencing Homelessness: A Scoping Review and Discussion for Improved Delivery of Care

There is a paucity of information surrounding dermatologic care for persons experiencing homelessness (PEH). This scoping review aims to map existing literature and provide a summary of the most common cutaneous manifestations among PEH, risk factors for dermatologic disease, describe any reported interventions, as well as identify research gaps for future studies. Search strategies developed for MEDLINE and hand searching yielded 486 articles. Out of the 486 articles screened, 93 articles met the inclusion criteria. The majority were cohort studies, cross-sectional studies, and case-control studies concentrated in North America and Europe. Excluding the pediatric population, the prevalence of dermatologic conditions ranged from 16.6% to 53.5%. Common skin conditions described in PEH were: acne, psoriasis, seborrheic dermatitis, atopic dermatitis, and lichen simplex chronicus. There were no studies comparing the extent or severity of these cutaneous diseases in PEH and the general population. PEH have a higher prevalence of skin infections and non-melanoma skin cancers. This scoping review has direct implications on public health interventions for PEH and highlights the need for evidence-based interventions to provide optimum and safe dermatologic healthcare for PEH. We propose several recommendations for improved care delivery, including addressing upstream factors and comorbidities impacting skin health, providing trauma informed care, reducing barriers to care, preventing and managing skin conditions, as well as including PEH in the planning and implementation of any proposed intervention.

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

Background

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

Objective

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

Methods

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

Results

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

Limitations

Retrospective analysis limits interpretation.

Conclusion

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

Molecular analysis of mitochrondrial cytb of Pediculus humanus capitis in Thailand revealed potential historical connection with South Asia

Background

Pediculus humanus capitis or head louse is an obligate ectoparasite and its infestation remains a major public health issue worldwide. Molecular analysis divides head lice into six clades and intra-clade genetic differences have been identified. Several hypotheses have been formulated to elucidate the discrepancies of the variety of head lice among different regions of the world. It is currently concluded that head lice distribution might be associated with human migration history. This study aims to investigate genetic data of human head lice in Thailand. We believe that the analysis could help establish the correlation between local and global head lice populations.

Method

We investigated mitochondrial cytochrome b (cytb) gene of the collected 214 head lice to evaluate genetic diversity from 15 provinces among 6 regions of Thailand. The head lice genes were added to the global pool for the phylogenetic tree, Bayesian tree, Skyline plot, and median joining network construction. The biodiversity, neutrality tests, and population genetic differentiation among the 6 Thailand geographic regions were analyzed by DNAsp version 6.

Results

The phylogenetic tree analysis of 214 collected head lice are of clade A and clade C accounting for roughly 65% and 35% respectively. The Bayesian tree revealed a correlation of clade diversification and ancient human dispersal timeline. In Thailand, clade A is widespread in the country. Clade C is confined to only the Central, Southern, and Northeastern regions. We identified 50 novel haplotypes. Statistical analysis showed congruent results between genetic differentiation and population migration especially with South Asia.

Conclusions

Pediculosis remains problematic among children in the rural areas in Thailand. Cytb gene analysis of human head lice illustrated clade distribution and intra-clade diversity of different areas. Our study reported novel haplotypes of head lice in Thailand. Moreover, the statistic calculation provided a better understanding of their relationship with human, as an obligate human parasite and might help provide a better insight into the history of human population migration. Determination of the correlation between phylogenetic data and pediculicide resistance gene as well as residing bacteria are of interest for future studies.

Common Dermatologic Conditions in Returning Travelers

Purpose of Review

Travel medicine practitioners often are confronted with returning travelers with dermatologic disorders that could be of infectious causes or inflammatory or allergic. Some dermatologic processes are the result of exposure to insects or acquired due to environmental exposures. There is a broad range of dermatosis of infectious and non-infectious etiologies that clinicians need to consider in the differential diagnosis of dermatosis in travelers.

Recent Findings

With increasing international travel to tropical destinations, many individuals may be exposed to rickettsia (i.e., African tick bite fever, scrub typhus, or Mediterranean spotted fever), parasitic infections (i.e., cutaneous larva migrans, cutaneous leishmaniasis, African trypanosomiasis, or American trypanosomiasis), viral infections (i.e., measles or Zika virus infection), bacterial (i.e., Buruli ulcer) or ectoparasites (scabies or tungiasis), and myiasis. Cutaneous lesions provide clinical clues to the diagnosis of specific exposures during travel among returned travelers.

Summary

Dermatologic disorders represent the third most common health problem in returned travelers, after gastrointestinal and respiratory illness. Many of these conditions may pose a risk of severe complications if there is any delay in diagnosis. Therefore, clinicians caring for travelers need to become familiar with the most frequent infectious and non-infectious skin disorders in travelers.

Abametapir for the Treatment of Head Lice: A Drug Review

OBJECTIVE

This article reviews the pharmacology, safety, efficacy, and clinical importance of abametapir 0.74% (Xeglyze) for the treatment of head lice.

DATA SOURCES

From 2020 to May 2021, a systematic review of the MEDLINE and EMBASE databases was conducted using the terms abametapir, Xeglyze, Ha44, and head lice. Bibliographies, Food and Drug Administration (FDA) drug package inserts, and ClinicalTrials.gov were searched for further information.

STUDY SELECTION AND DATA EXTRACTION

All relevant full-text articles in English were considered for inclusion, with a final article date range of 1999 to 2020.

DATA SYNTHESIS

Abametapir chelates heavy metal cations and inhibits metalloproteinases critical to louse ova development, hatching, and adult survival. In phase II, abametapir had direct ovicidal activity inhibiting 100% of treated louse eggs from hatching, compared with 64% in the vehicle-treated group. In two identical phase III clinical trials, subjects treated with a single 10-minute application of abametapir had greater treatment success compared with vehicle-treated subjects, with 81.1% success versus 50.9% in study 1 (P = 0.001) and 81.8% versus 47.2% in study 2 (P < 0.001). Abametapir was well tolerated, with only mild adverse effects.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Abametapir is a newly FDA-approved, single-application treatment for head lice in patients aged 6 months and older. This review highlights the safety and efficacy of abametapir in the treatment of head lice.

CONCLUSIONS

In the wake of increasing widespread resistance to first-line treatment options, abametapir offers a safe and effective new treatment option for head lice infestations.

Dynamics and optimal control in transmission of tungiasis diseases

This paper aims to model the transmission of tungiasis disease and assess the optimal control schemes to stop its occurrence. Based on the development stage of fleas and propagation process of diseases, we propose a human-flea model without control, in which the susceptible-infected in latent stage-infectious populations and the egg-larva-pupa-adult stage of fleas are all in involved. In the light of the Lyapunov function method, we prove global stability of equilibria. The model is extended by reformulating it as an optimal control problem, with the use of four time-dependent controls, to assess the impact of individual protection, treatment and two flea control strategies (killing adult fleas and reduction of eggs and larvae). By using Pontryagin’s maximum principle, we characterize the optimal control. Using the data of human and flea in Brazil and Nigeri, numerical simulations are performed. The numerical results show that enhancing the protection and treatment of people and increasing the killing efficacy of flea adults would contribute to prevent and control the spread of the disease appreciably.

Efficacy and safety of a dimethicone lotion in patients with pyrethroid-resistant head lice in an epidemic area, Okinawa, Japan

Pyrethroid insecticides are the only pesticides approved for the treatment of head lice (pediculosis capitis) infestations in Japan. However, in Okinawa Prefecture, 96% of head lice are resistant to pyrethroids. Here, we conducted a clinical trial to assess the safety and efficacy of a dimethicone preparation against head lice infestations in Okinawa Prefecture. Dimethicone‐containing lotion was applied over the entire scalp three times over a 7‐day period. Lice bodies (nymphs/adults) and eggs (nits) were counted before (day 0) and after treatment (day 8); a subset of eggs was collected to estimate viability based on hatch rate. Efficacy was evaluated based on improvement (reduction) in head lice counts post‐treatment with respect to baseline. Safety was evaluated based on subjects’ scalp condition and adverse event incidence. Utility was a composite end‐point combining efficacy and safety. In total, 35 subjects were enrolled. Efficacy and safety were evaluated in 23 and 35 subjects, respectively. No side‐effects of note were reported during the treatment period. The dimethicone lotion resulted in a utility rating of “marginally useful” or higher in over 80% of the study population, signifying the formulation to be both safe and effective. The dimethicone lotion was also a potent ovicide; 99.4% of eggs collected after treatment failed to hatch when incubated. Eradication of head lice remained successful for at least 4 weeks after the final topical dimethicone application in 25 of the 28 subjects reached by telephone survey. Lice bodies and eggs were genotyped to analyze the prevalence of three knockdown resistance (kdr)‐type mutations within the voltage‐sensitive sodium channel known to confer pyrethroid resistance. One or more kdr mutations were confirmed in 30 of the 32 subjects from whom specimens were collected (93.8%). Dimethicone was confirmed to be both safe and effective in treating pyrethroid‐resistant head lice.

A clinical review and history of pubic lice

The ectoparasite Pthirus pubis (PtP), commonly known as the crab or pubic louse, has plagued primates from prehistoric apes to Homo sapiens. We combed the literature from antiquity to the present day, reviewing the pubic louse's origins, its evolution with mankind, and its presentation and management. MEDLINE and EMBASE provided the greatest yield of literature compared with other databases. Estimates for PtP incidence range from 0.3% to 4.6% and for prevalence around 2% in adults. War, disasters and overcrowding support lice transmission, but modern pubic hair grooming has reduced the incidence of PtP in recent years. PtP, is usually found on pubic hair, but may infest scalp and body hair, eyebrows and eyelashes. Reports suggest the possibility of PtP as a vector for Bartonella spp. and Acinetobacter spp., which require further study. Transmission of PtP is via close contact, so sexual abuse and concomitant sexually transmitted infections should be considered. Symptoms and signs of infestation include pruritus, red papules and rust/brown deposits from feeding or faecal matter. Visualization of live lice confirms the diagnosis. Traditional treatments include hand-picking and combing, but in modern times pediculicidal products may generate faster resolution. Permethrin or pyrethrins are the first-line recommendations. Resistance to pediculicides is common with head lice and is presumed likely with PtP, although data are lacking. Pseudoresistance occurs as a result of poor compliance, incorrect or ineffective dosing, and reinfestation. In true resistance, a different pediculicide class should be used, e.g. second-line agents such as phenothrin, malathion or ivermectin. Lice have existed long before humans and given their adaptability, despite habitat challenges from fashion trends in body hair removal, are likely to continue to survive.

Effectiveness and tolerability of a squalane and dimethicone-based treatment for head lice

Head lice (Pediculus humanus capitis) are worldwide obligate human ectoparasites, with high implications in pediatrics. In Europe, first-line topical neurotoxic insecticidal therapeutic strategies are being replaced by topical physically acting agents as the first-choice treatment. Safety of the active ingredients and high efficacy in a one-time single-dose treatment with a brief treatment application time are key issues for consumer use and effective compliance. The aim of this study was to assess the in vitro efficacy of a newly developed squalane and dimethicone-based pediculicidal formula, against motile head lice and eggs after 2 and 5 min immersion in the product, as well as its skin tolerance and acceptability under dermatological and pediatric expert control in children with atopic skin. The results indicate that at both time points, 100% mortality rate of head lice crawling stages and late-stage eggs was achieved. The formula was well tolerated and suitable for children with atopic skin from 12 months of age. Showing high in vitro efficacy and good skin acceptability, this solution is presented as a new safe alternative therapy for treatment of head lice infestations.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: an emerging tool for studying the vectors of human infectious diseases

Arthropod vectors have historically been identified morphologically, and more recently using molecular biology methods. However, both of these methods are time-consuming and require specific expertise and equipment. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, which has revolutionized the routine identification of microorganisms in clinical microbiology laboratories, was recently successfully applied to the identification of arthropod vectors. Since then, the robustness of this identification technique has been confirmed, extended to a large panel of arthropod vectors, and assessed for detecting blood feeding behavior and identifying the infection status in regard to certain pathogenic agents. In this study, we summarize the state-of-the-art of matrix-assisted laser desorption ionization time-of-flight mass spectrometry applied to the identification of arthropod vectors (ticks, mosquitoes, phlebotomine sand-flies, fleas, triatomines, lice and Culicoides), their trophic preferences and their ability to discriminate between infection statuses.

Entodermoscopy Update: A Contemporary Review on Dermoscopy of Cutaneous Infections and Infestations

Infectious cutaneous diseases are very common, especially in certain geographic and tropical regions. Sometimes they may simulate other dermatoses, ordering verification of diagnosis with particular investigations. Dermoscopy is among one of the most important tools readily available in the outpatient setting for the dermatologist to confirm the diagnosis. In this up-to date review, literature concerning the various dermoscopic features of parasitic, viral, dermatophytic and bacterial cutaneous infections is composed. In addition artefacts as well as practical issues in dermoscopy usage are discussed; with the aim to empower dermatologists to promptly and non-invasively diagnose and manage cutaneous infections and infestations.

Nosocomial Infections: Do Not Forget the Parasites!

Nosocomial infections (NIs) pose an increasing threat to public health. The majority of NIs are bacterial, fungal, and viral infections; however, parasites also play a considerable role in NIs, particularly in our increasingly complex healthcare environment with a growing proportion of immunocompromised patients. Moreover, parasitic infections acquired via blood transfusion or organ transplantation are more likely to have severe or fatal disease outcomes compared with the normal route of infection. Many of these infections are preventable and most are treatable, but as the awareness for parasitic NIs is low, diagnosis and treatment are often delayed, resulting not only in higher health care costs but, importantly, also in prolonged courses of disease for the patients. For this article, we searched online databases and printed literature to give an overview of the causative agents of parasitic NIs, including the possible routes of infection and the diseases caused. Our review covers a broad spectrum of cases, ranging from widely known parasitic NIs, like blood transfusion malaria or water-borne cryptosporidiosis, to less well-known NIs, such as the transmission of Strongyloides stercoralis by solid organ transplantation or nosocomial myiasis. In addition, emerging NIs, such as babesiosis by blood transfusion or person-to-person transmitted scabies, are described.

Mass migration and climate change: Dermatologic manifestations

Major changes in climate resulting in mass migrations have unique dermatologic implications for global vulnerable populations. Dermatologic manifestations commonly accompany the infectious and communicable diseases that proliferate in the settings of confinement, crowding, and limited sanitation associated with mass migration. Ectoparasitic infestations abound in refugee camps, and poor nutrition, hygiene, and compromised immunity put refugees at an increased risk for more dangerous infectious diseases carried by these ectoparasites. Climate change also profoundly affects the worldwide distribution of various vector-borne illnesses, thereby leading to the emergence of various communicable diseases in previously nonendemic areas. Natural disasters not only disrupt important lifesaving treatments, but also challenge various infectious disease control measures that are critical in preventing rapid transmission of highly infectious diseases. This article reviews the infectious diseases commonly found in these scenarios and provides an in-depth discussion of important implications for the dermatologist.