RESUMEN
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.
Asunto(s)
Catecoles , Cymbopogon , Alcoholes Grasos , Insecticidas , Pediculus , Extractos Vegetales , Animales , Pediculus/efectos de los fármacos , Pediculus/ultraestructura , Cymbopogon/química , Extractos Vegetales/farmacología , Alcoholes Grasos/farmacología , Alcoholes Grasos/toxicidad , Catecoles/farmacología , Insecticidas/toxicidad , Hojas de la Planta , Microscopía Electrónica de Rastreo/veterinaria , Glutatión Transferasa/metabolismo , Infestaciones por Piojos/veterinaria , Infestaciones por Piojos/tratamiento farmacológico , Infestaciones por Piojos/parasitologíaAsunto(s)
Infestaciones por Piojos , Pediculus , Humanos , Animales , Infestaciones por Piojos/tratamiento farmacológico , Pediculus/efectos de los fármacos , Insecticidas/efectos adversos , Insecticidas/uso terapéutico , Insecticidas/administración & dosificación , Insecticidas/farmacología , Dermatosis del Cuero Cabelludo/tratamiento farmacológicoRESUMEN
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 FISâ >â 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.
Asunto(s)
Resistencia a los Insecticidas , Insecticidas , Pediculus , Permetrina , Animales , Permetrina/farmacología , Pediculus/genética , Pediculus/efectos de los fármacos , Argentina , Resistencia a los Insecticidas/genética , Insecticidas/farmacología , Variación Genética , Repeticiones de Microsatélite , Humanos , Femenino , MasculinoRESUMEN
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.
Asunto(s)
Monoterpenos Acíclicos , Eucaliptol , Eugenol , Monoterpenos , Monoterpenos/farmacología , Monoterpenos/química , Animales , Eugenol/farmacología , Eugenol/química , Eucaliptol/farmacología , Monoterpenos Acíclicos/farmacología , Monoterpenos Acíclicos/química , Pediculus/efectos de los fármacos , Insecticidas/farmacología , Insecticidas/química , Timol/farmacología , Timol/química , Micelas , Aceites Volátiles/farmacología , Aceites Volátiles/química , Nanopartículas/química , Infestaciones por Piojos/tratamiento farmacológicoRESUMEN
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.
Asunto(s)
Hexanos , Pediculus , Animales , Femenino , Masculino , Pediculus/efectos de los fármacos , Pediculus/química , Hexanos/química , Cromatografía de Gases y Espectrometría de Masas , Metanol/química , Conducta Animal/efectos de los fármacosRESUMEN
Knockdown resistance (kdr) is a common mechanism of insecticide resistance in head lice to the conventionally used pyrethroid pediculosis and can be the result of various amino acid substitutions within the voltage-sensitive sodium channel (VSSC). In this study, 54 sequences from varied specimens were investigated to monitor well-known resistance mutations and probable new mutations. The Pediculus humanus capitis de Geer specimens were collected from 13 provinces in Iran. The specimens were stored in 70% ethanol until DNA extraction and PCR amplification of ~900-bp fragment of VSSC. The sequences were analyzed using different bioinformatics software for the detection of well-known kdr substitutions and additional mutations potentially associated with kdr resistance in head lice. There were six new and an old (haplotype I) kdr haplotypes within the Iranian head louse population. K794E, F815I, and N818D amino acid substitutions were reported for the first time. The P813H mutation was the most prevalent amino acid substitution in eight provinces. Among 53 sequences, 26 (49%) were homozygous susceptible, and 27 (51%) were heterozygotes. Thus, 51% of the head lice collected in Iran harbored only the P813H allele. The exact test for the Hardy-Weinberg (H-W) equilibrium showed that genotype frequencies differed significantly from the expectation in East-Azerbaijan and Tehran provinces. Moreover, these populations had an inbreeding coefficient (Fis) <0, indicating the excess of heterozygotes. This observation suggests that the populations of head lice from Iran are currently under active selective pressure. For the rest of the populations, H-W equilibrium and the expectations were significantly in harmony. The results of the current study highlight molecular techniques in the accurate detection of resistance genotypes before their establishment within the head louse population. Accurate detection of resistant genotypes seems to be helpful in decision-making on lice control programs and resistance monitoring and management.
Asunto(s)
Resistencia a los Insecticidas/genética , Insecticidas/farmacología , Pediculus/efectos de los fármacos , Animales , Irán , Pediculus/genéticaRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Jasminum grandiflorum L. is a medicinal plant widely used in the traditional system of Medicine as an anthelmintic in ringworm infections, for treating ulcers, stomatitis, skin diseases, and wounds. AIM OF THE STUDY: The emergence of resistance by different parasites to currently used chemicals has been reported. There are increasing needs for more effective and safer parasiticides. Therefore, the current study was designed to investigate the methanolic extract of the aerial parts of J. grandiflorum subsp. Floribundum (JGTE) to confirm its traditional uses as anthelmintic through a bioassay-guided fractionation and isolation of the active components with anthelmintic activity. MATERIALS AND METHODS: The JGTE was partitioned into dichloromethane (DCM-F) and n-butanol (BuOH-F) fractions. The JGTE, fractions, and the isolated compounds were tested in vitro for their anthelmintic activity using two nematodes; one larval stage of cestode and one arthropod. Four major compounds were isolated from the most active fraction (BuOH-F) including two flavonoids and two secoirridoid glycosides, identified as kaempferol-3-O-neohesperoside (1), rutin (2), oleuropein (3), and ligstroside (4). RESULTS: Among the isolated compounds from most active fraction (BuOH-F), rutin (2) displayed the highest anthelmintic activity in a dose-dependent activity with IC50 of 41.04 µg/mL against H. muscae adult worm, followed by ligstroside (4) with IC50 of 50.56 µg/mL. CONCLUSIONS: These findings could advocate the traditional use of J. grandiflorum L. and provide further insight into the anthelmintic activity of flavonoids.
Asunto(s)
Antihelmínticos/farmacología , Jasminum/química , Fitoquímicos/farmacología , Extractos Vegetales/farmacología , Animales , Antihelmínticos/química , Antihelmínticos/aislamiento & purificación , Ascaridoidea/efectos de los fármacos , Ascaridoidea/ultraestructura , Cestodos/efectos de los fármacos , Cestodos/ultraestructura , Flavonoides/química , Flavonoides/aislamiento & purificación , Flavonoides/farmacología , Nematodos/efectos de los fármacos , Nematodos/ultraestructura , Pediculus/efectos de los fármacos , Pediculus/ultraestructura , Fitoquímicos/química , Fitoquímicos/aislamiento & purificación , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Spiruroidea/efectos de los fármacos , Spiruroidea/ultraestructuraRESUMEN
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.
Asunto(s)
Dimetilpolisiloxanos , Insecticidas , Infestaciones por Piojos/tratamiento farmacológico , Pediculus/efectos de los fármacos , Escualeno/análogos & derivados , Animales , Preescolar , Europa (Continente) , Femenino , Humanos , Lactante , Infestaciones por Piojos/parasitología , Masculino , Piel/parasitologíaRESUMEN
Control of infestation by cosmopolitan lice (Pediculus humanus) is increasingly difficult due to the transmission of parasites resistant to pediculicides. However, since the targets for pediculicides have no been identified in human lice so far, their mechanisms of action remain largely unknown. The macrocyclic lactone ivermectin is active against a broad range of insects including human lice. Isoxazolines are a new chemical class exhibiting a strong insecticidal potential. They preferentially act on the γ-aminobutyric acid (GABA) receptor made of the resistant to dieldrin (RDL) subunit and, to a lesser extent on glutamate-gated chloride channels (GluCls) in some species. Here, we addressed the pediculicidal potential of isoxazolines and deciphered the molecular targets of ivermectin and the ectoparasiticide lotilaner in the human body louse species Pediculus humanus humanus. Using toxicity bioassays, we showed that fipronil, ivermectin and lotilaner are efficient pediculicides on adult lice. The RDL (Phh-RDL) and GluCl (Phh-GluCl) subunits were cloned and characterized by two-electrode voltage clamp electrophysiology in Xenopus laevis oocytes. Phh-RDL and Phh-GluCl formed functional homomeric receptors respectively gated by GABA and L-glutamate with EC50 values of 16.0 µM and 9.3 µM. Importantly, ivermectin displayed a super agonist action on Phh-GluCl, whereas Phh-RDL receptors were weakly affected. Reversally, lotilaner strongly inhibited the GABA-evoked currents in Phh-RDL with an IC50 value of 40.7 nM, whereas it had no effect on Phh-GluCl. We report here for the first time the insecticidal activity of isoxazolines on human ectoparasites and reveal the mode of action of ivermectin and lotilaner on GluCl and RDL channels from human lice. These results emphasize an expected extension of the use of the isoxazoline drug class as new pediculicidal agents to tackle resistant-louse infestations in humans.
Asunto(s)
Canales de Cloruro/metabolismo , Ivermectina/farmacología , Infestaciones por Piojos/tratamiento farmacológico , Oxazoles/farmacología , Pediculus/efectos de los fármacos , Tiofenos/farmacología , Animales , Antiparasitarios/farmacología , Canales de Cloruro/genética , Femenino , Humanos , Infestaciones por Piojos/metabolismo , Infestaciones por Piojos/parasitología , Masculino , Oocitos/citología , Oocitos/efectos de los fármacos , Oocitos/metabolismo , Oocitos/parasitología , Subunidades de Proteína , Pruebas de Toxicidad , Xenopus laevisRESUMEN
Human head lice are blood-sucking insects causing an infestation in humans called pediculosis capitis. The infestation is more prevalent in the school-aged population. Scalp itching, a common presenting symptom, results in scratching and sleep disturbance. The condition can lead to social stigmatization which can lead to loss of self-esteem. Currently, the mainstay of treatment for pediculosis is chemical insecticides such as permethrin. The extended use of permethrin worldwide leads to growing pediculicide resistance. The aim of this study is to demonstrate the presence of the knockdown resistance (kdr) mutation in head lice populations from six different localities of Thailand. A total of 260 head lice samples in this study were collected from 15 provinces in the 6 regions of Thailand. Polymerase chain reaction (PCR) was used to amplify the α subunit of voltage-sensitive sodium channel (VSSC) gene, kdr mutation (CâT substitution). Restriction fragment length polymorphism (RFLP) patterns and sequencing were used to identify the kdr T917I mutation and demonstrated three genotypic forms including homozygous susceptible (SS), heterozygous genotype (RS), and homozygous resistant (RR). Of 260 samples from this study, 156 (60.00%) were SS, 58 (22.31%) were RS, and 46 (17.69%) were RR. The overall frequency of the kdr T917I mutation was 0.31. Genotypes frequencies determination using the exact test of Hardy-Weinberg equilibrium found that northern, central, northeastern, southern, and western region of Thailand differed from expectation. The five aforementioned localities had positive inbreeding coefficient value (Fis > 0) which indicated an excess of homozygotes. The nucleotide and amino acid sequences of RS and RR showed T917I and L920F point mutations. In conclusion, this is the first study detecting permethrin resistance among human head lice from Thailand. PCR-RFLP is an easy technique to demonstrate the kdr mutation in head louse. The data obtained from this study would increase awareness of increasing of the kdr mutation in head louse in Thailand.
Asunto(s)
Resistencia a los Insecticidas/genética , Insecticidas/farmacología , Infestaciones por Piojos/parasitología , Pediculus/genética , Permetrina/farmacología , Sustitución de Aminoácidos , Animales , Niño , Femenino , Genotipo , Humanos , Infestaciones por Piojos/epidemiología , Masculino , Mutación Missense , Pediculus/efectos de los fármacos , Mutación Puntual , Prevalencia , Instituciones Académicas , Estudiantes , Tailandia/epidemiologíaRESUMEN
Head lice infestation caused by Pediculus humanus capitis De Geer, 1767 is one of the most common public health problems. The relationship between humans and head lice dates back millions of years ago that differentiated into different phylogenetic clades. Treatment of head lice infestation usually based on insecticide-based products, which promotes the resistance in the head lice populations. In the present study, we aimed to screen the presence of permethrin resistance among collected P. h. capitis specimens in Turkey. Three mutation sites (T917I, L920F, and M815I) were screened using real-time PCR and resistance was identified by melt analysis. Of the studied specimens, resistance allele frequency (RAF) was found 0.98 for T917I, 0.99 for L920F, and 1.00 for M815I. The phylogenetic study revealed that Clade A and Clade B are present and overlap in Turkey. The present study is first to screen the resistance among Turkish head lice specimens. To not stimulate the pyrethroids resistance in head lice populations, early detection of resistance is crucial and will help the health professionals to choose suitable formula in the treatment. We suggest that the resistance status needs to be screened in randomly selected populations before any treatment application is given.
Asunto(s)
Resistencia a los Insecticidas/genética , Insecticidas/farmacología , Infestaciones por Piojos/tratamiento farmacológico , Pediculus/efectos de los fármacos , Permetrina/farmacología , Animales , Niño , Análisis por Conglomerados , Femenino , Frecuencia de los Genes , Humanos , Infestaciones por Piojos/parasitología , Masculino , Filogenia , Reacción en Cadena en Tiempo Real de la Polimerasa , Turquía/epidemiologíaRESUMEN
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.
Asunto(s)
Formación de Concepto , Infestaciones por Piojos/psicología , Estigma Social , Animales , Niño , Humanos , Infestaciones por Piojos/complicaciones , Pediculus/efectos de los fármacos , Pediculus/patogenicidad , Salud Pública/métodosRESUMEN
Introduction: Pediculosis Capitis (head lice infestation) is the most common disease of the bloodsucking insect which affects approximately six to twenty million cases and results considerable economic burden annually. In this study we aim to investigate some medieval Persian views on the role of non-pharmacological treatment strategies for prevention and control of pediculosis and compare their prescriptions with current findings. Materials and methods: In this qualitative study, we reviewed some well-known Persian medicine (PM) textbooks based on the selected keywords (Shepesh, Reshk, Ghamal and Seyban) to collect the viewpoint of PM scholars for pediculosis and its treatments. Also, we searched in the databases such as PubMed, Science direct and Scopus about the topic. Results: Persian medicine scientists believed that there are six essential health principles (SetteZaroorieh), which can affect human health and prevent diseases including air, nutrition, exercise, sleep and wakefulness, exertion of unnecessary materials from the body and finally psychological concepts. Proper management of these essential factors can improve lifestyle of people affected with pediculosis and also play a key role in prevention of head lice infestation. Conclusion: There are several suitable recommendations for prevention and control of pediculosis according to essential health principles in PM which can consider beside current drug treatments and the individual health recommendations for complete control of the disease
Asunto(s)
Humanos , Historia Medieval , Infestaciones por Piojos/terapia , Pediculus/efectos de los fármacos , Terapias Complementarias , Estudios de Evaluación como Asunto/historia , Medicina TradicionalAsunto(s)
Infestaciones por Piojos/tratamiento farmacológico , Macrólidos/administración & dosificación , Pediculus/parasitología , Phthiraptera/efectos de los fármacos , Dermatosis del Cuero Cabelludo/tratamiento farmacológico , Administración Tópica , Animales , Niño , Esquema de Medicación , Combinación de Medicamentos , Humanos , Pediculus/efectos de los fármacos , Factores de Riesgo , Dermatosis del Cuero Cabelludo/parasitología , Resultado del TratamientoRESUMEN
Head-lice infestation, pediculosis capitis, remains a public-health burden in many countries. The widely used first-line pediculicides and alternative treatments are often too costly for use in poor socio-economic settings. Ivermectin has been considered an alternate treatment for field practice. This study was composed of 2 parts, a cross-sectional survey and an intervention study. The main objectives were to determine the prevalence and potential factors associated with head-lice infestation, and to evaluate the effectiveness and safety of oral ivermectin administration. A community-based cross-sectional survey was conducted among 890 villagers in rural areas along Thai-Myanmar border. Females with infestations were eligible for the intervention study, and 181 participated in the intervention study. A post-treatment survey was conducted to assess acceptance of ivermectin as a treatment choice. Data analysis used descriptive statistics and a generalized-estimation-equation model adjusted for cluster effect. The study revealed the prevalence of head-lice infestation was 50% among females and only 3% among males. Age stratification showed a high prevalence among females aged <20 years, and among 50% of female school-children. The prevalence was persistent among those with a history of infestation. The major risk factors were residing in a setting with other infected cases, and sharing a hair comb. The study also confirmed that ivermectin was safe and effective for field-based practice. It was considered a preferable treatment option. In conclusion, behavior-change communication should be implemented to reduce the observed high prevalence of headlice infestation. Ivermectin may be an alternative choice for head-lice treatment, especially in remote areas.
Asunto(s)
Insecticidas/administración & dosificación , Ivermectina/administración & dosificación , Infestaciones por Piojos/tratamiento farmacológico , Pediculus/efectos de los fármacos , Administración Oral , Adolescente , Adulto , Animales , Niño , Femenino , Humanos , Infestaciones por Piojos/epidemiología , Infestaciones por Piojos/parasitología , Masculino , Persona de Mediana Edad , Pediculus/fisiología , Población Rural , Tailandia/epidemiología , Resultado del Tratamiento , Adulto JovenRESUMEN
BACKGROUND: Increasing resistance of head lice against neurotoxic agents and safety concerns have led to the search for treatment alternatives. Dimeticones with a physical mode of action are safe, and bear a reduced risk for the development of resistance. METHODS: We performed in vitro bioassays to assess pediculicidal and ovicidal activities of a new dimeticone-based product, and a randomized controlled clinical trial to assess efficacy, following 10 min application. Of 153 individuals screened, 100 participants with active head louse infestations were randomly assigned to treatment with either a dimeticone-based test product, or a 0.5% permethrin-based reference product (50 participants per group). Participants received two topical applications of either the test (10 min) or reference products (45 min) at days 0 and 7 or 8. Outcome measures included the efficacies of treatment and their safety, as well as global and local tolerability at baseline, and days 1, 7, and 10. RESULTS: After 10 min exposure, all lice treated with the dimeticone test product were classified as non-viable in the in vitro assay. Ovicidal activity after treatment of eggs with the dimeticone test product was 96.8%. In the clinical trial, 96 patients completed all study visits. In the full analysis set (FAS) population, on day 1 after one application, 98% of patients were cured in the test group, as compared to 84% cured in the reference group. All participants in both groups were free of head lice on day 10, following two applications (100% cure rate). In total, 42 adverse events (AEs) in 23 patients of both treatment groups were recorded, with the majority of AEs classified as mild. CONCLUSIONS: We have shown a high level of pediculicidal and ovicidal activity, and clinical efficacy and safety, of a brief application of a new dimeticone-based product. The short application time and reduced risk for the development of resistance are key drivers for improved patients' compliance. TRIAL REGISTRATION: EU Clinical Trials Register EudraCT 2016-004635-20 . Registered 14 November 2016.
Asunto(s)
Dimetilpolisiloxanos/uso terapéutico , Insecticidas/uso terapéutico , Infestaciones por Piojos/tratamiento farmacológico , Pediculus/efectos de los fármacos , Permetrina/uso terapéutico , Dermatosis del Cuero Cabelludo/tratamiento farmacológico , Administración Tópica , Adolescente , Adulto , Animales , Niño , Preescolar , Dimetilpolisiloxanos/efectos adversos , Dimetilpolisiloxanos/farmacología , Femenino , Humanos , Técnicas In Vitro , Insecticidas/efectos adversos , Insecticidas/farmacología , Masculino , Permetrina/farmacología , Método Simple CiegoRESUMEN
The infestation with the human ectoparasite, Pediculus humanus capitis (De Geer), is a common public health problem affecting schoolchildren worldwide. In Chile, the main active ingredients present in the over-the-counter pediculicides contain pyrethroids. Despite the extended use of these products, there is no evidence of the insecticide resistance status of the head lice geographically located in Chile. The most extended resistant mechanism of pyrethroids consists of the target site insensitivity (Kdr) determined by the presence of mutations linked to insecticide-binding sites in the voltage-sensitive sodium channel. T917I is recognized as the main mutation in head lice, and detection is considered to be a biomarker of resistance. The goal of the present study was to detect the presence and distribution of T917I mutation in five geographic locations of Chile. All five geographically selected louse populations had a frequency of pyrethroid resistance genes that ranged from 36 to 77%, and 94.9% of the collected head lice had one or two T917I mutant alleles. Moreover, the frequency of the aggregate resistant alleles was 50.5%. This is the first evidence that head lice in Chile had the mutations commonly associated with the resistance to pyrethroids. Moreover, the overrepresentation of heterozygotes in the studied populations suggests that head lice in Chile are currently under active selective pressure.
Asunto(s)
Resistencia a los Insecticidas/genética , Insecticidas/farmacología , Pediculus/genética , Piretrinas/farmacología , Alelos , Animales , Chile , Femenino , Proteínas de Insectos/análisis , Masculino , Ninfa/efectos de los fármacos , Ninfa/genética , Pediculus/efectos de los fármacos , Pediculus/crecimiento & desarrollo , Canales de Sodio/análisisRESUMEN
PURPOSE: To report the clinical features and outcomes of toxic keratitis after application of powdered custard apple seeds for hair washing for head lice infestation. METHODS: Retrospective review of all patients with toxic keratitis after application of powdered custard apple seed for head lice infestation during the time period from January 2015 to December 2017. Demographic details, clinical features, and visual outcomes were documented. RESULTS: Thirty-one eyes of 19 patients with toxic keratitis after application of crushed custard apple seeds for head lice infestation were included in the study. Eighteen females and 1 male with a median age of 14 years [interquartile range (IQR) 12-34 years] presented with severe epiphora, congestion, photophobia, and defective vision (median logMar visual acuity 0.4, IQR 0.2-0.8) after application of custard apple seed powder for hair washing. Ten eyes (32.2%) had an epithelial defect (median size 9 mm, IQR 5-12 mm), and 21 (67.7%) eyes had punctate epithelial erosions. All the patients were treated with topical antibiotics, and at 3 days follow-up, all of them had resolution of symptoms and signs with a median logarithm of the minimum angle of resolution (logMAR) visual acuity of 0 (IQR 0-0.2). CONCLUSIONS: Health education about the harmful effect of this traditional practice for head lice infestation will prevent further similar events.
Asunto(s)
Annona/toxicidad , Queratitis/inducido químicamente , Infestaciones por Piojos/tratamiento farmacológico , Pediculus/efectos de los fármacos , Administración Oftálmica , Adolescente , Adulto , Animales , Antibacterianos/uso terapéutico , Niño , Dolor Ocular/inducido químicamente , Dolor Ocular/diagnóstico , Dolor Ocular/tratamiento farmacológico , Femenino , Humanos , Queratitis/diagnóstico , Queratitis/tratamiento farmacológico , Enfermedades del Aparato Lagrimal/inducido químicamente , Enfermedades del Aparato Lagrimal/diagnóstico , Enfermedades del Aparato Lagrimal/tratamiento farmacológico , Masculino , Ofloxacino/uso terapéutico , Fotofobia/inducido químicamente , Fotofobia/diagnóstico , Fotofobia/tratamiento farmacológico , Estudios Retrospectivos , Trastornos de la Visión/inducido químicamente , Trastornos de la Visión/diagnóstico , Trastornos de la Visión/tratamiento farmacológico , Adulto JovenRESUMEN
Pediculus humanus is an obligate bloodsucking ectoparasite of human that includes two ecotypes, head louse and body louse, which differ slightly in morphology and biology, but have distinct ecologies. Phylogenetically, they are classified on six mitochondrial clades (A, B, C, D, E, and F), head louse encompasses the full genetic diversity of clades, while body louse belongs to clades A and D. Recent studies suggested that not only body louse, but also head louse can transmit disease, which warrants greater attention as a serious public health problem. The recent sequencing of body louse genome confirmed that P. humanus has the smallest genome of any hemimetabolous insect reported to date, and also revealed numerous interesting characteristics in the nuclear and mitochondrial genomes. The transcriptome analyses showed that body and head lice were almost genetically identical. Indeed, the phenotypic flexibility associated with the emergence of body lice, is probably a result of regulatory changes, perhaps epigenetic in origin, triggered by environmental signals. Current lice control strategies have proven unsuccessful. For instance, ivermectin represents a relatively new and very promising pediculicide. However, ivermectin resistance in the field has begun to be reported. Therefore, novel opportunities for pest control strategies are needed. Our objective here is to review the current state of knowledge on the biology, epidemiology, phylogeny, disease-vector and control of this fascinating and very intimate human parasite.
Asunto(s)
Infestaciones por Piojos/epidemiología , Infestaciones por Piojos/parasitología , Pediculus/clasificación , Pediculus/genética , Animales , Bacterias/clasificación , Control de Enfermedades Transmisibles , Evolución Molecular , Genoma , Humanos , Insectos Vectores/microbiología , Resistencia a los Insecticidas , Insecticidas , Infestaciones por Piojos/microbiología , Infestaciones por Piojos/terapia , Mitocondrias , Pediculus/efectos de los fármacos , Filogenia , FilogeografíaRESUMEN
BACKGROUND: Scabies and head lice are ubiquitous ectoparasitic infestations that are common across the Pacific Islands. Ivermectin is an effective treatment for both conditions, although the doses used vary. At a community level, mass drug administration (MDA) with ivermectin is an effective strategy to decrease prevalence of scabies. To what extent MDA with ivermectin will also reduce prevalence of head lice is unknown. METHODOLOGY: Head lice prevalence was assessed before and after MDA with oral ivermectin (at a dose of 200 micrograms per kilogram of body weight) administered on day 1 and day 8. The primary outcome was the change in prevalence of head louse infestation at two weeks compared to baseline. Longer term efficacy was assessed three months after MDA. RESULTS: 118 participants were enrolled. Baseline prevalence of active head louse infestation was 25.4% (95% CI 18.4-34.0). At two-week follow-up, prevalence was 2.5% (95% CI 0.9-7.2), a relative reduction of 89.1% (95% CI 72.7-91.4%, p<0.001). At three-month follow-up, prevalence was 7.5% (95% CI 2.7-12.3), a relative reduction of 70.6% (95% CI 72.7%-91.4%, p <0.001). Head louse infestation was associated with younger age (age ≤10 years: prevalence 46.7%; adjusted odds ratio compared to adults of 7.2, 95%CI 2.0-25.9) and with having at least one other member of the household with active head louse infestation (adjusted odds ratio 4.3, 95%CI 1.7-11.1). CONCLUSIONS: Head louse infestation is common in the Solomon Islands. This proof of principle study shows that oral ivermectin at a dose of 200 micrograms per kilogram can reduce the burden of active head louse infestation, offering an additional collateral benefit of MDA with ivermectin for scabies control. TRIAL REGISTRATION: ClinicalTrials.gov NCT03236168.