Transmission potential of the human head louse,Pediculus capitis(Anoplura: Pediculidae)

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

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Bacterial Symbiotes, Their Presence in Head Lice, and Potential Treatment Avenues

Journal of Cutaneous Medicine and Surgery ◽

10.1007/7140.2006.00003 ◽

2006 ◽

Vol 10 (1) ◽

pp. 2-6 ◽

Cited By ~ 5

Author(s):

Craig N. Burkhart ◽

Craig G. Burkhart

Keyword(s):

Head Louse ◽

Human Head ◽

Blood Feeding ◽

Symbiotic Bacteria ◽

Head Lice ◽

Pediculus Humanus ◽

Toxic Agents ◽

Anatomic Localization

Background: Pediculus humanus capitis (head lice) belongs to the order Anoplura, which are blood-feeding ectoparasites that live on human hair. Within these insects reside symbiotic bacteria that enable the insect to flourish on dietary sources of limited nutritional value. These symbiotic bacteria are essential to the survival of the insect. Objective: To assess the feasibility of treating head lice by altering their symbiotic bacteria. Methods: In addition to a literature review of the expanded role of symbiotic bacteria in other organisms, the anatomic localization of their presence in human head lice and molecular characterization of the head louse symbiont were analyzed. Results: Anatomically, the bacterial symbiotes are localized to the midgut mycetome in males and the ovaries in females. The 16S ribosomal ribonucleic acid phylogenetic analysis was presented. Features of this bacterial symbiote may make this symbiont accessible as a target for pediculocidal and ovicidal therapy by altering its habitat and existence. Conclusions: An understanding of the nature of bacterial symbiotes of head lice might lead to alternative strategies for eradication or inhibition of these necessary bacteria, thereby controlling head lice with less toxic agents than conventional insecticides, to which the organism continues to increase its resistance.

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A Rare Case of Coexisting Pediculosis Capitis and Tinea Capitis in a Healthy Adult Female

Skin Appendage Disorders ◽

10.1159/000517198 ◽

2021 ◽

pp. 1-3

Author(s):

Ahmed H. Nouh ◽

Mahmoud A. Rageh

Keyword(s):

Adult Female ◽

Lupus Erythematosus ◽

Tinea Capitis ◽

Healthy Adult ◽

Head Louse ◽

Cutaneous Lupus Erythematosus ◽

Human Head ◽

Pediculosis Capitis ◽

Clinical Appearance ◽

Lichen Planopilaris

Pediculosis capitis is a common condition caused by infestation with the human head louse, <i>Pediculus humanus capitis</i>, and primarily affects children in the age-group of 6–12 years. The most prominent symptom is intense scalp itching, yet moving lice or nonmoving nits may be seen on the scalp and hair. Tinea capitis, also known as scalp ringworm, is a superficial fungal infection caused by keratinophilic fungi termed dermatophytes. Tinea capitis is rare in adults, and its symptoms include hair loss, dry scaly areas, redness, and itching. We here report a case of a rare coexistence between pediculosis capitis and tinea capitis in an otherwise healthy adult female, motivating the search for a possible cause of this rare coexistence and alarming dermatologists to be aware of the modified clinical appearance of this coexistence which could be mistaken with other conditions such as cutaneous lupus erythematosus or lichen planopilaris.

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Head Louse Feces: Chemical Analysis and Behavioral Activity

Journal of Medical Entomology ◽

10.1093/jme/tjz184 ◽

2019 ◽

Author(s):

F G Galassi ◽

M I Picollo ◽

P Gonzalez-Audino

Keyword(s):

Acetic Acid ◽

Head Louse ◽

Skin Irritation ◽

Human Head ◽

Behavioral Activity ◽

Volatile Components ◽

Head Lice ◽

Pediculus Humanus ◽

Secondary Infections

Abstract Human head lice Pediculus humanus capitis (De Geer) (Phthiraptera: Pediculidae) are insect parasites closely associated with humans, feeding on the blood of their hosts and causing them skin irritation and probable secondary infections. Despite being a severe nuisance, very few studies have reported on intraspecific chemical communication in head lice. Here, we evaluated the attractive response of head lice to the volatile compounds and solvent extracts from their feces. We also chemically analyzed the main volatile components of these feces and those of the feces’ extracts. Head lice were attracted to the methanol extract of their feces but not to the hexane or dichloromethane extracts, suggesting the polar nature of bioactive chemicals present in head louse feces. Follow-up chemical identifications, in fact, showed the presence of hypoxanthine, uric acid, and another purine tentatively identified as either guanine or iso-guanine. Additionally, head lice were significantly attracted by volatiles emitted from samples containing feces. The volatiles emanated from feces alone contained 19 identified substances: 2-pentanone, hexanal, heptanal, 3-methyl-3-buten-1-ol, octanal, sulcatone, nonanal, acetic acid, 2-ethyl-1-hexanol, decanal, 1-octanol, butyric acid, 1-nonanol, hexanoic acid, octanoic acid, 2,6-dimethyl-7-octen-2-ol, 2-undecanone, geranylacetone, and hexadecane. The major compounds found were decanal, nonanal, hexanal, and acetic acid, together representing approximately 60% of the identified compounds. This work represents the first chemical evidence of intraspecies communication among head lice. The results support the existence of active substances present in the feces of P. humanus capitis that may be involved in its aggregation behavior.

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