Scanning Electron Microscopy of Adult Head Lice (Pediculus Humanus Capitis) with Focus on Clinical Implications

2000 ◽  
Vol 4 (4) ◽  
pp. 181-185 ◽  
Author(s):  
Craig N. Burkhart ◽  
Craig G. Burkhart ◽  
William T. Gunning
Keyword(s):  
Defense Mechanisms ◽  
Developmental Stages ◽  
Head Louse ◽  
Electron Microscopic Examination ◽  
Human Head ◽  
Head Lice ◽  
Electron Microscopic ◽  
Anatomic Structure ◽  
Pediculus Humanus ◽  
Scanning Electron

Background: The incidence of head lice infestations in North America is escalating with an estimated 12 million cases of head lice per year despite the existence of insecticidal therapies. Objective: To evaluate certain characteristics of the human head louse, including their chitinous structure, nymphal developmental stages, legs with claw adaptations, antennae with sensory perceptions, and spiracles by which oxygen exchange occurs, for assessment of possible means to control the spread and growth of this insect. Methods: Scanning electron-microscopic examination of head lice was performed. Results: Newer treatments of head lice must acknowledge defense mechanisms that are based on anatomic structure and physiologic characteristics, details of louse transmission, and the insects' ability to ‘resurrect’ after sham death. Conclusions: An understanding of lice entomology is essential in the pursuit of novel means to control the lice epidemic.

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

2006 ◽  
Vol 10 (1) ◽  
pp. 2-6 ◽  
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.

Head Louse Feces: Chemical Analysis and Behavioral Activity

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.

Pyrethroid Pediculicide Resistance of Head Lice in Canada Evaluated by Serial Invasive Signal Amplification Reaction

2010 ◽  
Vol 14 (3) ◽  
pp. 115-118 ◽  
Author(s):  
Danielle Marcoux ◽  
Kathleen G. Palma ◽  
Nalini Kaul ◽  
Hilliary Hodgdon ◽  
Andrea Van Geest ◽  
...  
Keyword(s):  
Allele Frequency ◽  
Signal Amplification ◽  
Head Louse ◽  
Human Head ◽  
The United States ◽  
Head Lice ◽  
Pediculus Humanus Capitis ◽  
Pediculus Humanus ◽  
S Allele ◽  
Amplification Reaction

Background: Most people in the United States and Canada with pediculosis will be treated with neurotoxic pediculicides containing pyrethrins or pyrethroids. Their widespread use led to significant resistance reported from various countries. Although treatment failures are frequently observed in Canada, the resistance frequency to pyrethroid pediculicide of human head lice (Pediculus humanus capitis) has not been determined. Objective: To determine the knockdown resistance ( kdr) allele frequency in human head louse populations in Canada. Methods: Patients infested with Pediculus humanus capitis, aged 4 to 65 years, residents of Ontario, Quebec, and British Columbia, were participants. Head lice were collected by combing and picking the enrolled subjects' hair. Lice were analyzed by serial invasive signal amplification reaction (SISAR) for genotyping the T917I mutation of lice indicating permethrin resistance. The permethrin-resistant kdr allele (R allele) frequency could then be evaluated in the head lice collected in Canada. Results: Of the head louse populations analyzed, 133 of 137 (97.1%) had a resistant (R) allele frequency, whereas only 4 of 137 (2.9%) had a susceptible (S) allele frequency. Conclusions: The 97.1% resistant (R) allele frequency in head lice from Canada could explain the treatment failures encountered with pyrethrin and pyrethroid pediculicide treatments in Canadian populations infested with Pediculus humanus capitis as the latter will not be eliminated by those pediculicides.

scholarly journals Molecular Characterization and Genetic Diversity of Clade E-Human Head Lice from Guinea

2020 ◽  
Author(s):  
Alissa Hammoud ◽  
Meriem Louni ◽  
Mamadou Cellou Baldé ◽  
Abdoul habib Beavogui ◽  
Philippe Gautret ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Polymorphism ◽  
Gene Polymorphisms ◽  
Head Louse ◽  
Public Health Problem ◽  
Human Head ◽  
Head Lice ◽  
Acinetobacter Species ◽  
Pediculus Humanus ◽  
Blood Sucking

Pediculus humanus capitis, the head louse, is an obligate blood-sucking ectoparasite that occurs in six divergent mitochondrial haplogroups (A, D, B, F, C and E), each exhibiting a particular geographic distribution. A few years ago, several studies reported the presence of different pathogenic agents in head lice specimens from different clades collected worldwide. These findings suggest that head louse could be a vector for dangerous diseases and therefore a serious public health problem. Herein, we aimed to study the mitochondrial genetic diversity, the PHUM540560 gene polymorphisms profile of head lice collected in Guinea, as well as to screen for the pathogens present in these lice. In 2018, a total of 155 head lice were collected from 49 individuals at the Medicals Centers of rural (Maférinyah village) and urban (Kindia city) areas, in Guinea. All head lice were subjected to genetic analysis and screened for the presence of several pathogens using molecular tools. The results showed that all head lice belonged to the haplogroups C/E using the duplex qPCR which detects both clades. Standard PCR and sequencing revealed that all specimens belonged to the haplogroup E, including 8 haplotypes, whither 6 new identified for the first time in this study. The study of the PHUM540560 gene polymorphisms in our Guinean head lice revealed that 7/40 (17.5%) of our tested samples exhibit three different polymorphism profiles compared to the clade A-head lice PHUM540560 gene profile, while the remaining specimens 33/40 (82,5%) showed the same PHUM540560 gene polymorphism profile as the previously reported clade A-body lice. Molecular investigations of the targeted pathogens revealed only the presence of Acinetobacter species in 9% of our samples using real time PCR. Sequencing results identified highlighted the presence of several Acinetobacter species, including Acinetobacter baumannii (14.3%), Acinetobacter nosocomialis (14.3%), Acinetobacter variabilis (14.3%), Acinetobacter haemolyticus (7.2%), Acinetobacter towneri (7.2%). Furthermore, a candidate new species of Acinetobacter sp. (7.2%) was detected. Positive specimens were collected from 24,5% individuals in Maférinyah. We also investigated in our study the carbapenem’s-resistant profile of A. baumannii, none of our specimens were positive for the following resistance genes blaOXA-21, blaOXA-24 and blaOXA-58. To the best of our knowledge, our study is the first to report the existence of the Guinean haplogroup E, the PHUM540560 gene polymorphism profile as well as the presence of Acinetobacter species in head lice collected from Guinea.

A Comparative Study of Fractographic Replicas

1974 ◽  
Vol 32 ◽  
pp. 566-567
Author(s):  
Loren Anderson ◽  
Pat Pizzo ◽  
Glen Haydon
Keyword(s):  
Electron Microscopy ◽  
Electron Microscopic Examination ◽  
Direct Examination ◽  
Electron Microscopic ◽  
Reliable Technique ◽  
Service Failures ◽  
Transmission Electron ◽  
Mode Of Failure ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

Transmission electron microscopy of replicas has long been used to study the fracture surfaces of components which fail in service. Recently, the scanning electron microscope (SEM) has gained popularity because it allows direct examination of the fracture surface. However, the somewhat lower resolution of the SEM coupled with a restriction on the sample size has served to limit the use of this instrument in investigating in-service failures. It is the intent of this paper to show that scanning electron microscopic examination of conventional negative replicas can be a convenient and reliable technique for determining mode of failure.

MOLECULAR STUDY OF HUMAN HEAD LICE, PEDICULUS HUMANUS CAPITIS COMPARISON WITH GOAT SUCKING LICE, LINOGNATHUS STENOPSIS (BURMEISTER) STRAINS

2020 ◽  
pp. 132-139
Keyword(s):  
Genetic Difference ◽  
Human Head ◽  
Molecular Study ◽  
Head Lice ◽  
Pediculus Humanus Capitis ◽  
School Students ◽  
Pediculus Humanus ◽  
Sucking Lice ◽  
Pcr Products ◽  
Amplicon Size

In this study, only (122) out of (915) primary school students were shown to be infected with head lice Pediculus. humanus capitis. The number and percentage of infected males were 46 (11.3%), while the number and percentage of infected females were 76 (14.9%). The results in our study also showed that the number and percentage of goats infected with goat sucking lice, Linognathus stenopsis was 70 (21.7%) of the total 322 animals, with the highest number and percentage among female goats 44 (62.9%) compared to the male goats 26 (37.1%). The study demonstrated that the rate of genetic difference between the studied samples was 89% and the similarity rate was 11%. Detection of OP-K01 gene pieces by PCR products showed that the amplicon size was 520 bp for P. humanus capitis isolated from humans, while the detection of OP-E20 and OP-M05 gene pieces with PCR product showed the lowest amplicon size 230 bp for Linognathus stenosis isolated from goats.

scholarly journals Scanning electron microscopic examination of enamel surface after fixed orthodontic treatment: In-vivo study

2012 ◽  
Vol 140 (1-2) ◽  
pp. 22-28 ◽  
Author(s):  
Tijana Sessa ◽  
Jelena Civovic ◽  
Tina Pajevic ◽  
Jovana Juloski ◽  
Milos Beloica ◽  
...  
Keyword(s):  
Electron Microscopic Examination ◽  
Surface Damage ◽  
Multivariate Regression Analysis ◽  
Enamel Surface ◽  
Orthodontic Appliances ◽  
Electron Microscopic ◽  
Fixed Orthodontic Appliances ◽  
Tooth Surfaces ◽  
Scanning Electron

Introduction. Therapy with fixed orthodontic appliances starts with bracket bonding and ends with debonding of brackets, leaving enamel surface varied. Objective. The aim of this pilot study was to examine enamel surface before and after debonding of orthodontic brackets by the use of scanning electron microscopy (SEM). Methods. Epoxy replicas of four patients? premolars indicated for therapy with fixed orthodontic appliances were made and brackets were bonded to their teeth with a different adhesives (Enlight, No-mix, Fuji Ortho LC and Heliosit Orthodontic) (n=4). Two months later, brackets on premolars were debonded and amounts of adhesive left on the tooth surfaces and the bracket bases were evaluated with the adhesive remnant index (ARI). After resin removal, epoxy replicas were made and the surface of premolars was evaluated with the enamel surface index (ESI). All replicas of premolars (n=32) were prepared for SEM examination and compared under different magnifications. Tooth damage was estimated based on correlation between ARItooth and ESI. Results. Pearson?s ?2 test showed no significant differences between ARItooth and ARIbracket of four materials used. Nonparametric correlations showed significant differences between ARItooth and ARIbracket, ESI and ARItooth, and between ESI and ARIbracket. Increasing of ARItooth is followed with the descent of ARIbracket and the ascent of ESI. Multivariate regression analysis showed a significant correlation between ESI and ARItooth. Conclusion. Most bond failures took place at enamel-adhesive interface. ARItooth was a predictor to enamel surface damage. The type of material did not affect enamel surface damage.

scholarly journals Presence of the knockdown resistance (kdr) mutations in the head lice (Pediculus humanus capitis) collected from primary school children of Thailand

2020 ◽  
Vol 14 (12) ◽  
pp. e0008955
Author(s):  
Narisa Brownell ◽  
Sakone Sunantaraporn ◽  
Kobpat Phadungsaksawasdi ◽  
Nirin Seatamanoch ◽  
Switt Kongdachalert ◽  
...  
Keyword(s):  
Head Louse ◽  
Point Mutations ◽  
Human Head ◽  
Amino Acid Sequences ◽  
Primary School Children ◽  
Head Lice ◽  
Knockdown Resistance ◽  
Pediculosis Capitis ◽  
Α Subunit ◽  
Blood Sucking

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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