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result(s) for
"Lice Infestations - parasitology"
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An ex vivo, assessor blind, randomised, parallel group, comparative efficacy trial of the ovicidal activity of three pediculicides after a single application - melaleuca oil and lavender oil, eucalyptus oil and lemon tea tree oil, and a \suffocation\ pediculicide
by
Barker, Stephen C
,
Altman, Phillip M
in
Acrylates - administration & dosage
,
Acrylates - pharmacology
,
Acrylates - therapeutic use
2011
Background
There are two components to the clinical efficacy of pediculicides: (i) efficacy against the crawling-stages (lousicidal efficacy); and (ii) efficacy against the eggs (ovicidal efficacy). Lousicidal efficacy and ovicidal efficacy are confounded in clinical trials. Here we report on a trial that was specially designed to rank the clinical ovicidal efficacy of pediculicides. Eggs were collected, pre-treatment and post-treatment, from subjects with different types of hair, different coloured hair and hair of different length.
Method
Subjects with at least 20 live eggs of
Pediculus capitis
(head lice) were randomised to one of three treatment-groups: a melaleuca oil (commonly called tea tree oil) and lavender oil pediculicide (TTO/LO); a eucalyptus oil and lemon tea tree oil pediculicide (EO/LTTO); or a \"suffocation\" pediculicide.
Pre-treatment
: 10 to 22 live eggs were taken from the head by cutting the single hair with the live egg attached, before the treatment (total of 1,062 eggs).
Treatment
:
The subjects then received a single treatment of one of the three pediculicides, according to the manufacturers' instructions.
Post-treatment
: 10 to 41 treated live eggs were taken from the head by cutting the single hair with the egg attached (total of 1,183 eggs). Eggs were incubated for 14 days. The proportion of eggs that had hatched after 14 days in the pre-treatment group was compared with the proportion of eggs that hatched in the post-treatment group. The primary outcome measure was
% ovicidal efficacy
for each of the three pediculicides.
Results
722 subjects were examined for the presence of eggs of head lice. 92 of these subjects were recruited and randomly assigned to: the \"suffocation\" pediculicide (n = 31); the melaleuca oil and lavender oil pediculicide (n = 31); and the eucalyptus oil and lemon tea tree oil pediculicide (n = 30 subjects). The group treated with eucalyptus oil and lemon tea tree oil had an
ovicidal efficacy
of 3.3% (SD 16%) whereas the group treated with melaleuca oil and lavender oil had an
ovicidal efficacy
of 44.4% (SD 23%) and the group treated with the \"suffocation\" pediculicide had an
ovicidal efficacy
of 68.3% (SD 38%).
Conclusion
Ovicidal efficacy varied substantially among treatments, from 3.3% to 68.3%. The \"suffocation\" pediculicide and the melaleuca oil and lavender oil pediculicide (TTO/LO) were significantly more ovicidal than eucalyptus oil and lemon tea tree oil pediculicide (EO/LTTO) (P < 0.0001). Ranking: 1. \"Suffocation\" pediculicide (68.3% efficacy against eggs); 2. Melaleuca oil and lavender oil (44.4%) pediculicide; 3. Eucalyptus oil and lemon tea tree oil (3.3%) pediculicide. The \"suffocation\" pediculicide and TTO/LO are also highly efficacious against the crawling-stages. Thus, the \"suffocation\" pediculicide and TTO/LO should be recommended as first line treatments.
Trial Registration
The study was listed at the Australian/New Zealand Clinical Trial Registry (ANZCTR): reg. no.
12609000884202
.
Journal Article
High prevalence and low intensity of Echinophthirius horridus infection in seals revealed by high effort sampling
2024
Seal lice (
Echinophthirius horridus
) are bloodsucking ectoparasites of phocid seals and vectors of pathogens like the heartworm,
Acanthocheilonema spirocauda
. Grey and harbour seal populations are recovering in German waters and wildlife health surveillance is crucial for wildlife conservation. A new, high effort sampling protocol for seal lice was applied for grey and harbour seals along the German North- and Baltic Sea coast. Freshly dead seals were systematically sampled within a health monitoring of stranded seals over 12 months. Prevalence, intensity and distribution patterns of seal lice were analysed. 58% of harbour seals (
n
= 71) and 70% of grey seals (
n
= 10) were infected with seal lice. A majority of harbour seals displayed mild levels of infection, while three were moderately and two were severely infected. The head was the preferred predilection site, indicating that
E. horridus
prefers body areas with frequent access to atmospheric oxygen. Nits and different developmental stages were recorded in all age classes in grey and harbour seals in all seasons. For the first time, copulating specimens of
E. horridus
were recorded on a dead harbour seal, highlighting that
E. horridus
reproduces throughout the year on seals of all age classes in German waters.
Journal Article
Chewing lice (Phthiraptera) on a wild Golden eagle (Aquila chrysaetos) and a zoo-kept Eurasian griffon vulture (Gyps fulvus) in Tyrol, Austria
by
Unterköfler, Maria Sophia
,
Glawischnig, Walter
,
Pikalo, Jutta
in
Animals
,
Animals, Zoo - parasitology
,
Aquila chrysaetos
2025
Chewing lice (Phthiraptera) are obligate and permanent ectoparasites commonly found on birds. The life cycle of these insects is completed on the body of the host and therefore many are host specific. This is the first report of chewing lice on a wild Golden eagle (
Aquila chrysaetos
) and a zoo-kept Eurasian griffon vulture (
Gyps fulvus
) in Tyrol, Austria. Three different species of chewing lice were identified:
Craspedorrhynchus aquilinus
was found on
Aquila chrysaetos
and
Colpocephalum turbinatum
and
Falcolipeurus quadripustulatus
were found on
Gyps fulvus
. The lice were identified morphologically and by barcoding. Chewing lice (Phthiraptera) of eagles, vultures, and other Accipitriformes are understudied, and further research is needed.
Journal Article
Knockdown-resistant mutations in head lice (Pediculus humanus capitis) collected from schoolchildren in Riyadh, Saudi Arabia
2025
Head lice infestation remains one of the most common child problems. This problem is not only attributed to the ability of head lice to spread rapidly but also because of the head lice resistance that develops from incomplete or improper treatment. Pyrethroids are a group of medications that have been widely used for the treatment of head lice. However, in recent years, several countries reported knockdown resistance (kdr). The aim of this study is to evaluate the frequency of pyrethroid-resistant mutations in Riyadh City, Saudi Arabia. To do that, Sanger sequencing was employed to find the frequency of mutated alleles in the voltage-sensitive sodium channel gene (VSSC). The result showed that the frequency of the resistant alleles in T917I was 0.83. In addition, three new mutations (L920F, V966F, and F967L) were detected in the examined samples. These findings highlight the significant prevalence of pyrethroid-resistant mutations, which may be attributed to the cultural and tourism openness that leads to the abundance of numerous job opportunities for different workforces from all around the world.
Journal Article
Pubic Lice
2024
A 59-year-old man presented with a 4-week history of severe itching in his pubic region after sexual contact with a new partner. On examination, nits and crab-shaped lice (shown in a video) were seen attached to pubic hairs.
Journal Article
The deeper the rounder: body shape variation in lice parasitizing diving hosts
2024
Seal lice, unique among insects, show remarkable adaptability to the extreme conditions of the deep sea. Evolving with their seal and sea lion hosts, they have managed to tolerate hypoxia, high salinity, low temperature, and elevated hydrostatic pressure. Given the diving capabilities of their mammalian hosts, which can reach depths of hundreds to thousands of meters, our study examines the morphological variation among closely related seal lice species infesting hosts with different maximum diving depths. In particular, our research reveals a significant morphological difference between lice associated with regular and deep-diving hosts, where lice from deep-diving hosts tend to be rounder. This could be an adaptation to withstand the high hydrostatic pressures found in the deep ocean. The rounded shape optimizes the louse’s ability to withstand external pressure by redistributing it over a larger ventral/dorsal plane. This in turn minimizes the internal energy required to support body deformations, thereby increasing the louse’s resilience in the deep sea environment.
Journal Article
Body Louse Pathogen Surveillance among Persons Experiencing Homelessness, Canada, 2020–2021
2024
We analyzed body lice collected from persons experiencing homelessness in Winnipeg, Manitoba, Canada, during 2020-2021 to confirm vector species and ecotype and to identify louseborne pathogens. Of 556 lice analyzed from 7 persons, 17 louse pools (218 lice) from 1 person were positive for the louseborne bacterium Bartonella quintana.
Journal Article
Pheromone Communication in Feather-Feeding Wing Lice (Insecta: Phthiraptera)
by
Harbison, Christopher W.
,
Roberto, Domenic P.
,
Hutchins, Charlotte E. C.
in
Aggregation pheromone
,
Animal feathers
,
Animals
2023
Pheromone communication is central to the life history of insect parasites. Determining how pheromones affect parasite behavior can provide insights into host-parasite interactions and suggest novel avenues for parasite control. Lice infest thousands of bird and mammal species and feed on the host's feathers or blood. Despite the pervasiveness of lice in wild populations and the costs they exact on livestock and poultry industries, little is known about pheromone communication in this diverse group. Here, we test for pheromone communication in the wing lice (Columbicola columbae) of Rock Doves (Columba livia). Wing lice spend the majority of their lives on bird flight feathers where they hide from host preening by inserting their bodies between coarse feather barbs. To feed, wing lice must migrate to bird body regions where they consume the insulating barbs of contour feathers. We first show that wing lice readily form aggregations on flight feathers. Next, using a Y-tube olfactometer, we demonstrate that wing lice use pheromone communication to move toward groups of nearby conspecifics. This pheromone is likely an aggregation pheromone, as wing lice only produce the pheromone when placed on flight feathers. Finally, we found that when forced to choose between groups of male and female lice, male lice move toward male groups and females toward female groups, suggesting the use of multiple pheromones. Ongoing work aims to determine the chemical identity and function of these pheromones.
Journal Article
New Data on Ectoparasites of the Caucasian Squirrel Sciurus anomalus (Rodentia: Sciuridae) in Türkiye: A Case Report
Güldenstädt, 1785, known as the Caucasian squirrel, is a rodent distributed in all geographical regions of Türkiye. The material of this study consists of ectoparasites collected from male
found dead on the highway (Karasu, Sakarya, Türkiye). As a result of microscopic examination, the specimens were identified: ticks as
Linnaeus, 1758 (larvae and nymph), sucking louses as
Ferris, 1923 (female), and fleas as
(Schrank, 1803) (female and male). In this study, the presence of
infestation on
is reported for the first time in Türkiye.
Journal Article
Presence of the knockdown resistance (kdr) mutations in the head lice (Pediculus humanus capitis) collected from primary school children of Thailand
by
Phadungsaksawasdi, Kobpat
,
Brownell, Narisa
,
Siriyasatien, Padet
in
Amino Acid Substitution
,
Animals
,
Biology and Life Sciences
2020
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 ( F is > 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.
Journal Article