[International Symposium on control of lice and lice-born diseases].
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Animals↗
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[On the possibility of transmission of tick relapsing fever by lice. 3. Further data on the fate of tick relapsing fever spirochaetae in the organism of body lice].
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Animals↗
[Possibilities of transmission of tick relapsing fever by lice. V. The dynamics of Bor. sogdianae multiplication in hemolymph of body lice].
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Animals↗
[On the possibility of transmission of tick relapsing fever by lice. II. The fate of spirochaetae of tick relapsing fever in the organism of body lice in the first day after infective feeding].
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Animals↗
Head lice on pillows, and strategies to make a small risk even less.
BACKGROUND: Due to a lack of evidence, controversy exists about the role of bedding in the transmission of head lice. AIMS: To determine the proportion of the head lice population found on pillowcases of people with head lice, and to test strategies available to householders to kill head lice on pillowcases. METHODS: To assess the incidence of head lice on pillowcases, people with active pediculosis had their head lice collected and counted and the pillowcase they had used the night before examined for head lice. To test strategies to kill head lice on pillowcases, live head lice were experimentally placed in miniature pillowcases, and the cases were subjected to a hot wash, a cold wash, hot dryer, and hanging out to dry on an outdoor clothes line. RESULTS: Forty-eight people and their pillowcases were recruited from Townsville, Qld, Australia (dry tropics). One thousand, eight hundred and forty-five lice were collected from their heads to give an average and median intensity of infection of 38.4 and 21 lice, respectively. Two of the 48 pillowcases contained live lice, one nymph on each, 2 h and 9 h after the pillowcases had been removed from the bed. Another pillowcase contained a dehydrated nymph. The incidence of live lice on pillowcases was 4.2% per night and the proportion of the head louse population on the pillowcases was 0.11%. Heat (hot wash and hot clothes dryer) killed head lice experimentally placed in pillowcases. Cold wash and hanging pillowcases out to dry did not kill head lice. CONCLUSIONS: Head lice transfer to pillowcases at night, but the incidence is low. Pillowcases pose a risk for re-infection with head lice, but the risk is low, and changing the pillowcase is a reasonably cost-efficient strategy to minimize this risk. Lice on pillowcases can be killed by heating the pillowcase by immersion in water at > 60 degrees C, by a hot wash, or by 15 min in a hot clothes dryer.
Adolescent↗
Interventions for treating headlice.
BACKGROUND: Infection with head lice is a widespread condition in developed and developing countries. Infection occurs most commonly in children, but also affects adults. If left untreated the condition can become intensely irritating and skin infections may occur if the bites are scratched. OBJECTIVES: The aim of this review was to assess the effects of interventions for head lice. SEARCH STRATEGY: Trials register of The Cochrane Infectious Diseases Group; Medline; Embase; Science Citation Index; Biosis and Toxline; reference lists of relevant articles; pharmaceutical companies producing pediculicides (published and unpublished trials); UK and US Regulatory Authorities. SELECTION CRITERIA: Randomised trials (published and unpublished) or trials using alternate allocation were sought which compared pediculicides with the same and different formulations of other pediculicides, and pediculicides with physical methods. DATA COLLECTION AND ANALYSIS: Of the 70 identified studies, only three met the inclusion criteria and one is awaiting assessment. Two reviewers independently assessed trial quality. One reviewer extracted the data. MAIN RESULTS: We found no evidence that any one pediculicide has greater effect than another. The two studies comparing malathion and permethrin with their respective vehicles showed a higher cure rate for the active ingredient than the vehicle. The third study comparing synergised pyrethrins with permethrin showed their effects to be equivalent. Adverse effects were reported in a number of trials and were all minor, although reporting quality varied between trials. REVIEWER'S CONCLUSIONS: Permethrin, synergised pyrethrin and malathion were effective in the treatment of head lice. However, the emergence of drug resistance since these trials were conducted means there is no direct contemporary evidence of the comparative effectiveness of these products. The 'best' choice will now depend on local resistance patterns. There is currently no evidence from trials to indicate the effectiveness of physical methods, such as combing/'BugBusting' or other chemical control methods such as the use of herbal treatments, when used in the curative treatment of head lice. Future trials should take into account the methodological recommendations that arise from this review.
Adult↗
Widespread insecticide resistance in head lice to the over-the-counter pediculocides in England, and the emergence of carbaryl resistance.
BACKGROUND: Increasing resistance to insecticides used for the control of head lice infestation has been documented over the last decade. Treatment failure and tolerance to insecticides have been validated in a number of studies undertaken in several U.K. centres. OBJECTIVES: To establish the extent of insecticide resistance in head lice and acetylcholinesterase activity in the presence of carbaryl in head lice. METHODS: Head lice were collected from school children in four centres across England (Exmouth, Loughborough, Leeds and South Shields), and tested in their response to the insecticides permethrin, phenothrin, malathion and carbaryl. Data were compared with information collected in Bristol and Bath in 1998 and with susceptible body lice. The activity of louse acetylcholinesterase was measured with and without carbaryl in head lice collected in Bristol, Leeds, Loughborough and in body lice. The efficacy of a 1% carbaryl lotion was compared in children in Bristol and Leeds. RESULTS: Compared with body lice, head lice from all six centres were significantly different in their response (P < 0.0001) to permethrin, phenothrin and malathion after 2-h exposure tests. There were significant differences in louse acetylcholinesterase activity in body lice, and head lice collected in Loughborough and Bristol in the presence or absence of carbaryl (P < 0.001), indicating enzyme inhibition. However, the difference for lice from Leeds was not significant (P = 0.363) suggesting that the enzyme was resistant to carbaryl. Eighty-nine per cent of children treated in Leeds with carbaryl were cured compared with 100% in Bristol. CONCLUSIONS: The data suggest head lice resistance is present in many parts of England to over-the-counter products containing synthetic insecticides (permethrin, phenothrin and malathion). They further suggest that resistance is starting to develop to carbaryl in head lice in Leeds and that extensive use of this product would lead to significant resistance.
Acetylcholinesterase↗
Virulence of Rickettsia prowazeki for head lice.
Wild head lice were obtained by combing out adult and instar lice from the uncut hair of school children. Normal body lice were selected from a colony of rabbit-adapted body lice obtained from the United States Department of Agriculture and maintained in the Department of Microbiology for more than 10 yr. Thirty-nine head lice and 60 body lice were fed on a rabbit that had been injected intravenously with a 10% suspension of a yolk sac pool from eggs heavily infected with the Ankara strain of virulent R. prowazeki. Five days after infection, 33 body lice and 16 head lice had survived and were feeding on a volunteer. Between Days 5 and 9, 13 head lice were dead or moribund and all of them were positive by IF for R. prowazeki. The three surviving head lice were also positive. Tests on the 33 body lice showed that 22 were positive for R. prowazeki, including four of the five body lice that survived until Day 15. In summary, head lice can be readily infected with R. prowazeki and disseminate virulent R. prowazeki organisms in their feces. Thus, theoretically, head lice appear to be highly potential as transmitters of R. prowazeki under optimal epidemiologic circumstances.
Animals↗
Spatial distribution and spread of sheep biting lice, Bovicola ovis, from point infestations.
The spatial distribution of chewing lice (Bovicola ovis) on their hosts was examined in Polypay and Columbia ewes initially artificially infested on the midside or the neck. Densities of lice were determined at 69 body sites in eight body regions at approximately monthly intervals for 2 years. In the second year, half of the ewes were mated and lice were counted at 26 body sites on the resulting lambs. Polypay ewes had higher densities of lice than Columbias at most inspections but there was little effect of infestation point or mating on either numbers or the distribution of lice. During periods of high louse numbers densities were generally greatest on the sides or the back. Densities on the head were also high at times and peaked later than overall louse densities. Shearing markedly reduced density but increased the proportion of lice found on the neck, belly and lowleg sites. The distribution of lice on the lambs was similar to that on the ewes except that fewer lice were found on the head. Comparisons of lice per part with the numbers of lice extracted from clipped patches indicated that a sheep with wool bearing area of 1 m2 and a mean count of one louse per 10 cm fleece parting carried approximately 2000 lice. At most times of the year inspections for sheep lice should be concentrated on the sides and back, but in recently shorn sheep greater attention should be paid to the lower neck and ventral regions. Implications of the observed distributions of lice for the efficacy of chemical treatments are discussed.
Abdomen↗
Permethrin-resistant human head lice, Pediculus capitis, and their treatment.
OBJECTIVE: To compare the pediculicidal activity of Ovide lotion and its active ingredient, 0.5% malathion, with Nix and its active ingredient, 1% permethrin, in permethrin-resistant head lice. DESIGN: In vitro pediculicidal product and active ingredient comparison. The presence of knockdown resistance-type mutations (T929I and L932F) was validated by DNA sequencing. SETTING: University of Massachusetts-Amherst; University of Miami School of Medicine, Miami, Fla; Plantation and Homestead, Fla; and Mathis, Tex. OTHER PARTICIPANTS: Lice were collected in 3 geographical regions within the United States and in Yamburara, Ecuador, from healthy but infested individuals. Intervention Within 3 to 6 hours of collection, lice were given a blood meal, exposed to products or active ingredients, and observed at regular intervals. MAIN OUTCOME MEASURES: Percent mortality of lice at regular intervals after exposure to products or active ingredients and presence of T929I and L932F mutations. RESULTS: South Florida lice exhibited a significantly slower mortality response to permethrin compared with susceptible Ecuadorian lice. Ovide and malathion killed permethrin-resistant lice faster than Nix or permethrin. The presence of T929I and L932F in permethrin-resistant south Florida lice was confirmed by DNA sequencing. The population of Texas lice from Mathis was slightly resistant to permethrin and included 13% with resistant genotypes. CONCLUSIONS: The presence of the T929I and L932F mutations was confirmed by DNA sequencing in lice collected from children in south Florida that were resistant to the pediculicidal effects of permethrin and the leading permethrin-based head lice product, Nix. Malathion resistance was not observed in this study. The data also show that Ovide killed these same permethrin-resistant head lice approximately 10 times faster than permethrin or Nix.
Animals↗
Head lice are not found on floors in primary school classrooms.
BACKGROUND: The control of head lice is frequently based on perceptions rather than evidence, as illustrated by the belief that vacuuming carpets is an essential component of treating head lice, and the less common practice of application of insecticides to floors as an adjunct to head lice treatment. OBJECTIVE: To 1) evaluate the importance of floors as a source of infection for head lice in primary schools to provide evidence on which to base decisions about the need to treat floors; 2) determine the prevalence of active pediculosis and average intensity of infection in primary school children in Townsville, north Queensland. METHODS: In Townsville, north Queensland, we examined preschool and primary classroom floors for lice by using a filter on a vacuum cleaner when the children were absent from the rooms. Active pediculosis was treated, head lice were collected and counted. RESULTS: Of the 2,230 children examined from 118 classrooms, 466 had head lice, a prevalence of 20.9%. A total of 14,033 lice were collected from these children to give an average intensity of infection of 30.1 (95% CI 21.9-38.3) lice per infected child and 129.9 (95% CI 90.7-169.2) lice per infected class. Of the 118 classrooms, 108 (91.5%) had at least one child with active pediculosis. No lice were recovered from the classroom floors. CONCLUSION: Classroom floors are not a risk in the transmission of head lice and no special anti-louse measures are required.
Animals↗
An effective nonchemical treatment for head lice: a lot of hot air.
OBJECTIVES: Head lice (Pediculus humanus capitis) are a major irritant to children and their parents around the world. Each year millions of children are infested with head lice, a condition known as pediculosis, which is responsible for tens of millions of lost school days. Head lice have evolved resistance to many of the currently used pediculicides; therefore, an effective new treatment for head lice is needed. In this study we examined the effectiveness of several methods that use hot air to kill head lice and their eggs. METHODS: We tested 6 different treatment methods on a total of 169 infested individuals. Each method delivers hot air to the scalp in a different way. We evaluated how well these methods kill lice and their eggs in situ. We also performed follow-up inspections to evaluate whether the sixth, most successful, method can cure head louse infestations. RESULTS: All 6 methods resulted in high egg mortality (> or = 88%), but they showed more-variable success in killing hatched lice. The most successful method, which used a custom-built machine called the LouseBuster, resulted in nearly 100% mortality of eggs and 80% mortality of hatched lice. The LouseBuster was effective in killing lice and their eggs when operated at a comfortable temperature, slightly cooler than a standard blow-dryer. Virtually all subjects were cured of head lice when examined 1 week after treatment with the LouseBuster. There were no adverse effects of treatment. CONCLUSIONS: Our findings demonstrate that one 30-minute application of hot air has the potential to eradicate head lice infestations. In summary, hot air is an effective, safe treatment and one to which lice are unlikely to evolve resistance.
Adolescent↗
Survey of permethrin and malathion resistance in human head lice populations from Denmark.
Head lice, Pediculis capitis De Geer, populations were investigated for permethrin and malathion resistance after initial establishment of a discriminating dose of topical application bioassay with body lice, Pediculus humanus L. For both insecticides, approximately 2 times the lethal dose (LD)95 at 4 h was selected, 2 ng of permethrin and 100 ng of malathion per head louse, respectively. Head lice were collected from heads of infested children in Denmark at 33 primary schools, one kindergarten, and seven boarding schools. The lice were collected by combing of dry hair, with a fine-toothed antilouse comb attached to a vacuum cleaner. A resistance survey covers head lice collected from 208 of 1,441 persons combed. The frequency of permethrin- and malathion-resistant head lice is high in Danish head lice populations. In 17 of 24 samples tested for permethrin resistance, all head lice survived the discriminating dose. Six samples had between 3 and 25% dead head lice, whereas one sample had 60% mortality. In nine of 25 samples tested for malathion resistance, all head lice survived the discriminating dose. Seven samples had <25% dead head lice, and four samples had a mortality of 50% or more at the discriminating dose. The connection between permethrin resistance and kdr-like mutations is confirmed by our findings. The frequency of the double mutation T929I-L932 F in the voltage-sensitive sodium channel gene associated with permethrin resistance was 0.95 in Danish head lice populations.
Adolescent↗
Efficacy of a 1% lambdacyhalothrin cattle Pour-on (Saber) against sucking and biting lice infesting beef cattle.
Four studies were conducted to determine the efficacy of a 1% lambdacyhalothrin pour-on (Saber Pour-on, Schering-Plough Animal Health) for control of sucking lice (Linognathus vituli, Haematopinus eurysternus, Solenopotes capillatus) and biting lice (Damalinia bovis) on beef cattle. Seventy-four mixed-breed cattle naturally infested with one or more species of lice at locations in Wisconsin, Nebraska, Oklahoma, and North Dakota were included in the study. Pretreatment lice samples were taken and identified by genus with the exception that sucking lice were not identified by genus at the North Dakota site. In January or February, half of the cattle at each location received a single application of 1% lambdacyhalothrin pour-on at 10 ml per head for cattle weighing less than 273 kg (600 lb) or 15 ml per head for cattle weighing 273 kg or more. The other cattle at each site served as untreated controls. Lice on designated body areas were counted 2, 4, 6, and 8 weeks after treatment, and the sum of all lice observed on each counting area was reported for each animal. The collective efficacy 6 weeks after treatment against three species of sucking lice (L. vituli, H. eurysternus, S. capillatus) was 88.4% at the Wisconsin site, 92.0% at the North Dakota site, and 100% at the Nebraska and Oklahoma sites. The 1% lambdacyhalothrin pour-on eliminated all biting lice within 2 weeks after treatment, and no biting lice were detected 8 weeks after treatment. A single treatment of 1% lambdacyhalothrin pour-on administered when lice populations were highest (January or February) provided effective season-long control of both biting and sucking lice on cattle.
Administration, Cutaneous↗
Phylogeny and classification, origins, and evolution of host associations of lice.
Lice are highly successful ectoparasites. Most species of mammals and birds are infested by at least 1 but up to 6 species of lice. Current opinion is that lice evolved from free-living Psocoptera (booklice, barklice and psocids). It is generally agreed that there are 4 main groups of lice: Anoplura, Amblycera, Ischnocera and Rhyncophthirina. In contrast, there is no agreement on the phylogenetic relationships of these groups and their classification. In particular, there is much debate over the validity of the taxon Mallophaga, which is almost certainly paraphyletic. For many years the sister-group of the Boopiidae, which almost exclusively infest Australasian marsupials, was thought to be a group of lice that now infest marsupials in South America. This, however, is almost certainly incorrect; the sister-group of the Boopiidae probably contains bird-infesting lice from the Menoponidae (Amblycera). Thus, menoponid lice transferred from birds to mammals and from these arose the Boopiidae. Transfers of lice between mammals and birds have occurred on other occasions during the evolution of the lice; 2 of the 4 main groups of lice, the Ischnocera and Amblycera, contain families that infest birds and families that infest mammals. Strict cospeciation and coevolution was thought to predominate among the lice; however, detailed studies indicate this to be incorrect. Consequently, the axiom that lice and their hosts invariably coevolve should be abandoned. Ironically, biologists may learn more about the evolutionary biology of hosts when host-switching has occurred.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Changes in physiological parameters and feeding behaviour of Atlantic salmon Salmo salar infected with sea lice Lepeophtheirus salmonis.
Atlantic salmon Salmo salar L. artificially infected with salmon lice Lepeophtheirus salmonis (Krøyer 1837) recovered from detrimental physiological changes and skin damage induced by preadult lice as the parasites matured. Growth rates of Atlantic salmon remained unaffected by lice infection, but food consumption decreased with increasing feeding and movement of the lice prior to and post-mating, correlating with the appearance of head erosions and detrimental changes in physiological integrity. Food consumption of the fish increased as the lice moulted to the adult stage and gravid female lice settled in a posterior location on the fish, subsequently reducing the impact of infection and allowing recovery of the skin damage. However, the impact of preadults was limited, as the decrease in food consumption of fish at 21 d post-infection had no effect on either the specific growth rate or condition factor of the fish. Furthermore, the intensity of lice infections at each of the sample days was not correlated with food consumption, specific growth rate or any of the haematological or physiological parameters measured, either before or after infection, indicating that lice intensity was independent of social dominance/subordinance. This work has provided the first evidence that infected fish can recover from the detrimental changes caused by lice infection, even when they are still infected with lice. If fish can survive the preadult stage of lice, then the mortal impact of lice infections is greatly reduced.
Animals↗
Survival away from sheep and alternative methods of transmission of sheep lice (Bovicola ovis).
Transmission of sheep lice is thought to occur mainly by sheep to sheep contact although the possibility of other sources of infestation is often suggested. This study investigated the period of survival of Bovicola ovis after removal from sheep under varying conditions and assessed the likelihood of new infestations arising from contaminated facilities, wool caught on fences and shearers' footwear. In laboratory studies with lice held away from sheep at 4, 20, 25 and 36.5 degrees C, adults and nymphs survived longest at 25 degrees C (LT90 of 11.7 and 24.1 days for adults and large nymphs, respectively). Nymphs survived longer than adults and lice provided with raw wool survived longer than lice provided with wool that had been degreased. Nymphal lice survived for up to 29 days on unscoured wool at 36.5 degrees C, but the LT50 was less than 9 days in most experiments. In shearing sheds in winter and early spring lice survived for up to 14 and 16 days, respectively. These periods of survival are considerably longer than previously indicated for B. ovis. Most lice dropped out of wool staples attached to a fence within 1 h and only two of a total of 225 lice were still present after 24 h, suggesting that sheep are unlikely to become infested from wool caught on fences. Adult and nymphal lice readily transferred to shearers' moccasins and survived there for up to 10 days, indicating that transmission of lice on the footwear of shearers or other sheep handlers may be a cause of new infestations. Microwaving each moccasin for 5 min killed all lice and may provide a simple method of reducing the likelihood of transmission of B. ovis between properties.
Animal Husbandry↗
Evidence for double resistance to permethrin and malathion in head lice.
A rising prevalence of head lice among school children and rising sales of insecticides with anecdotal evidence of their treatment failure, led us to examine whether head lice in Bristol and Bath were resistant to the insecticides available for treating head lice. Ten schools in Bristol and Bath were visited to collect field samples of head lice. A comparison was made of the survival rates of fully sensitive laboratory reared body lice and field samples of head lice on insecticide exposure. To confirm the in vitro relevance of these tests we performed supervised treatments of affected subjects with malathion or permethrin. There were significant differences (P < 10-6 Fishers exact test) between head and body lice survival for malathion and permethrin exposure, but not for carbaryl. There was an 87% failure rate for permethrin and a 64% failure rate for malathion with the topical treatment of a selected number of infested school children. We conclude that there is a high resistance to permethrin and malathion, but head lice remain fully sensitive to carbaryl. This is the first report of doubly resistant head lice. As permethrin, phenothrin (a very similar synthetic pyrethroid) or malathion are the active ingredients in all the over-the-counter head lice treatments in the U.K., then it is likely that head lice prevalence will continue to increase. The resistance against permethrin employed by the head louse is probably the kdr (knockdown resistance) mechanism, and an enzyme-mediated malathion-specific esterase is the likely mechanism against malathion.
Animals↗