Control Of Lice Research Articles

The near future of head louse control

Sac biti enfestasyonu tum dunyada yaygin bir halk sagligi sorunudur. Yuksek gelirli ulkelerde pedikulozis kapitis temel olarak okul cagindaki cocuklarda problemdir. Son 20 yilda ozellikle norotoksik yolla etkili pedikulositlere direnc gelisimi ve toksikolojik endiseler nedeniyle, dimetikon gibi fiziksel olarak etkili yeni urunlere egilim gorulmeye baslanmistir. Bu maddelerin trakeal sisteme girerek bitleri ve yumurtalarini bogdugu gosterilmistir. Bu niteligine bagli olarak bitlerin en azindan kolaylikla direnc gelistiremeyecegi beklenmektedir. Dimetikon kozmetik acidan kabul edilebilir, fizyolojik olarak etkisiz ve toksik olmayan bir urundur. Bu nedenle yakin gelecekte bitlerin tedavisinde secenek olmasi beklenmektedir

Buffalo healthcare management practices followed by the farmers of Ferozepur district of Punjab, India

The present study was conducted in the Ferozepur district of Punjab which is the breeding tract of Nili-Ravi breed of buffalo. The investigation was done in the year 2004 with the objective of identifying various buffalo management practices followed by the farmers. It was found that animal healthcare services in the form of veterinary hospital, dispensary or stockman centre were available in majority (86.25%) of cases. Regarding the prophylactic measures, almost all the farmers (96.25%) were adopting vaccination against the contagious diseases, only a few farmers (13.75%) were adopting deworming of adult animals whereas deworming of calves was adopted by comparatively higher percentage (42.50%) of farmers. It was observed that isolation of sick animals was done by only 20 per cent of the farmers and 31.25 per cent were taking tick or lice control measures for their buffaloes. Majority of the farmers (56.25%) did not adopt any special feeding practices to pregnant animals. Overall the healthcare management in the study area was quite satisfactory.

Spotted fever and the invention of its serodiagnosis and vaccination in the Austro-Hungarian army in World War I

After description of the medical institutions and epidemiological situations of the Austro-Hungarian army in World War I the provisions against spotted fever focused on louse control are discussed. The letter specified for the army had to be adjusted for the local populations. 1915 in the k.u.k. military service in Galicia Edmund Weil and Arthur Felix cultivated Proteus strains from urine of soldiers with spotted fever. As sera of such patients agglutinated these bacteria in considerable titers the investigators developed the reliable diagnostic "Weil-Felix-Test" used still today. In the same military area and time Rudolf Weigl invented the anal infection of lice. This enabled him to harvest a great amount of louse intestines containing the spotted fever Rickettsiae in their epithelial cells. Lots with defined numbers of intestines were homogenized, sterilized and used with success as vaccine for medical staff. This sort of vaccine still was used in World War II.

Human-induced evolution caught in action: SNP-array reveals rapid amphi-atlantic spread of pesticide resistance in the salmon ecotoparasite Lepeophtheirus salmonis.

BackgroundThe salmon louse, Lepeophtheirus salmonis, is an ectoparasite of salmonids that causes huge economic losses in salmon farming, and has also been causatively linked with declines of wild salmonid populations. Lice control on farms is reliant upon a few groups of pesticides that have all shown time-limited efficiency due to resistance development. However, to date, this example of human-induced evolution is poorly documented at the population level due to the lack of molecular tools. As such, important evolutionary and management questions, linked to the development and dispersal of pesticide resistance in this parasite, remain unanswered. Here, we introduce the first Single Nucleotide Polymorphism (SNP) array for the salmon louse, which includes 6000 markers, and present a population genomic scan using this array on 576 lice from twelve farms distributed across the North Atlantic.ResultsOur results support the hypothesis of a single panmictic population of lice in the Atlantic, and importantly, revealed very strong selective sweeps on linkage groups 1 and 5. These sweeps included candidate genes potentially connected to pesticide resistance. After genotyping a further 576 lice from 12 full sibling families, a genome-wide association analysis established a highly significant association between the major sweep on linkage group 5 and resistance to emamectin benzoate, the most widely used pesticide in salmonid aquaculture for more than a decade.ConclusionsThe analysis of conserved haplotypes across samples from the Atlantic strongly suggests that emamectin benzoate resistance developed at a single source, and rapidly spread across the Atlantic within the period 1999 when the chemical was first introduced, to 2010 when samples for the present study were obtained. These results provide unique insights into the development and spread of pesticide resistance in the marine environment, and identify a small genomic region strongly linked to emamectin benzoate resistance. Finally, these results have highly significant implications for the way pesticide resistance is considered and managed within the aquaculture industry.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-937) contains supplementary material, which is available to authorized users.

A SYSTEM DYNAMICS APPROACH TO SEA LICE CONTROL IN NORWAY

Various methodologies have been used to model the epidemiology and economics of aquatic diseases, including input-output models, benefit-cost analysis, linear programming, compartment models based on differential equations, and spatial models. Despite the virtues of each of these models, there is a need to develop a more integrated approach to the epidemiology and economics of disease that better represents and captures existing feedback mechanisms that can influence the success of disease control interventions and their cost-effectiveness. In this paper, we motivate the use of system dynamics (SD) modeling in the context of sea lice control in Norwegian farmed salmon. Separate models of sea lice and salmon growth were designed and integrated to capture the feedbacks between them. Different simulation scenarios highlight the benefits of the approach. Model results indicated that changing the timing and type of treatment vis-à-vis current practices can markedly reduce sea lice infection pressures; such simulated practices are also more cost effective. Our approach further highlights how delays and feedbacks present in these systems influence the success of any disease control protocol, and demonstrates the utility that SD models can play in aquatic health.

Seasonal infestation of donkeys by lice: Phenology, risk factors and management

A longitudinal study was undertaken over a 21 months period to examine the seasonal abundance of lice infesting donkeys, the risk factors which predispose donkeys to infestation and the effectiveness of louse management. All the lice seen were Bovicola (Werneckiella) ocellatus. A strong seasonal pattern, which was correlated with mean monthly temperature, was observed with higher prevalence and intensity in the cooler, winter months (October–March). Overall infestation in these animals was over-dispersed, suggesting that some individuals are strongly predisposed to infestation. Donkey age and mean hair length were characteristics which affected louse prevalence: older and younger donkeys and donkeys with longer hair harboured the highest numbers of lice. However, the practice of coat-clipping, to reduce the infestation, resulted in a lower louse prevalence only in the summer, suggesting that clipping is not an effective form of louse control in cooler months. Higher louse burdens were associated with larger areas of visible excoriation and hair damage, suggesting that B. ocellatus does adversely impact animal welfare. However, the ability of animal carers to estimate louse presence or absence accurately on an individual donkey was not sufficiently high to allow targeted selective treatment of heavily infested animals to be employed effectively. As animals are housed in closed herds these findings suggest that clipping in the summer and treating all animals with insecticide in late autumn, prior to turn-in may be an effective louse management strategy.

Parental and Child Attitudes Towards Pediculosis are a Major Cause Of Reinfection

Pediculosis can elicit considerable emotional distress in the infected and their carers, but the role of attitude in head lice reinfection has not been explored. Failure of head lice control is often attributed to insecticide resistance because human aspects of reinfestation are unknown. This study collected data from 128 teenagers with a history of pediculosis to retrospectively explore attitudes towards head lice. One third of female and two thirds of male teenagers were unconcerned about having head lice. One fifth of parents did nothing about their child’s head lice infections, while a few male students did not inform their parents when they had pediculosis. This is the first study on the prevalence of human lice carriers who are a primary cause of head lice reinfection. Medical and public health professions need to understand the social reasons for the failure of insecticide-based head lice control.

Prevalence of Head Lice in Two Socio-economically Different Schools in the Center of Izmir City, Turkey

The well-known and common infestation caused by Pediculus humanus capitis is an important public health and a social issue in many communities in the world. The aim of this study was to compare the head louse infestation rate in two schools having pupils from different socio-economic levels in the city center of Izmir. The pupils aged between 6 and 11 years, were screened for the presence of eggs and nymph/adult lice using a fine-tooth head louse comb. A total of 88 and 126 pupils from the schools with low and medium socio-economic level were screened and 24 (27.2%) and 5 (3.96%) of them were found to be positive for head lice, respectively. Overall, the infestation rate among girls was 3.14 times higher than in boys. Head louse infestation is a significant public health problem among primary schools. Increasing the knowledge about pediculosis and self-hygiene would be helpful in successfully reducing head louse infestation in the school setting. School authorities must encourage the parents to look for head lice routinely and a "school nurse" system is needed for effective head louse control in the schools.

Isolation and characterisation of four partial cDNA sequences encoding multidrug resistance-associated proteins (MRPs) in the salmon louse Lepeophtheirus salmonis (Krøyer, 1837)

The salmon louse Lepeophtheirus salmonis (Krøyer, 1837) is an ectoparasite of salmonid fish severely affecting cultured salmon production in the North Atlantic. Salmon louse control on farms currently relies in part upon the use of veterinary drugs; however, as only a limited number of salmon delousing agents are available, there are concerns about development of drug resistance in salmon lice. The common anti-salmon louse drug SLICE® (Merck Animal Health) contains the avermectin emamectin benzoate (EMB). Members of the large gene superfamily of ABC (ATP-binding cassette) transporters have been identified as potential avermectin resistance factors in parasitic nematodes. In salmon lice, only three ABC transporters have been cloned and studied to date. We report here upon the isolation of four novel L. salmonis ABC transporters, and employ an inhibitor-based approach to assess roles of L. salmonis ABC transporters in the toxicology of EMB. To isolate salmon louse ABC transporters, publicly available L. salmonis expressed sequence tags (ESTs) were subjected to homology searches, and the retrieved ESTs assembled into contiguous sequences and annotated. Potential ABC drug transporters isolated by this approach included four multidrug resistance-associated proteins (MRPs). In addition, five ABC proteins likely having roles unrelated to drug resistance were obtained. Quantitative real time PCR (RT-qPCR) was used to analyse mRNA levels of the MRPs in L. salmonis strains differing in EMB susceptibility. In the absence of EMB, all studied MRPs showed similar transcript levels in the drug-susceptible strain S and the moderately EMB-resistant strain R. Moreover, mRNA expression of the four studied MRPs remained unaffected by exposure to EMB. Taken together, the results of RT-qPCR analyses did not provide evidence for roles of the studied MRPs as factors affecting EMB susceptibility. Further experiments used an inhibitor-based approach to investigate the roles of ABC transporters in EMB toxicity. In immotility bioassays, salmon lice of the two strains were exposed to EMB, provided alone or in combination with cyclosporin A or verapamil, which are known inhibitors of P-glycoprotein and MRPs. Cyclosporin A increased EMB toxicity to a similar degree with both strains, suggesting the biochemical factors affected by this inhibitor show similar levels in both strains. In contrast, verapamil increased EMB effects only in the R strain. This result could be indicative of an enhanced expression of hitherto unknown ABC transporters in the moderately EMB-resistant R strain. More research is required to identify the target of verapamil in salmon lice.

The Biology and Taxonomy of Head and Body Lice—Implications for Louse-Borne Disease Prevention

Sucking lice (Phthiraptera: Anoplura) are obligate blood-feeding ectoparasites of placental mammals including humans. Worldwide, more than 550 species have been described and many are specific to a particular host species of mammal [1]. Three taxa uniquely parasitize humans: the head louse, body louse, and crab (pubic) louse. The body louse, in particular, has epidemiological importance because it is a vector of the causative agents of three important human diseases: epidemic typhus, trench fever, and louse-borne relapsing fever. Since the advent of antibiotics and more effective body louse control measures in the 1940s, these diseases have markedly diminished in incidence. However, due to 1) increasing pediculicide resistance in human lice, 2) reemergence of body louse populations in some geographic areas and demographic groups, 3) persistent head louse infestations, and 4) recent detection of body louse-borne pathogens in head lice, lice and louse-borne diseases are an emerging problem worldwide. This mini-review is focused on human body and head lice including their biological relationship to each other and its epidemiological relevance, the status and treatment of human louse-borne diseases, and current approaches to prevention and control of human louse infestations.

Forced-Use Dust Bags for Management of External Parasites

Dust bags are an effective method of horn fly and louse control. However, dust bags are only effective when hung in places where cattle are forced to use them. The best locations are areas where cattle must pass once or twice a day, or every other day, for instance between mineral boxes or water and pasture. During the field tests, forced-use dust bags provided an average of 90% horn fly control. Production was increased by an average of 34% over the normal management practice. This increase in production was equivalent to 1/3 lb/animal/day. This 5-page fact sheet was written by P. E. Kaufman and E. N. I. Weeks and published by the UF Department of Entomology and Nematology, November 2012.
 http://edis.ifas.ufl.edu/ig135

Lice infesting horses in three agroecological zones in central Oromia.

A cross-sectional study was conducted to determine the prevalence and species composition of lice infesting horses in three agroecological zones in seven different districts in central Oromia from November 2011 to April 2012. For this purpose, a total of 420 horses were thoroughly examined for presence of lice. Collected lice were identified to species level under a microscope. The study showed an overall prevalence of 28.8% (121/420) lice infestation on horses. We identified two spp. of lice on horses namely, Bovicola (Werneckiella) equi and Haematopinus asini with an overall prevalence of 22.9% (96/420) and 5.9% (25/420), respectively. The overall prevalence of lice infestation on horses in districts was 48.3, 43.3, 33.3, 23.3, 21.7, 18.3 and 13.3%, in Debre Brehan, Shashemene, Hawassa, Akaki, Adama, Modjo and Bishoftu, respectively. B. equi was encountered as the predominant species on horses in all districts. Higher overall prevalence of lice infestation was recorded in highland agroecology than mid and lowland agroecological zones. Similarly, our study revealed significantly higher overall prevalence of lice on saddle horses than on cart horses. In view of the findings of the present study two species of lice are responsible for health and welfare problems of horses in all the districts. Detailed epidemiological studies on the significance, prevalence and role of lice as vectors of zoonotic pathogens in different agroecological zones, breeds and management systems warrant urgent attention. Animal owners and veterinarians should consider lice control in horses as part of the ectoparasite control in other species of animals.

In vitro pediculicidal activity of herbal shampoo base on Thai local plants against head louse (Pediculus humanus capitis De Geer)

Head lice infestation, a worldwide head infestation caused Pediculus humanus capitis De Geer, is an important public health problem in Thailand. Several chemical pediculicides have lost in efficacy due to increasing resistance of lice against insecticide. Therefore, non-toxic alternative products, such as natural products from plants, e.g. plant extract pediculicides, are needed for head lice control. The aims of this study were to evaluate the potential of pediculicidal activity of herbal shampoo base on three species of Thai local plants (Accacia concinna (Willd.) DC, Averrhoa bilimbi Linn. and Tamarindus indica Linn.) against head lice and to compare them with carbaryl shampoo (Hafif shampoo®; 0.6% w/v carbaryl) and non-treatment control in order to assess their in vitro. Doses of 0.12 and 0.25 ml/cm2 of each herbal shampoo were applied to filter paper, and ten head lice were place on the filter paper. The mortalities of head lice on the filter paper were recorded at 1, 5, 10, 30 and 60 min by sterio-microscope. All herbal shampoos at 0.25 ml/cm2 were more effective pediculicide than carbaryl shampoo with 100% mortality at 5 min. The median lethal time (LT50) of all herbal shampoos at 0.25 ml/cm2 showed no significant differences over at 0.12 ml/cm2 (P<0.01). The most effective pediculicide was T. indica extract shampoo, followed by Av. bilimbi extract shampoo and Ac. concinna extract shampoo, with LT50 values<1.0 min. Our data showed that all herbal shampoos have high potential of pediculicide to head lice treatments for schoolchildren.

Housing and dustbathing effects on northern fowl mites (Ornithonyssus sylviarum) and chicken body lice (Menacanthus stramineus) on hens

Hen housing (cage or cage-free) did not impact overall abundances of northern fowl mites, Ornithonyssus sylviarum (Canestrini & Fanzago) (Acari: Macronyssidae), or chicken body lice, Menacanthus stramineus (Nitzsch) (Phthiraptera: Menoponidae). Cage-free hens received a dustbox with sand plus diatomaceous earth (DE), kaolin clay or sulphur. Weekly use varied from none to 100% of hens; 73% of hens used the dustbox at least once. Ectoparasite populations on dustbathing hens (users) were compared with those on non-user cage-free and caged hens. All materials reduced ectoparasites on user hens by 80-100% after 1 week of dustbox use. Diatomaceous earth and kaolin failed to reduce ectoparasites on non-user hens, and ectoparasites on user hens recovered after dustbox removal. A sulphur dustbox eliminated mites from all hens (including non-users) within 2-4 weeks. Residual sulphur controlled mites until the end of the experiment (up to 9 weeks), even after the dustbox was removed. Louse populations on hens using the sulphur dustbox were reduced in 1-2 weeks. Residual sulphur effects were less evident in lice, but the use of a sulphur dustbox by a higher proportion of hens extended louse control to all hens. This is the first experimental study to show that bird dustbathing in naturally and widely available dust materials (particularly kaolin) can suppress ectoparasites and thus the behaviour is probably adaptive.

Using abattoir surveillance and producer surveys to investigate the prevalence and current preventative management of Caseous lymphadenitis in Merino flocks in Australia

The prevalence of Caseous lymphadenitis (CLA) in Australia was estimated to be 5.2% using 2009 abattoir surveillance data from all States supplied by Animal Health Australia involving 5029 lines comprising 1 339 463 sheep. This is a decrease from the 26% estimated in a similar study in 1995. There was a significant difference (P &lt; 0.001) in CLA prevalence between all states except Tasmania and Victoria (P = 0.75) with prevalences of 12.8 and 12.9%, respectively. Western Australia recorded the lowest prevalence with 1.0%. The average CLA prevalence for New South Wales was 5.3% and within three surveyed Livestock Health and Pest Authority regions (Tablelands, Central North and Central West) was 2.9, 4.9 and 4.4%, respectively. The attitude of the majority of producers surveyed in these three Livestock Health and Pest Authority areas was that CLA was of little or no significance (75%) but were aware of the need for CLA control with ~68% using 6-in-1 vaccine, though only 39.9% as recommended. It appears that the prolonged use of CLA vaccination has been successful in reducing the prevalence of CLA across Australia and particularly in New South Wales. Further improvements in communication of information on preventative management practices associated with lice control, importance of using an approved vaccination program, plus increasing producers’ awareness of the importance of CLA control, are indicated.

Molecular cloning and characterisation of a novel P-glycoprotein in the salmon louse Lepeophtheirus salmonis

The salmon louse, Lepeophtheirus salmonis, is a crustacean ectoparasite of salmonid fish. At present, sea louse control on salmon farms relies heavily upon chemical treatments. Drug efflux transport, mediated by ABC transporters such as P-glycoprotein (Pgp), represents a major mechanism for drug resistance in parasites. We report here the molecular cloning of a new Pgp from the salmon louse, called SL-PGY1. A partial Pgp sequence was obtained by searching sea louse ESTs, and extended by rapid amplification of cDNA ends (RACE). The open reading frame of SL-PGY1 encodes a protein of 1438 amino acids that possesses typical structural traits of P-glycoproteins, and shows a high degree of sequence homology to invertebrate and vertebrate P-glycoproteins. In the absence of drug exposure, SL-PGY1 mRNA expression levels did not differ between a drug-susceptible strain of L. salmonis and a strain showing a ~7-fold decrease in sensitivity against emamectin benzoate, the active component of the in-feed sea louse treatment SLICE® (Merck Animal Health). Aqueous exposure of the hyposensitive salmon louse strain to emamectin benzoate (24h, 410μg/L) provoked a 2.9-fold upregulation of SL-PGY1. Adult male lice of both strains showed a greater abundance of SL-PGY1 mRNA than adult females.

Genomic Resources for Sea Lice: Analysis of ESTs and Mitochondrial Genomes

Sea lice are common parasites of both farmed and wild salmon. Salmon farming constitutes an important economic market in North America, South America, and Northern Europe. Infections with sea lice can result in significant production losses. A compilation of genomic information on different genera of sea lice is an important resource for understanding their biology as well as for the study of population genetics and control strategies. We report on over 150,000 expressed sequence tags (ESTs) from five different species (Pacific Lepeophtheirus salmonis (49,672 new ESTs in addition to 14,994 previously reported ESTs), Atlantic L. salmonis (57,349 ESTs), Caligus clemensi (14,821 ESTs), Caligus rogercresseyi (32,135 ESTs), and Lernaeocera branchialis (16,441 ESTs)). For each species, ESTs were assembled into complete or partial genes and annotated by comparisons to known proteins in public databases. In addition, whole mitochondrial (mt) genome sequences of C. clemensi (13,440 bp) and C. rogercresseyi (13,468 bp) were determined and compared to L. salmonis. Both nuclear and mtDNA genes show very high levels of sequence divergence between these ectoparastic copepods suggesting that the different species of sea lice have been in existence for 37–113 million years and that parasitic association with salmonids is also quite ancient. Our ESTs and mtDNA data provide a novel resource for the study of sea louse biology, population genetics, and control strategies. This genomic information provides the material basis for the development of a 38K sea louse microarray that can be used in conjunction with our existing 44K salmon microarray to study host–parasite interactions at the molecular level. This report represents the largest genomic resource for any copepod species to date.Electronic supplementary materialThe online version of this article (doi:10.1007/s10126-011-9398-z) contains supplementary material, which is available to authorized users.

Issues and advances in the integrated control of sheep lice

Ongoing pressure to minimise costs of production, growing markets for low residue and organic wool and meat, resistance to chemicals in louse populations, and the deregistration of diazinon for dipping and jetting have contributed to a move away from routine annual application of lousicides to more integrated approaches to controlling lice. Advances including improved methods for monitoring and detection of lice, an expanded range of louse control products and the availability of a web-accessible suite of decision support tools for wool growers (LiceBoss™) will aid this transition. Possibilities for the future include an on-farm detection test and non-chemical control methods. The design and extension of well-constructed resistance management programs to preserve the effectiveness of recently available new product groups should be a priority.

Determinants influencing prevalence of louse infestations on layers of District Faisalabad (Pakistan)

1. This paper describes the influence of some epidemiological determinants on the prevalence of louse infestation on layers in Faisalabad (Pakistan). 2. Seventy layer farms were screened to determine the prevalence of louse infestation and its determinants including age of the bird, availability of space per bird and frequency of litter change. Prevalence of Lipeurus caponis was highest (53·2%), followed by Menacanthus stramineus (22·16%), Goniodes dissimilis (12·37%) and Goniodes gallinae (12·37%). 3. Older birds (36 to 74 weeks of age) were found with a significantly higher prevalence of louse infestation than younger birds. 4. Month-wise prevalence of louse infestation was higher during the summer months (from April to August) and at older age. 5. Birds kept at floor area allowances ranging from 0·43 to 0·55 m2 were highly infested with lice as compared to those provided with a space of 0·61 m2 or higher per bird. 6. Litter change frequency after every 8 weeks resulted in a reduced chance of louse infestation as compared to less frequent litter changing practice. 7. It was concluded from the study that the louse infestation is a menace for the poultry production industry in Pakistan and age, space per bird and litter change frequency are the influencing determinants. 8. Further research on the chemotherapeutic trials and resistance in poultry should be continued for an effective lice control program.

Treatment of natural infestations of the biting louse ( Werneckiella equi) on horses using triflumuron, a benzoylurea derivative insect growth regulator

The horse biting louse ( Werneckiella equi) is a common global equine ectoparasite. To our knowledge, benzoyl(phenyl)urea insecticides (triflumuron, diflubenzuron) commonly used as sheep lousicides, have not been evaluated for efficacy against W. equi. The aim of this study was to determine louse control efficacy, general wellness and dermal safety following triflumuron application as a backline pour-on to horses. Two efficacy trials using 25 adult naturally infested lousy horses, and a dermal safety trial using 10 adult louse-free horses were conducted over a 14-month period. Lousy animals were selected by assessment of their lice status prior to treatment. For the efficacy trial, the triflumuron product was applied at a dose of 2.5 mg triflumuron per kg bodyweight (1 mL product per 10 kg bodyweight). For the safety study, triflumuron was applied at a 3× clinical dose of 7.5 mg triflumuron per kg bodyweight (3 mL product per 10 kg bodyweight). In our first efficacy trial, 100% lousicidal efficacy was achieved by day 44 post-treatment. In our second trial, no lice were identified on horses by day 71 post-treatment. In the safety trial, no adverse effects were seen. Results of this study demonstrate that the off-label, experimental pour-on application of triflumuron at 2.5 mg/kg bodyweight is convenient, highly effective and safe (at 3× the clinical dose) for the treatment of the horse biting louse, W. equi.