Factors that may be influencing the prevalence of head lice in British school children

Pyrethroid-linked resistance allelic mutations by molecular analysis in wild human head louse (Phthiraptera: Pediculidae) populations from schoolgirls of South Iran

Background

Human head louse, Pediculus humanus capitis De Geer, 1767 (Anoplura: Pediculidae), is one of the most frequent ectoparasites infesting Homo sapiens worldwide. Reduced sensitivity to treatment due to genetic mutations, in particular knockdown resistance (kdr) (or target site insensitivity) allele, has led to this infestation prevalence. Molecular characterization of this resistance has a crucial impact on selecting appropriate treatment protocol. The aim of this study was to investigate kdr gene mutations on voltage-sensitive sodium channel (VSSC) among wild head lice samples from Fars province, southern Iran.

Methods

Head lice were collected using plastic detection combs on girls enrolled in public schools from 10 counties in Fars province. The specimens were screened in 10 pools (each pool per county containing 35 specimens), with three pools (30%) being positive. Following species identification with valid entomological keys, 350 (68%) out of 514 randomly collected adult head lice were analyzed after their somatic genomic DNA extraction using Sinaclon kit. Samples were investigated by polymerase chain reactions (PCR), and the amplicon was subsequently sequenced.

Results

Sequence analysis showed that the sodium channel genes in the pooled ectoparasites had two intron and three exon regions. Single (L840F), double (I836L, E837K), and triple novel point mutations (V875L, Q876P, S879V); the last involving two concomitant allelic substitutions; were discovered in the second and third exon regions of head louse DNA on chromosome II from three (30%) counties. Other exon or intron regions remained non-mutated from the remaining seven counties.

Conclusions

The detection of six amino acid substitutions from 30% of examined head lice among infested schoolgirls reveal that mutants are minutely developing. These findings provide further incentive to recapitulate the legitimacy of current control measures and resolve dynamics of resistance in human head louse populations.

A nationwide survey of prevalence of pediculosis in children and adolescents in iran

BACKGROUND

Since 2005, pediculosis is one of the obligatory reportable diseases from community to the Center of Disease Control. This study is the first nationwide survey on the prevalence of pediculosis and some associated risk factors in Iranian children and adolescents.

METHODS

National data of the Ministry of Health and Medical Education were gathered in 2005 through school screening programs and obligatory reports from the country health centers.

RESULTS

12,359,448 Iranian children and adolescents were screened in 2005. Overall, 213,450 students, consisting of 198,947 girls and 14,320 boys were reported to have pediculosis. The prevalence of pediculosis was 581 per 100,000 population that varied from 1/100 000 to 8,303/100,000. In general, the highest prevalence of pediculosis was documented in south-eastern cities. The prevalence of pediculosis was significantly higher in girls than in boys (93% vs.7%, respectively, p<0.0001). In both genders, the highest prevalence of pediculosis was documented in the 6-10- year age group. Of those infected, 62% lived in rural areas, and 32% of those infected with pediculosis had a previous history of this infection. Most (99.37%) infected individuals had head lice, the rest had body and pubic pediculosis.

CONCLUSION

The prevalence of pediculosis is low in Iranian children and adolescents, but this infestation is still a health problem in some south-eastern cities with warm climate and low to middle socioeconomic status.

Household-wide ivermectin treatment for head lice in an impoverished community: randomized observer-blinded controlled trial

OBJECTIVE

To generate evidence on the effectiveness of household-wide treatment for preventing the transmission of pediculosis capitis (head lice) in resource-poor communities.

METHODS

We studied 132 children without head lice who lived in a slum in north-eastern Brazil. We randomized the households of the study participants into an intervention and a control group and prospectively calculated the incidence of infestation with head lice among the children in each group. In the intervention group, all of the children's family members who lived in the household were treated with ivermectin; in the control group, no family member was treated. We used the chi(2) test with continuity correction or Fisher's exact test to compare proportions. We performed survival analysis using Kaplan-Meier estimates with log rank testing and the Mann-Whitney U test to analyse the length of lice-free periods among sentinel children, and we used Cox regression to analyse survival data on a multivariate level. We also carried out a subgroup analysis based on gender.

FINDINGS

Children in the intervention group remained free from infestation with head lice significantly longer than children in the control group. The median infestation-free period in the intervention group was 24 days (interquartile range, IQR: 11-45), as compared to 14 days (IQR: 11-25) in the control group (P = 0.01). Household-wide treatment with ivermectin proved significantly more effective among boys than among girls (P = 0.005). After treatment with ivermectin, the estimated number of annual episodes of head lice infestation was reduced from 19 to 14 in girls and from 15 to 5 in boys. Female sex and extreme poverty were independent risk factors associated with a shortened disease-free period.

CONCLUSION

In an impoverished community, girls and the poorest of the poor are the population groups that are most vulnerable for head lice infestation. To decrease the number of head lice episodes per unit of time, control measures should include the treatment of all household contacts. Mass treatment with ivermectin may reduce the incidence of head lice infestation and associated morbidity in resource-poor communities.

Overcoming health inequalities by using the Bug Busting 'whole-school approach' to eradicate head lice

AIMS AND OBJECTIVES

The aim of this paper was to illustrate the socially inclusive nature of the Bug Busting 'whole-school approach' to head louse eradication.

BACKGROUND

In the UK, Belgium and Denmark, persistent head lice in families of all socio-economic status (SES) is a problem. Since 1995 in the UK and 1998 elsewhere, an educational programme intended to teach families how to detect and treat head lice by using the Bug Busting wet combing method has been organized in some areas. Local schools lead this community strategy for prevention, known as a 'whole-school approach' (UK).

DESIGN AND METHODS

We describe five studies applying the Bug Busting approach, four set in districts where some disadvantaged families live (UK and Belgium) and a fifth set in Denmark. Feasibility and consumer satisfaction are examined. One UK study analyses data on area prescribing for head lice and the impact in a deprived locality of raising the profile of Bug Busting.

RESULTS

We find parental education in Bug Busting enables families of all SES to participate in a 'whole-school approach' to head lice. Best results are obtained when each family has a Bug Buster Kit. This provides all the combs necessary with full instructions on their use with ordinary shampoo and conditioner to detect lice, eradicate an infestation mechanically, or to check the success of any treatment. In the UK, the promotion of the Bug Busting approach is reducing primary care expenditure on treatment for head lice and professional time spent with worried parents. As a result, healthcare providers can give time to the few families who require one-to-one guidance.

RELEVANCE TO CLINICAL PRACTICE

Incorporation of the Bug Busting approach to head lice into clinical practice in school communities contributes to sustainable control whilst overcoming health inequalities in participating families.

Prevalence of pediculosis and scabies in preschool nursery children of Afyon, Turkey

Scabies and pediculosis are ubiquitous, contagious, and debilitating parasitic dermatoses. The tendency of high prevalence of pediculosis and scabies among school and preschool age children has prompted us to conduct a head louse and scabies prevalence survey among preschool nursery children in our district. A school-based, crosssectional study was performed, with 1,134 children chosen for evaluation. All cases were evaluated by physical examination and a detailed, structured questionnaire. The infestation was found in 14 (1.2%) of 1,134 children; 9 (0.8%) with pediculosis capitis and 5 (0.4%) with scabies. We found that infestations were more frequent in children with mothers whose education levels were low. This indicates the necessity of an improvement in the economic and sociocultural status of the community and the promotion of hygiene concepts and practices in order to improve health of preschool age children.

Epidemiology and morbidity of scabies and pediculosis capitis in resource-poor communities in Brazil

BACKGROUND

Pediculosis capitis and scabies are common parasitic skin diseases, especially in resource-poor communities, but data on epidemiology and morbidity are scanty.

OBJECTIVES

To assess the prevalence, seasonal variation and morbidity of pediculosis capitis and scabies in poor neighbourhoods in north-east Brazil.

METHODS

The study comprised cross-sectional surveys of a representative population of an urban slum (n = 1460) in Fortaleza, the capital of Ceará State (Brazil) and a fishing community 60 km south of the city (n = 605). Study participants were examined for the presence of scabies and pediculosis capitis. In a longitudinal study in the slum, variation of prevalence in different seasons of the year was assessed.

RESULTS

Prevalence of pediculosis capitis was 43.4% in the slum and 28.1% in the fishing community. Children aged 10-14 years and females were most frequently affected. Scabies was present in 8.8% of the population in the slum and in 3.8% of the population in the fishing community. There was no consistent pattern of age distribution. Superinfection was common in patients with scabies, and cervical lymphadenopathy in patients with pediculosis capitis. Multivariate analysis showed that age < or = 15 years, being of female sex and living in the urban slum were independent factors contributing to the simultaneous coinfestation with pediculosis capitis and scabies. The longitudinal data from the urban slum showed a characteristic seasonal variation of pediculosis capitis, but no fluctuation of scabies.

CONCLUSIONS

Pediculosis capitis and scabies are hyperendemic in the study areas and are associated with considerable morbidity. There is an urgent need to develop control measures for these parasitic skin diseases in resource-poor communities. This is the first community-based study describing in detail the epidemiology and morbidity of scabies and head lice infestation in Brazil.

Method to measure force required to remove Pediculus humanus capitis (Phthiraptera: Pediculidae) eggs from human hair

Head lice are very common and mainly affect children between 3 and 12 yr old. Little is known about the way nits, the eggs of the head louse, are attached to the hair. In this report, an objective measurement procedure for the ease with which nits can be removed is presented. The first peak force, associated with the start of nit movement, and the average and maximal force during the sliding of the nit were measured. The three force variables correlated with the length of the cylinder by which the nit was attached to the hair. A negative correlation was found between the maximum force exerted and the distance of the nit from the scalp. The method described in this report can be used to determine the in vitro efficacy of various products to remove nits.

Managing head lice in an era of increasing resistance to insecticides

Head lice are present in all age groups, however, the peak age for infestation is 7-8 years and the incidence varies throughout the year with higher incidence during the winter. Different insecticides have been used over the past 60 years to manage this condition. There is now strong evidence of insecticide resistance established in many countries to such an extent that some of these chemicals have become obsolete. Resistance to some pediculicides can vary from country to country and region to region within a country. The lack of a local monitoring system of resistance patterns means that parents and pupils are hampered in making an informed decision regarding how to treat head lice. One should no longer assume that treatment failure is due to poor treatment compliance or re-infestation. Clear treatment guidelines drawn up by healthcare professionals with an interest in head lice and taking into account regional/national resistance patterns should be implemented. These guidelines should combine chemical and non-chemical approaches to treatment and be coordinated and regularly reviewed by local public health departments. Drug companies should be made to provide up-to-date efficacy of their products.

The prevalence of pediculosis capitis in schoolchildren in Mersin, Turkey

BACKGROUND

Pediculosis capitis is an endemic parasitosis affecting many countries of the world. The aim of this study was to investigate the incidence of head lice infestation in Mersin, Turkey.

METHODS

A total of 5318 elementary schoolchildren, aged 8-16 years, were examined for the presence of Pediculus capitis. If any evidence of head lice was detected, such as live or dead eggs, or nits, the child was considered to be infected. The following details were recorded for each child: age, sex, family size, monthly income, number of siblings, parents' education, presence or absence of social security of the family, pet (cat or dog) ownership, and frequency of hair washing (per week). The chi-squared test and logistic regression analysis were performed to analyze the results.

RESULTS

Pediculosis capitis was detected in 360 (6.8%) children. The prevalence of infestation was significantly higher in girls (13.3%) than in boys (1.1%) (chi2 = 313.2, d.f. = 1, P = 0.000). Children aged 8-9 years exhibited a significantly lower prevalence rate than those aged 10-11 years and those aged 12 years and above. The following variables were found to be statistically significantly related to pediculosis capitis: sex, age, father's education level, and pet ownership (cat or dog).

CONCLUSIONS

Our results show that the prevalence of pediculosis capitis is not very high in Mersin, Turkey, and is observed in all schools regardless of the socio-economic and personal hygiene status of the children.

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.