Introduction
Head lice infestation is a world-wide public health problem affecting persons of all ages and socioeconomic backgrounds. It usually affects children, the most common age group being 3 to12 year olds. The staff of the King Saud University (KSU) kindergarten, in Riyadh city, observed head lice infestation in the heads of several students. The Principal of the kindergarten contacted the Field Epidemiology Training Program (FETP) asking for help in investigating this outbreak and controlling the problem.
Methodology
A team from the Field Epidemiology Training Program visited the kindergarten, met with the principal and examined the kindergarten and children. A case control study was conducted using a self administrated questionnaire to be filled by the parents.A case was defined as any student who reported having head lice with or without at least one of the following symptoms: head itching, head wound, and feeling movement at hair in the period from January to March 2011 and/ or detected by physical examination. A control was defined as any student in the same classroom and not infested by head lice.41 cases and 67 controls were included in the study.
Results
Out of the 300 KG student, 41 were diagnosed with head lice infestation, giving a prevalence of 38%. Among cases there were 26 (63.4%) females and 15 (36.6%) males.The most common age group affected was four to six years old (mean 5.17 years, SD ± 0.83).Most of the cases were in upper KG 26 (63.4%) while the rest 15 (36.6%) were in nursery and lower KG. For the case control study, all 41 were considered as cases and a further 67 were selected as controls. There was a significant association between sharing accessories in the Kindergarten and head lice infestation, especially hats (OR 30.12, 95% CI 8.1-112.1). Other risk factors were sharing of towels (OR 9.17, 95% CI 1.03-81.51), sharing of costumes (clothes) (OR 7.94, 95% CI 2.62-24.0), sharing of hair ribbons and hair clips (OR 4, 95% CI 1.26-12.72 and OR 3.98, 95% CI 1.43-11.06 respectively), and sharing scarves (OR 2.55, 95% CI 0.75-8.66). Not Sleeping outside the home and not sharing pillows were found to be protective against head lice infestation (OR 0.84, 95% CI 0.30-2.32 and OR 0.67, 95% CI 0.16-2.78 respectively). Other family and parent factors associated with head lice infestation included mothers and fathers higher educational levels (OR 0.6, CI 0.08-4.43 and OR 0.93, CI 0.38-2.24, respectively), mothers' non employment status (OR 1.45, CI 0.65-3.23), and presence of an affected family member(OR 10.71 CI 3.57-32.13). Risk factors for subsequent re-infection included being female (OR 5.16, CI 0.57-46.83), living with over 5 family members (OR 2.56, CI 0.52-12.61), presence of an affected family member (OR 12.25, CI 1.34-111.90), low mothers' education (OR 4.57, CI 0.25-82.25) and mothers non employment status (OR 6, CI1.04-34.7). On interviewing the KG principle, it was revealed that there had been a celebration fancy dress /costume party a few days prior to the outbreak, where the students had shared clothes and accessories.
Conclusion
The prevalence of head lice infestation at the kindergarten was 38%. It is believed that sharing hair accessories and clothes in the kindergarten costume party was the source of the outbreak. Home and other family factors cannot be excluded.