The infestation with the human obligate ectoparasite Pediculus humanus capitis De Geer is a common public health problem affecting mainly schoolchildren worldwide. The aim of the present study was to investigate the infestation levels of head lice in elementary schools from Buenos Aires with resistant levels to permethrin >100. A total of 1,856 children aged 3-13 years old from eight selected elementary schools were examined for head lice. Pediculosis was observed in all the studied schools. The overall infestation rate was 29.7%. Girls were statistically significant more infested than boys, with infestation rate values of 36.1% and 26.7%, respectively (P < 0.0001). Only 42 of the infested girls (12%) and 23 of the infested boys (11.4%) had >10 lice on their hair. The proportions of infested children-both girls and boys-in each age group were not found to differ significantly from one another. The infestation rate among schools varied from 19.12% to 42.74%. This indicated that pediculosis is relatively common in elementary schools from Buenos Aires, and those levels are of epidemic importance. The differences of pediculosis among the studied schools could be explained by the different control strategies applied by parents or advisors to eradicate head lice.

Pediculosis is a worldwide disease affecting school-aged children produced by the presence of the head louse, Pediculus humanus capitis De Geer, an obligate ectoparasite on the human scalp feeding exclusively on blood. Transmission occurs primarily through direct physical head-to-head contact. In March 2020, the World Health Organization (WHO) declared the COVID-19 outbreak as a pandemic. COVID-19 is caused by SARS-CoV-2, a variant of the coronavirus. Therefore, on March 18, 2020, the Argentinean government established mandatory isolation for an indefinite period. This obligatory isolation interrupted regular classes avoiding direct contact between children, thus affecting the dispersal route of individuals and the evolution of head louse populations. In this study, we evaluated through an online survey how confinement affected the prevalence of lice during lockdown compared to the situation prior to confinement. The survey allowed to discriminate the different control strategies, the number of treatments, and the amount of insects recorded by parents. Data of 1118 children obtained from 627 surveys were analyzed. As the main result, it was observed that prevalence of lice decreased significantly from before (69.6%) to during (43.9%) COVID-19 lockdown. Moreover, head lice infestation was more effectively controlled in households with up to 2 children in comparison to households with 3 or more children. This is the first study that analyzed the prevalence of head lice during COVID-19 pandemic. In addition, this work demonstrated the impact of social distance in the population dynamics of head lice and how it could affect the control strategies in the future.

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