Dear editor: The head louse, Pediculus humanus capitis, has been linked to humans for thousands of years and even today affects millions of people.¹ Per general is not considered a major disease.² Personal characteristics, socioeconomic and cultural conditions and the development of insecticide resistance have also influenced the spread of this disease.³ In Mexico, there are only a few studies about the topic or its relation to Rickettsia transmission, with emphasis on body lice surveillance.⁴ A cross sectional study was carried out in Lacanja Chansayab, in Lacandon Jungle of Chiapas, from May to June 2015. The community has a population of 379 inhabitants, whom at least 68 are children of 6 to 14 years old. The sample size was obtained with IC95%. 54 children were included. Homes were visited to inform parents/guardians about the study and request the participation through informed consent (COBICIS-56/02/2016/02-UBE-RMSC).

Parents also answered a survey related with overcrowding degree, which included questions about housing and family members. We observed high head lice prevalence (72.2%). Socioeconomic status, hygiene, cultural practices and hair characteristics of children underwent visual inspection. Children were checked in detail using a plastic lice-comb. Children from 10 to 13 years of age were the most affected, with significant difference (p=0.133) between the age groups (table I).

Table I Prevalence and factors by age group of head lice observed in Lacandon children, Lacanja Chansayab, Chiapas, Mexico (N=54). 2015 

More boys than girls were included. Statistical analysis did not reveal a significant difference between infestation percentage and gender (p=0.208). Variables that influence the transmission are: 1) number of household members (p=0.034), 2) hair length (p<0.001) and 3) hair color (p=0.005). We believe that sisters transmitted lice to brothers because they typically wear long hair as well as sharing fomites and beds. We must also consider that the population studied has limited access to interact with people outside their community. Therefore, this condition is likely an overestimation in marginalized communities of other ethnicities. The head louse has greatly affected this indigenous group; 60% of the records in Mexico.⁵

Although overcrowding is common during historical head lice outbreaks, it is not a determining factor.³ However, the need for a regular surveillance and control program exists whenever there is a susceptible population and it is neglected in outbreak reports or suspected Rickettsiosis cases. For years, head lice have been given little attention as a disease vector and transmitter of pathogens like Rickettsia o Bartonella. Old and new reports all indicate that a lack of surveillance plays more than a small role during transmission.⁶ It also exposes the need to regularly carry out thorough entomologic and epidemiologic surveillance for head lice infestations, as well as a program for direct patient attention in highly vulnerable populations with little access to health care systems. Research was supported by DSA/103.5/15/6797(PRODEP).