Using human head lice to unravel neglect and cause of death

Forensic parasitology: a new frontier in criminalistics

Parasites are ubiquitous, diverse, and have close interactions with humans and other animals. Despite this, they have not garnered significant interest from forensic scientists, and their utility as indicators in criminal investigations has been largely overlooked. To foster the development of forensic parasitology we explore the utility of parasites as forensic indicators in five broad areas: (i) wildlife trafficking and exploitation, (ii) biological attacks, (iii) sex crimes, (iv) criminal neglect of humans and other animals, and (v) indicators of movement and travel. To encourage the development and growth of forensic parasitology as a field, we lay out a four-step roadmap to increase the use and utility of parasites in criminal investigations.

Head lice-induced anemia in a child and implications for oral health: Case report

Pediculosis capitis, colloquially referred to as head lice, engenders adverse social and economic consequences among children. While generally not considered a health hazard, chronic and severe head lice infestations have been linked to secondary iron-deficiency anemia. This case report documents a 7-year-old girl who presented for dental treatment with a history of social isolation and poor school attendance. Upon examination, the patient was found to have head lice and scabies infestations, resulting in secondary iron-deficiency anemia. The patient could return to full-time education after successful treatment for the head lice infestation administered by the dental team. This case underscores the need for treatment guidelines to manage children with diagnosed or suspected cases of head lice from a dental perspective. In instances of severe infestation, referral to a medical professional may be necessary for further management. This report highlights the importance of a multidisciplinary approach in managing head lice infestations and its implications on dental management.

HEAD LOUSE PALEOEPIDEMIOLOGY IN THE OSMORE RIVER VALLEY, SOUTHERN PERU

Recent studies of louse ectoparasites from mummies have developed robust data sets that allow a true epidemiological approach to the prehistory of louse parasitism. One epidemiological principle is that the binomial of overdispersion is normally negative, meaning that in a host population, parasites are aggregated in a few individuals. We demonstrate the overdispersion of lice in 3 different prehistoric communities that differ along 3 axes or variables: environmental setting, socioeconomic status, and cultural affiliation. Distinct cultural practices could have been involved in different patterns of louse infestation. Prevalence, intensity, and abundance of infestations exhibit statistically significant differences between the communities. We also find differences in prevalence between subadults and adults that contrasted by cultural affiliation and suggest conditions different from those seen today. We show that overall prevalence was affected primarily by ecological setting, not socioeconomic status nor cultural affiliation. These findings demonstrate that statistical analysis of archaeological data can reveal the states of infestation in past populations with lifestyles not seen in modern people. Our approach paves the way for future comparisons of subpopulations within archaeological communities.

Ancient human genomes and environmental DNA from the cement attaching 2,000 year-old head lice nits

Over the past few decades, there has been a growing demand for genome analysis of ancient human remains. Destructive sampling is increasingly difficult to obtain for ethical reasons, and standard methods of breaking the skull to access the petrous bone or sampling remaining teeth are often forbidden for curatorial reasons. However, most ancient humans carried head lice and their eggs abound in historical hair specimens. Here we show that host DNA is protected by the cement that glues head lice nits to the hair of ancient Argentinian mummies, 1,500–2,000 years old. The genetic affinities deciphered from genome-wide analyses of this DNA inform that this population migrated from north-west Amazonia to the Andes of central-west Argentina; a result confirmed using the mitochondria of the host lice. The cement preserves ancient environmental DNA of the skin, including the earliest recorded case of Merkel cell polyomavirus. We found that the percentage of human DNA obtained from nit cement equals human DNA obtained from the tooth, yield 2-fold compared with a petrous bone, and 4-fold to a bloodmeal of adult lice a millennium younger. In metric studies of sheaths, the length of the cement negatively correlates with the age of the specimens, whereas hair linear distance between nit and scalp informs about the environmental conditions at the time before death. Ectoparasitic lice sheaths can offer an alternative, nondestructive source of high-quality ancient DNA from a variety of host taxa where bones and teeth are not available and reveal complementary details of their history.

Forensic hair analysis - Worldwide survey results

Forensic hair analysis remains under the microscope. Although hair evidence can yield information pertinent to an investigation, past issues with associated expert testimony endure. The aim of this survey was to gain a better understanding of hair analysts by expanding on past findings by assessing methodology, terminology and bias, analysing demographic and workplace data and allowing participants to comment on current and future issues in hair analysis. An online survey was designed and disseminated to hair analysts worldwide and 176 analysts from 12 countries took part in the survey. Participants responded to questions regarding accreditation, the probative value of hair evidence, collection and packaging, contextual information, methodology, terminology and reporting results, conclusions and opinions. The probative value of hair evidence was supported and other than selection of mounting medium the survey identified a preference of collection methods, packaging materials, use of microscopy and notetaking. Terminology used when conducting hair analysis and reporting results varied and caution towards statistics was expressed while training and collaboration was encouraged. The survey data will be used in the development of validation studies in hair analysis for future dissemination.