External parasites found on the human body may provide information beyond the diagnosis of an infestation. They can contribute to an assessment of the healthcare a person has received, particularly when examining children, older adults, and individuals who depend on others for their daily needs. Lice are external parasites that feed on human blood. Clinical case reports have described an association between some severe, chronic infestations and iron deficiency anemia. However, these reports do not establish lice as the cause of anemia in every case. Nutritional factors and other medical causes must also be assessed. When neglect is suspected, investigators may document the severity of infestation, scratching injuries, and skin sores, then compare these findings with nutritional status, medical examinations, and treatment records. This assessment can help determine whether health deterioration occurred alongside a continuing lack of appropriate care. However, lice infestation alone does not prove neglect or identify a responsible person. Infestation can occur in people who receive adequate care. Findings must therefore be interpreted in relation to medical and social circumstances and access to treatment. In conclusion, external parasites may provide supporting evidence in neglect investigations when considered alongside medical findings and the wider circumstances of the case.