Body Lice Associated with Lower Hemoglobin Levels

Michael A Kohn, MD

A recent investigation into body lice found that the parasitic insects were associated with significantly lower hemoglobin levels in affected patients.

Considering that body lice survive off the blood of hosts, investigators hypothesized that body lice infestation could result in iron-deficiency anemia, adding that multiple case reports supported the association between severe or long-term infestation and anemia.

Despite this, no epidemiologic studies had been performed.

As such, investigators led by Michael A Kohn, MD, MPP, Department of Epidemiology and Biostatistics, University of California San Francisco School of Medicine, San Francisco, investigated the association between body life infestation and hemoglobin following an adjustment for potential confounders.

The team performed a retrospective, exposed-unexposed study that featured patients with and without body live who were matched in a 1:3 ratio on age, sex, and housing status.

Eligible patients including those who were hospitalized at the UCSF Moffitt-Long Hospital or Zuckerberg San Francisco General Hospital and received a dermatology consultation between November 1, 2017, and April 30, 2021.

Patients with alternate causes of anemia were excluded, and housing status of eligible patients was dichotomized into stable housing and homelessness.

The primary outcome was mean hemoglobin level at hospital admission, and the secondary outcome was anemia.

Investigators compared mean hemoglobin levels using a paired t test, and the association between infestation and hemoglobin level was assessed using multiple linear regression tests after adjustment for potential confounders including age, sec assigned at birth, self-identified race or ethnicity, and more.

The team also compared the proportion of anemia using χ2 testing.

The study featured 27 patients with lice and 81 without lice with a mean age of 53.8 years. Among these participants, 20 (18.5%) were women and 92 (85.2%) were homeless.

Investigators observed that patients with body life infestation had significantly lower mean hemoglobin levels (10.4 g/dL) compared to those without (12.9 g/dL) (P<.001). Body lice infestation was associated with 2.5 g/dL lower hemoglobin level after adjustment (P<.001).

Notably, the proportion of patients with anemia was higher in patients with body lice (70.4%) compared to those without lice (46.9%).

In addition to previous case reports that detailed anemia requiring transfusion in association with body lice, the current data suggested that anemia was a potential systemic complication of lice infestation.

Investigators suggested that further research was required to guide clinical recommendations and target public health interventions, especially given the rising rates of homelessness. This could mitigate and potentially eradicate the risk of body lice infestation.

“Future studies to demonstrate causation and to evaluate the role of sheltered status in the relationship between lice infestation and anemia are warranted,” the team wrote.

The study, "Association of Body Lice Infestation With Hemoglobin Values in Hospitalized Dermatology Patients," was published online in JAMA Dermatology.