Currently, neither head nor pubic lice are considered vectors for human pathogens. Of the three types that affect humans, only body lice are vectors for human pathogens. They are known to transmit relapsing fever, epidemic typhus, and trench fever, diseases caused by Borrelia recurrentis, Rickettsia prowazekii, and Bartonella Quintana. These pathogens have been found in lice feces and can be transmitted through the conjunctivae, mucous membranes, and contamination of bite sites.
Even though these three diseases have been known for at least a few centuries, they’re still a major health concern in developing countries; in populations living in poor-hygiene conditions because of social disruption, war, poverty, or simply put – bad health management. Poor-hygiene favors a higher prevalence of body lice, the main vectors for relapsing fever, trench fever, and typhus.
Trench fever occurs in both developing and developed countries among populations living in poor conditions, such as those in refugee camps, or homeless individuals. The mortality rate of epidemic typhus varies from 0.7 percent to whopping 60 percent for untreated cases. Relapsing fever is an infection caused by the spirochete Borrelia recurrentis. Although the disease has disappeared in most of the world, it is still a big health concern in some parts of Africa.