How it began
Edmond Sergent led the Pasteur Institute of Algeria from 1900 to 1963, and its team studied malaria, relapsing fever and other diseases of people, livestock and plants. In 1908 the Sergent brothers, working with the army physician Henry Foley, were the first to discover the role of the louse in the transmission of relapsing fever. A historical study of Foley places the clinical, epidemiological and experimental work at Beni Ounif de Figuig, in the south of the Oran region.
How it works
Relapsing fever is an infection that passes between people living in close contact. The Algerian work showed that the disease does not spread directly from one person to another but is carried by lice that feed on a patient and then on someone else. The louse is the vector, the living carrier of the microbe.
What changed first
The discovery led the researchers to incriminate the louse in the transmission of exanthematic typhus as well, a disease whose pattern of spread is practically the same. It gave public health workers a clear target, since controlling lice could interrupt both diseases.
What lasted
The same institute went on to identify the sandfly as the vector of leishmaniasis, to run campaigns against malaria in Algeria, and to study bovine piroplasmosis and a fungal disease of date palms. Sergent and his colleagues also introduced the concept of premunition, the idea that an existing infection protects against further infection. Modern reviews of louse-borne relapsing fever still cite the 1908 work.
