Leprosy Training Module for Medical Officers

Spread of Leprosy
Source of Infection :
Man is the only known source for M.leprae. Among human beings it is the
untreated MB leprosy patient who acts as a source of infection.
The occurrence or the non – occurrence of the disease is closely
associated with the cell – mediated immune response of the host , to the
challenge by the Leprosy bacillus.
Transmission of Leprosy :
Leprosy is transmitted from one untreated Multibacillary patient to another
person via mainly the respiratory tract or skin.
Portal of Exit :
The major sites from which bacilli escape from the body of an infectious
patient are the nose and mouth.
Lepromatous patients in their nasal secretions can excrete as
much as 10 million viable organisms per day.
Viability of M. Leprae outside the human host :
M. Leprae can survive up to 7 to 9 days in nasal secretions , in shady
places .
Portal of Entry :
As such portal of entry of M. Leprae into human body is not definitely
known, the two portals of entry seriously considered are the skin and the
upper respiratory tract. Although entry through respiratory route appears most
probable, other routes, particularly broken skin, cannot be ruled out.
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