Further studies on experimental leprosy and cultivation of mycobacterium leprae

The experiments reported describe the actual cultivation of Mycobacterium leprae on artificial culture medium in a gaseous tension of carbon dioxide and oxygen through sixteen generations over a period of eighteen months. Several new mediums have been prepared and inoculated but no growth appeared after six weeks incubation. Organisms from the ninth, tenth and eleventh serial transfers failed to produce experimental tissue changes in older monkeys then were used several months earlier when the culture which was not so distant from the host produced graniulomatous lesions by intradermal injection. Guines pigs and several varieties of mice manifested no pathologic changes when injected intracutaneously with these cultures. Serological data are givenm as a matter of record. A discussion of the possible mechanism of infection in human leprosy is presented. These studies are being continued

The roles of familial susceptibility and contagion in the epidemiology of leprosy

Two concepts of the epidemiology of leprosy were evolved in carlier times from essentially the same observations. On the one hand, the frequency with which cases could be traced to exposure resulted in the theory of contagion, while the fact that contagion was largely restricted to relatives seemed to point to hereditary transmission. The latter theory is discrepant in that leprosy is not congenitally transmitted. Nor does contagion appear to be the sole etiologic factor, since the disease usually fails to spread to nonrelated persons equaly exposed. Perhaps largely due to the discovery of the Hansen bacillus, the theory of contagion has taken precedence, although it has been necessary to qualify it by the doctrine of predisposing causes. Webster´s demonstration of inborn susceptibility to experimental infection, as well as epidemiologic findings in poliomyelitis which indicates that the paralytic disease is determined in large measure by individual susceptibility, often familial, suggest a similar concept of leprosy. Such an interpretation may harmonize the validities and adjust the discrepancies in the opposed theories. A preliminary study of the available records of the occurrence of leprosy in a restricted focus on the American continent, where it has persisted for many years, indicates blood relationship between the majority of individuals affected. In addition, there is evidence of frequent intermarriage within the afected lines. At present, epidemiologists concerned with the problem of leprosy are emphasizing as most important factors in the transmission of the disease the degree, duration and closeness of contact. The type of contact which young children experience with their elders appears to represent the degree and duration of intimacy which would satisfy this concept; that which occurs between adults is of another character and does not provide the factor of duration. One observes in various parts of the tropics for example, the mother of father holding the naked child for hours in his or her arms.

Cultivation of B. leprae with experimental lesions in monkeys

The experiments described include (1) the experimental production granulomatous lesions suggestive of early lesions of leprosy in two species of monkeys by intradermal inoculation of human leprosy material; (2) the cultivation of acid-fast (presumably B. leprae) bacilli from human leprosy nodules on several artificial mediums in various gaseous environments; and (3) the experimental production of granulomatous lesions, suggestive of early leprosy, in two species of monkeys by the intradermal inoculation of cultures of acid-fast bacilli from human leprosy material grown on artificial mediums. We believe the experiments indicate a step forward in the fulfillment of Koch´s postulates for the causative agent in the disease of leprosy.