Social and demographic aspects of a leprosy epidemic on a Polynesian atoll: implications of pattern.

This study reports the results of field research on a leprosy epidemic among the Kapingamarangi people, Polynesians living in two communities on Ponape Island and Kapingamarangi Atoll in the Federated States of Micronesia. The patterns of infection in the two communities are seen to replicate in detail patterns of personal mobility by age and gender and patterns of kinship and friendship relations that order people's social interactions in the communities. These patterns of demographic and social relationship form the context of infectious contact, enabling us to differentiate between more- and less-probable means by which Hansen's disease is spread. We compare coughing and sneezing with inoculation through the frayed fibers of pandanus leaf floor mats and sleeping mats as alternative ways of spreading leprosy infection. We find that frayed mats, because they are ubiquitous in the contexts in which people interact, are more likely to spread infection than coughing and sneezing. Finally, we find that demographic patterns of the communities are not identical with genealogical relationships such that people with close genealogical relationships often do not interact on a regular basis. Thus, genealogical distance and social distance are independent of each other in this community. This makes genetic assessment of inheritance of resistance and susceptibility to Mycobacterium leprae an enterprise unencumbered by a necessarily linked demographic variable.