Antibodies to the phenolic glycolipid-1 antigen for epidemiologic investigations of enzootic leprosy in armadillos (Dasypus novemcinctus).

Other than man, nine-banded armadillos (Dasypus novemcinctus) are the only known natural hosts of leprosy with high rates of disease. The origin, range and risk of their infection is not yet clear and a better description of the rate of leprosy over the armadillo's range is needed. Both histopathological examination of armadillo ear tissues and serologic screening for IgM antibodies to the phenolic glycolipid-1 (PGL-1) antigen of Mycobacterium leprae are good relative indices of enzootic prevalence. A survey of 216 armadillos from Louisiana and Florida detected infection only among Louisiana animals. Average antibody prevalence (12.5%) was five times higher than the fully disseminated disease rate described histopathologically (2.7%). The differences in antibody and histopathological prevalence are due to the sensitivity of the methods for detecting early infection. Histopathological examinations describe an advanced disease. The higher antibody prevalence of wild armadillos is not likely to be the result of false positive serologies from self-healing infections or other casual encounters with M. leprae as might be mimicked by lepromin injection. The environmental reservoir of M. leprae represented by infected armadillos is greater than could be previously estimated.