Various genotypes of Mycobacterium leprae from Mexico reveal distinct geographic distribution

To classify Mycobacterium leprae isolates from multiple areas in Mexico based on variable number of tandem repeats of 6 base within the rpoT gene and three single nucleotide polymorphism (SNP), and to analyse their geographic distribution in the context of the origin of leprosy in Mexico.

Analysis for rpoT genotyping of 64 samples collected in the west and southwestern areas revealed that 46 isolates were of the 4 copy type and 18 isolates were of the 3 copy type. All samples from the eastern coastal area (n = 24) and from the Yucatan peninsula (n = 12) were of the 3 copy type. Six isolates from the west and southwestern area were SNP-type 1, 13 isolates were SNP-type 2 and 45 isolates were SNP-type 3. Nineteen of 24 isolates from the eastern coastal area were SNP-type 3 and one was SNP-type 4. Seven isolates from the Yucatan peninsula were SNP-type 3 and one was SNP-type 4.

The difference of the proportion of each genotype between the western areas and the eastern areas indicated the expansion of leprosy through different paths in Mexico.