The pig tapeworm Taenia solium can cause the tropical disease cysticercosis. Humans are the only definitive hosts of the worm and pigs are the principal intermediate hosts.
The tapeworm can be divided into two mtDNA lineages, Asian and Afro-American, with disjunct geographical distributions. Recently it was found that both lineages exist in Madagascar. The first humans settled in Madagascar about 2000 years ago. Linguistic and archeological evidence suggests that people on Madagascar have ancestry from Island South-east Asia and East Africa. Recently, by studying mtDNA, a genetic contribution from India has been suggested.
By studying the genetics of the tapeworm insights for the distributional history of hosts and parasites can be gained.
In this paper, they collected larvae from pigs across five provinces on Madagascar. Their results indicate the importance of Indian influence on the diversity of people and culture in Madagascar, and that the tapeworms were introduced in Madagascar (within the past hundreds of years) multiple times with people and swines from East Africa. They also find evidence for hybridization between tapeworms with different genotypes.