An international team has identified six distinct lineages in the black rat's family tree, each originating from a different part of Asia, Australia's Commonwealth Scientific and Industrial Research Organization said Friday in a release .

Black Rats are carriers of many different human diseases, including plague, typhus and leptospirosis.

Lead author Ken Aplin, a CSIRO mammal expert, said the findings suggest the different lineages of black rats each carry a different set of diseases.

The six different lineages originated in India, East Asia, the Himalayas, Thailand, the Mekong Delta and Indonesia. The Indian lineage spread to the Middle-East around 20,000 years ago, then later to Europe. The East Asian lineage moved from Taiwan to Japan, the Philippines and Indonesia, arriving in Micronesia only 3,500 years ago. The other four lineages have not become so widespread, the report said.

"We need to know more about what types of black rats are moving around the world and what disease risks each of them might pose," Aplin said.