The idea that the Black Death was not caused by Plague has been repeatedly proposed by scholars, notably Samuel Cohn.

Modern genetic testing has confirmed that bodies from plague pits dating to the time of the great pandemics died of Yersinia Pestis (YP), the pathogen often called plague. For a systematic refutation of Cohn and the "plague denial" line of scholarship see:

• Benedictow, Ole. What Disease was Plague?: On the Controversy Over the Microbiological Identity of Plague Epidemics of the Past. Brill, 2011.

Some much older scholarship does argue that the only disease vectors for YP were common rats (rattus rattus) and the human flea (Pulex irritans). Cohn and several others lean heavily on out-of-date ideas about YP vector systems in their own attempted revisionism.

But modern research shows plague can be carried by cats, dogs, body lice, rat fleas, ground squirrels, marmosets, camels, and 200 other species of mammals. Though the majority of interhuman transmission does seem to occur through human ectoparasites such as fleas and body lice.

• Barbieri, R., et al. "Yersinia pestis: the natural history of plague." Clinical microbiology reviews 34.1 (2020): e00044-19.