Was the Black Death a parasite or bacteria or a virus?

Answer 1

We don't actually know what the Black Death was exactly.

The most accepted theory is that it was a form of Bubonic Plague, caused by a bacteria called Yersinia Pestis which was spread through the bites of fleas. This theory makes sense, because the bacteria is native to Asia, where the plague started. Black Rats from Asia managed to get into Europe on ships during trades, spreading the bacteria and therefore the plague into Europe.

Another theory, less popular that the one above, is that the plague was actually caused by an Ebola Virus. The virus's incubation period is longer than that of the Yersinia Pestis bacteria, which is believed to contributed to the Black Death spreading so quickly, because the virus survived longer in the hosts before becoming lethal. However, the theory would also explain how the plague travelled from human to human, as Ebola Viruses are passed on through human contact, whereas it is extremely rare for Yersinia Pestis to be passed on through human contact.

One of the most recent theories is Anthrax, which is a bacterial disease from cattle products. This theory is actually gaining popularity due to recent evidences.

Indeed, cattle was transported from Asia, where plague originated, to Europe in trades. A recent archaeological investigation into a plague pit discovered in Scotland (where dead bodies of plague victims were thrown in and buried), biological archaeologists discovered signs of anthrax spores.

Doctors, pathologists and physicians notes written during the Black Plague period reported symptoms of "boils, blisters, lesions, ulcers, Eschar ulcers, toxidemia, flu, vomiting blood and intestine inflammation". All of these are symptoms of Anthrax.

If it was indeed Anthrax, then the flu-like symptom would have helped the Anthrax bacteria spread through sneezes and coughs.

It has also been suggested that the Black Death was caused by a mixture of both Bubonic and Anthrax.

So there you have your theories.

The bubonic theory is the most widely accepted, but it does not explain how the Black Death managed to spread so fast and so far.

The Ebola theory is able to explain how the Black Death spread so far and so fast and also how it was passed on by human contact. However the symptoms do not match medical notes from the Black Plague period, so the theory is not very popular.

The Anthrax theory is not currently as popular as the bubonic theory, but is more popular than the Ebola theory. However it is rapidly gaining popularity as more and more evidence of the similarities between the symptoms of the Black Death and Anthrax are discovered as well as the discovery of Anthrax spores at archaeological dig sites.