Which study performed earlier this century established that the fourteenth-century black plague was spread from rats to humans via fleas?

descriptive

epidemiological

experimental

observational

epidemiological

Explanation:

Epidemiological studies are the ones that are conducted on human populations to determine the cause of the disease and also to evaluate the protective factors against the disease in a given population. These studies aim to identify a disease in the population, identify when, where and how it occurred so as to identify a definite cause and then to look for ways to eradicate the disease from the population or to decrease its frequency. The epidemiological studies were conducted in 14th century to determine the cause of black plague which caused the death of millions and the death was termed as black death. The epidemiological studies led to the conclusion that the deaths were caused due to the transmission of the plague from rats to humans via fleas.