Insomuch as the ague (or malaria) exacted a high toll in seventeenth-century Europe--especially in England--it would be reasonable to assume that, with typhoid and dietary disorders, this disease caused most of the illness in Virginia. When emphasis has been placed, by authorities, upon the location of Jamestown as a disease-producing factor, the implication has often been that the swampy area was a mosquito and malaria breeding place. A number of historians have asserted that malaria produced the highest mortality figures at Jamestown. Much is also made of the tragic circumstance that the arresting agent for the disease, cinchona bark or quinine, was known on the European continent by mid-seventeenth century but that little use was made of it. Dr. Blanton, the authority on seventeenth-century Virginia medicine, in contrast argues that "there is not evidence ... that malaria was responsible for a preponderating part of the great mortalities of the Seventeenth Century in Virginia." He bases this conclusion on a number of facts: he has been able to find only five or six references to the ague (malaria) in the records of the century; because the ague was well-known he does not believe its symptoms, such as the racking chill, would have escaped notice. On the other hand, he does not doubt the presence of the ague in Virginia throughout the century even though it did not cause the most distress. As in the case of the ague, a reasonable assumption would be that the plague existed in seventeenth-century Virginia. The Great Plague of London (1665) carried away 69,000 persons, and other cities of Europe had even more disastrous epidemics. During the two years before the first settlers arrived at Jamestown, over 2000 victims were buried in London. The accounts of the ocean voyage indicate rat-infested ships. Ships of the London Company reported plague and death aboard. Virginians took pains to describe their illnesses, and there would have been little difficulty in recognizing this well-known killer. Yet little evidence of the presence of the plague appears in the seventeenth-century Virginia record; cases are reported but the number is small. Why Virginia should have been spared--especially in view of the known rat-infestation aboard ship--remains a question. The evidence relative to yellow fever, or calenture, during this period in Virginia is contradictory. Early sources do make reference to numerous deaths from it at sea and even to an epidemic of it at Jamestown before 1610, but subsequent notices are infrequent and of questionable validity. Prevalence of the disease in the earlier years and its comparative infrequency in later is not a likely circumstance because with the increase of commerce, especially from tropical ports, an increase of the disease should have followed.