Confidence votes 175. Viruses can have either DNA or RNA (a virus will never have both at the same time, although some viruses can have each one separately at different stages of their life cycles). RNA viruses are much more common than DNA viruses. Nucleic Acid Amplification Testing for the Diagnosis of STDs The purpose of the nucleic acid amplification test (NAT or NAAT) is to find trace amounts of RNA or DNA in test samples.
SECTION 6. Man and Disease: The Black Death. Beginning in 1347 and continuing for a full five years, a devastating plague swept Europe, leaving in its wake more than twenty million people dead. This epidemic now known as the Black Death was an outbreak of bubonic plague which had begun somewhere in the heart of Asia and spread westward along trade routes.
Overview of the Black Death. The Black Death was first seen in Europe in 1328 and it lasted until 1351; although occasional outbreaks did occur for the next sixty years. The Black Death was able to reach even the most distant corners of the globe as it followed trade routes.