Emerging viral diseases are at the center of health news right now. The most significant of them, in terms of human cases and death toll, is the re-emergence of Ebola virus, which is causing the biggest outbreak of the disease in history. But there is also chikungunya fever, which appeared in the United States for the first time in July, and enterovirus D68, a previously rare disease causing an outbreak of respiratory illness among U.S. children.
Humans have come a long way in preventing viral diseases over the last century. Today, children in the U.S. routinely receive vaccinations against nine viral diseases, including many that used to cause life-threatening complications, such as polio.