Here are two recent stories about viruses. They started out alike, and ended up very differently.
In October, a woman in Guinea died of Ebola, leaving behind two daughters, one of them two years old, the other five. A relative named Aminata Gueye Tamboura took the orphaned children back to her home in northwest Mali–a 700-mile journey. Tamboura didn’t know it then, but the younger girl, named Fanta Conde, was infected with Ebola as well. For three days, they traveled on buses and in taxis as Fanta grew ill, developing a scorching fever and a perpetual nosebleed. Soon after arriving in Mali, she died.
Yet Tamboura never became infected with Ebola. Nor did Fanta’s sister or her uncle, who also made the trip. Nor did anyone else who shared the buses and taxis with Fanta, or who encountered Fanta elsewhere on her doomed journey. After Fanta’s death, the entire country of Mali braced for a devastating outbreak. But the outbreak never came.
The other story began in December. Someone–we don’t know who–paid a visit to Disneyland in California. That person, who we’ll call Patient Zero, was infected with the measles virus. But Patient Zero probably didn’t realize that he or she was incubating it, because the obvious symptoms, such as a rash and a high fever, wouldn’t emerge for several days. Strolling around Disneyland, Patient Zero cast off the measles virus in all directions, infecting dozens of people. Those people later developed measles, and may have spread the virus to others. By the end of January, the Disneyland outbreak had reached 94 cases, and that number is certain to rise higher.
These two stories show just how different viruses can be. For all the fear that Ebola can inspire, it’s a pretty bad transmitter. Measles, on the other hand, is among the most contagious viruses on Earth. There’s no single secret to measles’s power of contagion. Its adaptations for spreading are sprinkled across its whole life cycle.
Read full original article: How The Measles Virus Became A Master of Contagion
