by Craig Klugman, Ph.D.
On the season (series?) finale of the X-Files (Season 10, episode 6) this week, all of humanity is being attacked by the Spartan virus, a disease that seems to turn off the human immune system and permits other diseases to kill us. This episode is built on our fears of an inevitable worldwide pandemic and, of course, the recent concerns over Zika virus.
Zika is a virus spread by the Aedes mosquito. An adult who is infected may experience a “mild fever, skin rashes, conjunctivitis, muscle and joint pain, malaise or headache.” Zika has been known since 1947 when the virus was found in a rhesus macaque being used for research on yellow fever in Uganda. The first case of an infected human was in Nigeria in 1954. Human infections were rare until 2007 when an epidemic hit Yap Island, Micronesia. In 2014, in French Polynesia, there was a cluster of microcephaly and Guillain-Barre syndrome (GBS). The current epidemic was declared a Public Health Emergency by the World Health Organization (WHO) in February 2016.
What’s important to know is that there are two things occurring: (1) An increase in people who have been or are infected with Zika virus. And (2) a cluster of microcephaly and GBS in Brazil, French Polynesia, El Salvador, Venezuela, Colombia, and Suriname. This type of evidence is called correlative—they both are happening in similar populations. Correlation does not necessarily mean causation. For example, the divorce rate in Maine correlates with per capita consumption of margarine. That does not mean margarine cause divorce.