By Glynn Cosker
Managing Editor, In Homeland Security
Earlier this week, the Centers for Disease Control and Prevention (CDC) finally, unequivocally confirmed that the Zika virus causes microcephaly in infants – confirming what most scientists had long known. However, the story doesn’t end there because – in a new development – the Zika virus is also now known to cause autoimmune diseases in adults too. There is also alarming evidence that the virus can cause the deadly brain ailments meningitis and encephalitis in people of all ages.
What was a South American issue six months ago is soon to become a North American issue with an outbreak in the U.S. this summer almost inevitable, according to health officials. The virus is already infecting people in Puerto Rico and Mexico and – when one looks at the Zika virus map below – it’s easy to see why America is next. The map shows the likelihood of an outbreak.
The CDC is also on record for stating that the number of disease-carrying mosquitoes (named Aedes aegypt) is much higher than previous estimates, and health officials have confirmed that the virus doesn’t need the nasty little insect to spread; it’s also a sexually-transmitted disease with the first confirmed case of male-to-male sexual transmittal announced Friday in Texas; a man recently returned from a trip became sick with classic Zika virus symptoms and infected his partner of 10 years who soon came down with the same symptoms. Blood tests confirmed that both men had the Zika virus.
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What does all of this mean for the general American public, and how contagious is the Zika virus? Last week, some scientists estimated the impact by calculating the reproduction number, or “R0” (that’s an R followed by a zero). In layman terms, it’s a scientific equation that predicts the average number of people who will catch a disease from another infected person during an outbreak.
For instance, as reported by NPR, the nation of Colombia shows that Zika’s R0 was around four, i.e., each individual who contracted the virus, subsequently spread it to about four other people during the current Colombian outbreak. To give that R0 number some context, the R0 figure for the West African outbreak of Ebola in 2014 was around 1.75. However, Ebola is not spread by mosquitoes, while Zika is.
“An R0 of four tells you that you need to move fast, early on in an outbreak, to break transmission,” Dr. Scott Lillibridge told NPR. Dr. Lillibridge is an epidemiologist at the Texas A&M Health Science Center School of Public Health. “Obviously, we’re going to do mosquito control here in the U.S. So we’re going to interrupt Zika transmission.”
Prevention is the key to keeping the impact lower in the United States – simple placement of screen doors and sensible clothing goes a long way to prevent mosquito bites. That said, millions of people are bitten every summer in America, especially in southern states where the Zika virus is predicted to be most prevalent.
What is Zika’s R0 in America? Experts believe it’s similar to a devastating disease that affects the Western Hemisphere but rarely affects the Eastern Hemisphere: Dengue Fever. In fact, the World Health Organization (WHO) recently tweeted:
— WHO (@WHO) April 13, 2016
Dengue infects millions of people in Asia and the rest of the Western Hemisphere each year, including a recent outbreak on Hawaii’s Big Island.
Given that the WHO states that the risk of catching Dengue correlates to the risk of catching Zika – and given the devastating effects the latter disease has on newborns – the Zika virus map above becomes more ominous.