Last week brought the horrifying news that the Ebola virus can live in the eyeballs of survivors, even after it’s been eliminated from the rest of the body. It shouldn’t have been a surprise, though. Viruses have always hidden in parts of our bodies you’d never expect. In fact, we’re all walking virus reservoirs.
It’s not just rare diseases like Ebola. Ever had chickenpox? Or a cold sore? The herpesvirus that causes these two illnesses actually remains inside your nerve cells for a lifetime. They’re able to do it because your immune system can’t reach them there. Indeed, viruses generally hide by exploiting blind spots in the immune system. That means generally one of two things: 1) infecting areas of the body that aren’t entirely under the control of our immune systems or 2) going dormant inside cells so that the immune system can’t detect them.
Viruses are able to pull off these acts of subterfuge because they’re tiny and simple. They’re just short bits of genetic material—RNA or DNA—protected by a protein shell. Unlike other microbes, they cannot reproduce on their own, so they have to attack cells and hijack their protein-making machinery to replicate. Usually, our immune systems are there to fight back. But sometimes, they’re not. More here: How Viruses Hide Inside Your Eyeballs, Even When You’re No Longer Sick