“Poxviruses keep herds and swarms of living things in check, preventing them from growing too large and overwhelming their habitats. Viruses are an essential part of nature. If all the viruses on the planet were to disappear, a global catastrophe would ensue, and the natural ecosystems of the earth would collapse in a spectacular crash under burgeoning populations of insects. Viruses are nature’s crowd control, and a poxvirus can thin a crowd in a hurry.”