And in the process, I learned something very important. Every time we did a house-to-house
search, we had a spike in the number of reports of smallpox. When we didn't search, we had the illusion
that there was no disease. When we did search, we had the illusion that there was more disease. A
surveillance system was necessary because what we needed was early detection, early response. So, we
searched and we searched, and we found every case of smallpox in India. We had a reward. We raised the
reward. We continued to increase the reward. We had a scorecard that we wrote on every house. And as
we did that, the number of reported cases in the world dropped to zero, and in 1980 we declared the globe
free of smallpox.