When HIV first became prominent as a mysterious disease, people had many theories of how it was spread, almost all of them focused on the “immoral and drug-fueled” sexual activities of highly stigmatized groups. They not only held very strong views but they were absolutely certain that they were right. But the public, politicians and scientists were all challenged to rethink their ideas of spread when confronted by reports that the disease could be transmitted by infusing clotting factors from a donor to a patient with hemophilia.

In the early 2000’s WHO had adopted the ambitious goal of getting 3 million people on antiretroviral medicines by 2005. But some people thought this was too ambitious a goal and that it could never be achieved. Leaders were afraid of making a mistake and being wrong, so they were hesitant to act until they were certain they could achieve their goal. Yet waiting would cause costly delays as the disease raged on, and prevent otherwise ambitious and very important programs from making progress.

In the battle to eradicate smallpox in India in 1974, finding and containing thousands of outbreaks was the key to getting smallpox under control. In mid 1974, the number of new outbreaks was starting to decrease slightly. The strategy of surveillance and containment - which included a massive workforce, tireless efforts, and rewards for identifying new cases - was paying off. But then we started to notice that members of previously vaccinated families were still coming down with smallpox. We should not have been seeing these new cases.

The polio eradication program relied on strong surveillance efforts to inform vaccination efforts. Surveillance teams worldwide constantly searched for cases in which people had limbs that could not be moved and just hung limply, or cases of “flaccid paralysis.”When they found these cases, they would target vaccination to those regions. This was a very effective strategy when polio was widespread, because almost every case of flaccid paralysis was caused by polio. As vaccination coverage increased, cases of paralytic polio plummeted. As cases of flaccid paralysis began to disappear, polio was declared eliminated from many countries and regions. But in many areas polio persisted.