The risk of smallpox was accepted as just an unfortunate part of life. Getting sick was a person’s fate. But in the late 1700s, Dr. Edward Jenner saw things differently and applied a “cause and effect” mindset. After years of observation, he was convinced that having cowpox protected people from contracting smallpox.

In the early days of HIV/AIDS, AIDS was a mysterious disease. The cause of AIDS was unknown, and many blamed it on the most marginalized groups. But, without knowing that the disease was caused by a virus, it was easy to stigmatize, isolate and blame affected groups. The early approach towards understanding AIDS focused on who was getting infected, rather than the cause and effect of the disease. Epidemiologists saw that AIDS was affecting hemophiliacs, heroin addicts, homosexuals, and Haitians (the 4Hs of HIV) which biased the way people viewed the disease and the populations it first impacted. Infection did not seem to follow logic.

To apply the surveillance and containment strategy, it was necessary to know where the smallpox virus was, which villages had active cases of smallpox. The struggle against smallpox could not be won without knowing where the enemy was and what it was doing. But India did not have accurate surveillance data. Many villages with active cases had not been reported.

While Guinea worm was widespread in Nigeria and Ghana, the leaders thought Guinea worm impacted only a small number of people and for this reason they were not motivated to do anything to solve the problem. But what government leaders thought were a few hundred cases turned out to be over 650,000 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.

Partners in Health (PIH) is a non-profit global health organization established by Paul Farmer, Jim Kim, and three colleagues to bring health care to the poorest people in low-income countries. PIH believed that these people deserve healthcare that was as good as the healthcare that rich people in the most advanced countries received. They found that poor people living in a shanty town outside of Lima, Peru had very high rates of multidrug-resistant tuberculosis (MDRTB), a disease that was notoriously hard to treat.