Feb. 23 2017
In a Grand Rounds lecture, Susan Desmond-Hellmann describes how more precise disease surveillance can save lives in Africa and around the world

Speaking at the recent Dean’s Grand Rounds on the Future of Public Health, Susan Desmond-Hellmann, chief executive officer of the Bill & Melinda Gates Foundation, pushed back against the idea that “precision public health” is merely a buzzword riding on the coattails of precision medicine. Just as biomedical researchers are creating new therapies tailored to individual patients, she said, public health too is becoming more precise.

Desmond-Hellmann gave the example of neonatal morality. Globally, 2.6 million children die in their first month of life, yet very little is known about why. In response, a Gates Foundation project is seeking to provide greater specificity, particularly around preventable diseases. “Only if we can define those preventable diseases, can we more precisely target and solve those problems,” she said.

By analyzing tissue samples, researchers in Soweto, South Africa, found that women who lost their babies to Group B Streptococcus infection were seven times more likely to lose their next baby to the same kind of infection. With penicillin, the inexpensive and widely available antibiotic, the infection is preventable.

Public health is becoming more precise in the domestic context too, according to Desmond-Hellmann. She described a Cincinnati study that used mapping technology to reveal that children who made repeat visits to the ER for asthma also lived in Section Eight housing with a record of violations—often for mold, an asthma trigger.

This “geomarker”—the geographic equivalent of a biomarker—is a reminder of how health shaped by the physical environment. Following a legal intervention to push landlords to do abatement, asthma rates fell. “This is a beautiful example of precise targeting of the underlying root cause of these high rates of asthma,” she said. “This is precision public health when it gets real.”

In an article in the journal Nature, Desmond-Hellmann and co-authors at the Gates Foundation outlined four steps to precision public health: register all births and deaths, track disease, incorporate lab analysis, and train more people. Acknowledging the importance of traditional public health education, she said training must also support everyone from interviewers and counselors to community leaders. “Precision public health is a team sport.”

In an accompanying presentation at the February 22 Grand Rounds, Andrea Baccarelli, chair of Environmental Health Sciences and a pioneer in epigenetics, described his field’s promise for precision public health. He started with an elegant analogy: If you liken DNA to a musical score, said Baccarelli, then changes to the epigenome are the marks a musician makes on that score to aid in its interpretation.

These epigenetic changes serve as biomarkers for a host of exposures, from smoking to sexual abuse to aging. Baccarelli described a study he did that found exposure to air pollution sped up the “epigenetic clock”—an epigenetics-based estimation of age—and that these changes were linked to shorter lives. 

In the years ahead, he said the epigenetic clock could help public health scientists develop better interventions to extend lives. At the same time, it could potentially serve as a personal biosensor to guide individuals toward healthier lifestyle choices.

Desmond-Hellmann, an oncologist who played a role in the development of the first gene-targeted cancer drugs, Avastin and Herceptin, said one of the biggest frustrations with cancer is not being able to explain to patients and their families why they got sick. Now epigenetic insights from Baccarelli and others could change this dynamic, especially by pointing to environmental toxins. “That door has been closed and you’re opening it.”

Watch video of the Grand Rounds talk: