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The brothers Sack
David and Brad Sack in the office.

1950 Family Photo

Brad Sack in Bangladesh

David and Brad Farming
From top to bottom: This page, from top left: a 1950 family photo with Brad (middle rear) and David (middle front); Brad with a group in Bangladesh; and young David at the wheel and Brad in the back while farming.

Similar Sacks

By Elaine F. Weiss

They’re colleagues, office-mates and friends. But these two senior international medicine researchers are something more–they’re brothers.

The two physicians chatting in the elevator, talking shop as they descend, bear a certain resemblance—in their faces, in their manner. R. Bradley Sack and David Sack are colleagues, but they also are brothers with overlapping medical specialties and scientific interests. They grew up together in the Midwest and Oregon, and today their offices sit next to each other in the same cramped suite on the other side of the country on the East Baltimore campus.

As professors in the Department of International Health in the School of Hygiene and Public Health, with joint appointments at the School of Medicine, the Sack brothers have been professional partners for the past quarter-century. Sometimes working together, sometimes on parallel tracks, they have analyzed, predicted, prevented and treated the devastating diseases “of the gut” that kill millions of people, especially children, every year. They also have been instrumental in establishing Hopkins clinics—Brad directs the International Travel Clinic, David the Vaccine Testing Unit.

That these brothers have taken such proximate medical paths is “surely not coincidence,” David concedes. “But we’ve never sat down to figure it out.” Such self-absorption is not in their character. At 63, Brad is older (by eight years), taller, broader shouldered and more formal in manner. Nearly a third of his years on the faculty has been spent working abroad—at posts in India, Bangladesh and Peru.

David is more outgoing and more the workaholic, always enmeshed in 20 projects at once. But he, like his brother, has a long association with the International Centre for Diarrhoeal Disease Research in Dhaka, Bangladesh, and this fall will take a leave of absence to become the Centre’s director.

Suitcases Full of Culture Clusters

On this day, in the small suite of rooms that the Sack brothers share (the one with Vaccine Testing Unit stenciled on the glass door and souvenirs from exotic lands decorating the walls), two large, black suitcases lie open on the floor, stuffed with plastic culture clusters and specimen boxes. These are supplies for the field test of a new vaccine. David will carry them to Mexico the next day.

The Vaccine Testing Unit has used notices in newspaper travel sections to recruit 800 volunteers to participate in a test of a self-administered oral vaccine against travelers diarrhea at sites in Mexico and Guatemala. David visits these countries every few weeks to supervise trials. But before he takes off on this trip, he’ll make rounds on Osler 5, where he has a unit of volunteers coming down with symptoms of shigellosis (a bacterial infection that causes dysentery) in a dose-escalation study of a new vaccine.

David’s overarching goal is to make vaccines that are useable in crisis situations. When 40,000 people died in a cholera outbreak in refugee camps following the Rwandan civil war, he watched in frustration, knowing that an available cholera vaccine wasn’t being used, because its administration (it had to be mixed with buffers) was too complicated for such a chaotic environment.

His brother Brad’s early research on cholera—in Calcutta, at the JHU Center for Medical Research and Training—helped to isolate and identify the enterotoxigenic Eschericheia coli organism as one of the major causes of diarrheal disease and death. Brad later pioneered the study of oral rehydration as an essential, life-saving therapy for diarrheal diseases. “He’s made many of the major discoveries in diarrheal and intestinal illnesses—superb work that everyone relies on,” says William Greenough III, M.D., a professor of medicine and international health who has worked for years with the two. “But Brad is incredibly humble—too much so for this aggressive society.”

Using oral rehydration to save lives with diseases like cholera has been David’s calling, too. “People sometimes talk of cholera as nature’s way of eliminating the weak—but it’s not so,” he says, frustration creeping into his tone. “With cholera, you can take a perfectly healthy person and within eight hours, they are dead. But it is also what’s called a ‘Lazarus disease,’ where a patient with cholera can come to the hospital with no pulse and seeming dead, but with some simple rehydration, they’re sitting up, alert, within 15 minutes.”

In David’s office, where one entire wall is piled high with white boxes of vaccine kits, he points to an oral-rehydration powder based on a homemade treatment he learned in Bangladesh. “That remedy is the best for rehydrating the body, but it tastes like wallpaper paste,” he says. “So we took the principal from Bangladesh and used modern food technology to make it taste good.”

The result is “Cera Lyte 70,” a flavored, rice-based, oral electrolyte solution now manufactured by a small start-up company in Jessup, Md. Hopkins has a stake in the venture. The solution holds potential as a rehydration remedy for diarrheal complications in AIDS, for the elderly (for whom diarrheal diseases are deadly), for victims of short-bowel syndrome (who have trouble absorbing fluids and salts) and even for sweat-soaked athletes. “I see it as something of a reverse approach,” says David. “Take what we’ve learned in developing countries and use it here.” Exciting scientific challenges await David in Dhaka, perhaps none more pressing than the need to put new vaccines for rotavirus and E. coli infections to work under Third-World conditions.

“This ties into Brad’s current work,” David observes, referring to his brother’s development of an epidemiological model to predict cholera outbreaks based on environmental factors like weather patterns and plankton and algae growth in surface water. “If we can discover a pattern for these outbreaks,” Brad explains, “we can take precautionary measures, like vaccinating.”

A Struggle Against Working Together

Brad first came to Johns Hopkins a decade before his younger brother arrived in 1973 (to do a fellowship in infectious disease with Greenough). Greenough became David’s mentor, too, and he followed Brad to the cholera-research center in Bangladesh, tackling the enterotoxigenic E. coli organism and developing a new assay for its identification. David’s first paper, published in the New England Journal of Medicine, was co-written with Brad the next year. It would be the first of many collaborations. For a time, “I struggled against working with my brother,” David concedes, “but finally, I had to admit—that’s where the exciting things were happening.”

How medicine became their guiding light isn’t immediately obvious. The Sack siblings didn’t grow up in a medical family. Their father was a minister so “the idea of helping people was engendered in us early on,” Brad says. Two other brothers also became physicians and are now professors of psychiatry at the University of Oregon (where all four brothers earned their medical degrees). Their sister is a nurse-midwife.

Growing up, music was a family focal point, with an emphasis on church hymns. As they raised their own families, living- room musicales again became a favorite activity. “But when you see them together, they don’t interact as siblings,” insists Janet Shimko, the research nurse who supervises the vaccine testing unit. “They never discuss personal things in the office. They’re just very collegial and professional, very respectful of one another.”

That daily give and take will be challenged by David’s imminent departure for Bangladesh. Though the advent of e-mail should ease the transition, the brothers won’t be getting together for weekly lunches, nor riding the elevator talking shop. But Brad will visit Bangladesh twice a year for his research on cholera epidemics, and the Sacks will still be working together, albeit from a distance.

“Our research has been so closely related,” Brad reflects. “It’s not anything we planned. But it has made it, in a way, more satisfying for us both.”