A Lifelong Commitment to Preventing Diseases in Children

As a pediatric resident at Boston City Hospital in the mid-1970s, José Cordero treated many children with diseases that could have been prevented. He often thought, "Where do I want to spend my time – treating diseases or finding ways to prevent them?"

The answer came after Cordero heard about a unique, on-the-job experience at CDC known as the Epidemic Intelligence Service (EIS). He immediately applied for the program and joined the class of 1979. Cordero, a Puerto Rico native, was one of the first Hispanic EIS officers to join CDC's elite corps of disease detectives.

"The EIS was a dream come true," recalled Cordero, who was assigned to CDC's birth defects program. Then 30 years old, Cordero came to the position highly qualified, with a master's degree in public health from Harvard University and 6 years of clinical pediatric experience.

"My first investigation demonstrated how we in public health can have an impact by first detecting a disease, then reporting our findings and seeing it translated into new policy," Cordero recalled.

He was brought in to investigate a cluster of three cases of infants in Tennessee who appeared to have a rare genetic disease called Bartter Syndrome. The babies suffered from vomiting and dehydration, and had a condition called metabolic alkalosis. This condition can be caused by the loss of potassium and chloride, two essential minerals in the diet. The cause of the infants' illness was pinpointed to a chloride deficiency in their soy-based baby formula.

"Chloride is one of those elements that needs to be replaced daily because it is lost through the kidneys," Cordero explained.

Within days, Cordero and a fellow EIS officer Frank Greenberg found 27 more cases by contacting hospitals around the country. Their research firmly established the infant formula as the link to the infants' condition. Within a week of the EIS first being contacted, the formula was off the market.

They published their research findings in CDC's scientific publication, the Morbidity and Mortality Weekly Report. This and other research led Congress to pass the Infant Formula Act of 1980, signed into law by President Jimmy Carter. This law simply states that any food intended to be the sole source of nourishment for infants must contain all the nutrients the babies need to grow healthy.

Cordero was also assigned to an EIS investigation to determine whether Bendectin, a drug taken by half of all pregnant women to alleviate nausea and vomiting, was causing congenital birth defects, or babies being born with missing extremities.

"Our study conclusively showed that Bendectin did not cause birth defects," Cordero said.

Cordero's early EIS work formed a basis for a career at CDC that has been defined by steady improvements in children's health. He was part of a team that linked folic acid in women's diets as one way to prevent birth defects. He co-authored a study, with former EIS officers, Joseph Mulinare, David Erickson, and Robert Berry, that showed that women who take multivitamins daily significantly reduce the chance of their babies being born with neural tube defects, namely, spina bifida and anencephaly. Subsequent studies showed that folic acid was the key nutrient.

Those findings led the Public Health Service to recommend that all women capable of becoming pregnant should consume at least 400 micrograms of folic acid to reduce their risk of having a pregnancy that would result in a neural tube defect. The FDA also changed its regulations to require enriched cereals, breads and pastas to include folic acid.

This work had far-ranging effects beyond the United States. In China, a program that provided folic acid to women who were registering to marry led in some areas to an 85% reduction in neural tube defects among women who took folic acid before pregnancy began. Some countries also have added folic-acid supplements to cereals.

Cordero also joined two other Hispanic EIS officers, Gil Chávez and José Becerra, to conduct one of the first studies of birth defects among racial and ethnic groups in the United States. Using data from the Birth Defects Monitoring Program, they documented that spina bifida is most common in the U.S. population among Hispanics.

"We also learned that spina bifida strikes African Americans at about half the rate of whites and Hispanics," he said, noting that the varying needs for folic acid among population groups are a combination of environment and genetic susceptibility.

This research enabled CDC to establish folic acid programs in Puerto Rico and along the U.S.-Mexican border, where the most vulnerable populations lived.

In early 1994, Cordero joined the National Immunization Program as deputy director. He brought a child-health focus to the job as the program implemented the Childhood Immunization Initiative that intended to rapidly increase immunization coverage among pre-school children.

"In the last five years, the progress we have made in childhood immunizations has been remarkable," said Cordero, pointing out that the percentage of children completing the recommended vaccinations has gone from about 60% to over 90% for the most critical initial vaccine doses. "Today, we are enjoying the highest levels of vaccination coverage the United States has ever had, and at the same time, we are at record, or near record lows for diseases like measles, rubella and polio."

In September 1999, Cordero was promoted to assistant surgeon general for the U.S. Public Health Service. His future in immunization focuses on rubella, a mild disease among adults, but a cause of child deafness and eye and heart defects when the mother acquires it during early pregnancy.

Cordero also has been active in global efforts to eradicate rubella-caused birth defects in other countries, including hard-hit areas in the Western hemisphere.

"Most cases of rubella today are coming from Central and South America," Cordero said. "We're working with different countries, ensuring that they implement vaccination programs that will eliminate measles and rubella jointly instead of only focusing on one disease at a time."

Cordero strongly endorses the EIS as a worthwhile experience for young medical practitioners to use their investigative skills to improve the health of many people through prevention.

"The EIS for me was the best career move of my lifetime," Cordero said.

The health benefits that have come from the work of Cordero and other EIS officers continue to be felt.

"To me, that's what prevention is all about," Cordero says. "The fact that we have no smallpox and almost no polio today, that's the kind of impact that, to me, brings a tremendous satisfaction. I can look back and say, 'We've done a good job.'"