In 2003, the Nobel Prize winner David Baltimore, then president of Caltech, paused to reflect on his role as one of the world’s most decorated scientists.

“People keep e-mailing me to ask, ‘What is the meaning of life?’” Baltimore told an interviewer, with amusement. “And they want me to e-mail them back quickly with an answer!”

Baltimore was then 65, an age when many people are retired from public life, yet he was still actively leading one of the world’s top research universities. Others, he said, found their meaning “in friends, in dogs, in religion, in the self-reflectiveness of writing, etc. But Caltech people largely find it in the continual contest with nature.”

It was a contest that Baltimore waged right to the end of his life as a scientist, businessman and internationally respected conscience of the new world of biological engineering. He died Saturday at his home in Woods Hole, Mass., according to his wife, as reported by the New York Times. Baltimore was 87.

His death concludes one of the most illustrious careers in 20th century science. The bearded scientist with the penetrating blue eyes played a role, usually a leading one, in virtually every important national debate over the use and potential misuse of the science of genetic engineering, whether it was gene-splicing and the search for an AIDS vaccine, or the dangers of tinkering with the human genome.

But it was as a working scientist that he made his most enduring contributions, the role he was most proud of.

“When you are a scientist, and you are trying to prove or disprove a notion, you work at the bench doing the dullest, most routine things over and over and over again,” Baltimore once explained.

“I can’t tell you how many ways things go wrong. All the time you are doing this because there is an idea behind it.”

In a statement, Caltech President Thomas Rosenbaum said Baltimore’s “contributions as a virologist, discerning fundamental mechanisms and applying those insights to immunology, to cancer, to AIDS, have transformed biology and medicine.”

“David’s profound influence as a mentor to generations of students and postdocs, his generosity as a colleague, his leadership of great scientific institutions, and his deep involvement in international efforts to define ethical boundaries for biological advances, fill out an extraordinary intellectual life,” he added.

David Baltimore was born March 7, 1938, in New York City, the son of a garment industry merchant, Richard Baltimore, and Gertrude Lipschitz-Baltimore.

Richard’s family was Orthodox Jewish, from Lithuania, and though the Baltimores in America were not overtly religious, the family communicated a moral code that influenced their son’s concern for the underprivileged.

This led him to take public stands on social issues, such as the AIDS epidemic and nuclear proliferation, that other scientists shunned. In 1970, while performing experiments that would win him the Nobel Prize, he shut down his lab for a week and joined demonstrators in Boston against the Vietnam War-era invasion of Cambodia.

In high school, Baltimore enrolled in a summer program at the prestigious Jackson Laboratory at Bar Harbor, Maine, where he made a discovery that altered his life and set him on the path to science.

“It was the process of research. I discovered that I could investigate the unknown as a high school student, that the frontier of knowledge was actually very close and very accessible,” he said, many years later.

After graduating from Swarthmore College, Baltimore earned his doctorate from the Rockefeller Institute (now University), before doing three years of research at the Salk Institute in La Jolla, where he met his future wife, Alice Shih Huang. His postdoctoral student, Huang collaborated in his research on animal viruses, later becoming a full professor at Harvard Medical School. At this time, Baltimore was particularly interested in the poliovirus, which attacks the RNA (ribonucleic acid) in cells.

“He was on the cutting edge of molecular biology,” said science historian Daniel Kevles, his friend and colleague. “There was no molecular biology to speak of and very little virology. … It was a brave field of work.”

At the time, it was an ironclad rule in molecular biology that genetic information was a one-way street, flowing from the double-helix structure of DNA to the single-stranded RNA, which the cell’s machinery uses to make proteins. But some biologists were beginning to question that assumption, and Baltimore joined the hunt for evidence that genetic information might flow in both directions, which, if true, held enormous potential for understanding the spread of viruses.

After leaving the Salk, Baltimore returned to Boston and became an associate professor of microbiology at MIT. As it became apparent that not all viruses behaved alike, Baltimore launched a new classification system, one that is still in use, grouping them by families according to their genomes and replication systems.

It was during this work that he discovered an enzyme that enabled a virus made of RNA to be copied into DNA, a process known as reverse transcription. The discovery of reverse transcriptase was greeted with overheated predictions that science had at last found a cure for cancer. The thinking went, if one could use RNA to code DNA, scientists could seize control of the body’s defenses.

Baltimore knew his work did not augur a cure for cancer, but the discovery of reverse transcriptase was nonetheless important because it led to an understanding of how genes can modify cells, turning normal cells into cancer cells. Reverse transcriptase is also used by a unique family of viruses, known as retroviruses, to replicate themselves. This finding would be critical to understanding the AIDS virus, HIV, which is a retrovirus, and devising anti-HIV treatments.

Baltimore’s discovery was attended by great fanfare and led to his promotion to full professor at MIT. In 1973, he was awarded a lifetime research professorship by the American Cancer Society, and a year later was elected to the National Academy of Sciences and the American Academy of Arts and Sciences. Finally, in 1975, with Howard Temin, a friend and colleague who had discovered reverse transcriptase around the same time, Baltimore was awarded the Nobel Prize for physiology or medicine.

With the prize came fame; people began referring to Baltimore as the most influential biologist of his generation. To the general public, who did not necessarily understand what he had done, only that it was important, he became, at the age of 37, a full-fledged savant.

The award had a profound effect on colleagues.

“I don’t see it as a burden, but you can’t get away from it,” Baltimore said. “I know that when I talk to young scientists, they are looking at me and saying, ‘God, I am talking to a Nobel Prize winner.’ I try to break that down. It gets harder every year.”

His new celebrity status gave him a platform to address issues of broad cultural and scientific importance, a role Baltimore embraced.

In the 1970s, when people became concerned that gene-splicing techniques could lead to the production of super viruses, Baltimore organized a conference at Asilomar near Monterey to design a self-regulating system to monitor those experiments. In the early 1980s, he led the fight against a crash program to map all human genes, fearing, once again, unknown consequences. In each case, when it was shown the dangers had been overestimated, he then led the effort to relax federal restrictions. He became an early champion of federal AIDS research and chaired a national commission that concluded the federal government’s response to the epidemic was dangerously inadequate.

As his reputation grew, he took leadership roles on political issues. When Pope John Paul II wanted to warn President Reagan of the danger of nuclear weapons, Baltimore was one of four scientists the pontiff appointed to carry his message.

In 1984, Baltimore was chosen founding director of the new Whitehead Institute for Biomedical Research, molding it into one of the world’s leading institutions of its kind. Following that success, he was appointed president of the Rockefeller University.

Along the way, he became not only a respected link between the government and scientists but also a key player in the burgeoning biotechnology industry. His early involvement in the industry made him a “relatively wealthy man,” according to a 1997 Times magazine profile.

The profile described a man in the fullness of middle age, harvesting the benefits he had earned, drinking the best wines and single-malt scotch, driving appropriately luxurious but not ostentatious vehicles. “With his wife, Dr. Alice Huang, he shares a luxury duplex condominium on Union Wharf, which has a commanding view of Boston Harbor,” it said.

In person, “Baltimore’s practiced elegance frames a fierce pride and a sometimes brutal intellect, softened only by his insistence that professional criticism be leavened by personal respect.”

And then, the entire edifice crumbled as Baltimore became the focus and fall guy for one of the more infamous investigations of scientific misconduct in the last half of the 20th century. A colleague wrote a paper claiming sensational results. When others could not reproduce those results, allegations of fraud were aired, causing Congress to get involved. With the decline of the space program, biology had emerged as the preeminent science, and Congress was becoming skeptical about how millions of dollars in federal research grants were being spent.

The whiff of scandal was attached to Baltimore himself, even though his work was never questioned. Still, his refusal to admit error, or to abandon his problematic colleague, came to symbolize for many the arrogance of the new mandarins of the biological sciences.

“The Baltimore case is reminiscent of the Watergate scandal,” the New York Times wrote.

Four federal investigations and a grand jury probe later, Baltimore’s colleague, and Baltimore himself, were exonerated. The ordeal had consumed a decade of his life. Then, within months, everything changed. He was chosen to coordinate the federal effort to develop an AIDS vaccine and then appointed president of Caltech. It was a breathtaking reversal of fortune.

“It is even more breathtaking,” Baltimore said in 1997, shortly after taking the Caltech job, “to live through it.”

Kevles, a professor at Caltech at the time, recalled that when Baltimore’s name was announced to the assembled faculty, “the room erupted in cheers. I had never seen the biologists look so ecstatic. It legitimized their field.”

In his eight years as president, Baltimore raised the university’s profile, both as a place where cutting-edge biology is done and as a respected voice on pressing national scientific debates. Under his leadership, Caltech raised more than $1.1 billion. He cited the gift of $600 million to the school by Intel Corp. co-founder Gordon Moore and his wife, Betty, as the “decisive moment” of his presidency.

“Caltech is a wonderful place, the best place to do science I have ever seen,” Baltimore said in 2005, when he announced his resignation. “I will have done what I can do [as president], and it is time for somebody else to be thinking about it.”

As for what would come next, Baltimore said, “I have a fairly extensive life in science and in business that I will pursue.”

If he thought his return to the laboratory would be a placid coda to his career, he was soon proved wrong, by yet another advance in genetic engineering, this one called CRISPR. “I’ve seen revolution after revolution in biology,” Baltimore said in 2016. “This one is a big deal.”

As one writer noted, if the gene-splicing technology of the 1970s spurred images of laboratory-hatched plagues from the “Andromeda Strain” novel and movie, CRISPR inspired comparisons to “Brave New World.” MIT’s Technology Review wrote of labs in which “man rebuilds creation to suit himself” and warned of “a path toward a dystopia of superpeople.”

Just as he did decades earlier, Baltimore took a leadership role in starting a public discussion about how to manage the powerful new tool. “At Asilomar, we had identified the genetic modification of humans as the biggest coming issue,” Baltimore said. “We just didn’t know when it would come.”

A statement drafted by participants at a meeting in Napa in early 2015 spoke of the promise of “curing genetic disease” but also warned of “unknown risks to human health and well-being.”

The statement listed 18 authors, with Baltimore at the top. Though he wrote an op-ed for the Wall Street Journal entitled, “Let’s Hit ‘Pause’ Before Altering Humankind,” Baltimore admitted later that genome-editing would in all probability take place sooner rather than later.

After retiring as president of Caltech, he remained on staff in an emeritus capacity, and was appointed the Robert Andrews Millikan professor of biology. He finally shuttered his lab in 2019 but remained active in business. He helped found a number of companies, including Calimmune and Immune Design, which carried on the work he began in immunology and virology. Though he was most visible for his public advocacy of cancer and AIDS research, it was his work as a “lab-based, working biologist” that gave him the most pleasure, and for which he hoped to be remembered.

Besides the Nobel Prize, he received the National Medal of Science in 1999, and the Warren Alpert Foundation Prize in 2000. He was the 1999 recipient of the National Medal of Science and published more than 700 peer-reviewed articles.

He was also a member of numerous scientific advisory boards, including Amgen, the Broad Institute, Ragon Institute, and Regulus. Baltimore was past-president and chair of the American Assn. of the Advancement of Science.

He is survived by his wife, Alice, and daughter, T.K. Baltimore.

Johnson is a former Times staff writer. City News Service contributed to this report.

It’s one of the most insidious diseases you’ve never heard of, but Chagas is here in California and 29 other states across the U.S.

It kills more people in Latin America than malaria each year, and researchers think roughly 300,000 people in the U.S. currently have it but are unaware.

That’s because the illness tends to lie dormant for years, only making itself known when its victim keels over via heart attack, stroke or death.

Chagas disease is caused by the parasite Trypanosoma cruzi, which lives in a bloodsucking insect called the kissing bug. There are roughly a dozen species of kissing bugs in the U.S. and four in California known to carry the parasite. Research has shown that in some places, such as Los Angeles’ Griffith Park, about a third of all kissing bugs harbor the Chagas parasite.

It’s why a team of epidemiologists, researchers and medical doctors are calling on the World Health Organization and Centers for Disease Control and Prevention to label the disease as endemic, meaning consistently present, in the U.S. They hope that will bring awareness, education, dialogue and potentially public health investment to a disease that has long carried a stigma, falsely associated with poor, rural migrants from bug-infected homes in far-off tropical nations.

“This is a disease that has been neglected and has been impacting Latin Americans for many decades,” said Norman Beatty, a medical epidemiologist at the University of Florida and an expert on Chagas. “But it’s also here in the United States.”

“We had a kid from the Hollywood Hills who got it,” said Salvadore Hernandez, a cardiologist with Kaiser Permanente in Northern California. He said the patient had not traveled out of the country and probably got it in his leafy, affluent neighborhood, where kissing bugs are prevalent.

The parasite has also been detected in local wildlife, including wood rats, skunks and mice in Griffith Park, as well as bats, raccoons and black bears in other parts of the state.

“Kissing bugs are pretty equal opportunity when it comes to who they take a blood meal from,” said Sarah Hamer, an epidemiologist at Texas A&M University’s School of Veterinary Medicine and Biomedical Sciences, listing off a variety of animals, such as ocelots, bobcats, coyotes, birds, reptiles and amphibians.

“That means the reservoir for T. cruzi is pretty large,” she said.

California has the largest number of people in the U.S. infected with Chagas disease — between 70,000 and 100,000. That’s mostly because the state is home to so many people from countries where the disease is endemic. But it’s also because the parasite and vector live here, meaning some of those cases could be home-grown.

A small study by the state’s Department of Public Health, for instance, found that 31 of 40 human cases reported to the state between 2013 and 2023 — about 78% — were acquired in other countries. For the remaining cases, health officials couldn’t rule out local transmission.

Chagas is not a reportable disease in California, which means the state does not require physicians and health systems to report and investigate it, as it does with influenza, Lyme and malaria. However, it is reportable in Los Angeles and San Diego counties; Los Angeles was the first county in the state to mandate reporting of the disease.

Between 2019 and 2023, health officials confirmed about 18 cases of Chagas disease in L.A. County, “although many more cases likely go undiagnosed,” the department wrote in a statement. It said most of the identified cases were infected internationally, but some appear to be locally acquired.

Gabriel Hamer, an entomologist at Texas A&M, said that confirmed human cases in the U.S. represent “just the tip of the iceberg” and that nobody really knows how many people actually have the disease. “There’s no standardized reporting system. There’s no active surveillance.”

Most people find out they have the disease only after trying to donate blood, said Hamer.

Janeice Smith, a retired teacher in Florida, discovered she had it in 2022 after receiving a letter from her local donation center telling her she’d tested positive and should go see a physician.

Smith now runs a nonprofit to increase awareness of Chagas, which she said she probably got in 1966 when her family went to Mexico for vacation. She had returned home with a swollen eye and high fever, and was hospitalized for several weeks. No one found out what caused her symptoms until almost six decades later.

Hamer said proteins in the kissing bugs’ saliva can cause acute reactions, such as swollen limbs, eyes and anaphylaxis, all unrelated to the disease-carrying parasite.

But it’s the longer-term or chronic effects that cause the most harm. And because the disease is not well known, and its symptoms are often indistinguishable from other forms of cardiac and organ damage, it’s likely many people are showing up to their doctors’ offices with heart arrhythmia, a swollen esophagus, seizures and stroke, without ever being screened.

“The disease is definitely underdiagnosed,” said Hernandez, the Kaiser cardiologist. “If we screened for it and caught it early, most patients could be cured. The problem is we don’t, and people end up dying or requiring terrifically expensive care,” including organ transplants and surgery.

Anti-parasitic medications can be used to stop disease progression.

Chagas is also prevalent in dogs who show similar clinical signs, heart failure or arrhythmias.

“We’ll see these acutely infected, usually young dogs that might be puppies, or dogs less than 1 or 2 years of age that are really adversely affected. And then we would have dogs that would come in older, and they might be in heart failure,” said Ashley Saunders, a Texas A&M veterinary cardiologist.

She said dogs often acquire the disease by eating the bugs, which give a much higher “dose” of the parasite than a few bug poops in a cut.

The body of a woman was found by Pasadena firefighters responding to a house fire Saturday morning, officials said.

Firefighters responded at 6:25 a.m. to a house engulfed in flames in the 1500 block of Lancashire Place, said Lisa Derderian, a spokeswoman for the city of Pasadena. They found the body inside as they battled the flames, she said.

Officials are waiting for the coroner to identify the woman, Derderian said. “It appears she lived alone.”

The home, on a dead end street west of the Rose Bowl, was significantly damaged, Derderian said, but neighboring properties were not harmed.

Investigators are looking into the cause of the fire, she said.