(Jovan Jaric/iStock)

Some of the greatest challenges facing the United States aren’t terrorists or trade deficits, but public health threats. Experts are urging the next administration to support the Centers for Disease Control and Prevention and its international collaborations to protect people from preventable deaths.

The CDC, part of the Health and Human Services Department, tackles an array of domestic and foreign public health and safety threats. The agency’s mission includes detecting and responding to outbreaks of infectious disease, such as Ebola and Zika, as well as sexually transmitted infections, such as gonorrhea. The agency also plays a critical role in fighting the spread of antibiotic-resistant “superbugs,” preventing prescription drug overdoses and reducing chronic diseases such as diabetes, heart disease and cancer.

An enormous part of the CDC’s mission involves tackling problems globally. In today’s interconnected world, a disease that pops up in an isolated village can be transported to a major city in another country in less than 36 hours.

The incoming administration has offered few signals about its public health priorities.

Here’s a look at pandemics that made it to U.S. shores. (Gillian Brockell/The Washington Post)

The only thing officials have to go on is a single reference to “public health” in President-elect Donald Trump’s 100-day action plan. The plan says Trump would impose a hiring freeze on all federal employees, but exempt “the military, public safety, and public health.”

During the campaign, Trump talked repeatedly about pulling back on the United States’ global responsibilities. During the 2014 Ebola outbreak, he said that infected American health workers should be barred from returning home, tweeting that the United States “has enough problems.”

In an interview last week, CDC Director Tom Frieden described the most urgent public health threats at home and abroad. Domestically, the opioid crisis and antibiotic-resistant bacteria — microbes that can’t be stopped by drugs — are two problems that are getting worse. Globally, antibiotic resistance and disease outbreaks are among the gravest threats.

“We don’t know where the next threat will come from, or where it will happen, and what it will be, but we are certain it will come,” Frieden said, referring to future epidemics. “And if we’re not ready, shame on us.”

He and other experts say they hope that public health, and the CDC in particular, will continue to receive broad bipartisan support. Frieden cited the legacies of President George W. Bush, whose administration created the plan known as PEPFAR to fight AIDS in Africa; boosted resources for the Strategic National Stockpile, a national repository of drugs and other medical supplies; and increased funding for flu prevention.

“I think there’s agreement that Americans shouldn’t be infected or killed by things that we could have controlled,” Frieden said. “The plain truth is that we can’t protect Americans here without stopping diseases overseas,” he said. “There is broad recognition of the need to keep America safe, and we are the front line of defense for doing that.”

As part of that effort, U.S. officials have been collaborating with other nations to develop disease detection and monitoring systems. The push to develop a long-term strategy known as the Global Health Security Agenda gained urgency in the wake of the 2014 Ebola epidemic.

An Ebola patient is handed oral rehydration solution by a health worker before being taken by ambulance (a pickup truck) to the Bong County Ebola Treatment Unit on Sept. 17, 2014. (Michel du Cille/The Washington Post )

After Congress this year delayed funding the emergency Zika response for eight months, many public health experts say there needs to be a permanent public health emergency fund that would permit a quick government response before a potential hazard developed into a full-blown crisis. It’s not clear whether the new administration would support such a move.

Thomas V. Inglesby, director of the Center for Health Security at the University of Pittsburgh Medical Center, said the CDC has historically been one of the most popular government agencies because of its ability to fight infectious disease.

Given the global toll in recent decades from viral illnesses such as SARS, MERS, Ebola and now Zika, “it’s hard to imagine the new team coming in and deciding, ‘We don’t need to be out helping the least-prepared countries prevent outbreaks from spreading out of control,’ ” he said.

Some public health experts have expressed concern about the track record of Vice President-elect Mike Pence, who once declared that “smoking doesn’t kill.” They point to a 2015 HIV outbreak in Indiana, the worst in state history, that was fueled by opioid addiction and needle sharing. At the time, syringe exchanges were illegal in the state, and Pence, then Indiana’s governor, was against them.

A man in Seattle injects himself with heroin using a needle obtained from the People’s Harm Reduction Alliance, the nation's largest needle-exchange program. (David Ryder/Reuters)

After federal officials warned of the growing epidemic, Pence signed emergency legislation allowing syringe exchanges in rural Scott County, the epicenter of the outbreak. He eventually signed statewide legislation that allows needle exchanges, but only if counties ask for permission in light of a public health emergency.

Some experts say Pence ultimately adopted a pragmatic approach that they hope will continue once he becomes vice president.

One area at the CDC that is not likely to be embraced in a Trump-Pence administration is public health research on ways to reduce gun violence. Trump, who has voiced strong support for gun rights, has called for the elimination of gun restrictions and magazine bans.

The CDC’s National Center for Injury Prevention and Control, which focuses on research and prevention of prescription drug overdoses and youth sports concussions, among other things, has not engaged in firearm research since 1996. That’s when the National Rifle Association accused the agency of promoting gun control and Congress threatened to strip the agency’s funding.

Even after President Obama ordered the CDC to resume studying the causes of gun violence after the mass shooting at Sandy Hook Elementary School in Newtown, Conn., in 2012, Congress has blocked dedicated funding for the research.