Countries engaging in conflict can lead to public health crises, experts say.
As the Israel-Hamas conflict continues, stories of devastation have emerged including injuries, disablement, destruction of buildings and loss of life.
However, experts say war is not just an international relations crisis but also a public health crisis that can result in long-term consequences.
Israelis and Palestinians -- as well as residents in other conflict zones -- may be cut off from food and water, and be under severe mental health stress. Those who flee may suffer from health risks because of being displaced.
On ABC News Live at 8:30 p.m. on Thursday, Oct. 12, ABC News' James Longman, Matt Gutman and Ian Pannell look at the horrendous toll from Hamas' massacre, the Israelis and Palestinians caught in the middle and what comes next.
What's more, the physical distress and psychological effects are not just present of those living in war-torn areas but people abroad as well.
"One of the very disturbing things in virtually all wars nowadays is that civilians, noncombatant civilians, bear the brunt of war, be it the conventional war or terrorist attacks," Dr. Barry Levy, a physician and an adjunct professor at Tufts University School of Medicine who studies the public health impacts of war and terrorism, told ABC News.
"Civilians are the ones who are caught in the middle, and not only by the direct effects of explosive weapons, but by the indirect health effects that sometimes linger long after the war is over," he continued.
It's common for those living in war-torn areas to be unable to have access to food, clean water and heat.
Israel declared a "complete siege" on the Gaza Strip, blocking food and water and cutting off power to the area.
Levy said that civilian infrastructure being attacked and destroyed often prevents people from being able to search for food and leaves them without shelter or sanitation.
This raises the risk of malnutrition, particularly among infants and young children, which can lead to abnormal development and even cognitive impairment.
Research has shown people living in war zones are at increased risk of many mental health issues, including depression, anxiety, post-traumatic stress disorder (PTSD) and more.
However, there may be stress, anxiety, depression and PTSD experienced by the family and friends of loved ones in conflict areas and even the general population at large.
Dr. Jack Tsai, a professor and regional dean at UTHealth Houston School of Public Health in San Antonio, explained that the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition -- a diagnostic tool published by the American Psychiatric Association -- now classifies PTSD as something that someone can experience directly but can also be witnessed.
"So, some people can get PTSD by witnessing horrific events and I think now with social media, we see it now with the conflicts in Middle East, is really facilitating a lot of visuals that most people in the past weren't able to see," he said.
"And so, I do think that is increasing risk for PTSD, not just for people there, but lots of people just watching and observing what's happening."
He added that people seeing the events unfold in the conflict may not meet the full criteria for PTSD but still have some of the symptoms, which can linger and have an effect on a person's ability to function.
Many Israelis and Palestinians have been forced to flee to other cities, and even neighboring countries, which can affect mental health.
"It can be very disruptive to their mental health in everyday activities," Tsai said. "I imagine these folks that are being displaced are going to have to kind of reset, in new environments, new people and new cultures, and that can be unsettling in all kinds of ways they can affect their mental and physical health."
However, people who are forcibly displaced are at greater risk of communicable diseases such as COVID-19 and measles, which could lead to an outbreak.
Amid Russia's invasion of Ukraine, public health experts warned about the spread of COVID, particularly because Ukraine had a low vaccination rate prior to the war.
"Communicable diseases, infectious diseases are a major problem, mainly respiratory diseases, which often occur at increased rates during war, because people are crowded together," Levy said. "You can imagine people crowded together in shelters, for example, or in refugee camps or other areas."
He said another problem is the potential spread of diarrheal diseases, such as cholera, which often occur due to the lack of safe water supply.