Robert Brown|Health workers struggle to prevent an infectious disease 'disaster in waiting' in Gaza

In Gaza,Robert Brown the World Health Organization warns that illness may ultimately kill more people than Israel's offensive. Infectious diseases are "soaring," says the WHO. Over 100,000 cases of diarrhea have been reported, with rates among children 25 times higher than before the war.

War has shattered Gaza's health-care system, including its disease surveillance capabilities. So global health groups and health professionals are doing what they can to spot and prevent outbreaks in an increasingly desperate situation.

"It's our way of detecting the emergence of diseases that can result in an epidemic very, very, very quickly," says Rick Brennan, the WHO's Regional Emergency Director for the Eastern Mediterranean Region.

Before the war, despite the Israeli blockade, humanitarian groups say Gaza's public health system was doing a pretty good job. The 2 million-plus Palestinians living there had solid vaccination rates, access to three dozen hospitals and effective disease surveillance.

"There was a reasonably good system to detect disease outbreaks," says Brennan, "to pick up cases of infectious diseases, to transfer the specimens to test them in the laboratories, and then implement control measures."

But since the October 7 Hamas attack, that system — along with the rest of Gaza's health infrastructure — has crumbled amidst Israel's bombardment and ground offensive. Israel has accused Hamas of harboring weapons and fighters in and around hospitals, including in tunnels underneath them, which has put the facilities in the line of fire. WHO says only a quarter of Gaza's hospitals remain partially functional.

Dr. Tahrir Al-Sheikh, a pediatrician in Gaza, has seen that disintegration firsthand. She was working at Al-Nasr Children's Hospital until the war displaced her to the south where she's been offering medical help at a school-turned-shelter.

"We used to culture bacteria in Gaza," she says, and "prescribe medication based on the results. Now, we can't do cultures or anything, and the infections are spreading."

Al-Sheikh has seen brutal cases of diarrhea. "I treated a 4-month-old baby who had 20 bowel movements in a day," she recalls.

She's also witnessed a torrent of respiratory illnesses. "I've had cases that didn't respond to any treatment," she says. "But I can't tell [the shelter whether] they have COVID, and I can't diagnose it because I don't have the equipment."

The brew of conditions inside Gaza right now is accelerating the spread of disease.

"Wherever there's overcrowding," explains Marwan Al-Homs, director of the Mohammed Yousef El-Najar Hospital in Rafah, "these epidemics exist — inside shelters, even in tiny apartments where the number of inhabitants is 35 people."

Juliette Toumas, director of communications for UNRWA, the United Nations Relief and Works Agency, visited the Khan Younis Training Center in south Gaza, a shelter intended for 1,000 people but now hosting more than 30,000. "You have 400 people sharing one toilet," she says. The same goes for showers. "There's not much water to begin with, whether to wash or to stay clean. There's not much hygiene supplies."

Across Gaza, people's immune systems are compromised. There's also the colder winter weather to contend with, hospitals in tatters, and a lack of clean water, sanitation, and proper nutrition — services that are difficult to secure under Israel's near total siege of Gaza.

"It's a cauldron of possibility of infectious disease," says Amber Alayyan, deputy program manager for Doctors Without Borders in the Palestinian territories.

"If you have no access to antibiotics because you can't get to the doctor," she says, "then something that's so simple to treat can turn into something quite deadly. This really just is an infectious disaster in waiting."

Global health groups are racing to ramp up disease surveillance efforts in Gaza before there is widespread illness, which the WHO says could endanger even more lives than the combat.

Last weekend, Ayadil Saparbekov, WHO team lead for health emergencies in the Palestinian territories, traveled from Jerusalem to Gaza to ferry rapid diagnostics for hepatitis and cholera into the enclave.

"I am bringing the testing kits to timely detect and to respond to different infectious disease outbreaks," he said in a video posted on X, the site previously known as Twitter.

UNRWA's Toumas underscores the importance of regular and sustained humanitarian aid, including hygiene supplies, vaccines and chlorine tablets. "All those things are absolutely critical in disease prevention," she says.

WHO is hoping to resuscitate one or two of the local laboratories in Gaza that did pathogen screening before the war, though that will take effort and time.

In addition, they hope "to even bring a mobile laboratory from outside," says Brennan. "And we're also looking at options for bringing specimens outside the country, particularly to Egypt, for testing. That's proven a little bit more challenging than we'd expected."

While the logistics of those approaches are negotiated, Brennan says he's relieved that some of the really terrible diseases — like measles or cholera — haven't surfaced yet in Gaza. That's due in part due to pre-war vaccinations.

"If we get an influenza outbreak into those massively overcrowded shelters," says Brennan, "if we've got shigella dysentery, that could rip through a community very quickly and really impact the most vulnerable. To be honest, I'm grateful that we've got to this point. We've got increased rates but we haven't had a deadly outbreak yet."

Whether that good fortune lasts may depend on disease surveillance to identify the first handful of cases of something sinister — ideally, while it can still be contained.