Like other slums in the Tondo area of Manila, Philippines, there’s no clean water supply or sanitation.

Residents pay to fill water containers from a nearby condominium, and trenches funnel sewage into a blackened river.

Every spare centimetre has been claimed - alleyways between the two-storey shacks are barely shoulder-width, and the air is stagnant.

Disease proliferates, including tuberculosis (TB), which is caused by a bacterium that usually attacks the lungs, and spreads through the air, including when an infected person coughs or speaks.

Not everyone infected develops TB disease, but the death rate for those who do is about 50 per cent, if no treatment is given.

The grandfather in this extended household died with TB in 2020, during Covid-19 lockdowns.

Now, one of his sons is sick. His TB was identified through free screening provided by the Doctors Without Borders/Médecins Sans Frontières charity.

Its medical team are visiting the home to start two 3-year-olds and a 6-year-old on a preventative course of drugs.

Among them is a New Zealander, Jessa Pontevedra, who is medical coordinator for an ambitious and ground-breaking programme combating TB in Tondo.

The children’s mother - young enough to be mistaken for their sibling - and grandmother watch intently as Pontevedra and outreach nurses demonstrate how to measure the drugs.

A dosage schedule is taped to the wall, across from a shrine to Mother Teresa (more than 80 per cent of the country’s 114 million population is Catholic), and a framed school photo.

Cheska, 3, is wary of the medicine’s bitter taste, but soon beams at the strangers’ applause and her reward of a lollipop and square of chocolate. Success.

However, Pontevedra is worried about malnutrition, especially in Althea Jade, who at 6 isn’t much bigger than her younger brother and sister.

On the walk out of the slum, Pontevedra asks a resident how much it costs to fill a waist-high container with water. It’s 15 pesos, about NZ45 cents.

That’s prohibitive for people who sometimes can’t afford enough food.

“When we are talking about preventing tuberculosis, you need to have a clean space,” says Pontevedra, 37.

“But, a) you don’t have water to clean your space, b) you don’t have enough space, and c) you don’t even have the basics of a toilet.

Even when time is found, patients can be turned away without treatment.

TB drugs can only be distributed by government health centres, but medication is often out of stock, because orders made to manufacturers have been outstripped by demand.

Amgelex Espiritusanto is a lifelong Tondo resident, who volunteers to ensure TB patients start and complete the entire six-month course of medication (drug-resistant TB is on the rise, and can occur when doses are missed or stopped early.)

The newly-diagnosed can be in denial or ashamed, she says, and it sometimes takes weeks to convince them to start treatment.

That fragile momentum is halted if drugs aren’t available.

In contrast, private pharmacies are well stocked. The cost of generic drugs varies, but can be between 210 to 315 pesos a week (about NZ$6.35-$9.50).

Different medications are taken from months two to six, which aren’t in short supply.

Some residents can afford to pay - Tondo is home to the middle class, too - but Espiritusanto can only encourage those who can’t to keep checking if drugs have come in.

She sometimes dips into her own pocket to ensure they can at least start treatment, despite making a modest income herself from selling vegetables.

MSF is lobbying the government to increase drug orders. Data from its work is also supporting research into the feasibility of using AI detection of TB in large cities.

Pontevedra hopes the tool will be implemented around the world, making screening faster, cheaper and more accurate.

Currently, the 2030 elimination goal is unlikely, she says.

“I don’t think [elimination] is realistic unless the government - and not just the Philippines but every country that is suffering from TB - actually gets their act together, and walk the talk.”

The WHO has called on governments and private donors to back the development of new TB vaccines, saying Covid-19 had shown more investment “can be a game-changer”.

The only licensed TB vaccine was introduced in 1921, and provides moderate protection against severe forms of TB in infants and young children.

There is no vaccine that prevents TB disease in adults, either before or after exposure to infection, although some in late-stage trials have shown promise.

In June, the Wellcome charity and Bill and Melinda Gates Foundation announced US$550m ($945m) for Phase III trials of a vaccine, expected to take four to six years and involve 26,000 people.  

Testing will see how effective immunisation is at preventing latent TB, and include people with HIV, who are more vulnerable to illness and death.

“The world has made a huge mistake not investing more in TB," Microsoft co-founder and philanthropist Bill Gates told Reuters of the century-long wait for a breakthrough in fighting the disease.

She left Ukraine last December, and by February was in Manila. This assignment - her 23rd, and first long-term placement - appealed because Pontevedra considers the Philippines home, along with Aotearoa.

When she lived in New Jersey her family returned each year, and her grandmother made a point to take her and her brother to the Smokey Mountain dumpsite in Tondo, where tens of thousands lived and scavenged.

The landfill was closed by authorities after becoming globally infamous as a symbol of extreme poverty, and rubbish is now dumped in another area of Tondo, fittingly known as Aroma.

When we visit, bare-chested boys and men unload large plastic bags of rubbish from a truck, surrounded by the detritus of previous deliveries, already picked through for anything of value.

A large rat runs over the tangled electrical wires overhead, and two preschoolers sit by their mother as she sifts through an opened bag.

Some families were moved into nearby housing units after Smokey Mountain closed, but most live in shacks squeezed onto both public and private land, and enabled by a 1992 law that criminalised squatting, yet discouraged evictions except in certain cases.

(In the 1970s former president Ferdinand Marcos used martial law to criminalise and evict squatters, and impoverished areas have been periodically walled-off ahead of major events, including a Miss Universe pageant and papal visits. The “informal settler” population in metro Manila is now estimated at over two million.)

It’s often necessary to crouch when walking through the labyrinth alleyways between the buildings, to avoid the plastic sheets, drying clothes and wires overhead.

At ground level, the pathways act as drains and sewers - rubbish and plastic collects in puddles, as do swarms of flies and mosquitos - but also living rooms and communal areas.

Tiny stalls sell vegetables and “pagpag” - thrown-out food that’s recooked - and people do the washing while watching children play among dogs, kittens, and roosters tethered by the leg.

The path narrows and darkens as we go deeper - a maze known only to locals, and the MSF workers here to check up on recent patients.

Genevieve Sael, 47, sits peeling garlic into a plastic tub, as some of her eight children dart around, excited by our presence.

This work is irregular, and she mostly survives by scavenging.

She’s the sole earner after her husband’s stroke, and the family sometimes borrows food or money from neighbours.

Sael had a relative with TB - who coughed up blood - so took the chance to be screened.

She tested positive, as did one of her daughters, Crystal, 6.

Mother and daughter are now cured, and Crystal is gaining weight.

The family share a small two-room, airless shack. Christian Jay Hontiveros, the MSF worker checking on Sael, has seen worse overcrowding.

“One household had 32 family members. This is just a small room, like a studio. They cannot sleep all the time, but they were able to survive because half of them work in the morning, and half at night. There are multiple TB cases in the household.”

Other residents have nobody - down the alleyway Wilfredo Dionisio sits by the curtained entry to his home, which is a windowless plywood box, about the size of a narrow single bed.

The 65-year-old moved to the area in 1994 with his late wife. Unfit to work or scavenge, he survives off hand-outs from neighbours and a Catholic charity.

Dionisio was diagnosed in July.

“Before he had difficulty breathing, you could really see that he was very sick. Small movements made him exhausted. But he can now move again, he is gaining weight,” Hontiveros says.

Such results keep Pontevedra and the team going.

Her placement ends in February, and she longs for a Kiwi summer - blaming insomnia on the lack of open and green space in traffic-choked Manila.

However, she concedes it could also be related to her time in conflict zones.

In one recurring nightmare her old workplace, North Shore Hospital emergency department, is filled with children, who are awake but quiet.