In her home in the hillside favela in Recife, Inabela Tavares straps a support vest around the waist of her daughter, Gaziella, to help her sit up. Splints on the two-year-old’s legs and plastic boots teach her to stand.

Gaziella has epilepsy, myopia and is visually impaired after her mother was infected by the Zika virus in 2015.

“I never thought about being a therapist, but I had to learn,” says Tavares, 33, who is married to Filipe, an auditor a year younger than her, and also has a 12-year-old son, Flavia. “I became empowered by knowledge.”

Tavares was six months pregnant and working in a phone store when her second child was diagnosed withmicrocephaly, a rare birth defect linked to the mosquito-borne virus, which causes babies to be born with abnormally small heads and brain damage.

The virus affected thousands of Brazilian children – most of them in Brazil’s poor, dry north-east. By December, 3,037 “alterations in growth and development” possibly linked to the virus had been confirmed by the Brazilian government. Almost as many are still being investigated.

Between February and November 2016, amid fears the outbreak could spread across the Americas, the World Health Organization declared Zika a public health emergency. Some athletes cancelled their appearances at the Rio Olympics that summer. But cases of Zika-related microcephaly remained concentrated in Brazil.

While experts wonder where, when and how Zika might strike next, a generation of children have been left with severe developmental challenges – 438 of them in the state of Pernambuco alone.

Doctors are unable to answer the questions Tavares is asked when she takes Graziella on the bus. Will her daughter ever walk? Will she ever talk? How long will she last? “She’s not a battery,” Tavares says.

Graziella’s condition has pummelled the family and taken over her life. Tavares coordinates a non-profit group called Project Angel to help 170 other mothers of microcephalic babies, founded by a local businesswoman. But the cumulative weight of these experiences has drained her soul.

Inabela Tavares with her daughter, Gaziella, who was born with microcephaly after Inabela was infected by the Zika virus while pregnant. Photograph: Saulo Santiago/The Guardian

“We have a lot of love for these children. But it is also a lot of struggle,” says Tavares, wiping away tears as she cradles her daughter. “Sometimes when I wake up she is foaming, she had a seizure and I didn’t see. Today I don’t sleep any more. Today I don’t live any more.”

Dr Vanessa van der Linden, a Recife neuro-paediatrician, was the first doctor to spot the microcephaly surge in 2015. Having seen the calcifications it caused in brain scans, she anticipated children would be born with problems like visual impairment and epilepsy – which she found in 60-70% of patients in the first year. The seizures cause children like Graziella to forget things like swallowing. Hydrocephalus – the build-up of liquid on the brain – was a surprise.

Most children diagnosed at the peak of the crisis are now two; many have never spoken a word nor taken a step. More than half have no interaction between their eyes and their brain, Van der Linden says.

“You try everything with medication and even then, the patient has difficulty with control. And epilepsy disrupts development.”

Alice Bezerra, who was born in October 2015 with microcephaly, with her father, João. Photograph: Saulo Santiago/The Guardian

Alice Bezerra, who was born in October 2015 with microcephaly, had a feeding tube inserted into her stomach after struggling to gain weight. Her parents, Nadja, 43, and João, 56, spend hours each day watching a thickened milk formula flow into her stomach.

“Now she is getting fat,” says her mother, “[but] she has no teeth.”

Some parents in Recife have used hemp oil to help their children deal with the effects of microcephaly. Photograph: Saulo Santiago/The Guardian

Alice had 30 fits a day, until a group of employees at Recife airport, where her father cleans planes, grouped together to spend £366 on importing the drug cannabidiol from the US.

“She changed completely. It is like her brain started working, she is smarter,” Nadja says. But the drug would be impossible to buy on João’s monthly take-home salary of £156, and is not covered by his firm’s health insurance.

“Without this group, how would we survive?” she ponders.

Van der Linden cautions that cannabidiol doesn’t work for all children. “[It’s] not a world solution,” she says.

Jaqueline Vieira, 27, would like to try the drug on her two-year-old son Daniel, who is microcephalic and suffers from epilepsy. He vomits if he lies flat and so has to be propped up on pillows. He also has vision problems. He does not walk or talk, but sometimes gurgles to his mother. “Daniel is still a baby,” Jaqueline says.

He has had pneumonia three times, after inhaling food into his lungs. The tube inserted into his stomach, which prevents him from swimming or going to the beach, is damaged. Vieira has fixed the tube with tape while she waits for the government to pay for a new one.

Jaqueline Vieira, 27, with her son Daniel. Photograph: Saulo Santiago/The Guardian

When she got pregnant, she was living with Daniel’s father in a low-income community where water was sourced from a nearby tank. “There was no sanitation,” she says.

Lack of running water afflicts poor families across Recife, a gritty metropolitan sprawl of 4 million people. Coupled with poor sanitation, this creates perfect breeding conditions for the Aedes aegypti mosquito that spreads Zika.

A 2018 study by scientists from a research group based at the Brazilian government’s Fiocruz research institute in Recife found that people residing in areas with precarious living conditions had “a higher prevalence of microcephaly”.

Alto José Bonifacio, a district of Recife, Brazil. Photograph: Saulo Santiago/The Guardian

Mothers like Vieira get a benefit worth about £212 a month and free bus travel. Hundreds are in a group called Union of Mothers of Angels, run by Germana Soares, 26. Soares had tried to hide her son Guilhernme’s microcephaly when he was born in November 2015, before coming to terms with it.

The group has its own centre, funded by private donations, that it hopes to turn into a rehabilitation facility, with help from the University of Liverpool.

“It’s not just my son. It’s a generation,” says Soares.

Dozens of Recife’s “Zika children”, as some have dubbed them, attend the city’s Altino Ventura Foundation twice a week for free physiotherapy, occupational therapy and other sessions designed to improve problems like dysphagia, where children have difficulty swallowing.

Children with microcephaly and their parents at Recife’s Altino Ventura Foundation. Photograph: Saulo Santiago/The Guardian

Doctors at the foundation, which supports low-income citizens affected by vision defects or disability, say many children have developed other, less severe neurological problems as a result of their mothers being infected by Zika.

“This is the top of the pyramid,” says the centre’s technical director, paediatrician Katia Guimarães. “I have never been through a public health issue like this.”

But she stressed that therapy does help, a viewpoint shared by Germany Maia, 27.

Her daughter Giovanna, two, has milder microcephaly. She does not suffer from epilepsy and can say “daddy” and “granny”, and point to her nose. She can’t walk, but recently propelled herself across the floor of her family’s apartment using her good leg and her good arm. Now her parents want to find a school that can handle her.

“We do everything possible to improve her,” says Maia, who gave up her job at a logistics company to care for her daughter. “It is possible to have a life.”