Volunteers in Salvador’s favelas are collecting data on deadly infections and inequality to help campaign for better sanitation

Wearing crisp, white T-shirts and carrying tablets, the students fan out through Marechal Rondon – a bustling favela spread over hillsides and a valley in Brazil’s north-eastern city of Salvador. As they walk, they map blocked drains and piles of rubbish on their tablets. These are the “infection points” that attract the rats and mosquitoes which, in turn, spread diseases like leptospirosis and the Zika virus, both prevalent here.

Student Alexandre Santos, 20, stops before a weigh-high tangle of wild plants overlooking a housing block. “We look at sewers, rubble, garbage. Now there is high vegetation,” Santos says, tapping in the data. “It goes straight into the data bank.”

Tourists flock to Salvador for its vibrant Afro-Brazilian culture and colonial architecture. But just 10km away, the health issues in its favelas are studied by doctors and researchers from international universities for the Urban Health Programme – an international project that recruits locals like Santos to research their own communities.

“People are impressed to find out about our work as we go through the neighbourhood or territory,” says student Jonas Nascimento, 19, plotting infection points with Santos. “They can see we want to help.”

Facebook Twitter Pinterest ‘People can see we want to help,’ says volunteer Jonas Nascimento. Photograph: Dom Phillips/The Guardian

Their favela is home to more than 20,000 people who battle the health issues compounded by poverty, unemployment and poor sanitation. Armed drug gangs operate here, their teenage lookouts scouting the neighbourhood for rivals and police for £50 a week.

It is one of several neighbourhoods studied by the programme, which was set up in 2003 by academics and researchers from the Federal University of Bahia, Brazil’s Oswaldo Cruz Foundation, a government research institute, and the Yale School of Public Health in the US. The programme was expanded in 2010 with researchers from Liverpool and Lancaster Universities and is funded by the National Institutes of Health in the US and Medical Research Council in the UK.

In Marechal Rondon, a young man leads a horse into a swamp covered in green vegetation into which raw sewage flows. Ricardo Lustosa, a postdoctoral researcher in public health at the Federal University of Bahia, who runs the programme in this community, warns him of the risk of catching leptospirosis if he has a cut in his bare feet. Lustosa gestures towards pieces of wood and broken plastic piled up beside a road. “This is the perfect place for mosquitoes and rats to reproduce,” he says.

Facebook Twitter Pinterest Poor sanitation in favelas such as Marechal Rondon leads to the spread of disease. Photograph: Dom Phillips/The Guardian

Deeper into the favela, three young men, one carrying a revolver, walk briskly down an alleyway beside a murky stream reeking with raw sewage. Adriana da Costa, 43, says it has often overflowed into the tiny house she shares with her children Eloa Sofia, nine months, Alana, 18, and Iago, 14, just a few metres away. “I’ve lost clothes. I’ve lost a fridge. Bed, mattresses – my God,” she says.

Like many locals, she has a knee-high wall of bricks built across the door to keep the water out and has sealed the gap between the top of her walls and the roof to stop the rats jumping in. “It was full of rats. Rats on top of us,” she says. “I was scared for the children.” Da Costa keeps her family with £60 a month from the bolsa família government cash transfer scheme and says she often misses meals.

Facebook Twitter Pinterest Urban Health Programme research shows how leptospirosis cases are concentrated near an open sewer. Photograph: Ricardo Lustosa/Urban Health Programme and Worldview

In Marechal Rondon, 11% of the population has the leptospirosis bacteria. About 10% of people with the bacteria develop a severe form of disease causing multiple-organ dysfunction, which is fatal in 5-15% of cases. Salvador reported 113 suspected cases last year, of which 42 were later confirmed.

On a laptop, Elliott Rogers, a student from the London School of Hygiene and Tropical Medicine, uses charts to show how leptospirosis and Zika cases are concentrated in low-lying areas of favelas. Later he will address an attentive circle of student volunteers before they head out to watch a demonstration on how a drone can help their work. “I’ve never seen research so connected to the community,” he says.

Programme organisers hope young favela residents volunteering for the programme will also campaign for the structural changes needed to alleviate health problems.

“Our objective is to create activists and community leaders,” says Lustosa.

Santos says he would welcome such a role. As well as interning at the programme, he also founded his own tech start-up with Nascimento and other students. “Many young people here have talents they can never show,” he says.

Facebook Twitter Pinterest Adriana da Costa has lost count of the number of times sewage has overflowed into her tiny, two-room house. Photograph: Dom Phillips/The Guardian

Miguel de Palma, 17, joined a drug gang after his parents separated. “I got involved in this cruel world,” he says. He started doing drug deliveries, moved up to dealing, and served time in juvenile prison. Then he heard about the Urban Health Programme and volunteered. “There was a person inside me I didn’t know existed. I only found out when I came here,” he says.

Working with local people has helped researchers study health issues in favela communities in detail. In the Pau da Lima favela, for example, research made possible by years of monitoring was valuable in understanding how people previously exposed to dengue fever may have been protected from the Zika virus.

Facebook Twitter Pinterest ‘The more you go down, the less money there is’: Gielson do Sacramento, a field manager for the programme in Pau da Lima. Photograph: Dom Phillips/The Guardian

Researchers also track inequalities within the favelas. On higher ground, streets are paved and houses solidly built. Down in the valleys these are replaced by shacks, muddy paths and open sewers. As a result, disease rates are higher.

“The more you go down, the less money there is,” says Gielson do Sacramento, a field manager for the programme in Pau de Lima favela, as he leads the way down a steep alley, greeting residents as he goes. Beside him is Albert Ko, professor of epidemiology and medicine and department chair at the Yale School of Public Health, who first began studying leptospirosis here in 1996.

At the bottom of the valley, they point out where a stream carrying raw sewage was finally piped underground a few months ago, following years of pressure from residents.

“We worked with community associations and gave them data on leptospirosis and they gave it to government,” says Ko, “using leptospirosis as a model of the neglect.”

Facebook Twitter Pinterest Albert Ko, from the Yale School of Public Health, works with communities to help them campaign for better sanitation. Photograph: Dom Phillips/The Guardian

In Pau da Lima, 15% of the population has tested positive for leptospirosis bacteria, including Alexsandro Santos, 42. He points to the muddy ground which the sewage now runs underneath. “They still need to pave it here,” he says.

A few dozen yards away, Vera de Oliveira, 40, says that since the sanitation has worked, raw sewage no longer floods the small house she shares with her youngest son Uanderson, 18. “We suffered a lot here,” she says. “There are still rats.”

