At the time, in 2004, Chibanda was one of only two psychiatrists working in public healthcare in the whole of Zimbabwe, a country of over 12.5 million people. Both were based in Harare, the capital city. Erica, on the other hand, lived in a remote village nestled in the highlands of eastern Zimbabwe, next to the border with Mozambique.
Erica had passed her exams at school but was unable to find a job. Her family, she thought, wanted her only to find a husband. To them, the role of a woman was to be a wife and a mother. She wondered what her bride price might be. A cow? A few goats? As it turned out, the man she hoped to marry chose another woman. Erica felt totally worthless.
Erica and Chibanda met every month for a year or so, sitting opposite one another in a small office at the hospital. Chibanda prescribed Erica an old-fashioned antidepressant called amitriptyline, hoping that after a month or so, she might be better able to cope with the difficulties back home in the highlands.
You can overcome some life events, no matter how serious, when they come one at a time or in a small number. But when combined, they can snowball and become something altogether more dangerous.
For Erica, it was lethal. She took her own life in 2005.
Today, an estimated 322 million people around the world live with depression, the majority in non-Western nations. It's the leading cause of disability, judged by how many years are 'lost' to a disease, yet only a small percentage of people with the illness receive treatment that has been proven to help.
In low-income countries such as Zimbabwe, over 90 per cent of people don't have access to evidence-based talking therapies or modern antidepressants. Estimates vary, but even in high-income countries such as the UK, some research shows that around two-thirds of people with depression are not treated.
As Shekhar Saxena, the Director of the Department of Mental Health and Substance Abuse at the World Health Organization, has put it: "When it comes to mental health, we are all developing countries."
Soon after Erica's death, Chibanda changed his career plans. Instead of pursuing his original goal of opening his own private practice -- a role that would, to an extent, limit his services to the wealthy -- he founded a project that aimed to provide mental health care to the most disadvantaged communities in Harare.
"There are millions of people like Erica," Chibanda says.
Discovering Zimbabwe's high levels of depression
In the early 1990s, Harare -- nicknamed the Sunshine City -- appeared to radiate positivity. A survey from the city reported that fewer than 1 in every 4,000 patients (0.001 per cent) that visited the Outpatients department had depression.
In comparison, around 9 per cent of women in Camberwell in London were found to be depressed.
This data fits snugly within the theoretical environment of the 20th century. Depression, it was said, was a Westernised disease, a product of civilisation. It wasn't found in, say, the highlands of Zimbabwe or by the shores of Lake Victoria.
A handy metaphor of modernity, depression was just another division between the colonisers and the colonised.
But in 1991 and 1992, Melanie Abas, now a senior lecturer in international mental health at King's College London, conducted a research visit to a low-income district in southern Harare named Glen Norah.
Along with her colleagues, Abas found that there was no equivalent word for depression in Shona, the most common language in Zimbabwe. There were, however, local idioms that seemed to describe the same symptoms.
Through discussions with traditional healers and local health workers, her team found that kufungisisa, or 'thinking too much', was the most common descriptor for emotional distress. This is very similar to the English word 'rumination' that describes the negative thought patterns that often lie at the core of depression and anxiety. (Sometimes diagnosed together under the umbrella term 'common mental disorders', or CMDs, depression and anxiety are often experienced together.)
"Although all of the [socioeconomic] conditions were different," Abas says, "I was seeing what I recognised as pretty classical depression."
Using terms such as kufungisisa as screening tools, Abas and her team found that depression was in fact nearly twice as common as in a similar community in Camberwell.
In 1978, the British sociologist George Brown had published The Social Origins of Depression, a seminal book that showed that unemployment, chronic disease in loved ones, abusive relationships and other examples of long-term social stress were often associated with depression in women.
Following the same research methods as Brown, Abas found that events of the same severity produced the same rate of depression, whether in Zimbabwe or in London. "It was just that, in Zimbabwe, there were a lot more of these events," she explains.
In the early 1990s, for example, nearly a quarter of adults in Zimbabwe were infected with HIV. Without medication, thousands of households lost caregivers, breadwinners or both.
For every 1,000 live births in Zimbabwe in 1994, around 87 children died before the age of five, a mortality rate 11 times higher than that of the UK. The death of a child left behind grief, trauma and, as Abas and her team found, a husband who might abuse his wife for her 'failure' as a mother.
Adding to earlier reports from Ghana, Uganda and Nigeria, Abas's work was a classic study that helped demonstrate that depression wasn't a Westernised disease, as psychiatrists like Carothers had once thought.
It was a universal human experience.
A novel solution: the Friendship Bench
In the mid-2000s, Harare was hit hard by Robert Mugabe's Operation Murambatsvina, or 'Clear out the Rubbish', a nationwide military-enforced removal of those livelihoods deemed to be either illegal or informal. Chibanda was the first to measure the psychological toll of Mugabe's policies, finding that a large majority of those he surveyed met the threshold for clinical depression.
"It was then decided that something needed to be done," Chibanda says.
There was no money for mental health services in Mbare. There was no option to bring therapists in from abroad. And the nurses already there were far too busy with dealing with infectious diseases, including cholera, TB and HIV. Whatever the solution -- if one actually existed -- it had to be founded on the scant resources the country already had.
A turning point came when Chibanda took on a group of new colleagues: 14 elderly women.