It wasn’t what researchers at HE²RO, the Health Economics and Epidemiology Research Office at Wits University, set out to investigate. In 2020, when interviewing a group of 150 men in Joburg, they were trying to figure out where the “missing men” were, referring to the fact that men tend to use health services far less frequently than women, a pattern that has been seen for years.
But as they analysed the data and interviews from the men they recruited, the researchers uncovered something unexpected: two in every five of the men were internal migrants, South Africans moving from one place in the country to another. Even more striking was that one in five of the internal migrants said they were living with HIV, triple the rate of local men who hadn’t moved.
The study was small, but the findings had the researchers asking new questions: why are HIV rates so high among internal migrants? What role is climate change playing in driving people to migrate? And how can South Africa’s health system adapt to people who are on the move — especially given the sudden US funding cuts that have weakened South Africa’s HIV programmes, leaving cracks in an already fragile health system.
“This is such a triple whammy. In Southern Africa, there is HIV, which is huge, there is climate change, and then health services that are difficult to access,” says Caroline Govathson, who conducted the HE²RO study. “We have migration as a central feature in South Africa, and we need to better understand how these issues impact one another.”
The science is still emerging, but the links are getting harder to ignore: more and more studies are connecting the dots between climate change, extreme weather events, migration and HIV.
The domino effect
At the Africa Health Research Institute (Ahri), researchers have been exploring how droughts, floods and other extreme weather events raise the risk of HIV infection or of people falling out of HIV treatment. Collins Iwuji, a senior researcher at Ahri, says there is an indirect but logical flow to HIV threats as the effects of climate change and migration become clearer.
It’s a sort of sprawling domino effect that works something like this: an extensive body of research by the world’s leading authorities on climate change shows that climate change is driving more extreme weather events: prolonged droughts, searing heat and sudden destructive floods. When the weather turns extreme, people move, seeking safety, shelter or livelihoods elsewhere. And forced migration can have serious consequences for their HIV risk and treatment.
But, says Iwuji, migrants’ experiences can differ widely. If people are displaced from their homes, like during sudden flooding catastrophes in one part of the country, what follows may be a massive movement of people to a different part within a very short space of time. But there are also slow-onset climate-related events like droughts. People are still forced by climate to flee, but it is a decision that happens over time.
What is common to both forms of migration is that it can push people into situations where HIV becomes a bigger threat, Iwuji says.
t’s so many bad things happening at the same time to create the perfect storm
— Collins Iwuji
Where migration meets HIV
A study of six African countries that looked at migration, food insecurity and transactional sex (sex in exchange for food, shelter or other basic needs) shows that women who migrated because they could not rely on a steady food supply were significantly more likely to report transactional sex. This nearly doubled their HIV risk. The researchers were looking at Eswatini, Lesotho, Namibia, Tanzania, Uganda, and Zambia, but the same factors are at play for migrant women in South Africa.
In 2015, a Lancet study showed that both migrant men and women in rural KwaZulu-Natal were more likely to engage in risky sexual behaviour than nonmigrants.
“There’s disconnection from social networks or family members, people who would normally provide some sort of social comfort,” explains Iwuji, adding that while they often relocate for work, migrants are still likely to be unemployed. “All these social factors lead to high-risk sexual behaviour, which can take the form of transactional sex [most often it is women who rely on sexual relationships with men to survive] or it can be in the form of formal commercial sex work or having multiple sexual partners, or not using condoms.”
Coceka Nogoduka, a Gauteng-based UNAids adviser for HIV and pandemics preparedness and response, says she has been advocating for countries to develop plans to deal with the health effects of climate for the past 15 years.
“From the field, we are also increasingly hearing of men having sex in a transactional sense. It’s a phenomenon that’s growing — and they will do that for economic benefits, and not necessarily because they are gay by nature.”
These types of high-risk sex, often linked to moving for work or survival, put people at risk of getting HIV.
And that risk cuts two ways. As Iwuji and Nogoduka explain, migrants face the danger of becoming newly infected. And for those who are living with HIV and are on treatment, there’s the danger of being cut off from their medication.
Iwuji’s research includes a rural KZN study that shows how drought uproots people’s entire lives. They often move away as a “livelihood strategy”, as he calls it, meaning they believe that they will be better able to support themselves and survive elsewhere. The irony is that in the process, their antiretroviral schedule is disrupted, which actually puts their lives at risk.
In a session on climate change, mobility and HIV at the 13th IAS Conference on HIV Science in Kigali in July, Rutendo Mukondwa of the nonprofit Organisation for Public Health Interventions & Development in Zimbabwe was one of the speakers making the climate connection.
Mukondwa reported on a survey of nearly 900 people across Zimbabwe. Of those living with HIV, three-quarters had experienced interruptions to treatment linked to climate change. He showed how climate shocks collide with poverty and hunger to disrupt HIV treatment. As one HIV-positive study participant explained to the researchers: “When the crops fail and animals die, there is no food, no income — and without food, taking the pills makes us sick. Sometimes we have to choose between eating and going to the clinic.”
The devastating floods in Durban in April 2022 showed how quickly things can fall apart here in South Africa. Bhekisisa reported how some people missed doses for up to two weeks after losing their IDs, which they needed to pick up their antiretroviral medication, or found clinics closed because staff couldn’t get to work because of roads that were damaged during the floods.
Missing HIV treatment for even just a few days can give the virus enough opportunity to multiply in people’s bodies. A patient’s risk of disease or death increases the longer they don’t take the medication, because the more the virus multiplies, the more it weakens their immune system. This makes them more likely to get sick or even die. Stopping treatment for too long can also make the medicine stop working properly in future.
When people are forced to move, or even when they choose to move, their lives are upended. But their treatment is usually disrupted too and that can put their health on the line, Iwuji says.
“That’s a double jeopardy, and when you then add to that the US government’s Pepfar funding cuts and their impact on people whose livelihoods are already precarious, it’s so many bad things happening at the same time to create the perfect storm.”
After floods, people can be cut off from their HIV medication in two main ways, he says. Either the clinics themselves become inaccessible because of damaged roads or infrastructure, or people have had to move and now find themselves in unfamiliar places, where they are not known to health-care staff, which makes it harder to get the care they need.
If a clinic is flooded or its records are gone, you’re in trouble!
— Coceka Nogoduka
The cracks in the system
As floods, droughts and heatwaves drive people from their homes, HIV services are disrupted. Some people drop out of treatment; others start over at new clinics, having to rebuild trust with unfamiliar health workers. Each move exposes cracks in the health system.
When disaster strikes, HIV patients can lose everything: shacks, documents, even their pill containers.
“If a clinic is flooded or its records are gone, you’re in trouble!” Nogoduka says.
She worries about the individual migrant who is a vulnerable “nobody” without patient records — or the ability to advocate for the care they need.
Nogoduka, who prior to her UNAids role was the acting CEO of the South African National Aids Council and the Eastern Cape co-ordinator at Pepfar, is just as concerned about what that invisibility means at scale, saying poor data makes it impossible for the health system to plan or budget properly.
She says field reports confirm that patients who move from one clinic to another often fall through the cracks because, except for the Western Cape, South Africa still lacks an electronic patient record system. Because most clinics still use paper-based records, a new clinic that a patient moves to wouldn’t know which medications that patient had been taking, unless the patient brings along their paper patient card.
“But patients have found a workaround,” she says. “They simply test afresh for HIV, even if they know they are living with HIV and have been on treatment for years. Then they are treated as a ‘new patient’.”
Electronic patient records will make it possible to use a patient’s ID number or a code unique to each patient to track a patient’s medical records.
A study in rural northeastern South Africa has shown that undocumented clinic transfers can seriously skew estimates of how many people stay on HIV treatment. Researchers tracking progress towards the use of unique patient identification in the Southern African Development Community found that without a unique ID, it’s hard to follow people through testing, treatment and ongoing HIV care.
Right now, South Africa’s data collection system shows the country is falling behind a UN target that tracks how many people who know they have HIV are on treatment.
Until we have electronic patient records, says Nogoduka, floods or disasters can cut thousands off from treatment.
South Africa’s National Digital Health Strategy, 2019-2024 promised such a unique patient identifier to “facilitate the movement of patients within and across provinces” by 2022, a recommendation which was also in the 2012-2016 eHealth strategy. More than a decade later, it’s still not in place.
Solving the problem
For Iwuji, the solution is long overdue.
He points to a World Health Organisation guide published more than a decade ago that countries can use to test how ready clinics and health centres are for climate shocks. It gives clear steps for spotting and fixing weak points, like how clinics can cope with heatwaves or disease outbreaks and how to keep track of patients who relocate.
A 2025 study shows that countries that plan for climate shocks like droughts, floods or displacement as part of their HIV response are much better at keeping services running during crises.
The first step is facing the system’s failures, says Iwuji.
“You can’t solve a problem you don’t know about. Once we identify the gaps, we can start scaling up interventions so we can better take care of people on the move.”
This story was produced by the Bhekisisa Centre for Health Journalism. Sign up for the newsletter.
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