Are Migrants Driving the Epidemic?

People waiting for the Ferry to Botswana in Kazungula.

When “Treatment as Prevention” was named Science magazine’s Breakthrough of the Year in 2011, there was optimism that we were closing in on AIDS. Results published from the HPTN 052 trial that year showed that in discordant couples, giving antiretroviral treatment (ART) to people with HIV not only was good for their own health, but also lowered the levels of HIV in their blood to undetectable levels, making the chance of infecting their partners extremely unlikely.

The hope was that by testing everyone for HIV and providing ART to all HIV-positive people, the rate of new infections would steadily decline, ending the epidemic. Research on “treatment as prevention” was rapidly boosted.

The Botswana Harvard Partnership (BHP) participated in that landmark HPTN 052 study and is now a partner in the Botswana Combination Prevention Project (BCPP), a clinical trial underway in 30 villages in Botswana. The BCPP is designed to test whether ART, along with other HIV-prevention measures, can significantly reduce HIV incidence—the rate of new infections at the population level.

For its citizens, Botswana currently follows the World Health Organization (WHO) recommended policy of “universal test and treat,” but migrants are excluded from the national ART program. (Migrant is here defined as a person who lives in Botswana but is not a citizen.)

The number of migrants in Botswana is not well-documented and varies widely from region to region. Migrants may be seasonal workers, political or economic refugees from neighboring countries, or long-term residents living with their extended families. Migrants may have work permits or may be undocumented. In the 2011 National Census, it was estimated that 14% of the employed and 9% of the unemployed population of Francistown, the second largest city in Botswana, were migrants.

Tafireyi Marukutira, who worked with the CDC on the BCPP, presented data from the on-going study at the 2017 CROI meeting in Seattle.

Collecting blood sample for HIV testing in a village participating in the Botswana Combination Prevention Project (BCPP).
Collecting blood sample for HIV testing in a village participating in the Botswana Combination Prevention Project (BCPP). Photo by Dominic Chavez

From October 2013 to February 2016, the BCPP field teams conducted HIV testing campaigns in 15 intervention communities. Testing was offered to anyone over 16, citizens and migrants alike.

Of the 48,640 people tested for HIV, 3% self-identified as migrants. About 20% of migrants were HIV-positive, similar to the 22% rate among citizens. But in contrast to citizens, the vast majority of HIV-positive migrants did not know their status. Only 27% of HIV-positive migrants were on ART, compared to 71% of citizens or spouses of citizens.

These results raise concerns.

“Given the high ART coverage rates in the general population in Botswana, lack of free ART coverage for non-citizens may result in a disproportionate contribution to incident HIV infections,” said Marukutira.

Dr. Vlad Novitsky, a virologist and part of Harvard’s BCPP team, agrees that migrants may contribute to new HIV infections. He would like to see more research and emphasizes that because migrants are a vulnerable population, research must meet the highest ethical standards.

“Without information, you cannot convince the government that all residents, irrespective of citizenship, should be treated because they participate in transmission,” said Novitsky. “Determining how migrant populations are impacting HIV transmission has the potential to change government policy on access to treatment.”

“Failure to provide ARV treatment to migrants is likely to jeopardize the Treatment-as-Prevention policy and curtail the efficacy of interventions among key populations that share sexual network with migrants” said Novitsky. Though he supports providing ART for everyone in Botswana, regardless of citizenship, Novitsky recognizes the limits of his role as a scientist.

“It’s up to the government and the Ministry of Health to decide what to do,” he said.


Feature image: Kazungula, Zambia. People waiting for the Ferry to Botswana, photo by Bernhard Richter