HIV infections in sub-Saharan Africa spread faster in the lead up to violent conflicts, a new study reports. Surprisingly, however, rates of transmission fall when violence breaks out. The unexpected relationship may teach us something about two of the modern world's most frequent killers, but as yet we don't know what.
The chart below indicates the rate of HIV over a 22 year period in Nigeria, including the period from 2000 to 2004 when religious violence broke out between Muslims and Christians before four years of peace and renewed conflict.
Number of infections per 1,000 people per year in Nigeria over conflict stages. Credit: Brady Bennett.
Alone this might be considered a local oddity, the sort of thing that could be featured on the spurious correlations website. However, Nigeria is just one of the 36 sub-Saharan countries Brown University student Brady Bennett studied for a paper in PLOS ONE.
“Compared to times of peace, the HIV incidence rate increased by 2.1 per 1000 infections per year in the five years prior to conflict,” Bennett and his co-authors reported. However, once fighting broke out, there was an average decrease of 0.7 new infections per 1000 people per year in areas where between 25 and 1000 people were killed through large-scale violence. When battle deaths exceeded one thousand the infection rate fell further still, by 1.5 infections per 1000 people per year.
Sub-Saharan Africa has been the site of most of the 40 million deaths from AIDS over the last 30 years. Twenty-two countries suffered conflict at different times during this period, so the authors controlled for the continental peak in transmission in 1996 and local factors such as economic development and refugee movements from surrounding countries.
Previous studies, using more limited data, have produced contradictory results as to whether conflict has increased or decreased HIV infection rates, with the increases in sexual violence and disruptions to medical programs counterbalanced by interruption of travel networks that can spread the virus, and possibly the arrival of humanitarian aid.
Bennett acknowledged the reduction in recorded infection rates during war time may be partly an artifact of failures in detection and reporting. The paper noted, “Conclusions drawn from nations long at war, such as Democratic Republic of the Congo, must be taken with caution.”
However, the rise beforehand, also observed in Burundi, Eritrea and Uganda is more unexpected, and harder to explain. "It implies that there is something going on in social, political, and health care environments in those years that are conducive to HIV spread," Bennett said in a statement.
Explaining the connection could help public health officials understand conditions that facilitate HIV's spread. The authors suggest future studies should consider data “at the regional or community level” rather than using nation-wide infection rates. They also suggest investigating behavior changes, such as increases in sexual violence, that may be associated with the build up to conflicts as well as the wars themselves.
“We need to better understand the precipitating factors that drive conflict precisely because we’ve identified that as a period of particular vulnerability where HIV incidence is likely to be increased,” said senior author Dr Mark Lurie.
