According to the Joint U.N. Programme on HIV/AIDS (UNAIDS), 34.2 million people around the world were infected with the disease in 2011, the most recent data available. Last year, the virus led to 1.7 million deaths.
Though the number of afflicted people is rising, the rate of new infections is slowing down and infected people are living longer, in part due to better education and more affordable treatments reaching those who need it. While HIV still has no cure or vaccine, certain drugs can help manage the disease so that infected people can live more productive lives, and can help reduce transmission.
However, some of this progress may be lost as the planet changes, with extreme weather events and higher average temperatures cutting food security, creating refugee crises as people flee stricken regions and spread the disease.
Sex workers wearing masks launched a protest march in downtown Nairobi, Kenya, in March, seeking more access to health care and legal services. They have a high rate of exposure to HIV/AIDS. Photo courtesy of the Joint U.N. Programme on HIV/AIDS.
"I think mainly the interaction between climate change and AIDS is in the future," said Colin Butler, an associate professor at the National Centre for Epidemiology and Population Health at Australian National University. Like climate change itself, the HIV epidemic took decades to develop and could be even more disastrous in the coming century if there is no intervention. And some climate change impacts are already becoming apparent, so their influence on the current HIV problem could be a harbinger of things to come, according to Butler.
In 2009, Butler co-authored a UNAIDS paper on the links between climate change and the virus. "Populations with currently high rates of HIV are the most vulnerable to a worsening or prolongation of the epidemic due to [climate change]," said the report. "This places the people of [sub-Saharan Africa] at the greatest risk ... though outside Africa populations in north east India and New Guinea may also be significantly impacted."
The relationship between climate change and HIV is a little tricky. The human immunodeficiency virus, or HIV, targets the body's cellular defense systems and causes acquired immunodeficiency syndrome (AIDS). It does not spread directly through weather-related trends, like the way flooding leads to cholera illnesses or the way West Nile virus infections correlate with higher temperatures. Rather, HIV spreads mainly through risky behaviors like unprotected sex and intravenous drug use, as well as from mother to child and through blood transfusions.
Migration, poverty and food scarcity can spread the disease
These behaviors can change as populations merge and disband, driven by fighting over increasingly scarce water and arable land. As civil institutions break down, coercive sex and drug use can also increase, thereby enhancing HIV infection risks, Butler observed.
Severe heat, storms and floods stemming from climate change can also destroy homes and livelihoods, harming people economically. Whether a cause or consequence of the disease, financial woes can then exacerbate HIV. The poor are less likely to use prophylactics to protect themselves from the disease and less able to afford the medications to keep infections in check. "Poverty is a very important magnifier of risk of AIDS," Butler said.
A refugee arrives in Mogadishu, Somalia, with an 8-day-old baby. Even measuring the AIDS/HIV rate is difficult in this war-ravaged country. Photo courtesy of the Joint U.N. Programme on HIV/AIDS.
Mkaya Mwamburi, an assistant professor at the Tufts University School of Medicine, said adequate nutrition is another important variable in how the disease spreads and progresses. "There's a huge link between HIV and food security," he said. "Not only is it important in [disease] transmission, it's important in treatment. In areas with scarce resources, they have to prioritize whether it's health care or food."
Shifting weather patterns have already driven up food prices and withered crop harvests in regions where the virus is endemic (ClimateWire, Aug. 22). "With climate change, that directly affects food insecurity in places like rural Kenya," Mwamburi said. "It trickles down and affects the care that they're getting" for HIV.
This HIV-nutrition link is a common thread in cases around the world, including in the United States, according to Sheri Weiser, an assistant professor of medicine in the HIV and AIDS division at San Francisco General Hospital at the University of California, San Francisco. "We are finding a much higher prevalence of food insecurity of HIV-infected people, even among the urban poor," she said.
Undernourishment can speed up the disease because the virus may face less resistance in people struggling to feed themselves. Weiser noted past studies have shown links between food insecurity and lower immune cell numbers. "Food insecurity is leading people to have less suppressed viral loads," she said.
Nutrition's physical impacts then blend with social issues surrounding infected people. "Food insecurity is really about the lived experience," Weiser said. "It's not just insufficient quantities of food, and it's not just insufficient quality of food." In struggling to eat, many patients can see their mental health deteriorate, making it more difficult to ensure they take medication to suppress the disease and take precautions to prevent its spread.
Weakening defenses against other diseases
Other diseases that spread in relation to climate change can further harm HIV patients. Because the virus chips away at the body's defenses, opportunistic infections can strike when a person's immunological guard is down. Diseases that a healthy person may shrug off can be fatal to people with a compromised immune system, while deadlier illnesses like cholera and malaria are more likely to afflict them.
"The recent and tragic experience with HIV/AIDS, particularly in sub-Saharan Africa and South Asia, has shown how the activity of the otherwise mostly dormant tuberculosis bacterium is much increased when the body's immune surveillance is crippled by the human immunodeficiency virus," Anthony McMichael, a professor of population health at Australian National University and co-author of the UNAIDS report, said in an email.
Researchers are now concerned about these variables intersecting in regions facing war, famine, and refugees stemming from climate change and leading to food shortages (ClimateWire, June 27). Patterns have already emerged in some countries. "We found a link between food insecurity and opportunistic infections in Uganda," Weiser said. In addition, Mwamburi noted that people facing losses stemming from climate change are more likely to despair and resort to intravenous drug use, increasing HIV transmission.
McMichael, however, cautioned that the link between food security and disease susceptibility isn't always a sure thing, whether for HIV or for related opportunistic infections. "Indeed, undernourished people may be a less attractive milieu for many pathogens," he said. "After all, their objective is not to kill the weak and starving. Rather, they are seeking, first, an ample source of nutrients and energy for replication and, second, a host fit enough to pass on the next generation of pathogens to another human host."
Different manifestations of climate change can also have differing influence on the virus. Desertification in central Africa could hasten the disease's spread, while increased rainfall in East Asia may slow it down, for example.
Scientists are using manifold approaches to address the epidemic. Mwamburi noted that there are ongoing experiments studying nutritional supplements to HIV patients in sub-Saharan Africa, coupled with programs to distribute condoms and educate the public. Social programs that alleviate poverty, like microfinance and gender empowerment, can also soften climate's blows to the global disease effort, according to Weiser.
"The best case would be the world stops thinking that we can just adapt to climate change and starts thinking we have to prevent it, as well," Butler said. The same strategies that help people mitigate or adapt to climate change, such as reducing greenhouse gas emissions and developing new agriculture techniques, could bolster the fight against HIV.
But for that to happen, Butler said, policymakers have to understand that there is a problem and properly deploy resources as sea levels rise, deserts creep in and humanity moves. "Drought doesn't necessarily mean famine, and it doesn't necessarily mean HIV," Butler said.
Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. 202-628-6500. E&E Publishing is the leading source for comprehensive, daily coverage of environmental and energy issues. Click here to start a free trial to E&E's information services.