Refrigeration and HIV Meds in Resource-limited Settings
Posted Oct 22 2008 4:32pm
I'm Charlie Raver.
One of the distinguishing characteristics between the AIDS epidemic in the developed world and that in Africa and the developing world is a simple lack of the infrastructure to deal with the disease. Infrastructure includes everything from roads to electricity to hospitals. One example that most of us rarely think of as a gift, couldn’t dream of walking into a home and not finding, and would be lost without is something to which many in the developing world do not have access. What am I talking about? Refrigeration. Without this amazing piece of technology we would not be able to easily enjoy fresh meats, fish, dairy, and many simple nutritional luxuries that we as Americans take for granted. In addition to problems with food preservation, hospitals and health clinics would be unable to store blood, vaccines, heat intolerant medicines, and many laboratory supplies.
For many in the developing world that is exactly the problem. Without refrigeration they have no means to store many of the supplies necessary for maintaining a health clinic. Without this infrastructure, access to basic care, essential for the treatment of AIDS, is extremely limited. Recently, the WHO recommended the use of a ritonavir boosted protease inhibitor as part of the drug regimen. Aside from being able to obtain the drug, one problem is that ritonavir requires refrigeration in hot climates. Currently only one of the ritonavir boosted PIs is available in a heat stable form which, obviously puts a huge constraint on the availability of the drug in the developing world. A confounding issue is the high rates of coinfection of diseases such as tuberculosis and malaria in these resource poor areas. In addition to proper care, access to testing for HIV and TB has been cited as one of the first obstacles to fighting the epidemic. The WHO estimates that less than 10% of people living with HIV/AIDS in parts of Sub-Saharan Africa are aware of their HIV status.
In addition to poor access to health care, the epidemic is only made worse by the staggering rates of malnutrition. In their recommendations for antiretroviral therapy, the WHO emphasized the importance of nutrition not just for the overall health of the affected individuals but also because of the link between nutrition and the effectiveness of ART. However, in some parts of Sub-Saharan Africa, it is estimated that as much as 50% of the population is malnourished. Many Africans do not even have the means to buy or grow the most basic foods. This problem is again only made worse by the lack of refrigeration. Some form of food preservation could allow rural communities and individuals to grow crops in excess and store the surplus to either sell and trade with other communities or even just maintain a supply during the non-productive parts of the year. However, when you consider that over 500 million people in Sub-Saharan Africa do not have access to electricity the idea of refrigeration is a long shot.
Unfortunately providing those in rural Africa with electricity is a problem unto itself. Without economic stability there is little room for expansion and improvement of infrastructure whether it is roads, electricity or health care. These lacks in infrastructure only make the AIDS epidemic harder to fight which further hinders economic growth. However, small improvements like access to refrigeration could be a catalyst for change.
One type of refrigeration that requires no electricity is sorption refrigeration. This form of refrigeration works by having two chambers connected by some type of tube. One chamber, the hot side, contains an absorbent material. The other chamber, the cold side, contains a refrigerant. The tube connecting the two would be filled with refrigerant vapor. The vapor in the tube is then absorbed on the hot side causing a drop in pressure in the connecting tube. This causes evaporation of the refrigerant which in the process absorbs heat and causes cooling on the cold side. This continues until all the refrigerant has vaporized and been absorbed on the hot side. To restart the cooling process, the hot side must be heated gently to drive the refrigerant vapor out of the absorbent material and back to the cold side. In the late 1920s, Powell Crosley Jr. developed a commercial version using ammonia and water that was used throughout the rural United States prior to wide-spread access to electricity. Although this is by no means a large scale solution to the infrastructure problem, adaptation of these ideas for use in the developing world could provide one of the basic necessities for health care and food preservation.