What's the Problem?

Many diseases which are no longer of much concern among wealthier populations, such as malaria and tuberculosis, are still killing millions of people in poorer parts of the world. Others, such as HIV infections and AIDS, which are still of concern in wealthier countries, but are being treated fairly effectively, are killing millions more in these same resource-poor areas, because of a shortage of effective treatment facilities and resources.

A growing problem in dealing with the epidemics of such diseases in these resource-poor areas, now that lower-cost drugs are being made available, is monitoring the effectiveness of drug treatment. This has been discussed, among other places, in articles in Science (304, 1936 (2004)) and the Journal of the American Medical Association (288(2), 151 (2002)). Standard hematology testing methods for any of these diseases require equipment costing $50,000 to $100,000, maintained by trained technicians under controlled clinical conditions, which are available in very few third-world locations. Infected people in remote areas are often unable, or unwilling, to travel to such facilities, even when they exist. The anecdotal archetype is the woman with AIDS in an African village, saying, “I’m not going away to that clinic in the city – because when people go there, they don’t come back” (which becomes a self-fulfilling prophecy, as people then avoid the central clinics until their infections are untreatable). This has led to treatments being applied in remote areas without monitoring their effectiveness, which amounts to simply “throwing money at the problem” without knowing if it is really solving the problem.

Possible solutions: The need for point-of-care monitoring of treatments for AIDS and other diseases is being addressed in a variety of ways. One is the development of lower-cost flow cytometers such as the Guava “EasyCD4” (http://guavatechnologies.com) or Partec “CyFlow” systems (http://www.partec.com), but these are neither truly portable nor low-cost systems ($20,000 and up). An analysis by Dr. Howard Shapiro in “Personal Cytometers: Slow Flow or No Flow?” (Cytometry 69A, 620 (2006)) shows that any instrument involving the pumps, valves, and other complexities of a flow cytometer is likely to cost more than the $5,000 maximum he sets for a “personal cytometer”. He and others (such as the “LabNow” group in Austin, TX) are working on the development of low-cost imaging cytometers, using custom-built components, which could be made for less than $5,000 per unit, and are small enough in weight, size, and power requirements that they could easily be transported to, and used in, remote third-world locations. No such instruments are presently available, however, and the time required for custom manufacturing of a large enough number of them to make an impact would appear to make this a distant future solution to the problem. A third approach involves microscope-based diagnostic tests – for example, counting of CD4-labeled lymphocytes for AIDS infections; or for malaria, counting parasite-infected cells using Giemsa or fluorescent staining. For equipment, these assays require only a microscope (about $1000-$2000, and readily available), but they also require a skilled lab technician to spend at least 10-15 minutes per sample making the visual counts. The labor-intensive nature of these tests, plus the shortage of people with the necessary skills where they are needed, means this approach is unlikely to make a large impact on the need for point-of-care testing in the near future.