|One Hundred and One Technologies - From the South for the South (IDRC, 1992, 231 p.)|
The spread of AIDS through blood transfusion has largely been eliminated in the North through routine screening of blood supplies. However, in many countries of the South, there is a lack of resources and facilities to screen blood for the human immunodeficiency virus (HIV). In Africa, 5-10% of HIV infections occur through blood transfusions, which are very common. Freshly-donated blood is used to treat life-threatening anemia in children (common in areas where malaria is endemic). The lack of routine testing of donated blood is hampering efforts to prevent the spread of AIDS.
PATH Canada (Program for Appropriate Technology in Health) and PATH International have developed a simple, rapid, and inexpensive test ideal for areas where sophisticated equipment and trained staff are not available to do the kind of HIV screening done in the North. The HIV ImmunoDot Test is a plastic dipstick in the shape of a comb (which allows the user to test up to eight samples at once) that is dipped into serum, plasma, or whole blood samples for 10 minutes. It is then rinsed and incubated for 10 minutes in a reagent solution. If HIV antibodies are present, a red dot appears at the end of the stick.
The method uses a synthetic peptide which is immobilized on the comb and which captures the HIV antibody. A solution of colloidal gold conjugated to protein A is used to produce the red dot.
The new process has the following advantages:
· It is ideal for remote areas where only a small number of tests are done at one time (current tests are geared to high volumes);
· Electricity or special equipment not needed;
· Minimal training is required;
· The whole process takes about 20 minutes, as opposed to the 2-4 hours needed for conventional tests;
· The testing material doesnt require refrigeration, and will remain stable for up to a year at temperatures typical of equatorial Africa;
· The method costs US 50 cents or less per test, as opposed to current tests that cost at least US $2, and sometimes as much as US $7.
Laboratory trials in Canada, the US, and Europe, and field trials in Brazil, China, Kenya, Thailand, and Uganda confirm that the new test performs as well as the best available commercial screening tests and has a sensitivity (ability to detect antibodies) approaching 100% and a specificity (ability to detect the absence of antibodies) of 98%. The test can be used to detect antibodies to the HIV 1 virus. Work is currently underway to adapt the dipstick for combined HIV 1 and HIV 2 testing, as well as for the hepatitis B virus.
PATH itself does not commercially produce the test. It has prepared the documentation and master files necessary to transfer the know-how for manufacture to the public and private sectors in developing countries. Plans for local production of the test have begun in Brazil, Cameroon, China, Indonesia, and Zimbabwe, and it is hoped that the test will eventually be widely available throughout the South.
Blood banks in developing countries, clinics in poor areas, bush hospitals, and other blood transfusion settings, especially in remote areas.
Cost and availability
The test is not being produced commercially in the North, but will become available through the public sector of countries in the South.
Dr Milton R. Tam PATH 4 Nickerson Street Seattle, WA, USA 98109-1699 Tel.: (206) 285-3500 Fax: (206) 285-6619 Telex: 4740049 PATH UI
NB: PATH is not a supplier of the test. It is assisting countries of the South with local production.