Methods to Prevent and Treat AIDS: HIV Tests, Condoms

by Food and Drug Administration (FDA)

Preventing and treating AIDS is one of the Food and Drug Administration's top priorities. A new class of drugs, a home blood test collection kit, an oral diagnostic test, an HIV antigen test, an HIV-1 antigen test for blood supply, and an HIV viral load test are among the most recent in a long line of products FDA has approved to prevent, diagnose and treat infection with HIV, the virus that causes AIDS.

HIV Tests

The 1992 National Health Interview Survey by the Centers for Disease Control and Prevention found that only 20 percent of people at increased risk for HIV infection — such as intravenous drug users, male homosexuals, and prostitutes — agreed to be tested for HIV. More than twice that many people in the same risk group said they might use a home testing and counseling service if one were available. At the time, however, testing could be done only by a professional.

The situation changed, in May 1996, when FDA approved the first HIV test system with a home-use blood collection kit. The only one on the market, as of December 1997, is the Home Access Express HIV-1 Test System. It is hoped that home testing will make diagnosis easier and more accessible, especially in populations among whom the recent rise in cases of HIV is greatest, such as women, African Americans, and Hispanics. The tests are highly reliable and are designed to protect the user's anonymity.

FDA's approval on June 3, 1996, of OraSure Western blot, a laboratory test that does not require a blood sample, is also expected to increase participation in testing for HIV. Instead of pricking a finger — a procedure shunned by many individuals — OraSure uses a treated cotton pad to collect an oral specimen from between the gum and cheek.

The sample is tested for antibodies to HIV by a procedure that has been shown to be highly accurate. An earlier version of OraSure used a less reliable method to screen for HIV antibodies, and people who tested positive had to undergo a standard blood test to confirm the presence of the virus.

In March 1996, FDA approved the Coulter HIV-1 p24 Antigen Assay, the first blood screening test to detect antigens rather than antibodies. In screening routinely carried out since the mid-1980s, technicians check donated blood for HIV-1 antibodies by using enzyme-linked immunosorbent assay (ELISA) test kits. Since a small number of ELISA test results are nonspecific or falsely positive, the standard procedure uses a second, more specific test — the Western blot test — to validate the positive results from ELISA testing.

The Coulter test, which is used in addition to ELISA, screens blood for antigens — proteins found on the surface of the virus — that are detectable about one week earlier than HIV antibodies. The new test reduces the so-called "window" period, typically up to three months long, during which standard blood tests show no HIV antibodies, even though the donor may be infected.

The Amplicor HIV-1 Monitor Test, another new blood test approved last year, enables physicians to predict the risk of HIV disease progression by precisely measuring virus levels in blood. The test, which amplifies copies of genetic material from the virus by using polymerase chain reaction technology, is based on clinical studies showing that higher virus levels can be correlated with increased risk that the disease will progress to AIDS, and AIDS-related infection or death.

Condoms

Other than abstinence, latex-rubber condoms are the best protection against sexual transmission of HIV. Latex condoms should always be used for oral, anal and vaginal sex in any relationship that isn't mutually monogamous, and if there is any other chance that either partner may be infected. Condom manufacturers in the United States electronically test all condoms for holes and weak spots. In addition, FDA requires manufacturers to use a water test to examine samples from each batch of condoms for leakage. If the test detects a defect rate of more than 4 per 1,000, the entire lot is discarded.

The agency also encourages manufacturers to test samples of their products for breakage by using an air burst test in accordance with specifications of the International Standards Organization.

Under an FDA proposal, the labeling on latex condoms should state that "this product contains natural rubber latex." FDA has also requested manufacturers to state on the label that "[if] used properly, latex condoms will help reduce the risk of transmission of HIV infection (AIDS) and many other sexually-transmitted diseases."

Consumers should make sure the condom package is undamaged, and check each condom for damage as it is unrolled to be used. The condom should not be used if it is gummy or brittle, discolored, or has a hole. Condoms also should not be used after their expiration date or, if they don't have an expiration date, more than five years after the date of manufacture. Only water-based lubricants (for instance, glycerine or K-Y jelly) should be used with latex condoms, because oil-based lubricants such as petroleum jelly weaken natural rubber.

For people allergic to latex, FDA has approved several polyurethane condoms, which have been shown in laboratory tests to be comparable to latex condoms as a barrier to sperm and HIV virus. Each package of polyurethane condoms is labeled "For Latex Sensitive Condom Users." Natural membrane (lambskin) condoms, which are useful in preventing pregnancy, are not effective protection against HIV or other sexually transmitted diseases. Although sperm cannot pass through the lambskin material, small microorganisms, including HIV, can penetrate these condoms.

One product available for women — the polyurethane Reality Female Condom — provides limited protection against sexually transmitted diseases. FDA requires the labeling of Reality to indicate that "highly effective protection" against STDs is provided if the male partner uses a latex condom for men. Male and female condoms, however, should not be used at the same time because they won't stay in place.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.