Anergy Skin Testing and Prevention Therapy for HIV-Infected Persons
Having HIV increases the risk of developing other infections which are called opportunistic infections. (Opportunistic, simply means that because of HIV infection, other infections can now invade the body more easily.) The Public Health Service and the Infectious Disease Society of American have compiled a list of recommendations for preventing opportunistic infections in HIV infection.
The word prophylaxis is probably used often by your health care provider. Prophylaxis means to use medication to prevent the development of a new infection or a reactivation of a past infection. (To ward off, or prevent infection before it happens). Primary prophylaxis is the use of a medication to prevent the first episode of an infection. When your T-cell count falls below 200, your health care provider will prescribe either Bactrim, Dapsone, Mepron or Pentamidine to prevent the first episode of Pneumocytis pneumonia (PCP).
If you have been exposed to someone else who has had active tuberculosis or if you have a positive PPD (skin test) your health care provider may prescribe INH everyday for the next 12 months to decrease your risks of developing an active infection. (Exposed: for example someone with Tuberculosis has coughed on you.)
If you have already developed and been treated for an infection, then the medication prescribed to prevent the reactivation (coming back again) of this infection is referred to as a secondary prophylaxis, (treatment to stop infection/disease from attacking the body again). Secondary prophylaxis can include continuing fluconazole after receiving acute treatment for a cryptococcal infection, or ganciclovir to suppress your Cytomegalovirus.(CMV is a virus which is in the herpes virus family).
Current Recommendations for Prophylaxis
The CDC (Centers for Disease Control and Prevention) also has published recommendations for prophylaxis to prevent the development of first episodes of opportunistic infections. These recommendations are listed in the table on the following page.
Anergy testing is the use of a skin test to assess your response to an antigen. Also, if you have been exposed to a disease. (Anything that is foreign in your body which will stimulate an immune response). For example if you have been exposed to tuberculosis (TB) and a PPD (skin test) is placed on your forearm and a red bump appears that is greater than 5mm, it means you have been exposed and that your immune system has mounted a response. This does not mean you have an active infection, you have simply been exposed. When the immune system has been damaged, it is possible that when you are exposed to a disease like TB, you may not have a reaction or response to the skin test; this is called anergy. (Unable to react to specific antigens like, bacteria).
Control skin tests are sometimes used when PPD testing is performed. Mumps and Candida antigens are sometimes used as a control test. If these controls cause no reaction then the person is considered anergic and the response to a PPD can not be read (Mumps; virus which is contagious, usually affects the salivary glands. Candida; a yeast infection). This means that your body may have lost it's ability to respond to PPD antigen testing but can still respond to other antigens. Furthermore, a valid demonstration of anergy does not predict infection with Mycobacterium tuberculosis or the need for TB prevention therapy. To determine if TB is actually present a chest X-ray will need to be done. Recent studies conclude that anergy testing is no longer recommended for people with HIV.
Highly Active Antiretroviral Therapies (HAART)
The current use of highly active antiretroviral therapy is changing the way we treat HIV-infection. (HAART: any type of agressive therapy to treat HIV, such as a protease inhibitor combined with 2 nucleoside analogues or 2 protease inhibitors combined with other medications including non-nucleoside reverse transcriptase inhibitors.) Many HIV-infected individuals whose dropping T-cell counts require primary prophylaxis therapies have now experienced an increase in their T-cell count. A big question now is, can we stop previously instituted prophylaxis when T-cell counts rise as a result of medications.
Current Research Studies
Currently the AIDS Clinical Trial Group (ACTG) is looking to answer the question of whether or not to stop prophylaxis. At this time, it is not clear if the new T-cells, that come back after taking medications, are going to be able to fight off new infections. There is some concern that when the T-cell count has been very low a person may not regain the ability to fight off new infections, even if the number of T-cells increases.
The ACTG protocol will look at patients who have had a T-cell count less than 50 and now have a T-cell count over 100. The patient who chooses to enroll will be randomized to receive azithromycin (two 600mg tablets once weekly) or placebo. (Randomize: Selection an individual without knowing who this person will be, similar to a lottery drawing. Placebo; Inactive substance given to same numbers of individuals that are taking the real medications in order to get accurate results.) The study will look at the risk of developing MAC (Mycobacterium Avium Complex) and other infections when T-cell counts are maintained above 100. The study will also measure viral load every four months. (Viral Load: measurement of the amount of HIV virus in your blood).
Prior to the availability of HAART lifelong maintenance therapy for CMV retinitis has been recommended. If suppression of viral load can lead to improvement in immune function it might be possible to discontinue therapy at some point. This strategy of stopping CMV maintenance in people who have responded to HAART is currently under investigation.
A substudy will also look at skin testing to antigens to see how these responses correlate with protection against new infections. The substudy will also look at testing with MAC antigens to see if MAC might be predicted by the results of the skin test.
The antiretroviral therapies that are available have increased T-cell counts, lowered viral loads and improved quality of life for HIV-infected persons. Preserving immune function is important for preventing opportunistic infections. In the future, data will be available to show whether improvements in T-cell numbers are associated with restored immune function, and whether primary or secondary prophylaxis can be discontinued.
New information on the treatment of HIV infection is becoming available at a rapid pace. One way to take control of your HIV disease is by learning as much as possible and by becoming an active participant in your health care decisions. Ask questions about laboratory values or terms you do not understand. Each person must become an activist and a treatment advocate on their own behalf.
If you need to develop self advocacy skills, call your treatment advocate. You can reach Marilyn Howell at Women Alive: 800.554.4876.
This article was provided by Women Alive. It is a part of the publication Women Alive Newsletter.