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Is it too late for PEP?

Jul 13, 2007

Hello. Thank you so much for the speedy response to my question from a few days ago (see below). At the risk of wearing out my welcome, is it too late for me to consider PEP? I will follow-up with a HIV specialist, as you suggested, but may not be able to get an appointment for another week or so, so if you can answer this question for me, I'd REALLY appreciate it. (If you want to, you can just e-mail me at rather than posting your response on the board -- whatever works for you.) Thanks again for all your help for me and the other users of this board.

Please help me understand Western blot results Jul 11, 2007

I get tested for HIV about once a year at a local anonymous testing site. I tested HIV-negative in the summer of 2006, but a couple of weeks ago, I had a rapid fingerprick test come back "faintly" positive (i.e. a barely perceptible pink line at the "T" mark). The counsellor first told me I was HIV-negative and then looked again at the dipstick and wasn't sure. I requested another rapid fingerstick test and it was also faintly positive. I left without providing a blood sample for additional testing. The next day, I went to another testing site and the oral swab test had such a light pink line at the "T" mark that the counsellor wasn't sure what it meant. We did another finger-prick test and that was negative (no line). I went to my doctor two days later and submitted a blood sample for Elisa and Western Blot tests as well as another sample for HIV RNA viral load. The Elisas came back as positive as did the Western blot, but the HIV viral load came back as undetectable. The Western Blot band results are the following: P18 Reactive P24 Reactive P31 Indeterminate P40 Reactive GP41 Indeterminate P55 Reactive P65 Indeterminate GP120 Indeterminate GP160 Reactive

My questions are the following: What is the difference between "Indeterminate" and "Negative" results for the WB bands? (I had no "Negative" results, but I assume they exist.) According to some reading I've done online since getting these results, it seems that prior to 1993, my WB would have been considered "Indeterminate" due to the non-reactive P31 band. So, is there any hope -- especially since my viral load is undetectable and the longest I could have been infected is a year and I've obviously had no treatment -- that I might have some false positive results here?

Response from Dr. Frascino


Your ELISA is reactive (positive); your Western Blot (WB) is indeterminate. Indeterminate means the presence of any band pattern that does not meet the criteria for a positive test result. Negative means no bands. A positive WB is defined as reactivity to gp120/160 plus either gp41 or p24. You have reactivity to gp160 and p24; consequently, the odds are very strong that you are indeed HIV positive, despite the indeterminate results for gp120 and gp41. The causes of indeterminate Western Blot tests include serologic tests done during the process of seroconversion, late-stage HIV infection, cross-reacting nonspecific antibodies, infection with O strain or HIV-2, HIV vaccine recipients and technical or clerical errors.

The most important factor in evaluating indeterminate results is risk assessment. Folks in low-risk categories with indeterminate tests are almost never infected with either HIV-1 or HIV-2. I don't know what your risk profile is.

I would suggest you contact an HIV specialist in your area for additional follow-up. A repeat of your serological tests, plus a DNA PCR and evaluation of potential causes for indeterminate or false-positive results by the HIV specialist should firmly and definitively establish your HIV status one way or the other. From the information you presented, close follow-up for presumed primary HIV infection is certainly warranted.

Good luck. I'm here if you need me.

Dr. Bob

Response from Dr. Frascino


PEP (post-exposure prophylaxis) should be started as soon as possible and no later than 72 hours after a significant HIV exposure. I'm assuming your HIV exposure was greater than 72 hours ago and consequently PEP would not be an option. You can read more about PEP in the archives. (See below.)

Good luck.

Dr. Bob

What Is Post-Exposure Prophylaxis? Prophylaxis means disease prevention. Post-exposure prophylaxis (or PEP) means taking antiretroviral medications (ARVs) as soon as possible after exposure to HIV, so that the exposure will not result in HIV infection. These medications are only available with a prescription. PEP should begin as soon as possible after exposure to HIV, but certainly within 72 hours. Treatment with 2 or 3 ARVs should continue for 4 weeks, if tolerated.

Who Should Use PEP? Workplace Exposure PEP has been standard procedure since 1996 for healthcare workers exposed to HIV. Workers start taking medications within a few hours of exposure. Usually the exposure is from a "needle stick," when a health care worker accidentally gets jabbed with a needle containing HIV-infected blood. PEP reduced the rate of HIV infection from workplace exposures by 79%. However, some health care workers who take PEP still get HIV infection. Other Exposure In 2005, the Centers for Disease Control reviewed information on PEP. They concluded that it should also be available for use after HIV exposures that are not work-related. People can be exposed to HIV during unsafe sexual activity, when a condom breaks during sex, or if they share needles for injecting drugs. Infants can be exposed if they drink breast milk from an infected woman. In a study of PEP in 400 cases of possible sexual exposure to HIV, not one person became infected with HIV.

Should PEP Be Used for Non-Occupational Exposure? HIV exposure at work is usually a one-time accident. Other HIV exposures may be due to unsafe behaviors that can occur many times. Some people think that PEP might encourage this unsafe behavior if people think that PEP is an easy way to avoid HIV infection. There are other reasons why PEP might not be a good idea for non-occupational exposure:

There is no research to show that PEP works for non-occupational exposure. We don't know how soon after exposure to HIV someone has to start PEP.

PEP is not a "morning-after pill." It is a program of several drugs, several times each day, for at least 30 days. PEP costs between $600 and $1,000.

For best results, you have to take every dose of every PEP medication. Missing doses could mean that you develop HIV infection. It could also allow the virus to develop resistance to the medications. If that happens they would no longer work for you.

The medications have serious side effects. About 40% of health care workers did not complete PEP because of the side effects. Despite these concerns, there is growing interest in PEP for non-occupational exposure. Most programs include counseling to inform and encourage people to avoid exposure to HIV.

How Is PEP Taken? PEP should be started as soon as possible after exposure to HIV. The medications used in PEP depend on the exposure to HIV. The following situations are considered serious exposure:

Exposure to a large amount of blood; Blood came in contact with cuts or open sores on the skin; Blood was visible on a needle that stuck someone; and Exposure to blood from someone who has a high viral load (a large amount of virus in the blood). For serious exposures, the U.S. Public Health Service recommends using a combination of three approved ARVs for four weeks. For less serious exposure, the guidelines recommend four weeks of treatment with two drugs: AZT and 3TC.

In January 2001, the Centers for Disease Control warned against using nevirapine for PEP because of the risk of liver damage. See Fact Sheet 431 for more information on nevirapine. The CDC has updated its PEP recommendations in September of 2005.

What Are the Side Effects? The most common side effects from PEP medications are nausea and generally not feeling well. Other possible side effects include headaches, fatigue, vomiting and diarrhea. For more information, see the fact sheets on individual ARVs.

The Bottom Line Post-exposure prophylaxis (PEP) is the use of ARVs as soon as possible after exposure to HIV, to prevent HIV infection. PEP can reduce the rate of infection in health care workers exposed to HIV by 79%. The benefits of PEP for non-occupational exposure have not been proven. This use of PEP is controversial because some people fear it will encourage unsafe behaviors.

PEP is a four-week program of two or three ARVs, several times a day. The medications have serious side effects that can make it difficult to finish the program. PEP is not 100% effective; it cannot guarantee that exposure to HIV will not become a case of HIV infection.

For More Information CDC guidelines on PEP are on the Internet. Occupational exposure:

Non-occupational exposure:

-------------------------------------------------------------------------------- This article was provided by AIDS InfoNet.

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