Re: Re: Re: Re: Re: Reply to Noble: Recreational drugs can cause 'HIV' positivity 20 July 2004
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Nicholas Bennett,
Infectious Disease Postdoc/Clinician
Department of Pediatrics, University Hospital, Syracuse NY

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Re: Re: Re: Re: Re: Re: Reply to Noble: Recreational drugs can cause 'HIV' positivity

I am more than a little saddened to read the future Dr Pandraud's contribution. I can only point to a few basic facts, solid and unshakeable, that will hopefully make sense.

AIDS is a single disease. It is a specific decline in CD4+ helper T cells with a reversal of the CD4/CD8 T cell ratio. No other cause, be it immunosuppressive drugs, malnutrition, or whatever has ever been shown to cause such a specific decline in CD4 T cell immunity. The closest thing is idiopathic T cell lymphopenia, which doesn't cause such a profound functional immune deficit. The specific decline in cellular immunity opens the door to well recognised opportunitic infections (OIs), mostly viruses, that are normally held in check by cellular immunity.

The clinical definition includes OIs and cancers that were shown very early on to be vastly more common in those with HIV than normal people. Kaposi's sarcoma is 33,000 times more common in people with HIV - so common that at one stage it was thought that HIV might even cause that particular type of KS (there are four types, AIDS-KS is the worst). The definition is rather circular, I readily admit, but it's for good reason not for the sake of proving that HIV causes AIDS!

HIV is obviously not 100% deadly, only those arguing against it say that. It was, again, recognised early on that up to 10% of people may be LTNPs. Such people do indeed have better anti-HIV immune responses, they are able to fight the infection better. The time taken is still 8-10 years in the West, but in some African cohorts can be as low as 2 years to progress to AIDS. The 15-20 year definition is that time at which various LTNP studies have said "above this, you are an LTNP and we'll include them in the analysis"

Antibodies are not entirely protective against viruses. Cellular immunity is more important, as it is for anticancer surveillance. Having antibodies and still having virus is common, and is seen in CMV, Herpes Simplex, Hep B and C etc. HIV is readily detected from seropositive people, as I showed a few posts back with papers from Jackson and Ho, but since antibody tests are far easier to perform these are excellent surrogate replacements.

As for how can one know if disease X was caught because of HIV or not...well, the best thing would be to take an HIV test. If a 20 year old man presented to hospital with his third serious pneumonia in as many months, I would be seriously concerned that his immune system was damaged. In the workup would be an HIV test, and if it came up positive then clinical judgement says that's the likely cause. It's no different than any other clinical judgement call. All the AIDS-defining conditions (with in my opinion the dubious exception of cervical cancer, only about 2-3 times as common in HIV+ women) are rare in fully immune-competent individuals. Just by finding someone with extensive oral candidiasis, or KS, or CMV pneumonitis or PCP you're making it highly unlikely they don't have HIV.

I hope that helps at any rate. HIV=AIDS is about 90% certain (within 8-10 years), and sadly AIDS=DEATH is 100% certain, since without treatment (which is pretty much a holding pattern unless drug resistance is avoided) AIDS rather quickly progresses to fulminant immune system failure. All this is well documented in the literature through some excellent longitudinal cohort studies: with a morbid regularity you can see people seroconvert and watch their CD4 cells start to drop (all in the pre- treatment era). It's scary.

Competing interests: None declared