Re: What is the evidence that "HIV" causes PCP? 8 December 2004
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Peter J Flegg,
Physician
Blackpool, UK, FY3 8NR

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Re: Re: What is the evidence that "HIV" causes PCP?

Concerning Pneumocystis infection, The Perth Group are still missing the point. It is totally irrelevant how one diagnoses PCP – the criteria are still the same whether the person has HIV or not.

I repeat: ”Where are all the (millions of) cases of PCP in HIV-negative individuals? (or for that matter cerebral toxoplasmosis, or CMV retinopathy, or PML etc? ) If the Perth Group’s notion that predisposition to these is due to other factors (“many gay men are at risk of malnutrition” (no comment necessary!); talk of “semen exposure” and so on) then should be millions of HIV-negative people with these conditions.

In respect of PCP the Perth Group ask:

“Is the rarity of PCP reporting before the 1980s due to its very low frequency?” Answer: In my opinion, yes.

“Would Peter Flegg please tell us how often he was requesting open lung biopsies for the differential diagnosis of lung disease in his drug abusing patients, or any other patient, in "the pre-HIV era" or even today?” Answer: Hardly ever, since clinical diagnosis, the exclusion of other possible differential diagnoses, and most tellingly a characteristic (and in itself diagnostic) response to specific anti-PCP therapy is more than sufficient to arrive at a firm diagnosis.

“Is it possible that the very high frequency of PCP reported in the last 24 years in gay men, haemophiliacs and drug users is, at least in part, due to the use of unreliable "definitive" diagnosis?” Answer – No. The diagnosis may not be always supported by obtaining specific microbiology or histology, but is certainly not “unreliable” as a consequence. Furthermore, can the Perth Group explain why this “unreliable diagnosis” would be selectively applied to only HIV-infected people, and not HIV-negative gay men, hemophiliacs and drug users?

“We asked Peter Flegg what method he is using to diagnose PCP in his patients.” Answer – see above.

“Is it possible that the reported high frequency of PCP in the Jacobs et al study (btw I do not regard the occurrence of 5 cases as “high frequency”) and in many, if not all AIDS patients, is not real but the result of a non specific test?” Answer – No it is not possible; the high incidence is real.

Competing interests: None declared