Peter J Flegg,
Blackpool, UK FY3 8NR
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It appears as though the Perth Group, having spent the last 20 years trying to alter the rules of virology, is now trying to drive a coach and horse through the fields of orthodox microbiology, clinical medicine and epidemiology. Pneumocystis typically occurs in a setting of immunodeficiency. The predominant cause of this is HIV infection. Attempts by the Perth Group to pretend there has not been a dramatic epidemic of PCP since the start of the HIV epidemic are doomed to failure.
They claim that “nearly any lung disease can be diagnosed as PCP”, a patently incorrect observation which I suspect has been made by someone who has never even seen a case, and which will probably be greeted by the sound of clinicians everywhere choking over their keyboards. The Perth Group cannot explain away what is a very characteristic clinical and radiological type of pneumonia that responds only to a specific type of therapy in this dismissive manner. For them to also talk about definitive diagnosis versus presumptive diagnosis is entirely specious. Even if one excludes cases which are “presumptively diagnosed”, the epidemic of PCP still totals many hundreds of thousands of cases globally.
In the USA alone, there have been over two hundred thousand cases of PCP recorded in HIV positive patients since 1981, the majority of these being diagnosed “definitively” (1). If the Perth Group is to be believed, then HIV-negative individuals within “high risk” groups should be equally at risk of these opportunistic infections, and there should be millions of cases of PCP occurring in HIV-negative people. Where are they?
I find it puzzling that the Perth Group refers again to the Jacobs study of 5 cases of PCP in HIV-uninfected people (2). Firstly they misconstrued this study (which was coincidentally published the same year that over 20000 cases of PCP were recorded in the USA in HIV-positive patients) in order to try and show how common PCP was. Now they actually seem to be disputing the original diagnosis of PCP in 2 of the 5 cases, which only undermines their original surmise that PCP frequently occurs in the HIV-uninfected.
I repeat, Where are all the HIV-seronegative cases of PCP?
The Perth Group also quote one of my own research studies in an attempt to imply I indicated anticardiolipin antibodies are a predictor for a positive HIV antibody test. On the 18th October I mentioned that: “If the Perth Group are true to form, they will now probably look up some of my work and use it against me as “proof” HIV does not exist. (At least it would be interesting to see how they can misinterpret my work)”.
I hate to say it, but I told you so.
Finally, a bit of basic global epidemiology concerning PCP, which the Perth Group claims is “seldom if ever reported in African AIDS patients”. The opportunistic infections that any immunodeficient individual develops are mostly dependent upon the prevalence of those opportunistic infections in his own environment. Hence, a patient in the UK is likely to develop PCP, or toxoplasmosis, or CMV for example, whereas in Africa an AIDS patient may be more likely to present with enteric pathogens, cryptococcus or tuberculosis. PCP may be less common a presenting feature of AIDS in Africa than in the West, but actually it is far commoner than many realise (or at least those who fail to keep abreast of developments in the field).
The Perth Group need not take my word for it, they can look at the paper published last year by Fisk et al, which reviews 35 other published studies on PCP in the developing world (3). The authors conclude: “(PCP) is now recognized as a significant AIDS-associated opportunistic infection in many developing countries. In contrast to reports from Africa issued in the early period of the pandemic, PCP now comprises a significant proportion of cases of respiratory symptoms in HIV-infected patients in Africa and in other regions in the developing world.”
(2) Jacobs JL, Libby DM, Winters RA, Gelmont DM, Fried ED, Hartman BJ, et al. A Cluster of Pneumocystis Carinii Pneumonia in Adults without predisposing illnesses. N Engl J Med 1991;324:246-250.
(3) David T. Fisk, Steven Meshnick, Powel H. Kazanjian. Pneumocystis carinii Pneumonia in Patients in the Developing World Who Have Acquired Immunodeficiency Syndrome. Clinical Infectious Diseases 2003;36:70-78
Competing interests: None declared