Department of Medical Physics, Royal Perth Hospital, Western Australia, 6001,
Valendar F Turner, John Papadimitriou, Barry Page, David Causer, Helman Alfonso, Sam Mhlongo, Todd Miller, Christian Fiala
Send response to journal:
"HIV" – "a necessary or sufficient cause" for AIDS?
In his rapid response, "Re: "HIV is not sufficient nor necessary for KS", 8 September, Christopher Noble wrote: "The Perth Group argue: If "HIV" is BOTH, neither "sufficient nor necessary", how is it possible for anybody including Nicholas Bennett to attribute a role, any role, to "HIV" in the causation of KS? It is rare to see such blatant examples of illogic and confused thinking. 1. Cigarette smoking is neither a sufficient nor a necessary cause of lung cancer. Non-smokers get lung cancer and many heavy smokers never get lung cancer. 2. Driving an automobile while under the influence of alcohol is neither a necessary nor a sufficient cause of accidents. Sober people have accidents and many people survive drinking while drunk. 3. Etc… How is it possible to attribute a role, any role, of drink driving in the causation of traffic accidents? The answer is quite simple – for people other than the Perth Group. Cigarette smoking dramatically increases the risk for lung-cancer. Drink driving increases the risk of car accidents."
Since cigarette smoking in the absence of any other carcinogen may cause lung cancer some will say that cigarette smoking is sufficient for the development of lung cancer. However, because not everyone who smokes cigarettes develops lung cancer others will say that cigarette smoking is not sufficient to cause lung cancer. It is only a risk factor. A similar argument applies to “Driving an automobile while under the influence of alcohol”.
As far as KS and “HIV” is concerned, at present it is accepted “HIV-1 infection is clearly not required for KS development”. And it is “unclear what role [if any] HIV-1 plays in KS”.1 That is, at present it is not known if “HIV” is a risk factor for KS.
Christopher Noble wrote: "The increased risk of PCP with HIV infection is so high that if somebody is diagnosed with PCP then we can predict with a high degree of certainty that that person is infected with HIV and is immune suppressed. Hence PCP can be used as an AIDS indicator disease."
There is overwhelming evidence "that if somebody is diagnosed with PCP then we can[not] predict with a high degree of certainty that that person is infected with HIV and is immune suppressed". A few examples will suffice to illustrate this point.
In a paper entitled "Pneumocystis carinii in young immunocompetent infants", published in 1980 the authors concluded: "These results indicate that P. carinii singly or in combination with other infectious agents may be an important cause of pneumonia in young immunocompetent inants with no underlying illnesses".2
In 1991 Jacobs et al reported that at the New York Hospital-Cornell Medical Center during a three month period, they diagnosed PCP in five adults. Two out of three patients tested for T-lymphocyte subsets had T4 > 40% and all had normal T4/T8 ratios. "Cultures of peripheral-blood mononuclear cells for retroviruses were negative", in 4/5 patients (the 5th apparently was not tested). The "HIV-1,2" antibody tests were negative in all cases.3. An "HIV" negative gay man developed oral candidiasis, conjunctivitis and PCP. "He received 3 weeks of therapy with trimethoprim-sulfamethoxazole, which resulted in total resolution of symptoms…During the following 10 months, three HIV-1 antibody tests by EIA were negative, as were an EIA for HIV-2, an HIV-1 p24 antigen assay, and a polymerase chain reaction (PCR) test for HIV-1. Four months later, his CD4+ lymphocyte count was 660/mm".4 (This was the first time that the CD4s were determined). In a paper entitled "Detection of pneumocystis carinii among children with chronic respiratory disorders in the absence of HIV infection and immunodeficiency" published in 1998 the authors concluded: "These results suggest an association between P carinii and exacerbation of CLD (chronic lung disorders) in childhood, in the absence of HIV infection or other immunodeficiency syndromes".5
Eduardo Dei-Cas from the Pasteur Institute wrote in 2000: "Thus the real clinical and epidemiological impact of pneumocystis infections is most likely underestimated, and probably, we recognise at present only the tip of the iceberg".6
Christopher Noble wrote: "Nobody is saying that HIV infection is a necessary or sufficient cause of any of the AIDS indicator opportunistic infections or malignancies."
If "HIV" is not necessary or sufficient for AIDS, some will say that “HIV” is not the cause of AIDS. Others will say that “HIV” is a risk factor for AIDS. Which means that at most “HIV” is one of a number of other risk factors for AIDS. That is, "HIV" is not the only cause of AIDS.
1. Nickoloff BJ, Foreman KE. Etiology and pathogenesis of Kaposi's sarcoma. Recent Results in Cancer Research 2002;160:332-42.
2. Stagno S, Pifer LL, Hughes WT, Brasfield DM, Tiller RE. Pneumocystis carinii pneumonitis in young immunocompetent infants. Pediatrics 1980;66:56-62.
3. Jacobs JL, Libby DM, Winters RA, Gelmont DM, Fried ED, Hartman BJ, et al. A Cluster of Pneumocystis Carinni Pneumonia in Adults without predisposing illnesses. N Engl J Med 1991;324:246-250.
4. Torres RA, Barr MR. AIDS-associated illness and HIV negativity. Ann Int Med 1992;117:973.
5. Contini C, Villa MP, Romani R, Merolla R, Delia S, Ronchetti R. Detection of Pneumocystis carinii among children with chronic respiratory disorders in the absence of HIV infection and immunodeficiency. Journal of Medical Microbiology 1998;47:329-33.
6. Dei-Cas E. Pneumocystis infections: the iceberg? Medecal Mycology 2000;38 Suppl 1:23-32.
Competing interests: None declared