Re: Re: Horizontal Transmission ? Reply to Perth 27 March 2004
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James E Parker,
Retired Paediatrician
289 McCallum Rd Abbotsford B.C CANADA v2s 8a1

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Re: Re: Re: Horizontal Transmission ? Reply to Perth

I would like to thank Eleni Papadopulos-Eliopulos for her response to my submission of March % 2004.

Proving Koch's postulates to everyone's satisfaction is a problem when dealing with diseases which have a long period of latency. While it is perhaps easier to comprehend in the case of FeLV infected cats where this may be up to 4 years,in the HIV 'infected' human this may be 12-15 years or longer.

Once again the Perth group do not appear to believe in the existence of exogenous retroviruses. This is not incompatible with prevailing philosophy of 30 years ago (which is why I referred to Schneider's publication ). Indeed the very mention of the possibility of a horizontally transmitted agent playing any role in leukaemia or cancer was anathema to many in the establishment. I can well remember raising the question of cat leukaemia with my former mentor and teacher at HSC Toronto after a lecture back then. This was met with a dogmatic 'there is no evidence' as he angrily left the hall refusing further comment. At the time the pathfinding discovery of cat leukaemia virus by Jarrett's group in 1964 ( Nature May 9, 202 566-568 ) was not greeted with enthusiasm in medical circles where the inbred 'mouse' model was given precedence over the outbred cat.

At the Feb 1972 London symposium of the Royal College of Pathologists on Host-Virus Reactions (J Clin Path 25 Suppl 1972 43) Jarrett presented a paper on Feline leukaemia in which he outlined the modes of transmission. ' the original transmission experiment was attempted because I found a cluster of eight cases in a household colony of unrelated cats.' 'Epidemiological evidence from the United States of America (Brody, McDonagh, Frye and Hardy, 1970) indicated that the introduction of an infected tom cat for breeding purposes led to the establishment of infection in the indigenous cats. '

Acceptance of the possibility of horizontal transmission of FeLV was slow. In a letter received from Professor Jarrett in Oct 1974 to me he wrote 'We have just had an interesting meeting which I ran on this subject at the Rockefeller Center at Bellagio in Italy with 20 people all active in the field hammering over the details and the final unanimous consensus admitted even by those from NIH who had been very sceptical before, was that there was no question of horizontal transmission and the epidemiological pictures we have proposed are true'.

Cat leukaemia finally reached the editorial pages of Lancet on Mar 1 1975 (' As in Cats, So in Man ). In the second last paragraph of which we read 'An important consequence of FeLV infection is the onset of a state of immunosuppression so that cats which receive a heavy infecting dose do not mount a substantial immune response; they subsequently develop tumor or one of the other FeLV associated diseases. 32,35' These principles of disease progression came several years before events in San Francisco. !!

In 1976 Hardy and associates published the results of their 'test and removal' program in Nature (263 326 1976). In her response to me concerning this, Eleni Papadopulos-Eliopulos writes 'The removal of infected cats and subsequent reduction in the incidence of disease in multiple cat households is not proof that FeLV is horizontally transmitted or that the cause of disease lymphosarcoma is FeLV'........'The causes of the disease may not be infectious, it may be congenital or some cats may be susceptible to factors in the households or the diet'.

Perhaps the opinion of the Oct 16 1976 leading article of the Veterinary Reccord should be noted and readers judge for themselves.

"In a recent article in Nature W D Hardy Jr and his colleagues in New York gave a progress report after a two year period. They studied 76 multiple cat households in which FeLV was present; In 51 the FeLV infected cats were removed and in 25 they were not. It was found on retesting after three months that only 0.5 per cent of the previously uninfected cats had become FeLV-positive in the households from which the infected cats were removed, but that a staggering 20 per cent had become positive in the houses in which the source infection remained (see p120)

Over the two year period no case of an FeLV-related disease was observed from the households in the programme, while the incidence of disease in the control households continued unabaited. "

Do I demonstrate bias when suggesting that the evidence for horizontal transmission of FeLV and an infectious component is something more than anecdotal ?. The Perth group's implication that antibody tests may be artifactual are somehow belied by the final sentence regarding disease itself.

Lymphosarcoma is not the only condition associated with FeLV although this seems to be intimated in the Perth response. The veterinary researchers (Jarret in particular) have been far ahead of their medical counterparts when it came to retroviral research and their experience with cat leukaemia provided valuable clues regarding HIV in the human situation.

Despite it's African adventures Cuba contained AIDS by the application of orthodox public health measures which come closer to 'test and removal' than other situatons. These also point toward an infectious aetiology.

While I do not have an epidemiological study to present (I would defer to someone like Brian Foley), I have a newspaper cutting from the Toronto Globe & Mail (March 15 1994) with the large headline 'AIDS widow awarded $500.000'. This outlined a situation in which a man died of HIV related pneumonia, without knowing he was infected by a tainted blood transfusion received during previous surgery in 1984. His widow was probably infected in the last year of his life. Interviewed on the radio a week or so ago she is now receiving AIDS therapy. Does this answer the final question posed -which of the Perth group's views are dangerous and why ?

James E Parker

Competing interests: None declared