Date: 24 Aug 92 03:43:44 GMT
Newsgroups: aus.religion
Subject: Re: AIDS and the common cup
Distribution: aus

ricko@ee.uts.edu.au (Rick Jelliffe) writes:

>pieloor@tasman.cc.utas.edu.au (Jason Pieloor) writes:

>>boutland@monu6.cc.monash.edu.au (John Boutland) writes:

>>>Has anyone given any thought to the possible risk of becoming
>>>HIV+ from the shared communion cup ? 

>>I remember one paper declaring
>>that a scientist had said that to catch aids from kissing, 15 gallons of saliva
>>would have to be shared.  Phew! (Yuckie)

I should have said "one newspaper" sorry.  That probably indicates a bit better
that the figure is fiarly dodgy at best.  However, let us assume that it was
tre enough.

>Presumably that means to be 100% sure of getting HIV. On first read it
>sounds like the scientist thinks it's a toxin, and that less than a certain
>amount is safe. Whereas you'd think that less exposure means less risk
>to  some extent since its a virus.

I would have interpreted it as being X% sure or getting HIV where X is the
substantial risk measure - take it as anywhere between 10% and 90%.  However,
without a few more facts we are pretty much in the dark.

>If 15 gallons means 100% certainty, and if it`s directly proportional, doesn't
>that make 1 ml have about .0014% chance? (15gall=100%,1pint=600ml=.83%,
>100ml=.14, 1ml=.0014) (Does 1ml sound about right for saliva?)

They'd have to be very dribbly I think.  In fact, if they were dribbling this
much into the communion cup, they'd need a bib! (and a separate cup too, so
they didn't give everyone their other germs like cold's, sore throats, etc.).

>I'm lousy at statistics, but doesn't that mean that (though individual's
>                                                                       chances
>remain tiny) if 100 churches of 50 weekly communicants each (and each with one
>HIV+ communicant who is also a bit dribbly), then the chances of one person 
>being infected is up to 7%, about 4 people per year? Please correct me if my 
>rough math or stats or figures are wrong, but if they're vaguely correct then
>it might be prudent for HIV+ people to take communion last, or arrange with
>the priest to use a separate vessel or something. 

Within one church, and assuming the HIV+ person (one only) goes first.  The
probability of one or more of the other communicants getting the virus will be
given by
	Prob = 1 - [(1-p)^(N-1)] 	 {assuming Bernoulli trials}
where p is the probability of getting the virus from a sip of the cup, and N is
the number of people in the church taking communion.  Thus for one church, with
50 people and a value for p of 0.0014%, the value for Prob will be 0.069%
(if you account for the fact that the HIV+ person will not always be first the
 probability will be even lower)

Using a similar logic for the number of churches, then, for the above case
being true in each church, the probability of one or more people getting HIV
in one week over 100 churches will be 6.63%, and over the 50 weeks of the year
this means a cumulative probability of 96.8%!!!!

(in rough terms, if every person has a risk of 0.0014% of getting HIV from a
 single sip of the communion cup, then over a year (50 sips) this amounts to
 0.07% per person, and for 100 churches of 50 people each this means a very
 good chance that some-one will luck-out and get the HIV virus).

DON'T PANIC!!!!

We have made some very glib assuptions here, and this probabilistic analysis is
fairly sensitive to the initial assumptions.  Please note that my original
memories are suspect, as well as the source I related.  If the probability were
one tenth the cummulative drops to 29%, and at 100th the probability, the
cummulative drops to only 3.4%.  Still, its still too high I suppose.  I (and
I'm sure everyone else) would appreciate a bit more scientific fact here, since
what we have is so dodgy!  (And if anyone can poke a hole in my statistics, I
would be quite happy).

>Of course, if the wine is hostile to the virus, the chances would be lessened,
>etc. etc. Some scientific facts would be helpful though, this is really just
>speculation.

Yeah.

>-ricko

Yours in love,

	Jason

------------------------------------------------------------------------------
Jason Pieloor              Department of Electrical and Electronic Engineering
(Phantom)                                    University of Tasmania, Australia
"The man who never sleeps"                       Jason.Pieloor@eee.utas.edu.au

 "Some people are so heavenly minded, they're no earthly use"
				(recounted by a guest preacher at my church)

Newsgroups: aus.religion