Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.csd.uwm.edu!cs.utexas.edu!turpin
From: turpin@cs.utexas.edu (Russell Turpin)
Newsgroups: sci.bio
Subject: Re: What's the Why and How of Mosquito Bites?
Summary: More on mosquito vectored diseases.
Message-ID: <6715@cs.utexas.edu>
Date: 17 Aug 89 00:40:05 GMT
References: <5399@mtgzy.att.com> <4948@tank.uchicago.edu> <9263@chinet.chi.il.us> <24875@joyce.istc.sri.com>
Organization: U. Texas CS Dept., Austin, Texas
Lines: 38

ARF says:
> > Have you never smashed a blood-gorged mosquito sitting on your arm?  All
> > the senario needs to transfer, is for the mosquito to have taken a prior,
> > partial meal, from an AIDS carrier.

No, it also requires blood from the last meal to be left in the
mosquito's proboscis, that the mosquito's proboscis is still in
your arm, and that you smash the mosquito in such a fashion that
the blood is injected into your arm.  The chance of developing an
infection depends (at low levels) on the amount of exposure to
the disease causing agent.  Thus, not all needle stick accidents
in hospitals and labs involving active HIV samples result in HIV
infection.

> > Not quite as improbable as your virgin birth!
> > Certainly not improbable enough to ignore as seems to be the case.

The chance of HIV infection from smashing a mosquito may be
greater than the chance of virgin birth, but if this mode of
transmission occurs, it is so rare that it does not show up in
epidemiological studies in Africa and elsewhere.  If it worries
you, the solution is obvious: don't slap that mosquito.

In article <24875@joyce.istc.sri.com>, alan@apptek11.uucp (Alan Algustyniak) writes:
> BTW, if mosquitos need blood to propogate, then how do the ones deep in
> the swamps do it?  Where do they find their victims?  Oh, so that's
> what those bumps on the backs of alligators are...:-)

There are many, varied species of mosquitos.  Not all require
blood, and of those which do, many are happy with animal hosts,
including some that are responsible for human diseases.  The
anopheles mosquito that spreads malaria, for instance, prefers
cattle to people.  One of the reasons for the retreat of malaria
from England in the 17th century was an increase in cattle herds.
The mosquitos moved from human to cattle hosts, and because
cattle are not sucseptible to malaria, the chain of infection was
curtailed.  (William McNeill, "Plagues and People", p 218.)

Russell