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From: hlaufman@magnus.acs.ohio-state.edu (Harry B Laufman)
Newsgroups: sci.med.aids
Subject: re: AIDS from insect bites
Message-ID: <1991Jun21.141927.10582@cs.ucla.edu>
Date: 21 Jun 91 14:04:22 GMT
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Without permission, typographical errors are HBL's.
From NATURAL HISTORY, 7/91, page 54:

   _Can Mosquitoes Transmit AIDS?_

   Acquired Immune Deficiency Syndrome (AIDS), the deadly epidemic
   caused by the HIV virus, is most often transmitted by con-
   taminated hypodermic needles or through sexual contact.  Since
   mosquitoes feed on human blood and may attack a series of
   individuals, the question arises: Can you get AIDS from a
   mosquito bite?

   According to Jonathan F. Day, of the University of Florida's
   Medical Entomology Laboratory, insects can transmit viruses
   in two ways, mechanically and biologically.  With mechanical
   transmission, infected blood on the insect's mouthparts might
   be carried to another host while the blood is still fresh and
   the virus still alive.  Infection by this means is possible
   but highly unlikely, because mosquitoes seldom have fresh blood
   on the outside of their mouthparts.  Mechanical transmission
   does occur in horses, however, with equine infectious anemia,
   a virus closely related to AIDS and transmitted by horseflies.
   These flies are "pool feeders"; their bite causes a small
   puddle of blood to form, and they immerse their mouthparts,
   head and front legs while lapping it up.  If disturbed, however,
   they quickly move on to another horse, where the fresh blood of
   the two hosts may mingle.  Blood feeding mosquitoes are much
   neater and more surgical; they insert a tube for drawing blood,
   and by the time they are ready for their next meal, even on a
   second host following an interrupted meal, any viruses from the
   first meal are safely stored in their midgut.

   With biological transmission, the pathogen must complete a
   portion of its life cycle within a carrier, or vector, species.
   Protozoans that cause malaria, for instance, go through an
   extremely complex cycle inside the mosquito, eventually con-
   gregating in the salivary glands, from which they may infect
   avian, primate or reptilian hosts, depending on the malaria
   species.  The HIV virus, however, does not replicate or develop
   in the mosquito; once in the insect's gut, the virus quickly
   dies.  Repeated studies since 1986 show that AIDS-infected blood
   fed to mosquitoes and other arthropods does not live to be
   passed on and that there is no biological-transmission cycle of
   AIDS in blood-feeding arthropods, which frequently ingest the
   virus as part of their blood meal. -R.M.
                   --------------------------------

Regards, Harrington  hlaufman@magnus.acs.ohio-state.edu