As a paraisitology teaching assistant for four years in a row, I had
to chime in on this one. Coccidian parasites are one of my favorites and I
lecture every year about Toxoplasma gondi.
Toxoplasma gondi is carried by cats. It is a protozoan parasite.
Cats are its definitive host; it sexually reproduces only in cats. It
reproduces asexually in its intermediate hosts which include any animal that
comes into contact with cat feces including humans, pigs, cows, mice and
rats. Most humans have been exposed to Toxoplasmosis and usually it is a
mild, asymptomatic event. After that, humans have antibodies that fight the
organism rather effectively.
However, the greatest risk is to pregnant women. Toxoplasma can be
transmitted through the placenta to the fetus and cause severe brain damage,
blindness and death to the fetus. Under no circumstances should a pregnant
woman change a litter box. Even if the cat is an indoor cat, it can still
have Toxoplasma. Immunocompromised individuals, such as the elderly and
AIDs patients, are also at risk. The rest of the population is at little
risk from this parasite.
It is still a good idea to throughly cook meat, especially pork.
Pigs eat anything and they cary many different parasites. It is not worth
the risk. Cows are a little more picky about what they eat and rare beef is
less risky (but the risk exists).
In case you don't think this is bird related, Toxoplasma gondi has
been found in birds as well (afterall, cats eat birds).

At 16:52 11/9/97 -0700, you wrote:
>M. Donahue wrote:
>>Furthermore, cats can carry the toxoplasma parasite, which is a very real
>>human health hazard, for pregnant women and people that have compromised
>>immune systems.
>
>Well, yes, cats can carry it, and under some (usually easily avoided)
>circumstances can transmit it to humans (maybe--there's some controversy).
>But a much bigger source of infection is from meat. Anyone at risk from
>toxoplasmosis shouldn't handle raw meats (or at least should be extra
>careful about it), and shouldn't eat rare meats.
>
(snip)
Deb Beutler
Department of Zoology
Washington State Univerisity
Pullman, Whitman Co., WA
dbeutler at wsunix.wsu.edu