Treatment Review #17 - March 1995
A recent meeting about cryptosporidiosis was held at The AIDS
Center of Mount Sinai Medical Center in Manhattan. These
meetings are open to anyone interested. The number to call if
you're interested in getting notices about the meetings is
(212) 241-1897. The presenter was Dr. Rosemary Soave, who's
doing research at NYU/Cornell.
Cryptosporidiosis is a protozoal infection. Infection can come
from water, or person to person. Infection causes watery
diarrhea that can last for weeks. Once infected, even if the
infection is controlled by your immune system, it appears that
you can become ill again.
The individual protozoa are called oocysts. The oocysts are
resistant to the environment, which means they can last many
months in water and continue to be infectious. The oocysts are
also resistant to disinfectants. Pure undiluted bleach won't
kill the oocysts until at least 20 minutes have gone by. A
swimming pool is only 1-2% chlorine, so swimming pool water is
Once you're infected with cryptosporidiosis, the oocysts make
more of themselves, infecting new cells. Different species of
cryptosporidiosis infect cattle, humans, birds and fish. The
same species, called C. parvum, infects both cattle and humans.
Cow stool can potentially wash into reservoirs. Pasteurizing
milk kills cryptosporidiosis. We don't yet know whether bird or
fish species can infect humans.
We don't know how cryptosporidiosis causes infection. Large
adult animals, like cows, are commonly infected but don't get
sick. Veterinarians have been looking for a treatment since the
seventies because the infection can kill newborn calves.
Small animals like mice don't get symptomatic infection so
there's been nothing to study in the lab. Cryptosporidiosis is
found everywhere, but we don't know how many people are
carrying the organism. In people with AIDS, 10-20% appear to
We don't know which part of cryptosporidiosis your immune
system responds to in order to make antibodies. It's impossible
to grow cryptosporidiosis in the lab because researchers can't
clean up stool enough to make sure there isn't contamination
from something else. Because it's impossible to grow
cryptosporidiosis in the lab, and because there are no small
animals that come down with the disease, there are still many
unanswered questions about cryptosporidiosis.
It's pretty clear that transmission happens between people
because if one person in a family has cryptosporidiosis, other
members in the family are likely to be infected. Sexual
transmission probably also occurs. Cryptosporidiosis is water
born. People's awareness of cryptosporidiosis was heightened by
the outbreak in Milwaukee in 1993. Doctors don't automatically
look for cryptosporidiosis as a cause of infection. Be sure and
ask your doctor to tell the lab to test for cryptosporidiosis,
if you have diarrhea for several weeks.
All the outbreaks have been in cities with public water
filtering systems. New York City doesn't have a filtered water
system, but it doesn't make a difference anyway. Pressure to
install filtered systems at huge expense is political, and not
based on scientific fact.
Dr. Soave feels that awareness of cryptosporidiosis is high in
New York City. We are not at risk of an epidemic. In examining
the water, 1-2 oocysts have been found in stains of 100 liters
of water. A stain is a process in the lab by which researchers
can see the organisms. We don't know if these 2 oocysts are
definitely cryptosporidiosis, if they are dead or alive, or how
many you need to become infected. Since nobody sits down and
drinks 100 liters of water at one time, so the risk of
infection from drinking water in New York City appears to be
The big question is, "What do you advise people to do?" Dr.
Soave suggests, if you're uncomfortable about the potential for
infection, boil all your drinking water for one minute. One
minute is enough to kill the oocysts - if they exist. Once you
start boiling your drinking water though, you should also brush
your teeth with boiled water and wash your vegetables with
boiled water. Dr. Soave felt this was burdensome, and that
boiling all the water you use is not necessary based on what we
Some bottled waters make claims to be cryptosporidiosis free,
but Dr. Soave said there is no data, and that none of the
waters or bottling plants are regularly tested for
No really good treatment exists for cryptosporidiosis.
Azithromycin at high doses is effective in some people. Another
treatment being studied is Humatin. Most people who participate
in Dr. Soave's trials have failed Humatin and Azithromycin. Dr.
Soave emphasized that, if you are going to take Azithromycin,
be sure and get the drug directly from Pfizer through their
compassionate use program. This drug is better absorbed. Call
The Network if you need the phone number.
A new study is enrolling using IGX for the treatment of
cryptosporidiosis. IGX is made from chicken egg yolks. The
chickens are treated so they make high levels of
immuno-globulins which fight cryptosporidiosis infection.
Participants in the trial drink a nog made of the egg yolks
five times a day. The eggs are irradiated so there is no
possibility of salmonella or other infection. Dr. Soave has
already seen nutritional benefit from the treatment.
Controlling the diarrhea with IGX has the added benefit of
helping someone who's lost weight put it back on. To
participate in this trial, you must be HIV+ and have
cryptosporidiosis. You cannot have other infections in your
intestines, a history of KS, CMV or MAC in your intestines, or
be allergic to eggs. Call The Network for more information.