Treatment Review #17 - March 1995

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 potentially infectious.

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 be infected.

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 very small.

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 know.

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 cryptosporidiosis.

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.

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