Nasty Infectious Diseases You Want To Avoid - Cryptosporidiosis
One of the more recently discovered types of food poisoning is caused by a protozoan Cryptosporidium, which means "hidden spore" in Greek. Cryptosporidium is a type of parasite and is about 1/60th the size of an average dust particle. It has been found in up to 87 percent of surface water samples in the United States. The egglike form of the organism, called oocysts, are passed into the feces of infectious animals, finding their way into water supplies, where they can then enter human intestines. Once in the intestine, they release an infective spore that begins another reproductive cycle. A healthy infected human will experience watery diarrhea and cramps that pass in about a week, but those with impaired immune systems may have a much more serious (or fatal) case. Boiling water for one minute at sea level and three minutes over 6,000 feet is the only way to kill this bacteria, since they can live in chlorinated water. This tiny invisible microbe infects cells lining the intestinal tract, and it was not identified as a cause of human disease until 1976. It is a major threat to the water supply of many developed countries. In the United States, the number of outbreaks that occur each year aren't well documented. However, in 1993, more than 400,000 Milwaukee residents got sick after drinking water contaminated with Cryptosporidium.
Cause - This parasite lives its entire life within the intestinal cells; it produces worms (oocysts) that are excreted in feces. These infectious oocysts can survive outside the human body for long periods of time, passing into food and drinking water, onto objects, and spread from hand to mouth. Unfortunately, chlorine does not kill the protozoan; instead, drinking water must be filtered to eliminate it. Many municipal water supplies do not have the technology to provide this filter. Because the parasite is transmitted by the fecal-oral route, the greatest risk occurs in those infected people who have diarrhea, those with poor personal hygiene, and diapered children.
Symptoms - Between 1 to 12 days after infection, the most common symptom is a watery diarrhea together with stomach cramps, nausea and vomiting, fever, headache, and loss of appetite. Some people with the infection don't experience any symptoms at all. Healthy patients usually exhibit symptoms for about two weeks, but those with impaired immune systems may have a severe and lasting illness. In the Milwaukee outbreak, those affected noticed symptoms between 2 and 10 days after exposure. Some deaths were reported.
Diagnosis - The infection is diagnosed by identifying the parasite during examination of the stool. If cryptosporidiosis is suspected, a specific lab test should be requested, since most labs don't yet routinely perform the necessary tests.
Treatment - There is no standard treatment, but some patients may respond to some antibiotics (paromomycin). Intravenous fluids may be necessary, and antidiarrhea drugs may help.
Prevention - Eradication of the organism from drinking water depends on adequate filtration, not chlorination. Scientists are studying new ways to protect water supplies, including reverse osmosis, membrane filtration. or radiation.
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