PARASITES

Toxoplasma, the cause of the disease, toxoplasmosis (TOX-o-plaz-MO-sis), is a single-celled, microscopic parasite found throughout the world. It is interesting to note that these organisms can only carry out their reproductive cycle within members of the cat family. In this parasite-host relationship, the cat is the definitive host. The infective stage (oocyst) develops in the gut of the cat. The oocysts are then shed into the environment with cat feces.

The CDC says it's found Naegleria fowleri, an almost always deadly amoeba, in drinking water supplies for the first time in the United States.
The CDC says it’s found Naegleria fowleri, an almost always deadly amoeba, in a U.S. drinking water supply for the first time.

A deadly brain amoeba that’s killed two boys this year has been found in a U.S. drinking water supply system for the first time, officials said Monday — in a New Orleans-area system.

The Naegleria fowleri parasite killed a 4-year-old Mississippi boy who likely got it playing on a back yard Slip ‘N Slide, Centers for Disease Control and Prevention officials say. Tests show it’s present throughout the water supply system in St. Bernard Parish, directly southeast of New Orleans.

“We have never seen Naegleria colonizing a treated water supply before,” said Dr. Michael Beach, head of water safety for the CDC. “From a U.S. perspective this is a unique situation.”

N. fowleri is a heat-loving amoeba that’s usually harmless, unless it gets up someone’s nose. It’s not entirely clear how or why, but in rare instances it can attach to one of the nerves that takes smell signals to the brain. There, the amoeba reproduces and the brain swelling and infection that follows is almost always deadly.

Amoebas—blob-shaped microbes linked to several deadly diseases—contaminate drinking-water systems around the world, according to a new analysis. The study finds that amoebas are appearing often enough in water supplies and even in treated tap water to be considered a potential health risk.

A number of these microorganisms can directly trigger disease, from a blinding corneal infection to a rapidly lethal brain inflammation. But many amoebas possess an equally sinister if less well-recognized alter ego: As Trojan horses, they can carry around harmful bacteria, allowing many types to not only multiply inside amoeba cells but also evade disinfection agents at water-treatment facilities.

  THE TOPIC IS GIARDIA, CRYTOSPORIDIUM, AND WATERBORNE DISEASE. GIARDIA AND CRYTOSPORIDIUM ARE BECOMING THE MOST WIDESPREAD INTESTINAL PARASITES, I.E., DISEASE CAUSING ORGANISMS, ASSOCIATED WITH WATERBORNE DISEASE.These organisms are not bacteria or viruses, but protozoans with complex life cycles. Outside of the host, the organisms are in a cyst stage, which is much like a seed for a plant or microscopic egg.  The size of the Giardia cyst is approximately 8 to 14 um; whereas, the Crytosporidium oocysts are usually 4 to 6 microns in diameter.  (Note: 1 micron = 0.001 mm = 0.00004 inches ), which is too small to see with the naked eye. These organisms are reasonable for over 100,000 causes of reported outbreaks of waterborne, since 1979.  These are not new organisms and in fact Van Leeuwenhoek first describe Giardia cysts in 1681, but these organisms have not been identified as disease causing agents until the last two decades.
The Disease:Upon ingestion, the acids in the stomach cause the cysts or oocysts to begin to ex-cyst (“like hatching an egg”) and the organism begins to reproduce in the intestines. As few as 10 Giardiacysts have been shown to cause the disease giardiasis and it is not currently known the minimum number of oocysts need to get the disease cryptosporidiosis.  The disease creates symptoms that mimic other gastrointestinal problems and the common symptoms are persistent diarrhea, weight loss, abdominal cramps, nausea, and dehydration. In general, the symptoms begin within a week after exposure and the acute symptoms can last for up to 2 weeks, but chronic symptoms can last for up to 2 months.