FORMS OF MICRO-ORGANISMS IN DRINKING WATER, PART II

　　Investigating Microorganisms in Drinking Water: Part II – INTestinal PARAsites Parasitic worms, belonging to the animalia kingdom, consist of three discrete groups—platyhelminthes, nematodes, and rotifers—which are frequently encountered in aquatic settings. These organisms primarily reside on the substrates of aquatic bodies, playing essential roles as decomposers. Rotifers are unique among these, living close to the water’s surface and flourishing mainly in stagnant freshwater. Water can sometimes become tainted with the eggs and larvae of various gut parasites originating from humans and other endothermic animals. Contamination of this nature seldom causes extensive infections, primarily due to the parasites’ relative scarcity and their size, which facilitates easy removal via filtration systems. Parasitic worms, such as flukes, tapeworms, hookworms, Ascaris, pinworms, trichinae, and filariae, are generally 30 to 50 microns in diameter.

　　PROTOZOAProtozoa are a fundamental group within the Protista domain, known as microscopic, animal-like organisms. They inhabit a range of aquatic environments, from the surface to the depths of the ocean, with many existing parasitically within hosts. Protozoa, like other life forms, can have either positive or negative impacts. On occasion, drinking water may be contaminated with protozoa that, although not illness-causing, produce an undesirable fishy taste and odor. These organisms can be either aerobic or anaerobic, depending on the availability of oxygen. Some protozoa form cysts as a protective measure in adverse conditions. In a more favorable environment, such as within a warm-blooded creature, they shed their cyst walls and circulate in the host’s bloodstream. One type of cyst-forming protozoan is responsible for amoebic dysentery, a condition that currently lacks a universal remedy. Giardia lamblia and cryptosporidium are well-known for causing Acute Gastrointestinal Illness (AGI), the most frequently diagnosed waterborne disease in the United States. AGI symptoms, including severe dehydration, weight loss, and fatigue, can last for several months. These cysts, which range from 2 to 50 microns in diameter, are larger than bacteria and can be removed through fine water filtration.

　　NEMATODESNematodes, categorized within the phylum of worms known as roundworms, have elongated, unsegmented cylindrical bodies. Nematodes that parasitize humans and warm-blooded animals are often visible to the naked eye, whereas their freshwater and soil counterparts are typically microscopic. These creatures can pollute drinking water, leading to unpleasant tastes and odors. Although they are suspected of harboring disease-causing bacteria from the intestines of endothermic animals, this is considered a rare event. Nematodes are commonly found in municipal water supplies that originate from surface waters. (Continued)