What are waterborne pathogens?

Pathos is Greek for suffering, and -gen is a suffix meaning producer, also from Greek. Thus, a waterborne pathogen is a disease maker that occurs in the water. These “germs” are living microscopic organisms-microorganisms or microbes--that take in food, give off wastes, grow, reproduce, and die. The most common types of waterborne pathogens are bacteria, but they also include viruses, protozoa, and certain kinds of algae. Not all microorganisms, however, are harmful. In fact, most microorganisms are beneficial and we depend on them, for example, as producers of foods (for example, cheese, yogurts, and other dairy products) or as decomposers of wastes and nutrient recyclers.

Pathogen Pathways
Most microorganisms thrive in places that are warm, wet, dark, and rich in nutrients. Our intestinal tract is all of that and therefore an ideal environment for many pathogens to live and multiply. An infected animal or human host daily excretes millions of pathogenic microbes. The majority of these will not survive the harsh conditions of the outside world. But some of them may find their way into lakes and streams and, perhaps, from there into another host. Almost always, waterborne pathogens enter the water with waste. The waste enters the water with runoff from developments or feedlots, direct releases of untreated sewage, or indirect releases from underground leaks of sewage pipes. Other common sources of pathogens in the water or at the beach are the droppings of seagulls and waterfowl or pet wastes.

Bacteria
Bacteria-tiny, single-celled life forms visible only under a microscope--cause most waterborne diseases. But not all bacteria cause harm and disease. Bacteria are in fact the most common life forms on the planet and play many critical roles in the food chain, as decomposers, and by recycling nutrients essential for animals and plants. Key bacterial pathogens responsible for waterborne disease include Salmonella typhi (typhoid fever), Shigella (shigellosis), and Vibrio cholerae (cholera). These pathogens measure from 0.4 to 14 m (one m or “micrometer” equals one one-thousandth of a millimeter) in length and 0.2 to 1.2 m in width.

Faecal Coliform
Faecal coliform bacteria are a group of bacteria that occur in large numbers in the gut and faeces of humans and other mammals. They enter streams and lakes with sewage or wastes. Most faecal coliforms are normal inhabitants of the digestive tract and considered relatively harmless. In fact, their absence can lead to some types of vitamin deficiencies in humans. However, their detection in water may indicate the presence of more harmful microorganisms found in faeces. E. coli is the major species of the faecal coliform group.

E.Coli
Escherichia coli (or E. coli for short) is a common bacterium that lives in human and animal intestines, where it is present in large numbers. There are hundreds of E. coli strains and most are relatively harmless, causing illnesses such as traveler’s diarrhea only when consumed in exceedingly high numbers. A notorious exception is E. coli strain 0157:H7, an emerging pathogen that produces a powerful toxin and can cause severe illness. E. coli O157:H7 was first recognized as a cause of illness during an outbreak in 1982 traced to contaminated hamburgers. Since seen, incidents were also reported were people became sick after drinking or swimming in water contaminated by E. coli 0157:H7. Symptoms of poisoning by E. coli 0157:H7 include bloody diarrhea, kidney damage, and occasionally death.

More on pathogens may be read here.

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