Waterborne Illnesses
All of these pathogenic microbes are transmitted via the Fecal-Oral route, which means the infected stool of a person or animal enters the digestive tract of an uninfected person. This can occur from swimming or drinking water from a river downstream from a cattle pasture or drinking water from a well that has been infected from broken sewage pipes.
This river is central to Mayan life in Belize, Central America. It is clear and beautiful but is full of harmful microbes that can cause waterborne illnesses or WAD.
Certain issues can lead to increased risk of waterborne illnesses or WAD.
- Increased rainfall can lead to increased run-off from farm and ranch land, and sewage
- Sewage leakage from faulty or damaged septic systems
- Higher concentration of people in popular recreation spots leads naturally to a higher concentration of pathogenic microbes in the water
- Cattle pastures upstream or up elevation from your location
Waterborne illnesses or WAD can be caused by bacteria, viruses or protozoan cysts. We will not explore the characteristics of these pathogenic microbes here but instead will concentrate on prevention. All you must know now is that it can take as little as 10 of some of these microbes to infect you or your family, many times less than what you could fit on the end of a needle. It is not my intent to make germophobes out of you, but just to impart an understanding of how to prevent infection.
We’ll take one particular type from each category to do our comparisons. For our bacteria we’ll use Shigella, for our virus, Norovirus and we’ll use Cryptosporidium for our protozoan cyst.
There are three primary techniques to disinfect water. First let’s define disinfection. Disinfection is the process of reducing or inhibiting microbial growth. Notice that not ALL of the microbes are killed; that is called sterilization, something you are less likely to do in the wilderness.
The three techniques are:
- Halogenation – the use of chemicals such as iodine or chlorine. As you’ll see below, some of these microbes are resistant to chemical disinfectants. Also, halogenation can be affected by low temperature and poor water quality (turbidity).
- Filtration – passing water through a filter matrix, preventing the passage of harmful microbes. Filtration works on most all bacteria and protozoan cysts but the majority of filter matrixes have too large a pore size to stop viruses from freely passing through. The EPA’s Office of Pesticides, Antimicrobial Division developed a standard for microbial water purifiers that requires they remove 99.99% of poliovirus type 1 which is a mere 25 nm in size (Note #1: notice that most filtration systems are measured in micrometers or microns. The chart here is in nanometers. There are 1,000 nanometers in 1 micrometer.) There are filters called structured matrix units that can remove many different viruses not by restrictive pores but through isoelectric points and hydrophobicity (scared of water). These systems rely on the chemical nature of the protein coat of the virus. The question of water turbidity (murky water) or biofilm (slim) buildup after prolonged use arises as a potential problem, blocking the filters properties.
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Pasteurization – heating the water. Prolonged boiling is required to sterilize water but most pathogens are killed within minutes at temperatures of 80-90 C.
(Note #2: Be careful when a product says that it removes 99.99% of harmful bacteria. If you start with a million pathogenic microbes in your water bottle (low amount), a 99.99% reduction brings you to 100 harmful bacteria some of which you only need to ingest 10 to cause serious infection. Bottom line is don’t rely solely on filtration if your water source is in question. Or run it through your filter two to three times because you will remove 99.99% of each newly filter sample.)
The following chart compares the disinfection techniques in regard to each type of pathogenic microbe we are discussing.
The parasite Cryptosporidium is not killed by freezing or by the usual levels of chlorine in swimming pools or drinking water as it is protected by an outer shell that makes it resistant to chlorine.
Recommendations to avoid waterborne illnesses or WAD:
- Experts recommend pasteurization or the combination of filtration followed by halogenation.
- Take your water from the first 12 inches of the steam or lake as the UV from the sun kills many microbes. UV sticks are actually a fourth type of disinfectant that works well.
- Spend the money on good filtration for you and your family
- Remember that just because it’s a clear mountain or jungle stream, it still has harmful microbes. Who knows what the village over the hill is doing in it.
- Know what is upstream from you if at all possible
REHYDRATION, REHYDRATION, REHYDRATION
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