Water Disinfection for Travelers

Presented by Dr. Gary Podolsky

Why Disinfect Water?

• Eliminate:
• Invasive Bacteria such as: Salmonella, Shigella, Yersinia, Campylobacter
• Non-invasive Bacteria such as: Entero-toxigenic E. coli, Cholera
• Gastrointestinal Viruses such as: rotavirus, Adenovirus, Noroviruses
• Viruses that enter through the gastrointestinal tract including Polio, Coxsackie, Echo, Hepatitis A and E (B and C?)
• Parasites such as Amoebae, Giardia, and Cryptosporidia
• Viral Enteritis can result in 10-25 watery stools daily. There is no effective therapy
• Viral Enteritis can be debilitating, resulting in dehydration and the need for IV fluids

Cryptosporidia

• Cryptosporidium parvum is an intracellular parasite.
• Cryptosporidia was first detected in Rodents in 1907.
• The first case in humans was in 1976
• Role of immunity was first appreciated in 1980's
• 1993: outbreak in Milwaukee caused > 403, 000 infections; Attack rate over 50%. Resulted in > 100 deaths.
• 1994: outbreak in Las Vegas
• Cryptosporidia is now recognized worldwide. It causes 20% of diarrhea requiring hospitalization. It has been found in >90% of U.S. surface water.
• Note: all it takes is one spore to infect the water supply
• The sporocysts are resistant to most chemical disinfectants but are susceptible to drying and the ultraviolet portion of sunlight which is important in preventing infections.
• Intestinal Cryptosporidiosis is characterized by severe watery diarrhea but may be asymptomatic. Watery diarrhea usually lasts 2-4 days. In some outbreaks diarrhea have lasted 1-4 weeks.
• Pulmonary and Tracheal cryptosporidiosis in humans is associated with coughing, frequently a low-grade fever and severe intestinal distress
• Cryptosporidium could occur on any food touched by a contaminated person
• Known causes include child day care centres that serve food and fertilizing salad vegetables with manure. Large outbreaks occur with contaminated water supplies
• There is no known effective drug for the treatment of cryptosporidiosis.
• Immunocompromised individuals, especially AIDS patients may have the disease for life, with the severe watery diarrhea contributing to death. Therefore, it is feared by HIV patients.
• Invasion of the pulmonary system may also be fatal.
• Cryptosporidium is highly resistant to chlorine and iodine.
• It can be destroyed by boiling; removed by micro filtration

Cyclospora

• In Nepal 10 of 12 British Soldiers developed cyclosporiasis after drinking water disinfected with chlorine
• Known from Guatemala strawberries

Brainerd Diarrhea

• 1983 outbreak in Brainerd, Minn,. Involved 122 people; 10 to 15 daily episodes of explosive watery diarrhea, associated with incontinence
• Typically lasts about 4 weeks.
• Self-Limited and resolves after 3 years
• No effective treatment
• Unknown etiology
• 7 outbreaks since 1983. 6 being in the U.S.
• Sporadic cases do occur
• Unpasteurized milk or poorly disinfected water are involved in transmission

Clean Water: Desirable Features

•  Must eliminate viruses and parasites

•  Bacteria eliminated by all effective techniques

•  Must be simple and convenient

•  Must be relatively fast

•  Must be small and lightweight

•  Must be reliable

•  Available systems are boiling, micro filtration with halides (I 2 and Cl 2 ) and ultraviolet light

Boiling

• Effective for all organisms
• In order to be effective water must achieve a rolling boil for one minute. If above 2, 000 meters (6, 500 feet) the water must be boiled for three minutes in order to be effective.
• Boiling temperature of water falls 1°C per 1, 000 feet of ascent. Temperature should reach 71°C or 160°F at 29, 000 ft
• Boiling is a slow process and is inconvenient. It requires fuel (wood or stove fuel). Wood fires also leave ugly residue
• Boiling is not simple or convenient. It is not small and lightweight. However, it is HIGHLY reliable

Portable Water Filters

• Size comparison

• Water filters are bulky and relatively heavy, expensive, and they readily become obstructed
• Viruses as well as small bacteria may not be removed

Iodine Water Disinfection

• Developed at Harvard in 1945 to make up for unreliable chlorine-based systems being used by the military to disinfect water.
• Iodine was found to be fully effective for bacteria, viruses, and amoebic cysts
• Later iodine was found to be effective for Giardia Cysts
• Iodine concentration of 8mg/l (8ppm) became the standard. 8 mg/l needed only for parasitic cysts
• Unfortunately, 8 mg/l has a strong unpleasant iodine taste
• 0.5 to 1 mg/l kills viruses and bacteria
• Filtered water with 0.5 to 1 mg/l of Iodine has been used in Florida prisons for 15 years (with careful testing)
• Exposure time of 10 minutes is standard
• 90 seconds is adequate for bacteria and viruses
• Standard contact times (With margin of safety):
• Warm water (>5°C or 40°F) takes 10 minutes
• Cold water (<5°C or 40°F) takes 20 minutes

Iodine Toxicity

• Iodine is stable, pH insensitive, and is only mildly bound by organic materials
• “… iodine is highly toxic is a common fallacy (Goodman and Gillman: The pharmacologic Bases of Therapeutics, 3 rd Ed).”
• Toxic dose: 2g-10g. Ingestion produces gastric irritation and vomiting.
• From 1915 to 1936, 327 attempted suicides with iodine reached Boston City Hospital. Not a single one died!
• Prolonged iodine use
• Florida prisoners had no thyroid abnormalities
• 101 babies born after 122 to 270 days in prison had no thyroid enlargement or dysfunction
• Real Problems: taste, allergy, thyroid problems

Eliminating the taste of iodine

• Adding citrate or ascorbic acid (fruit flavourings), Activated charcoal, or Sodium Thiosulfate
• Must not be added until disinfection is complete
• Prolonging contact time: iodine disinfection is a “straight line” reaction; ½ Iodine for twice the contact time or ¼ iodine for four times the contact time are just as effective
• 8 mg I 2 in 4 L water for 40 minutes; 8 mg I 2 in 5 Gallons overnight; 2 mg/l of I 2 is taste threshold

Other Iodine Problems

• Persons with thyroid disorders should try iodine disinfected water at home
• Those intolerant or allergic must use another system
• Reliable iodine systems
• Iodine Resins: Tri-to Pentaiodide Resin filters added to regular filters to kill viruses. There is no indicator of exhaustion (Filter obstruction is possible)
• Tetraglycine Hydroperiodide: Potable Aqua ® , Globaline ® , EDWGT ® Tablets, Tablets provide 8mg iodine, if fresh. Tablets are convenient and small bottles resist breaking. They have a long shelf life when unopened. However, there is a strong iodine taste and there is no way to measure 1mg.
• Saturated Aqueous Solution: contains 2mg of Crystalline I 2 in 1oz bottle. The bottle contains a paper cap liner. Fill with water and place in pocket for 1 hour. The Solution contains 16-18mg of Iodine. Disadvantages of this solution: Iodine crystal toxicity and ineffectiveness against Giardia cysts.
• Tincture of Iodine: Useful in Urban emergencies when electric power or gas supplies have been interrupted. It is very reliable and readily available. However, excess iodine (Nal, Kl) has no disinfecting action. This solution produces a stronger iodine taste than other preparations with the same iodine concentration. The USP tincture is 2%.

Chlorine Water Disinfection

• Preparations are unstable, slow, pH sensitive, and bound by organic compounds
• Effective chlorine disinfectants include: chlorine bleach, “Superchlorinators.” For example, Sierra Water Purifier and SafeAqua.com, and MSR MIOX Purifier
• Liquid Bleach is 5% Sodium Hypochlorite
• Antimicrobial activity in water is unproven
• Unstable (loses chlorine when agitated)
• In order to disinfect in cold water (<60°F or 16°C) use 2 drops of liquid bleach and let stand for 45 minutes. In warmer water use 2 drops of liquid bleach and let stand for 30 minutes.
• The trouble with “Superchlorinators” is that they add far more chlorine than needed.
• After 10 to 20 minutes chlorine is driven off with 30% H 2 O 2 or Zinc.
• Chlorine water disinfection is more suitable for quantities of water larger than one litter.

MIOX MSR “Purifier”

• In Fall of 2003 MIOX and (MSR) released a new chlorine-based water disinfection system
• Larger units using same “Electrolysis” procedure have been in operation since 1994.
• Grand award winner in general innovation category for popular science's “Best of what's New” issue.
• Electrical current through saline solution produces oxidants, particularly hypochlorous acid, which is the most effective chlorine-based disinfectant
• Effectively eliminates bacteria and viruses from water in 30 minutes
• Cryptosporidia takes 4 hours to kill with this purifier

Ultraviolet Water Disinfection

• “Steri-Pen”® is a recently devised ultraviolet water disinfection device
• Disinfects 16 oz of water in 45-60 seconds.
• 4 alkaline batteries provide 20-40 treatments. Rechargeable batteries provide 60-70 treatments. Lithium batteries provide 120-140 treatments.
• Weighs 6-8 oz depending on the type of batteries; costs $100.00
• Website states “Steri-Pen” meets EPA Standards: destroys 99.9999% of bacteria, 99.99% of virus, and 99.9% of protozoa (including cryptosporidia)
• Reports of investigations at UME, UAZ, UNC, and OR HSU are available on website
• 2001 “Invention of the year” by Time magazine
• ? Disinfects only 16 oz at a time.

Essentials of Water Disinfection for Wilderness and Developing Countries

• Filtration to remove Cryptosporidia and Halides to kill viruses
• Ultraviolet Light
• Close attention to food preparation and water disinfection