CRYPTOSPORIDIUM
CRYPTOSPORIDIUM
Cryptosporidium, ?crypto? for short, is a widespread, water borne protozoa. If you get infected you get a disease called Cryptosporidiosis and you will get very sick but probably won?t die. If you get Cryptosporidiosis and have or catch nearly any other series disease at the same time, including ?regular? influenza you will probably die. However, if you get Cryptosporidiosis and Bird Flu, you will surely die.
In discussing Cryptosporidium, it is worth noting that there is a similar pathogen called Giardia, which is just as widespread, if not more so, and which causes Giardiasis and is another disease you do not want to be catching either. However, in the grand scheme of things, Giardia is not quite as bad as Crypto and any mediation efforts done for Crypto will automatically take care of Giardia. In fact, many of the efforts to eradicate Crypto will also take care of most pathogens, with the possible exception of a virus.
Cryptosporidium is already in the raw water of most municipal water supplies as nearly all surface water sources are polluted with Crypto and it is getting worse every year. Crypto has a life cycle where its eggs, called cysts, have a nearly impenetrable hard outer shell. In this stage it is VERY HARD to kill. As a result your municipal water source has added or increased the methods used to try to kill it and usually added additional and very extensive filtering to prevent it from getting through and coming out your tap.
Occasionally, however, something goes wrong and, as a result of Cryptosporidium, bad things can happen to a lot of people. In the Milwaukee incident, 400,000 people were infected, thousands hospitalized, and hundreds died. Many of those who were infected never completely recovered and have lasting side affects. Smaller Crypto infections are occurring with increasing frequency every year, including recent outbreaks in Nevada, Oregon and Georgia.
The reason you are even reading this paper is because you expect to be in a situation where the water coming out of your tap is suspect or there is no water coming out of your tap and most likely the alternative source of water that you will be using is polluted. If that water is surface water there is a high probability that it is already infected with Cryptosporidium. As the Milwaukee incident revealed however, it does not take an outside factor to occur for you to get infected with Cryptosporidium.
How hard are Cryptosporidium cysts to kill? As noted in Disinfection and oocyst survival ?Few commercial disinfectants are effective against the oocysts, nor is chlorination at normal drinking water treatment levels? and one study noted that ?long-term exposure to 70-100% bleach is necessary to completely eliminate infectivity? and ?3% chlorine as Na hypochlorite for up to 18 h does not affect viability.? Another report noted that ?crypto cysts suspended in 5.25% aqueous Na hypochlorite (full-strength Clorox bleach) for up to 2 h still initiated infection.?
For more information on Cryptosporidium, see: A Review of Cryptosporidiosis and Cryptosporidium parvum: an emerging pathogen
What will disinfect water of Cryptosporidium? According to the Army:
Chlorine: Ineffective, even at high CT values. (CT= Concentration X Time in mg minutes per liter)
Chlorine Dioxide: Effective at high CT values. If possible, use longer contact times instead of higher dosages to achieve adequate CT values. Colder water temperatures require higher CT values. Use a two-fold increase in CT for every 10? C decrease.
Iodine: Not Effective
UV: Effective at reasonable doses.
The bottom line for our emergency water scenarios is that there is nothing you can add to polluted water to be 100% sure of killing Cryptosporidium, despite what others may be saying. The only viable additive solution for our purposes that might POSSIBLY kill Cryptosporidium is Chlorine Dioxide, covered in the Chemical section, below.
However, all is not lost. Crypto can be killed with heat and is relatively easy to filter out of water. The heating methods are discussed immediately below and for filtering all you need is a mechanical filter with an absolute pore size of 2 microns, ideally 1 micron. This is covered in the Filter section.
When selecting a filtration system for Cryptosporidium, the system should have one or all of the following characteristics (Juranek, 1995):
? it can remove particles that are 0.1-1 micrometers in size
? filters water by reverse osmosis
? it has an "absolute" 1-micron filter
? meets NSF standard no. 53 for "cyst removal"
On the other hand, filters that have the following characteristics do NOT guarantee >99% removal of Cryptosporidium oocysts (Juranek, 1995):
? filters with a "nominal" 1-micron rating
? only employs ultraviolet light
? uses only activated carbon for filtration
? utilizes pentiodide-impregnated resins
? it is listed as effective against the Giardia species
All this and more in my (free and I'm not selling any thing) Water Report. ~95 pages. Send me ane-mail to get a copy. pwag@lycos.com
CRYPTOSPORIDIUM
Cryptosporidium, ?crypto? for short, is a widespread, water borne protozoa. If you get infected you get a disease called Cryptosporidiosis and you will get very sick but probably won?t die. If you get Cryptosporidiosis and have or catch nearly any other series disease at the same time, including ?regular? influenza you will probably die. However, if you get Cryptosporidiosis and Bird Flu, you will surely die.
In discussing Cryptosporidium, it is worth noting that there is a similar pathogen called Giardia, which is just as widespread, if not more so, and which causes Giardiasis and is another disease you do not want to be catching either. However, in the grand scheme of things, Giardia is not quite as bad as Crypto and any mediation efforts done for Crypto will automatically take care of Giardia. In fact, many of the efforts to eradicate Crypto will also take care of most pathogens, with the possible exception of a virus.
Cryptosporidium is already in the raw water of most municipal water supplies as nearly all surface water sources are polluted with Crypto and it is getting worse every year. Crypto has a life cycle where its eggs, called cysts, have a nearly impenetrable hard outer shell. In this stage it is VERY HARD to kill. As a result your municipal water source has added or increased the methods used to try to kill it and usually added additional and very extensive filtering to prevent it from getting through and coming out your tap.
Occasionally, however, something goes wrong and, as a result of Cryptosporidium, bad things can happen to a lot of people. In the Milwaukee incident, 400,000 people were infected, thousands hospitalized, and hundreds died. Many of those who were infected never completely recovered and have lasting side affects. Smaller Crypto infections are occurring with increasing frequency every year, including recent outbreaks in Nevada, Oregon and Georgia.
The reason you are even reading this paper is because you expect to be in a situation where the water coming out of your tap is suspect or there is no water coming out of your tap and most likely the alternative source of water that you will be using is polluted. If that water is surface water there is a high probability that it is already infected with Cryptosporidium. As the Milwaukee incident revealed however, it does not take an outside factor to occur for you to get infected with Cryptosporidium.
How hard are Cryptosporidium cysts to kill? As noted in Disinfection and oocyst survival ?Few commercial disinfectants are effective against the oocysts, nor is chlorination at normal drinking water treatment levels? and one study noted that ?long-term exposure to 70-100% bleach is necessary to completely eliminate infectivity? and ?3% chlorine as Na hypochlorite for up to 18 h does not affect viability.? Another report noted that ?crypto cysts suspended in 5.25% aqueous Na hypochlorite (full-strength Clorox bleach) for up to 2 h still initiated infection.?
For more information on Cryptosporidium, see: A Review of Cryptosporidiosis and Cryptosporidium parvum: an emerging pathogen
What will disinfect water of Cryptosporidium? According to the Army:
Chlorine: Ineffective, even at high CT values. (CT= Concentration X Time in mg minutes per liter)
Chlorine Dioxide: Effective at high CT values. If possible, use longer contact times instead of higher dosages to achieve adequate CT values. Colder water temperatures require higher CT values. Use a two-fold increase in CT for every 10? C decrease.
Iodine: Not Effective
UV: Effective at reasonable doses.
The bottom line for our emergency water scenarios is that there is nothing you can add to polluted water to be 100% sure of killing Cryptosporidium, despite what others may be saying. The only viable additive solution for our purposes that might POSSIBLY kill Cryptosporidium is Chlorine Dioxide, covered in the Chemical section, below.
However, all is not lost. Crypto can be killed with heat and is relatively easy to filter out of water. The heating methods are discussed immediately below and for filtering all you need is a mechanical filter with an absolute pore size of 2 microns, ideally 1 micron. This is covered in the Filter section.
When selecting a filtration system for Cryptosporidium, the system should have one or all of the following characteristics (Juranek, 1995):
? it can remove particles that are 0.1-1 micrometers in size
? filters water by reverse osmosis
? it has an "absolute" 1-micron filter
? meets NSF standard no. 53 for "cyst removal"
On the other hand, filters that have the following characteristics do NOT guarantee >99% removal of Cryptosporidium oocysts (Juranek, 1995):
? filters with a "nominal" 1-micron rating
? only employs ultraviolet light
? uses only activated carbon for filtration
? utilizes pentiodide-impregnated resins
? it is listed as effective against the Giardia species
All this and more in my (free and I'm not selling any thing) Water Report. ~95 pages. Send me ane-mail to get a copy. pwag@lycos.com
