Published By: Water Quality
Overview
Protozoa are unicellular microorganisms, generally slightly larger than bacteria (i.e. 1 to 25 mm) with a more complex cell structure. They are usually transmitted in the cyst form (a dormant, protected state), which can be resistant to disinfection. Disinfection alone, therefore, needs to be optimized for removing the particular cysts that may be present in water supplies. Some of the pathogenic protozoans that may be transmitted by water are:
Cryptosporidium
The San Francisco Public Utilities Commission (SFPUC) continues its commitment to provide safe, high quality drinking water through aggressive watershed protection and appropriate water treatment. While tap water is safe, it is not sterile. People with weakened immune systems may be more vulnerable to Cryptosporidium than others and should seek advice about protective measures, including precautions related to drinking water, from their health care provider.
The SFPUC tests for Cryptosporidium in both source and treated water supplies at least once a month. Occasionally (about 6 percent of the time) very low levels of Cryptosporidium are detected in the Hetch Hetchy, East Bay and San Francisco Peninsula source waters. No Cryptosporidium was detected in the City of San Francisco's tap water in 2002, while in 2000 and 2001 Cryptosporidium was occasionally found at very low levels.
What is Cryptosporidium?
Cryptosporidium (KRIP-toe-spor-ID-ee-um) is a one-celled organism that can cause a diarrheal disease known as cryptosporidiosis. Cryptosporidium can live in the intestines of humans, farm animals, wild animals and household pets. Cryptosporidium is too small to be seen by the naked eye. It can live outside the body for a long time in water and on surfaces, but cannot multiply unless it is in the intestines. If a person or animal swallows cryptosporidium, they can get sick and have watery diarrhea, stomach cramps, an upset stomach or a slight fever.
Where is Cryptosporidium Found?
Both human and animal feces (that is, bowel movements) can contain cryptosporidium. Cryptosporidium has found its way into most lakes, rivers and streams (surface waters) in all parts of the United States. It may also sometimes be found in wells, springs, and even in bottled water. San Francisco's pristine water sources have very little cryptosporidium.
How Can Cryptosporidium Affect My Health?
Two to ten days after cryptosporidium is swallowed, symptoms such as watery diarrhea, stomach cramps, vomiting, upset stomach or a slight fever may appear. Healthy individuals with normal immune systems may have symptoms that last for 2 weeks or less, although they may feel better and then worse. Some people with cryptosporidiosis may not get sick, but they can still pass the disease to others. After infection, cryptosporidium can be passed in feces for up to 2 months, and may infect other people. People with severely weakened immune systems may have cryptosporidiosis for a longer time and should talk with their health care providers to learn how to avoid cryptosporidiosis. Examples of people with weakened immune systems include HIV/AIDS patients and cancer and transplant patients. HIV/AIDS patients may be able to receive highly active antiretroviral therapy to improve their immune status to help them avoid cryptosporidiosis.
How Would I Know If I Have Cryptosporidiosis?
If you have severe diarrhea for more than 4 days, you should ask your doctor to have your feces tested for cryptosporidium. If you have a very young child with severe diarrhea, you should go even sooner. Only a test of your feces can show whether or not you have cryptosporidiosis. Most people will recover on their own.
What Is the Treatment for Cryptosporidiosis?
In July 2005, the Food and Drug Administration approved the drug Alina (nitazoxanide) for the treatment of cryptosporidiosis in immunocompetent adults and children. Most people will still recover on their own. You should drink plenty of fluids if you have diarrhea. Alina has not been shown to be effective against infection in immunosuppressed individuals; if you have a weakened immune system, you should seek medical advice. Treatment with highly active antiretroviral therapy can improve immune status and help prevent or manage cryptosporidiosis.
How Is Cryptosporidiosis Spread?
You can become infected only by swallowing cryptosporidium oocysts. Even a small amount may cause disease. Some sources of disease are:
- Contact with the feces of infected persons (e.g., changing diapers, sexual practices).
- Contact with the feces of infected animals (e.g., pets and farm animals).
- Hand-to-mouth transfer of cryptosporidium from surfaces or objects that may have gotten infected feces on them (e.g., diaper changing tables, garden soil, bathrooms).
- Swallowing water with cryptosporidium in it while swimming.
- Drinking water with cryptosporidium in it.
- Eating raw or undercooked food that has cryptosporidium in it.
How Can I Protect Myself?
- Always wash your hands with soap and water any time you might have touched human or animal feces, changed diapers, cleaned up feces, or gardened.
- Always wash your hands before eating.
- Avoid sex that may involve contact with feces.
- Know the source of your water: (a) do not drink or swallow water directly from rivers, lakes, streams, pools or spas, (b) if you travel outside the United States you may want to avoid drinking water that has not been boiled or filtered for cryptosporidium.
If you are immunocompromised you should consider additional protective steps such as boiling your drinking water for one minute, which will kill any crypto in it. You could also use a water filter certified by National Sanitation Foundation (NSF) International to remove cysts or drink only bottled water certified by NSF International or canned and bottled bubbly drinks. If you are an HIV/AIDS patient, you should talk to your health care provider about receiving highly active antiretroviral therapy, which can improve your immune status and provide protection against cryptosporidiosis.
For More Information
- Call NSF International to learn more about water filters and bottled water (1-877-867-3435)
- Call the SFPUC Water Quality Bureau for water quality information (650-652-3127 or 877-737-8297)
- Call the Environmental Protection Agency (EPA) Safe Drinking Water Hotline for information on water quality and associated regulations (800-426-4791)
- Call the Centers for Disease Control and Prevention (CDC) if you have a severely compromised immune system and would like further information on cryptosporidiosis (1-800-232-4636)
- Follow the links below for additional information on Cryptosporidium
Cyclospora
The San Francisco Public Utilities Commission (SFPUC) continues its commitment to provide safe, high quality drinking water through aggressive watershed protection and appropriate water treatment. While tap water is safe, it is not sterile. People with weakened immune systems may be more vulnerable to Cyclospora than others and should seek advice about protective measures, including precautions related to drinking water, from their health care provider.
What is Cyclospora?
Cyclospora is a protozoan parasite that was originally thought to be large Cryptosporidium or blue green algae. Infections caused by Cyclospora have been found in both immunodeficient and immunocompetent persons. Before 1996, only three outbreaks of cyclosporiasis infection had been reported in the United States. The first outbreak was reported in Illinois in 1990, where 14 cases of cyclosporiasis infection were attributed to drinking contaminated water. More recent cases have largely been associated with foodborne transmission as in the almost 1,000 laboratory-confirmed cases reported to the Centers for Disease Control and Prevention (CDC) between May 1 and mid-July 1996, which were attributed to eating contaminated strawberries.
How can Cyclosporiasis Affect My Health?
Common symptoms of cyclosporiasis infections are watery diarrhea, nausea, loss of appetite, abdominal cramping, fatigue, vomiting, and weight loss. Infected persons can also suffer from low-grade fever, but this is less common. The incubation period between infection and the onset of symptoms is approximately one week. Those who are infected may display symptoms for several weeks. Others may experience symptoms that tend to cease and then relapse over a span of months. Cyclosporiasis can be diagnosed through examination of stool samples. However, identification of Cyclospora requires special laboratory tests. Therefore, your physician should specifically request testing for Cyclospora.
What is the Method of Treatment for Cyclosporiasis?
The standard treatment method for cyclosporiasis includes the antibiotics trimethoprim and sulfamethoxazole. Treatment for those individuals who are sulfa-intolerant has not been identified. People infected with Cyclospora should drink plenty of fluids and rest.
How is Cyclosporiasis Spread?
Cyclospora is found in the feces of infected individuals and is transmitted by contaminated water and food. Cyclospora requires days or weeks after being excreted in feces to develop into its infective state. Hence, person-to-person transmission is unlikely. Drinking water and recreational water have been implicated in some outbreaks, but most outbreaks have been foodborne. Raspberries imported from Guatemala have been associated with outbreaks of cyclosporiasis in the United States, strawberries from Mexico caused an outbreak in 1997, and basil grown either in Mexico or the United States was implicated in a 1999 outbreak.
How Can I Protect Myself?
- Always wash your hands with soap and water any time you might have touched human or animal feces, changed diapers, cleaned up feces, or gardened.
- Always wash your hands before eating.
- Avoid sex that may involve contact with feces.
- Know the source of your water: (a) do not drink or swallow water directly from rivers, lakes, streams, pools, or spas, (b) if you travel outside the United States you may want to avoid drinking water that has not been boiled or filtered for Cyclospora.
If you are immunocompromised you should consider additional protective steps such as boiling your drinking water for one minute, which will kill any Cyclospora in it. You could also use a water filter certified by National Science Foundation (NSF) International to remove cysts or drink only bottled water certified by NSF or canned and bottled bubbly drinks.
For Further Information
- Call NSF International to learn more about water filters and bottled water (1-800-673-8010)
- Call the SFPUC Water Quality Bureau for water quality information (650-652-3127 or 877-737-8297)
- Call the Environmental Protection Agency (EPA) Safe Drinking Water Hotline for information on water quality and associated regulations (800-426-4791)
- Call the Centers for Disease Control and Prevention (CDC) if you have a severely compromised immune system and would like further information on Cyclospora (1- 800-232-4636)
- Follow the links below if you would like more information on Cyclospora
Giardia
The San Francisco Public Utilities Commission (SFPUC) continues its commitment to provide safe, high quality drinking water through aggressive watershed protection and appropriate water treatment.
The SFPUC tests for Giardia in both source and treated water supplies at least once a month. Occasionally (about 15 percent of the time) very low levels of Giardia are detected in the Hetch Hetchy, East Bay and San Francisco Peninsula source waters. The City of San Francisco's tap water has an overall average level of less than 1 Giardia cyst per 100 liters of water.
While tap water is safe, it is not sterile. People with weakened immune systems may be more vulnerable to Giardia than others and should seek advice about protective measures, including precautions related to drinking water, from their health care provider.
What is Giardia?
Giardia is a microscopic one-celled organism that can cause a diarrheal disease known as giardiasis. Giardia can live in the intestines of humans, farm animals, wild animals and household pets. It can live outside the body for a long time in water and on surfaces, but cannot multiply unless it is in the intestines. If a person or animal swallows Giardia, they can get sick and have a smelly diarrhea, stomach cramps, an upset stomach or nausea.
Where is Giardia Found?
Both human and animal feces (that is, bowel movements) can contain Giardia. Giardia has found its way into most lakes, rivers and streams (surface waters) in all parts of the United States. It may also sometimes be found in wells, springs, and even bottled water. San Francisco's pristine water sources have very little Giardia.
How Would I Know If I Have Giardiasis?
Seven to twenty-one days after you swallow Giardia symptoms appear. If you have severe diarrhea for more than 4 days, you should ask your doctor to have your feces tested for Giardia. If you have a very young child with severe diarrhea, you should go even sooner. Only a test of your feces can show whether or not you have Giardiasis.
What Is the Treatment for Giardiasis?
Many people will recover on their own. You should drink plenty of fluids if you have diarrhea. A doctor may prescribe anti-parasitic drugs.
How Is Giardiasis Spread?
You can become infected only by swallowing Giardia. A small amount may cause disease. Some sources of disease are:
- Contact with the feces of infected persons (e.g., changing diapers, sexual practices).
- Contact with the feces of infected animals (e.g., pets and farm animals).
- Hand-to-mouth transfer of Giardia from surfaces or objects that may have gotten infected feces on them (e.g., diaper changing tables, garden soil, bathrooms).
- Swallowing water with Giardia in it while swimming.
- Drinking water with Giardia in it.
- Eating raw or undercooked food that has Giardia in it.
How Can I Protect Myself?
- Always wash your hands with soap and water any time you might have touched human or animal feces, changed diapers, cleaned up feces, or gardened.
- Always wash your hands before eating.
- Avoid sex that may involve contact with feces.
- Know the source of your water: (a) do not drink or swallow water directly from rivers, lakes, streams, pools or spas, (b) if you travel outside the United States you may want to avoid drinking water that has not been boiled or filtered for Giardia.
If you are immunocompromised you should consider additional protective steps such as boiling your drinking water for one minute, which will kill any Giardia in it. You could also use a water filter certified by National Sanitation Foundation (NSF) International to remove cysts or drink only bottled water certified by NSF International or canned and bottled bubbly drinks.
For Further Information
- Call NSF International to learn more about water filters and bottled water (1-800-673-8010)
- Call the SFPUC Water Quality Bureau for water quality information (650-652-3127 or 877-737-8297)
- Call the Environmental Protection Agency (EPA) Safe Drinking Water Hotline for information on water quality and associated regulations (800-426-4791)
- Call the Centers for Disease Control and Prevention (CDC) if you have a severely compromised immune system and would like further information on Giardiasis (1- 800-232-4636)
- Follow the links below for additional information on Giardia
Microsporidium
The San Francisco Public Utilities Commission (SFPUC) continues its commitment to provide safe, high quality drinking water through aggressive watershed protection and appropriate water treatment. While tap water is safe, it is not sterile. People with weakened immune systems may be more vulnerable to Microsporidia than others and should seek advice about protective measures, including precautions related to drinking water, from their health care provider.
What is Microsporidia?
Microsporidia, similar to Cryptosporidium and Giardia, are protozoans. Microsporidia spores are generally 1 to 4.5 microns in diameter. They are known to infect fish, birds, and some mammals. Only recently has Microsporidia been recognized to cause disease in humans and has increased in its public health significance. While microsporidiosis is more common in people with weakened immune systems (i.e., immunocompromised), cases do occur among those with normal immune systems. Some Microsporidia have the potential to be waterborne because they are released in feces and urine. The most frequent cause of human infection is Enterocytozoon bieneusi. Others include Encephalitozoon hellem, Encephalitozoon cuniculi, Encephalitozoon intestinalis, and Nosema corneum.
How can Microsporidiosis Affect My Health?
In some cases, the person infected with Microsporidia will not demonstrate symptoms. In other cases, infections can result in intestinal symptoms (e.g. diarrhea) and respiratory symptoms (e.g. bronchitis, pneumonia, and sinusitis). Microsporidia may also be a frequent cause of otherwise unexplained cholangitis in HIV-infected patients. Microsporidiosis can be diagnosed through examination of stool, urine, or nasal washings.
What is the Treatment for Microsporidiosis?
Currently, there is no standard treatment for microsporidiosis. Albendazole, metronidazole, and thalidomide have all been used to treat microsporidiosis with limited success.
How is Microsporidiosis Spread?
Microsporidia enter individuals via ingestion or inhalation. Resistant spores are formed within the host and are secreted from the body in feces and urine, and possibly through mucous secretion although this has not been documented. Therefore, microsporidiosis is predisposed to spread via fecal-oral, urine-oral, and waterborne transmission. Microsporidia spores have been shown to survive prolonged periods of time in water (up to 4 months) and have been detected in surface water. The levels of Microsporidia spores found in raw sewage are comparable to that of Cryptosporidium and Giardia.
How Can I Protect Myself?
- Always wash your hands with soap and water any time you might have touched human or animal feces, changed diapers, cleaned up feces, or gardened.
- Always wash your hands before eating.
- Avoid sex that may involve contact with feces.
- Know the source of your water: (a) do not drink or swallow water directly from rivers, lakes, streams, pools, or spas, (b) if you travel outside the United States you may want to avoid drinking water that has not been boiled or filtered for Microsporidia.
If you are immunocompromised you should consider additional protective steps such as boiling your drinking water for one minute, which will kill any Microsporidia in it. You could also use a water filter certified by National Science Foundation (NSF) International to remove cysts or drink only bottled water certified by NSF or canned and bottled bubbly drinks.
For Further Information on Microsporidia?
- Call NSF International to learn more about water filters and bottled water (1-800-673-8010)
- Call the SFPUC Water Quality Bureau for water quality information (650-652-3127 or 877-737-8297)
- Call the Environmental Protection Agency (EPA) Safe Drinking Water Hotline for information on water quality and associated regulations (800-426-4791)
- Call the Centers for Disease Control and Prevention (CDC) if you have a severely compromised immune system and would like further information on Microsporidia (1- 800-232-4636)
- Follow the link below for additional information on Microsporidia
Toxoplasma
The San Francisco Public Utilities Commission (SFPUC) continues its commitment to provide safe, high quality drinking water through aggressive watershed protection and appropriate water treatment. While tap water is safe, it is not sterile. People with weakened immune systems may be more vulnerable to Toxoplasma than others and should seek advice about protective measures, including precautions related to drinking water, from their health care provider.
What is Toxoplasma?
Toxoplasma gondii is a protozoan, 10 to 12 microns in diameter, that causes latent infection (termed Toxoplasmosis) of the central nervous system. It is also the most common opportunistic pathogen of the brain in AIDS patients. Toxoplasma infection primarily occurs due to the ingestion of raw or undercooked meat or contact with cat excrement. However, there has also been one documented outbreak of toxoplasmosis due to contaminated drinking water, which took place in British Columbia, Canada, in 1995.
How can Toxoplasmosis Affect My Health?
The most common symptoms of toxoplasmosis are headaches, confusion, fever, and inflammation of the brain. These symptoms appear 5 to 23 days after exposure. Toxoplasmosis may also involve the heart, lung, pancreas, and testis. People infected with the acute form of the disease may experience symptoms similar to mononucleosis. Infection during primary stages of pregnancy may lead to brain damage, blindness, or even death of the fetus. If the infection occurs in the later stages of pregnancy, it may result in mild or subclinical fetal disease with delayed manifestations. Toxoplasmosis is a common infection which does not produce symptoms in most cases. However, individuals who are HIV-infected have a much greater risk of developing cerebral toxoplasmosis.
What is the Treatment for Toxoplasmosis?
Diagnosis of toxoplasmosis is determined by reviewing a CAT (Computerized Axial Tomography) scan, MRI (Magnetic Resonance Imaging), and blood work. The standard treatment method for people with toxoplasmic encephalitis is a combination of pyrimethamine and sulfadiazine. Other methods of treatment are currently being considered due to the adverse reactions that occur with this regimen.
How is Toxoplasmosis Spread?
Cats and other felines acquire the infection from consuming infected mammals or birds. The parasite then reproduces in the intestinal tract and is excreted from their system via feces. The infective parasite is capable of remaining in water or moist soil for prolonged periods of time. Humans ingest the parasite and it develops into tissue cysts. Intermediate hosts that may carry the infective tissue cysts in their muscle or brain include: sheep, cattle, goats, rodents, swine, and chickens.
Toxoplasmosis may therefore be spread from raw or undercooked meat, raw milk, or water/food contaminated with feline feces. Ingestion of Toxoplasma from hands contaminated with feline feces is another route of infection. Toxoplasmosis is not transmitted from person-to-person except in utero (mother-fetus).
How Can I Protect Myself?
- Avoid eating raw or undercooked meat, or drinking raw milk. Cook meat thoroughly (until color changes). Freezing meat reduces infectivity but does not eliminate it.
- You should not drink or swallow water directly from rivers, lakes, or streams.
- Always wash your hands with soap and water any time you might have touched feline feces, gardened, touched soil that may have been contaminated by cat feces, and after handling raw meat. Always wash your hands before eating.
- Cat feces and litter should be disposed of daily. Feces should be flushed down the toilet, burned, or deeply buried. Litter pans should be disinfected daily by scalding and dry litter should be disposed of without shaking. Also, wear gloves when handling potentially infective material.
- Guidelines have been published by the United States Public Health Service and Infectious Disease Society of America for the prevention of toxoplasmosis in severely immunocompromised. Patients with HIV who are seropositive for Toxoplasma with a CD4+ count less than 100 cells/mm3 should receive prophylactic treatment. The standard protocol involves Trimethoprim/sulfamethoxazole (TMP/SMZ) although alternatives are available.
- Call the SFPUC Water Quality Bureau for water quality information (650-652-3127 or 877-737-8297)
- Call the Environmental Protection Agency (EPA) Safe Drinking Water Hotline for information on water quality and associated regulations (800-426-4791)
- Call the Centers for Disease Control and Prevention (CDC) if you have a severely compromised immune system and would like further information on Toxoplasmosis (1- 800-232-4636)
- Follow the links below for additional information on Toxoplasmosis
