BACTERIA
Bacteria are diverse unicellular microorganisms (1-5 mm in size ) with relatively simple structures including genetic material and structures enabling self replication. They have adapted to live and reproduce in a variety of environments including animals, humans, water, soil, and food. Most bacteria are effectively eliminated during water disinfection. Small numbers may, however, survive and enter the water distribution system. Some are present in sufficient quantity to infect individuals while others grow within consumer plumbing. The bacteria may then detach from the pipes and subsequently infect human beings. The following section reviews some of the pathogenic bacteria found in surface water including:
- Coliforms
- E.Coli
- Legionella
- Mycobacterium
- Helicobacter
- Cholera
- Campylobacter
Coliform Bacteria. Many drinking water sources contain varying levels of disease causing microorganisms known as pathogens. One of the primary objectives of the treatment of drinking water is the removal or reduction of these pathogens in order to ensure consumer safety. Although most of the more problematic pathogens are identifiable, it is generally too cumbersome to measure each pathogen species on a regular basis. Thus, other microorganisms which are more easily measured and are typically found associated with pathogens are used to"indicate" their presence. The most commonly used pathogen indicator is a group of microorganisms known as Coliform bacteria. Coliform bacteria acts as good indicators because they originate from the same sources as pathogens and also behave similarly to environmental influences and treatment processes.
Coliforms refer to a variety of microorganisms detected by a special laboratory procedure. The organisms detected typically originate from the intestines of humans and other animals. The total coliform test has been useful for testing water (and foods) since it is inexpensive, quick to analyze, and a good indicator of potential microbial risks. Its limitations include its lack of specificity for pathogenic organisms and the fact that it can grow in water samples thereby giving rise to false positives.
- Fecal Coliforms. A refinement on total coliform is to test for a subgroup: Fecal coliforms. This test is more specific for the types of organisms which may cause disease. The test, however, does not distinguish between human and animal sources.
- E. Coli. A specific organism that can be detected in either total or fecal coliform test is Escherichia coli (E. Coli). This requires an additional testing step to be confirmed. Many E. Coli cause no health problems. There are a few species, however, that do cause disease. One of them is Type 0157:H7 which was implicated in the disease outbreak associated with undercooked hamburgers and unpasteurized apple juice.
Escherichia coli 0157:H7. Most illnesses are associated with undercooked ground beef.
Escherichia coli (termed E. Coli) O157:H7 is an emerging cause of foodborne illness. An estimated 10,000 to 20,000 cases of infection occur in the United States each year. Infection often leads to bloody diarrhea, and occasionally to kidney failure. Most illness has been associated with eating undercooked, contaminated ground beef. Person-to-person contact in families and child care centers is also an important mode of transmission. Infection can also occur after drinking raw milk and after swimming in or drinking sewage-contaminated water.
What is Escherichia coli 0157:H7? While most strains of E. Coli are harmless, there are a few which can cause serious illness.
E. Coli 0157:H7, first recognized as a cause of illness in 1982, is one of hundreds of strains of the bacterium Escherichia coli. Although most strains are harmless and live in the intestines of healthy humans and animals, this strain produces a powerful toxin and can cause severe illness.
What Illness Does E. Coli 0157:H7 Cause? E. Coli 0157:H7 infection often causes severe bloody diarrhea and abdominal cramps; sometimes the infection causes nonbloody diarrhea or no symptoms. Usually little or no fever is present, and the illness resolves in five to ten days. Symptoms will normally appear 12 to 60 hours after exposure.
In two percent to seven percent of infections, particularly in children under five years of age and in the elderly, the infection can also cause a complication called hemolytic uremic syndrome, in which the red blood cells are destroyed and the kidneys fail.
Infection with E. Coli 0157:H7 is diagnosed by testing stools samples on sorbitol-MacConkey (SMAC) agar for this organism. All persons who suddenly have diarrhea with blood should get their stool tested for E. Coli 0157:H7.
How is the Illness Treated? Most individuals will recover without any specific treatment in 5 to 10 days.
Most persons recover without antibiotics or other specific treatment in five to ten days. There is no evidence that antibiotics improve the course of disease, and it is thought that some antibiotic treatments may precipitate kidney complications. Antidiarrheal agents, such as loperamide (Imodium), should also be avoided.
Hemolytic uremic syndrome is a life-threatening condition usually treated in an intensive care unit. Blood transfusions and kidney dialysis are often required. With intensive care, the death rate for hemolytic uremic syndrome is three to five percent.
How is E. Coli 0157:H7 Spread?
- The organism can be found on a small number of cattle farms and can live in the intestines of healthy cattle. Meat can become contaminated during slaughter, and organisms can be thoroughly mixed into beef when it is ground. Bacteria present on the cow's udders or on equipment may get into raw milk.
- Unpasteurized milk and juices as well as undercooked meat can spread E. Coli.
- Eating meat, especially ground beef, that has not been cooked sufficiently to kill E. Coli 0157:H7 can cause infection. Contaminated meat looks and smells normal. Although the number of organisms required to cause disease is not known, it is suspected to be very small.
- Drinking unpasteurized milk and swimming in or drinking sewage-contaminated water can also cause infection.
- Bacteria in diarrheal stools of infected persons can be passed from one person to another if hygiene or hand washing habits are inadequate. This is particularly likely among toddlers who are not toilet trained. Family members and playmates of these children are at high risk of becoming infected.
- Young children typically shed the organism in their feces for a week or two after their illness resolves. Older children rarely carry the organism without symptoms.
- What Can You do to Prevent E. Coli 0157:H7 Infection? Cook all ground beef or hamburger thoroughly. Make sure that the cooked meat is gray or brown throughout (not pink), any juices run clear, and the inside is hot. If you are served an undercooked hamburger in a restaurant, send it back for further cooking. Consume only pasteurized milk and milk products. Avoid raw milk. Make sure that infected persons, especially children, wash their hands carefully and frequently with soap to reduce the risk of spreading the infection. Drink municipal water that has been treated with adequate levels of chlorine or other effective disinfectants (Note: San Francisco's water sources are of high quality and E.Coli has never been detected in tap water).
Legionella. Individuals with compromised immune systems (e.g., those undergoing chemotherapy, recent transplants, acquired immune deficiency syndrome, etc.) are susceptible to infections by a variety of microbes including Salmonella, Campylobacter, Shigella, Pneumocystis, Cryptosporidium, and Cytomegalovirus. These can be transmitted through other people, food, pets, and water. Preventing exposure is the best means of avoiding illness. There are some general guidelines available on request. This fact sheet addresess one of these microbes: Legionella.
What is Legionella? Legionella is a small bacterium found almost everywhere. There are many different types, only one of which, Legionella pneumophila, serogroup 1, that is thought to account for the disease that caused an outbreak of pneumonia at the 1976 Convention of the American Legion resulting in 182 cases and 29 deaths.
How Does One Become Exposed? Exposure occurs through inhalation of aerosols from cooling towers, hot water systems, and whirlpool spas.
The primary source of Legionella appears to be water. The key exposure route is, however, not drinking of tap water but inhalation of aerosols associated with hot water systems, air conditioning cooling towers, evaporative condensers, and whirlpool spas. Legionella has also been isolated from hot and cold water taps and from creeks, ponds, and surrounding soil. Legionella is not transmitted from person-to-person.
What Happens if One is Exposed? Infections occur most often in older smokers and the immunocompromised.
For many people exposure to Legionella may have no effect, for others it may cause mild symptoms such as headache and fever, while a few may become seriously ill. Infections most often occur in middle-aged and older persons, particularly those who smoke or have chronic lung disease. Also at increased risk are immunocompromised individuals such as those with cancer, diabetes, or AIDS. Symptoms of the disease will usually apear 2 to 10 days after exposure.
What are the Disease Symptoms? If an individual cannot recover on their own, antibiotics can be effectively used.
Infection by Legionella (i.e. Legionellosis) can cause Legionnaires' disease or Pontiac Fever. With both, fever and chills generally develop within a day. A dry cough, abdominal pain, diarrhea, muscle aches, tiredness, and loss of appetite are common. Pneumonia is frequently associated with Legionnaires' disease but not with Pontiac Fever. Individuals with Pontiac Fever generally recover in 2 to 5 days without treatment.
Is it Treatable? Legionellosis is readily treated by antibiotics (e.g., rifampicin and erythromycin) which are, in most instances, administered intravenously.
The focus of Legionella control is large buildings and institutional settings though certain measures can be implemented in the home.
What's Being Done to Control Legionella? Water treatment practices of disinfection and filtration are the industry standard and deliver safe, potable water. Even with these processes, however, small amounts of Legionella can survive, and given the proper conditions, can colonize ends of plumbing systems. Consequently, a key element for controlling Legionella is the improved design and maintenance of cooling towers and plumbing systems to limit Legionella growth and aerosolization. In addition, increasing the temperature of hot water systems may limit exposure to Legionella. Other measures include super-chlorination of plumbing systems and maintaining chlorine residuals in decorative fountains.
While most of the airborne infections have been associated with buildings, there are some precautionary measures that can also be taken in the household. These include: cleaning the shower head by soaking in household bleach for 15-minutes every month and raising the temperature of the hot water heater to 155 F.
Mycobacterium Avium Complex. Immunocompromised individuals are susceptible to infections.
Individuals with compromised immune systems (e.g., those undergoing chemotherapy, recent transplants, acquired immune deficiency syndrome, etc.) are susceptible to infections by a variety of microbes including Salmonella, Campylobacter, Shigella, Pneumocystis, Cryptosporidium, and Cytomegalovirus. These can be transmitted through other people, food, pets, and water. Preventing exposure is the best means of avoiding illness. There are some general guidelines available on request. The purpose of this fact sheet is to address one of these microbes: Mycobacterium Avium Complex (or MAC for short).
Exposure occurs through food and water (i.e., inhalation of aerosols and ingestion of infected tap water).
What is MAC and How Does One Become Exposed? MAC is a small bacterium found almost everywhere. There are many different types, several of which may cause disease The sources of MAC are food (e.g., eggs, milk, cheese) soil and water. The water exposure route is both drinking of tap water and inhalation of aerosols associated with hot water systems, air conditioning cooling towers, evaporative condensers, and whirlpool spas. MAC has also been isolated from hot and cold water taps and from creeks, ponds, and surrounding soil.
What Happens if One is Exposed? Infections occur most often in the immunocompromised.
For many people exposure to MAC will have no effect, for others it may cause respiratory tract infections, while a few may become seriously ill. Infections most often occur in middle-aged and older persons, particularly those who smoke or have chronic lung disease. Also at increased risk are immunocompromised individuals such as those with cancer, diabetes, or AIDS.
What are the Disease Symptoms? If an individual cannot recover on their own, antibiotics can be effectively used.
Infection by MAC can cause wound infections, skin ulcers, pulmonary disease or systemic blood-borne disease. With the latter, the symptoms include fever and drenching sweats, fatigue and weight loss. Individuals with severely compromised immune systems generally require medications to clear the disease (though these are not always effective).
Helicobacter. What is Helicobacter? Helicobacter pylori is a rod-shaped bacillus, 1 to 5 microns in size, that is found throughout the world. This stomach infection has just recently been reported and is estimated to occur in approximately fifty percent of the world population. It is thought to be the most common cause of chronic bacterial infection in humans. Many infected individuals do not exhibit symptoms, but still have an inflammation of the stomach lining which is called gastritis.
How can Helicobacter Affect My Health? Helicobacter causes both chronic gastritis and duodenal ulcer disease. However, duodenal ulcer disease is not common. Gastritis is known to cause ulcers, other digestive complaints, and conceivably cancer of the stomach. The incubation period between infection and the onset of symptoms is 5 to 10 days, however, the majority of people infected with Helicobacter do not exhibit symptoms. If left untreated, Helicobacter infections will remain in the host through life. Diagnosis of Helicobacter infections is done via a blood test. An upper gastrointentinal series examination can also be done to check for cancer in those infected with Helicobacter.
What is the Method of Treatment for Helicobacter? The standard method of treatment for Helicobacter includes metronidazole, amoxacillin, and omeperazole. Infected people should also take a bismuth-containing compound. An additional blood test should be done approximately 8 weeks after treatment to test for Helicobacter. If the infection is resistant to the treatment, alternative treatment including the use of clarithromycin, and tetracycline, can be used.
How is Helicobacter Spread? The only known reservoir for Helicobacter is humans. Currently, the mode of transmittal for Heliobacter is not known. Ingestion, however, is the most likely route of the infection via oral-oral or fecal-oral transmission. Currently, there is no evidence of transmission via drinking water.
How Can I Protect Myself?
1. Always wash your hands with soap and water any time you might have touched human feces, changed diapers, or cleaned up feces. Also, always wash your hands before eating.
2. Avoid sex that may involve contact with feces.
Campylobacter. What is Campylobacter? Campylobacter is a family of bacteria, 1 to 5 microns in size ,which causes a diarrheal disease known as campylobacteriosis. The bacteria replicates in the intestines of infected humans and animals, most commonly cattle and poultry, but also pets and other farm animals.
Where is Campylobacter Found? Campylobacter is present in the feces of infected humans and animals. Surface waters such as streams, rivers and lakes may be contaminated with the bacteria, as well as unchlorinated drinking water, unpasteurized milk and food, especially chicken.
What are the Symptoms of Campylobacteriosis? Symptoms for campylobacteriosis appear three to five days after swallowing the bacteria. Common symptoms include diarrhea with blood and mucus, abdominal pain, fever, nausea and vomiting. Severe cases may include a typhoid-like syndrome, arthritis or symptoms similar to acute appendicitis. Some people may not show evidence of the disease. If you have severe diarrhea for more than 4 days, you should ask your doctor to have your feces tested for Campylobacter. If you have a young child with severe diarrhea you should go sooner. Only a test of your feces will show if you have campylobacteriosis.
What is the Treatment for Campylobacteriosis? Most people will recover on their own within 2-5 days, and symptoms usually does not last more than 10 days. Drink lots of fluids if you have diarrhea. In severe cases, a doctor may prescribe a short course of antibiotics.
How is Campylobacteriosis Spread? Campylobacteriosis is contracted only by ingestion of the bacterium. It is generally transmitted from person to person or animal to person through the fecal-oral route and therefore the following precautions should always be taken.
How Can I Protect Myself?
1. 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.
2. 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.
3. Avoid sex that may involve contact with feces.
4. If you are immunocompromised you should consider additional protective steps such as boiling your drinking water for one minute, which will kill any Campylobacter in it. You could also use a water filter certified by NSF International to remove parhculate matter, 1-5 microns in size (Class II), or drink only bottled water certified by NSF or drink only canned and bottled bubbly drinks.
Source: http://www.ci.sf.ca.us/puc/wqfs/outbreak.htm