Education

Water '101'

Clinical Features:

A range of syndromes, including acute dehydrating diarrhea (cholera), prolonged febrile illness with abdominal symptoms (typhoid fever), acute bloody diarrhea (dysentery), and chronic diarrhea (Brainerd diarrhea).

Common agents:

include Vibrio cholerae, Campylobacter, Salmonella, Shigella, and the diarrheogenic Escherichia coli.

Incidence:

each year, an estimated 3-5 billion episodes of diarrhea result in an estimated 3 million deaths, mostly among children. Waterborne bacterial infections may account for as many as half of these episodes and deaths. Many deaths among infants and young children are due to dehydration, malnutrition, or other complications of waterborne bacterial infections.

Transmission:

Contaminated surface water sources and large poorly functioning municipal water distribution systems contribute to transmission of waterborne bacterial diseases. Chlorination and safe water handling can eliminate the risk of waterborne bacterial diseases.

Risk Groups:

Over 2 billion persons living in poverty in the developing world are at high risk. Sporadic cases are under-reported. CDC surveillance may detect a small proportion of outbreaks in the United States; outbreaks abroad are often missed.

Despite global efforts during the water and sanitation decade, improvements in water and sanitation infrastructure have barely kept pace with population increases and migrations in the developing world.

Centralized water treatment and distribution systems are expensive and take years to complete. To provide the under-served with potable water in the short term requires innovative practical solutions such as point-of-use disinfection and safe water storage vessels.

Parasitic Agents

Giardia lamblia is a one-celled agent that is commonly found in rivers and streams, but may also be found in conventional sources of drinking water. The agent enters the environment from the feces of infected animals or other people. The organism lives in the intestine, but because it has a protective shell, it can survive for long periods of time outside the body. Infections may occur through accidental ingestion of the agent when it is in food, soil, or water. Symptoms may take one to two weeks to appear after infection and may persist for two to six weeks.

Symptoms may include (CDC, 2004a):

• Diarrhea
• Gas or flatulence
• Greasy stools that tend to float
• Stomach cramps
• Upset stomach or nausea

Cryptopsoridium is a microscopic parasite that lives in the intestines of its hosts. It is protected by a hard outer shell that provides it some protection from chemical water treatment systems and allows it to live outside the body for extended periods. It may be found in recreational and drinking water almost anywhere in the United States. Cryptopsoridium may be found in soil, food, water, or any surface that has come into contact with either human or animal feces infected with it.

Most commonly, sufferers experience watery diarrhea (CDC, 2005c). Other symptoms include:

• Dehydration
• Weight loss
• Stomach cramps or pain
• Fever
• Nausea
• Vomiting

Cyclosporiasis has been observed only since 1979. It is a one-celled parasite that may be spread by ingesting contaminated food or water contaminated with feces. One possible way the infection is spread is through contaminated fresh fruit and vegetables that have been handled improperly or washed with contaminated water. Person-to-person transmission is unlikely. Recent outbreaks have included cases resulting from consumption of contaminated raspberries imported from Guatemala. While the precise mechanism of contamination is unknown, Nelson (2004) states, “… it is likely that rinsing of the implicated raspberries with contaminated water prior to their export had occurred.”

Symptoms, if they appear, may last a week or more to a month and may include (CDC, 2004b):

• Watery diarrhea
• Frequent, explosive bowel movements
• Loss of appetite
• Weight loss
• Bloating
• Gas
• Stomach cramps
• Nausea
• Vomiting
• Low-grade fever
• Fatigue

Bacterial Agents

Escherichia coli is a very common bacterium that exists in many varieties. Harmless varieties live in human (and animal) large intestines and are essential to normal digestion. Some types are harmful (E. coli O157:H7), producing a potentially fatal toxin when ingested through contaminated food or water. One well-publicized outbreak in 1993 involved contaminated hamburgers sold through a popular western food chain. It was later determined that the hamburgers had not been cooked to 155 degrees Farenheit, the temperature which effectively kills E. coli that often are found in ground beef. Person-to-person transmission may occur and it may be spread through drinking raw milk or drinking or swimming in contaminated water.

Symptoms, if they appear, include (CDC, 2004c):

• Little or no fever
• Bloody diarrhea
• Abdominal cramping
• Among children younger than five and the elderly, hemolytic uremic syndrome may develop, which causes red blood cells to rupture and the kidneys to fail

Salmonella is a bacterium that is most commonly associated with eating undercooked meat, poultry, and eggs, but can affect water supplies. It can be acquired directly from animals (not just reptiles). It can be spread by food workers who have not practiced good hygiene or through washing fruits and vegetables in contaminated water. Failure to properly wash plates and utensils used to prepare meats and poultry may also cause infection. Salmonella is also commonly associated with reptiles. The illness is usually uncomfortable but not dangerous, except for young children, the elderly, and the immuno-compromised, who may become dangerously dehydrated. Onset of symptoms begins within 12 to 72 hours of infection and illness may last five to seven days. Laboratory testing to establish correct antibiotic treatment may be necessary. Many cases of salmonellosis probably go undetected.

Symptoms include (CDC, 2004d):

• Diarrhea
• Fever
• Abdominal cramps

Campylobacter is a spiral-shaped bacterium that is spread and causes illness in a manner very similar to salmonella—it is commonly associated with poultry and can be contracted by improper cooking and handling of food and improper washing of dishes, utensils, and cutting boards. It can also be acquired directly from animals. Contaminated water and raw milk are also potential culprits. It is one of the most common bacterial causes of diarrheal illness in the United States. Onset of symptoms begins within two to five days of exposure and typically last a week to 10 days. Treatment including antibiotics is usually unnecessary, but some victims suffer serious, long-term complications, including arthritis and Guillain-Barré syndrome. Guillain-Barré is a condition in which gradually progressive paralysis overtakes the subject, but the paralysis usually reverses. It is estimated that one in 1,000 cases of Campylobacter infection will result in Guillain-Barré and that 40 percent of Guillain-Barré cases are associated with Campylobacter.

Symptoms include (CDC, 2004e):

• Diarrhea
• Bloody diarrhea
• Cramping
• Abdominal pain
• Fever

Shigella is a family of bacteria that causes illness very similar to salmonella and campylobacter, but is usually spreads differently—through the fecal-oral route, facilitated by improper hand washing. Most of the types of Shigella found in the United States cause an uncomfortable illness that is not dangerous, but in the developing world Shigella dysenteriae type 1 causes deadly epidemics. As with several other bacterial infections, Shigella may necessitate hospitalization of the very young or elderly because of profound diarrhea. Some infected individuals show no symptoms but easily pass the illness on to others. Onset of symptoms begins within one or two days after exposure and usually last five to seven days. Treatment with antibiotics is usually done, but antibiotic-resistant strains of Shigella have evolved. About 3 percent of victims of Shigella flexneri suffer a serious, long-term complication known as Reiter’s syndrome, which causes painful joints, irritation of the eyes, painful urination, and perhaps long-term arthritis. The syndrome may last months or years.

Symptoms include (CDC, 2005d):

• Diarrhea
• Bloody diarrhea
• Cramping
• Fever

Vibrio cholerae, causative agent of cholera (see discussion of John Snow above) has been almost completely eliminated from the United States for the past 100 years or so. The United States has been spared except for imported cases, or clusters of infections from imported food. During 1993 and 1994, 69 cholera cases were reported to CDC, and 65 were associated with foreign travel (Todar, 2002). There was a major outbreak in 1991 in South America that affected several countries, as well as an outbreak in Bangladesh in 1992. Despite the history of serious illness and death associated with cholera, illness may be mild or asymptomatic, but in severe cases dehydration and shock may lead to death within hours without treatment. The organism is usually spread by eating contaminated seafood (usually shellfish) and drinking contaminated water. Antibiotics may shorten the duration of illness but re-hydration is critical to reducing the chance of death.

Symptoms include (CDC, 2004f):

• Profuse, watery diarrhea
• Vomiting
• Leg cramps

Conclusion

More disease-causing agents than these exist, mainly affecting people in developing nations. Many medical scientists have recently thought infectious diseases had been conquered by the advent of antibiotics. What they failed to recognize was that bacteria develop resistance to antibiotics, and viruses can mutate in such a way as to render vaccines ineffective. In addition to these forces, modern travel has enabled microbes that normally were confined to remote, isolated populations to spread beyond their normal habitats. It behooves us to exercise care in choosing drinking water sources, particularly when traveling, and to invest resources at home to assure safe municipal water supplies.

There are several ways to treat water that is of questionable microbial quality (CDC, 2005e): boiling, chemical treatment, and filtering. Water should be boiled vigorously for 1 minute and allowed to cool naturally (don’t add ice). At elevations above 6,500 feet, boil for 3 minutes (water boils at lower temperatures as atmospheric pressure drops with altitude). Chemical disinfection may be done with iodine-based products available in sporting goods stores, but certain parasites such as Cryptosporidium, Cyclospora, and Toxoplasma, may not be killed. Portable filters are available commercially and will effectively remove parasites; however, they are ineffective against viruses, which are orders of magnitude smaller than parasites and bacteria. Another alternative is to drink bottled water. At home, make sure the septic system is working properly without any surface discharge. And, finally, always wash your hands!

References

Blackburn, B.G., Craun, G.F., Yoder, J.S., Hill, V., Calderon, R.L., Chen, N., et al. Surveillance for Waterborne-Disease Outbreaks Associated with Drinking Water—United States, 2001–2002. Morbidity and Mortality Weekly Report, October 22, 2004/53(SS08); 23–45.

CDC. 2004a. http://www.cdc.gov/ncidod/dpd/parasites/giardiasis/2004_PDF _Giardiasis.pdf
CDC. 2004b.http://www.cdc.gov/ncidod/dpd/parasites/cyclospora/factsht_ cyclospora.htm
CDC. 2004c. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/escherichiacoli_g.htm
CDC. 2004d. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/salmonellosis_g.htm
CDC. 2004e. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/campylobacter_g.htm
CDC. 2004f. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/cholera_g.htm
CDC. 2005a. http://www.cdc.gov/ncidod/diseases/hepatitis/a/fact.htm
CDC. 2005b. http://www.cdc.gov/ncidod/dvrd/revb/gastro/noro-qa.pdf
CDC. 2005c. http://www.cdc.gov/ncidod/dpd/parasites/cryptosporidiosis/factsht_ cryptosporidiosis.htm
CDC. 2005d. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/shigellosis_g.htm
CDC. 2005e. http://www.cdc.gov/travel/water_treatment.htm

Craun, G., Calderon, R.L., and Nwachuku, N. Causes of Waterborne Outbreaks Reported in the United States, 1991–1998. In: Drinking Water and Infectious Disease, Establishing the Links. 2003. CRC Press LLC, London.

Nelson, K.E. Emerging and New Infectious Diseases. 2004. In: Infectious Disease Epidemiology, Theory and Practice, Kenrad E. Nelson, Carolyn M. Williams, and Neil M.H. Graham, Eds. Jones and Bartlett Publishers.

Ohio Department of Health. 2005. www2.odh.ohio.gov/Data/ Inf_Dis/idann/Idsum03/03annsum.pdf

Summers, Judith. 1989. Soho—A History of London’s Most Colourful Neighborhood, Bloomsbury, London, pp. 113-117.

Todar, K. 2002. Todar’s Online Textbook of Bacteriology.textbookofbacteriology.net/cholera.html

WHO. 2004. www.who.int/water_sanitation_health/diseases/burden /en/index.html

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Source of information:

Centers for Disease Control and Prevention
National Center for Infectious Diseases
Division of Bacterial and Mycotic Diseases