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Waterborne Diseases
Based upon a lesson by Beverly Ferg and Nicole Veltre as part of the AAI Teacher Research Fellowship

Modified for the PULSE curriculum by Rachel Hughes


Time: 2-3 class periods
Preparation Time: 20 minutes to photocopy sheets
Materials: Water-borne Diseases Information Sheet
Disease Description Cards / Symptom Cards-
(You may wish to laminate these)

Abstract
In this lesson students review some cases and are introduced to a number of water borne diseases that could have caused a certain disease. Once students have identified the disease that has caused the symptoms they must draw upon their earlier experiences in this learning cycle to explain what the reaction of the immune system to the disease might be.

Objectives
Students will be able:

1. Compare symptoms of several well-known water-borne diseases.
2. Use the symptoms and background information on the disease to explain some of the aspects in terms of immune response.

Teacher Background
(This information is also provided to the students in the Water-borne Diseases Information Sheet.)

Waterborne diseases are those acquired through the ingestion of contaminated water. About 80 percent of all diseases are water-related. In many of these illnesses, water infiltrated with sewage spread the disease. An infected person or animal may pass pathogenic bacteria, viruses, or protozoa through waste into the water supply. Some bacteria, however, are indigenous to water environments and are naturally occurring in estuarine bodies of water. The microorganisms that cause illness cannot be seen, smelled, or tasted; contaminated water often appears fresh and clear. This causes particular concern with municipal water supplies. Contamination may not be detected until a noticeable number of people have become ill. One specific bacterium has been isolated from water sediment, plankton and shellfish (oysters, clams and crabs) located in the Gulf of Mexico, the Atlantic Coast as far north as Cape Cod and the entire West Coast. Cases of illness have also been associated with brackish lakes in New Mexico and Oklahoma.

Most ailments are caused by the ingestion of water infiltrated with sewage are intestinal, causing gas, cramping and diarrhea. Some pathogens (harmful microorganisms) attach to intestinal linings and produce toxic materials which the body then tries to purge. Others invade intestinal epithelial cells and cause inflammation but do not produce toxins. Still other bacterium occurs naturally and is not caused by pollution. It does not affect sea life, but in people, can cause wound infections, gastroenteritis, (diarrhea and other stomach and intestinal symptoms), septicemia (blood poisoning) and even death. Fluids containing disease-fighting white blood cells are secreted into the intestine to aid in the attacking or flushing of harmful organisms form the body. Unfortunately, this loss of fluids from the body also causes dehydration, the major concern of patients with these types of diseases. Another concern is to individuals who have a compromised immune system. In those people, the bacteria can infect the bloodstream, causing severe life-threatening illness that can induce fever and chills, decreased blood pressure and skin sores. When this bacterium causes a bloodstream infection, it is fatal about 50 percent of the time. [CDC (Vibrio vulnifcus)]

If a patient is very young, elderly, or malnourished, dehydration can be life-threatening. Children with diarrhea must be closely monitored. They have not yet developed the immunities of adults, and their systems can be quickly overwhelmed by the shear number of pathogens. As many as one-third of pediatric deaths in developing countries can be attributed to diarrhea and resulting dehydration. Africa, Asia and Latin America experience an estimated 3-5 billion cases of diarrhea, with 5-10 million deaths each year. Vibrio cholerae, Salmonella sp., and Shigella species of bacteria are among the leading causes of bacterial diarrhea. Vibrio vulnificus is a leading cause of reported death from food-borne illnesses in coastal states such as Florida. Bacteria are everywhere, including our water. However, water supplies are monitored to prevent contamination by fecal pathogens in concentrations that will produce infections in humans. Water treatment facilities routinely test for these pathogens by checking the level of indicator bacteria, such as Escherichia coli (a common organism in our intestines). If these organisms rise above a set level, fecal contamination has occurred and more intensive water testing should begin. This does not mean pathogens are present, but serves as an “indicator” that they may be. It may be necessary to accelerate water treatment procedures. Also, the source of contamination must be located and protective measures taken to avoid further contamination.

Until recently, Americans have regularly suffered through epidemics of waterborne illness such as cholera and typhoid fever. Improvements in wastewater disposal practices and the development, protection and treatment of water supplies have significantly reduced the incidence of these diseases. The treatment and chlorinating of municipal water have made infection by microorganisms rare in developed countries. However, in many developing countries, treatment of waste water is minimal or nonexistent. In some cases, sewage and other wastes are dumped directly into rivers that are used by people downstream for drinking and washing.

Epidemiologists study the incidence, transmission, distribution, and control of disease. When outbreaks of a particular disease occur, epidemiologists research symptoms, incidence, and distribution of cases; they try to determine the cause of the disease, its means of spreading, and possible methods for controlling or preventing the illness. With waterborne diseases, determining how the water supply was contaminated is critical to solving the problem. The case histories of affected patients and any association among patients help epidemiologists solve the mysteries of the disease.

 

 

Activity
Prior to class you will photocopy the Disease Description cards and the Symptom cards. You may also wish to laminate them.

1. Share with students that they are going to compare symptoms and mode of transmission of waterborne diseases. From the information about the disease and the symptoms, students will match the symptoms to a disease and explain using their prior knowledge of how the body’s immune system responded and why. This will require that they draw upon information from earlier lessons on the immune system.

2. Hand out the symptom cards in 1 envelope per group of 4 students.

3. Pass out the Disease Description cards. Have students try to match up the “patients” with their disease.

4. Direct the students to read each card from the envelope and circle or underline important details. Construct a chart to keep track of the comparisons and matches.

5. Compare each of the cards, looking for commonalities until they think they have them correctly matched.

6. Check that students correctly matched the patients and diseases.

7. Students should have found six or seven patients who although they have common symptoms, do not match any of the disease description cards. This provides an opportunity to have students use details to provide a description.

8. Then ask students to review the details of the symptoms. Pick one disease and, drawing upon their earlier studies in the lesson ‘Launching a Defense’ what can they say about how the body defends against these pathogens? What are the roles of the different levels of the immune system? Students should use their notes from the earlier lesson, but also provide them with the student reading. They can respond within a class discussion or in individual written forms.


Homework
If applicable

Embedded Assessment

1. Are students able to use the symptom cards to correctly identify the disease?

2. Does the class discussion or written responses to the question, “How does the body defend against these pathogens?” indicate they’re able to integrate earlier learning about the immune system and apply it to these specific diseases?




 

 


PULSE is a project of the Community Outreach and Education Program of the Southwest Environmental Health Sciences Center and is funded by:


an
NIH/NCRR award #16260-01A1
The Community Outreach and Education Program is part of the Southwest Environmental Health Sciences Center: an NIEHS Award

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Supported by NIEHS grant # ES06694


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Last update: November 10, 2009
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