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Waterborne disease teacher's notes

This unit was created by Keith Johnson, KUMC Medical Student

There are 2 parts to this unit, (1) the discussion, case study and activity below and (2) a laboratory exercise which uses material from the bacteria lab from the Kansas River Science curriculum (created by Heidi Mehl)

The day will begin with an overview of bacteria, diarrhea and how it relates to water.

Included in the Powerpoint for this intro will be pictures and a table that will allow you to adjust the depth of that information your group can cover. Most the information is for completeness but the basic information I think students should get I will mention in this document. I list options for those with high school students and wish to challenge them. The general discussions are for all grade levels.

Objectives for the day:

  • Know the health consequences of drinking contaminated water (diseases).
  • Know basic ways to sanitized drinking water (treatment and prevention).
  • Know the common bacteria found in drinking water (causes).
  • Know the difference between distilled water, purified water, and spring water.
  • How to grow bacteria in a Petri medium (Lab activity).
  • Learn the difference between a prokaryote and a eukaryote.

 

1. Define bacteria (prokaryotes) and its characteristics versus human (eukaryotic) cells.

Unicellular versus the membrane bound organelles of a eukaryotic cell found in humans. Bacteria are small and less than 5um, have no nucleus and circular DNA. Contrast to Eukaryotic cells that have a nucleus, are larger that 10um and have linear DNA

An option can be to have students compare and contrast bacteria to human cells, prokaryotes versus eukaryotes. Middle school students could draw out examples.

2. Describe diarrhea and its positive and negative health effects.

Good bacteria work to help maintain a healthy nutritional and  microbiologic  balance within the body. When this balance is disturbed diarrhea can result in an attempt to restore the body to a healthier environment. Excess watery stool is the descriptive feature of diarrhea and the effect is to either wash out pathogens or to remove excess water from the system.

Good bacteria of the intestine help humans by assisting in the metabolic functions of the intestine by absorbing carbohydrates and breaking down proteins. They fight off infections and reduce the risk of disease such as inflammatory bowl disease. Yogurts often contain healthy bacteria (probiotics) that help treat diarrhea.

The adverse effects of excess removal of fluids from the body is malnutrition due to the loss of the absorptive action of the intestines. Dehydration can occur and coupled with malnutrition can leave the body vulnerable to infection, disease and death.

Information for student discussion is posted on the HS Disease page and the MS Disease page.

An option here is to have students find healthy intestine bacteria (probiotics) and list them.

            Examples include: Lactobacillus (many different species), Bifidobaterium (Bifidus regularis Activa!!)

3. How does the quality of water relate to overall health?

Clean freshwater is essential for many organisms and dictates where organisms live. It is a renewable resource as long as it is not polluted or contaminated or overused. When bacteria that harm the balance of the body are found in contaminated water, the negative consequences of diarrhea can harm a persons health.

An option here would be to ask the students to find water born bacteria that harm the body and list them.

            Examples would include: Staph aureus, E. coli, Giardia, Salmonella typhi, Shigella


Case Study

Following the above discussion, definitions and background, Cholera will be presented as an example of a modern day disease that involves illness due to excess diarrhea and is transmitted via water contamination. Reiterating the aforementioned questions during your discussion of Cholera will help reinforce main concepts.

Go to Cholera Powerpoint


Cholera


These three links give background video information on Cholera in Haiti (9min) and the two most common water born bacteria illness sources E. coli (2min) and Staph aureus (2min). These are for background only and can be used or not depending on time and need. The Cholera portion of the Powerpoint used to guide this lesson is more towards the high school students but can be used as a discussion point with the middle school students depending on interest and ability.

http://www.youtube.com/watch?v=Rlyfc-5fVqI&feature=related


http://www.youtube.com/watch?v=EkGPOoIJCoc&feature=related



http://www.pbs.org/newshour/bb/health/jan-june11/haiti_01-14.html

REPORT AIR DATE: Jan. 14, 2011
Cholera Outbreak Compounds Haiti's Woes

SUMMARY
Jeffrey Brown looks at the battle against a cholera epidemic in Haiti, one year after a devastating earthquake upset an already fragile infrastructure.




Activity

The main activity for the session will be student driven research to answer the following questions.

Middle School Activity

Middle school students can draw out on poster paper information sheets for the diseases listed below, stating the disease name, how to prevent, how to treat and the symptoms of the diseases as the activity. They can then present the information sheets on each disease to each other. Lab time can also be used for presentations as the lab activity will only take about 30min. Each groups will be assigned a disease:

Typhoid fever (Salmonella typhi)

E.coli poisoning

Giardia

Dysentery (Shigella)

http://www.cdc.gov/legionella/patient_facts.htm


  • Other topics to discuss or explore are:
  • How might social economics effect spread of disease?
  • Why is a disease like cholera that is so easy to treat killing so many people?
  • What is Epidemiology?

 

High School Activity

The high school groups breaking up into small groups to research one disease each and then presenting each disease to the other groups using whatever media they choose. At the very minimum they should answer each question in a formal typed document and turned in online, one per group is fine. Students can do a Powerpoint, media style presentation or just each take a subtopic about the groups disease and present it to the class.

Students will be asked to break up into 4 small groups.

Each groups will be assigned a disease

Typhoid fever (Salmonella typhi)

E.coli poisoning

Giardia

Dysentery (Shigellosis)

http://www.cdc.gov/legionella/patient_facts.htm

And then asked to determine and cite the following information for that disease to be presented to the group. They should have 30 minutes to gather the information and 30 minutes for everyone to present the answers to the other groups. Lab time can also be used for presentations as the lab activity will only take about 30min.

  • What is Epidemiology?
  • What is Prevalence?
  • What is Incidence?
  • What are the causes of this disease and in what locations in the world are they found? Map these locations (for example, the UNICEF Google Earth map can be used for finding locations).
  • Describe in detail the characteristics of the organism responsible for the cause of your disease. i.e the life cycle of the pathogen and how that life style relates to symptoms and spread of the disease.
  • What are the symptoms of this disease and what is occurring within the body that causes these symptoms?
  • How do you treat this disease?
  • How might social economic status effect the chances of contracting this disease and how might it effect the course of treatment?
  • How does the prevalence of this disease in certain locations relate to the social economical status of that area?
  • What can be done to prevent the spread of this disease?




Disease information for instructors.

The following is an example of what could be complied from a student. All information can be found at the PubMed Health links provided. Students will need to put into their own words and can use other reliable edu or gov sources.

1. What is Epidemiology?

The branch of medicine that deals with the incidence, prevalence, distribution, and possible control of diseases and other factors relating to health.

2. What is Prevalence?

The prevalence of a health-related state (typically disease, but also other things like smoking or seatbelt use) in a statistical population is defined as the total number of cases of the risk factor in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population. It is used as an estimate of how common a disease is within a population over a certain period of time. It helps physicians or other health professionals understand the probability of certain diagnoses and is routinely used by epidemiologists, health care providers, government agencies and insurers.

3. What is Incidence?

A measure of the risk of developing some new condition within a specified period of time. The incidence rate is the number of new cases per population in a given time period

Salmonella/ Typhoid fever

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002308/

4. What are the causes of this disease and in what locations in the world are they found? Map these locations.

Bacteria of the genus Salmonella are highly adapted for growth in both humans and animals and cause a wide spectrum of disease. The growth of serotypes S. typhi and S. paratyphi is restricted to human hosts, in whom these organisms cause enteric (typhoid) fever. All Salmonella infections begin with ingestion of organisms, most commonly in contaminated food or water.

More than 1 million cases occur each year in the United States, and the prevalence is even greater in other countries especially southern Asia and other developing regions of Asia, Africa, the Caribbean, and Central and South America and who will be exposed to potentially contaminated food and drink. Infection is strongly associated with travel to India, Mexico, the Philippines, Pakistan, El Salvador, and Haiti. Humans are the sole reservoir for S. typhi and S. paratyphi and transmission occurs from person to person or via food or contaminated water.

Infection is most common in young children and the elderly, with peak incidence in summer and fall. Transmission is usually through contaminated food, particularly raw or undercooked meat, poultry, eggs, and milk.

5. Describe in detail the characteristics of the organism responsible for the cause of your disease.

Salmonellae are gram-negative, non-spore-forming, facultatively anaerobic bacilli

6. What are the symptoms of this disease and what is occurring within the body that causes these symptoms?

Patients experience anorexia, abdominal pain, bloating, nausea, vomiting, and bloody diarrhea followed by a short asymptomatic phase that gives way to bacteremia and fever with flu-like symptoms. Salmonella infections are clinically indistinguishable from those caused by other enteric pathogens, and symptoms range from loose stools to cholera-like profuse diarrhea to dysentery. Fever often resolves within 2 days, but diarrhea can persist for a week and organisms can be shed in the stool for several weeks after resolution. Antibiotic therapy is not recommended in most cases, because it can prolong the carrier state or even cause relapse and does not typically shorten the duration of diarrhea. Most Salmonella infections are self-limited, but deaths do occur. The risk of severe illness and complications is increased in patients with malignancies, immunosuppression, alcoholism, cardiovascular dysfunction, sickle cell disease, and hemolytic anemia.

7. How do you treat this disease?

Prompt administration of appropriate antibiotic therapy prevents severe complications of enteric fever and results in a case-fatality rate of <1%. The initial choice of antibiotics depends on the susceptibility of the S. typhi and S. paratyphi strains in the area of residence or travel

8. What can be done to prevent the spread of this disease?

Theoretically, it is possible to eliminate the salmonellae that cause enteric fever since they survive only in human hosts and are spread by contaminated food and water. However, given the high prevalence of the disease in developing countries that lack adequate sewage disposal and water treatment, this goal is currently unrealistic. Thus, travelers to developing countries should be advised to monitor their food and water intake carefully and to consider vaccination. There are two types of vaccines available.

9. Discussion Questions with various answers:

  • How might social economic status effect the chances of contracting this disease and how might it effect the course of treatment?
  • How does the prevalence of this disease in certain locations relate to the social economical status of that area?

 


References:

Giardiasis

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001333/

 

Shigellosis/Dysentary

http://www.cdc.gov/nczved/divisions/dfbmd/diseases/shigellosis/

 

E.coli

http://www.niaid.nih.gov/topics/ecoli/understanding/pages/overview.aspx

http://water.epa.gov/drink/contaminants/basicinformation/ecoli.cfm