Which of these modes of transmission require a bodily opening, either natural or artificial? In this state, the person can easily be infected with normally harmless bacteria that live inside of us. Is the concentration and size of boxes the same at all locations on the map? Model 2 illustrates several methods by which diseases may be transmitted. Is there a relationship between the number of black boxes and any of the water pumps? What do the relative sizes of the boxes represent? An organism that is used by a pathogen to move from one person to another is called a vector. Avoiding contact with body fluids. These include viruses, bacteria, and parasites. They can spread via contaminated food and water; from one sick person to a healthy person; through contact with blood-containing pathogens; endogenous infection during an immunocompromised state.
In a recent Scientific American article February 2010 , The Art of Bacterial Warfare, the authors state that 33% of humans are carrying the Mycobacterium tuberculosis bacteria—many without actually getting sick. Knowing that carriers are individuals who often do not show any visible signs of disease, what challenges can you think of for health care officials trying to control these types of communicable diseases? Brainstorm with your group the possible ways that cholera could have been transmitted from an infected indi- vidual into the water. The Spread of Pathogens How do we get sick? Pathogens are any microorganisms that cause disease. . Cholera is caused by bacteria found in the fecal material of infected individuals. Be specific and detailed in your answer. Model 1 is a map of an area in London where a large number of cases of cholera occurred in 1854.
Identify the mode s of trans- mission from Model 2 that is most appropriate based on the description. Bubonic plague is caused by the bacteria Yersinia pestis, which is spread by an insect vector carried by rats and other rodents. Water- and food-borne pathogens are spread via uncooked meat, improperly washed fruits and vegetables, and unsanitary practices of food handlers. How many water pumps are shown on the map? Why might diseases transmitted by vectors be harder to control than those transmitted by other means? Hand washing and good personal hygiene. Pump 3Pump 4 Pump 1 1. Preventing the contamination of food and water supplies. With your group, brainstorm a list of other organisms besides the one shown in the diagram that could be vectors for transmitting pathogens.
Based on this information, what action would you have taken if you had been responsible for public health in London in 1854? Considering all of the different ways disease may be transmitted, which modes are more likely to cause large numbers of individuals to get sick in the United States? What do the black boxes represent on the map? Where exactly on the map does the size and concentration of the boxes appear to be the highest? Based on the information provided in the map, propose a way cholera may be transmitted. In the 14th century in Europe, the bubonic plague killed approximately one third of the popula- tion. Consider the information given below concerning several diseases. The Spread of Pathogens 3 10. The Spread of Pathogens 5 Extension Question 15. How is control of a disease such as bubonic plague complicated by the fact that it spreads across multiple animal species? You may list a disease under more than one category. In addition, 50% of the human population is carrying the bacteria Helicobacter pylori which causes stomach ulcers , and 50% is carrying Staphylococcus aureus which causes skin infections.
A person can be immunocompromised when the patient is undergoing chemotherapy, chronic or prolonged use of corticosteroids, or if he or she is simply born with a weak immune system. Consider the distribution of deaths shown on the map as you develop your response. The Spread of Pathogens 1 2. List the six modes of disease transmission shown in Model 2. Model 1 — The 1854 London Cholera Outbreak Relative number of deaths due to cholera.
Under each method of control, list the diseases from Question 11 that could be prevented with that method. This disease can be spread to other animals besides humans. What vector is shown in Model 2? Below are several methods used by society to control disease. . . . .
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