What environmental factors facilitate the spread of Guinea worm disease, and other diseases, and what steps are needed to eradicate them?
Interactive Study Guide
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Guiding Question 6.3
What environmental factors facilitate the spread of Guinea worm disease, and other diseases, and what steps are needed to eradicate them?
Why You Should Care
Any programs that seek to decrease environmental diseases must identify all modifiable environmental hazards. In the case of Guinea worm disease, the modifiable hazards are the conditions that allow the parasite to survive and spread to new human hosts.
Environmental conditions that allow the GWD parasite to travel between humans and copepods (typically in contaminated sources of drinking water) are the first place to begin modifying human habits and treating water supplies to kill the copepod host. Treating the water supplies with pesticides to kill the copepod host is more expensive but easier to implement. Modifying human habits requires changing behaviors of everyone in the community—just one infected adult coming into contact with drinking water can reinfect the whole community.
Important environmental diseases vary from tiny (cholera viruses) to large (elephantiasis worms are several inches long), but all share one particular characteristic: They are modifiable because humans can break the infection cycle. Cholera spreads through sewage-contaminated water, so programs that prevent sewage mixing with drinking water are the best bet. Elephantiasis is spread by mosquitoes to humans and then back again, so preventing mosquito breeding is very effective. The key is always identifying the environmental variables and then modifying them to stop the disease’s spread.
Test Your Vocabulary
Fill in the correct term for each of the following definitions:
are diseases that are spread between infected animals (not merely vectors that transmit the pathogen, but other hosts that harbor the pathogen through their life-cycle) and humans.
are diseases that are new to humans or that have recently increased significantly in incidence, in some cases by spreading to new ranges.
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Question Sequence
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Guinea worm disease is caused by which of the following pathogen types?
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Of the five examples in Infographic 6.4, how many have transmission that requires water?
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3.
Which of the following is a factor in the increased spread of Lyme disease?
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4.
Why do urban areas have increased transmission of waterborne diseases?
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Which of the following are hazards for spreading GWD?
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Which of the following are NOT treatments for stopping the spread of GWD?
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7.
Why is GWD infection more likely in the dry season in the savanna?
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8.
What would have to happen to reintroduce GWD to areas where it was recently eradicated?
To reintroduce GWD would involve recreating the environmental conditions that allow the parasite to spread between both the copepods and humans. Since the copepods occur naturally already, the larvae would have to be reintroduced to the drinking water ponds. This would complete the cycle and allow humans to be infected again. Finally, the infected humans would need to be carrying larvae into the drinking-water ponds to reinfect the copepods.
Question Sequence
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Which of the following countries did NOT eradicate Guinea worm disease between 1986 and 2010?
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10.
Which countries still have cases of Guinea worm disease in 2010?
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11.
Mali and Nigeria still have GWD cases in 2010, and both have armed conflict within their countries. Why does armed conflict limit eradication programs?
Armed conflict within any country disrupts key aspects of an environmental health program. First, money and effort are diverted away from the program to fund the war effort and its recovery. Second, the conflict disrupts transportation of both health professionals and supplies needed (think of the water purification equipment needed to avoid contracting the GWD). Finally, with a country at war, the focus is taken away from the education effort against the health threat and instead focused on the war itself.
