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Ch. 25 - Pathogenic RNA Viruses
Bauman - Microbiology with Diseases by Taxonomy 6th Edition
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302Not the one you use?Change textbook
All textbooksBauman 6th EditionCh. 25 - Pathogenic RNA VirusesProblem 10
Chapter 25, Problem 10

Why are there more cases of West Nile virus encephalitis in summer than in winter of every year?

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1
Understand the transmission cycle of West Nile virus, which primarily involves mosquitoes as vectors and birds as reservoirs.
Recognize that mosquito activity is highly dependent on temperature and environmental conditions, with warmer temperatures in summer increasing mosquito breeding and biting rates.
Note that in summer, the population of mosquitoes rises significantly, leading to more opportunities for the virus to be transmitted to humans.
Consider that the virus replicates more efficiently within mosquitoes at higher temperatures, shortening the incubation period and increasing transmission potential.
Conclude that these factors combined—higher mosquito populations, increased biting activity, and faster viral replication—result in more cases of West Nile virus encephalitis during summer compared to winter.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

West Nile Virus Transmission Cycle

West Nile virus is primarily transmitted through the bite of infected mosquitoes, especially Culex species. These mosquitoes become carriers after feeding on infected birds, which serve as the virus's natural reservoir. Understanding this cycle is crucial to explain seasonal variations in infection rates.
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Mosquito Activity and Seasonal Temperature Effects

Mosquitoes are cold-blooded and their activity, breeding, and lifespan increase in warm temperatures typical of summer. Higher temperatures accelerate the virus replication within mosquitoes, leading to more frequent and intense transmission during summer months compared to winter.
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Human Exposure Patterns

During summer, people spend more time outdoors, increasing their exposure to mosquito bites. In contrast, colder winter temperatures reduce outdoor activities and mosquito populations, resulting in fewer human infections. This behavioral factor contributes to the seasonal rise in West Nile virus encephalitis cases.
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Related Practice
Textbook Question

A horror movie portrays victims of biological warfare with uncontrolled bleeding from the eyes, mouth, nose, ears, and anus. What actual virus causes these symptoms?


a. Ebola virus

b. Bunyavirus

c. Hantavirus

d. Human immunodeficiency virus

Textbook Question

Several laboratory tests are used to identify viruses. From your study of this chapter alone, which tests would you surmise are the most common?

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Textbook Question

Compare influenzavirus A 2009 (H1N1) to the 1918–1919 pandemic influenzavirus.

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Textbook Question

Which of the following is an accurate statement concerning zoonoses?

a. They are animal diseases that spread to humans.

b. They are diseases specifically transmitted by mosquitoes and ticks.

c. They are mucus-borne viruses, which are transmitted in the droplets of moisture in a sneeze or cough.

d. They are diseases that can be transmitted from humans to an animal population.

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Textbook Question

Reoviruses, such as rotaviruses and coltiviruses, are unique in ___________.

a. Being naked

b. Having double-stranded RNA

c. Being both arboviruses and zoonotic

d. Having protein spikes

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