The causative agent of yellow fever, a zoonotic disease predominant in Africa & Tropical America is?

Appeared in: MNS 2024

Explanation

Yellow fever is an acute viral hemorrhagic disease endemic to tropical regions of Africa and the Americas.
The causative agent is the yellow fever virus, which is an arbovirus (arthropod-borne virus) belonging to the genus Flavivirus.
It is a zoonotic disease, with monkeys serving as the primary reservoir in the wild.
Transmission to humans occurs through the bite of infected mosquitoes, most notably Aedes aegypti in urban settings.

Option A: Plasmodium vivax is a protozoan parasite, not a virus. It is one of the main causative agents of malaria.
Option C: Salmonella typhi is a bacterium that causes typhoid fever. It is transmitted via the fecal-oral route, typically through contaminated food and water, not by mosquitoes.
Option D: Brucella abortus is a bacterium that causes brucellosis, a zoonotic disease transmitted from animals like cattle, goats, and sheep, often through the consumption of unpasteurized dairy products or direct contact.

Clinical Relevance

Nursing practice connection: Knowing Causative agents of major infectious diseases helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
A patient's travel history is a critical assessment component for nurses. A patient presenting with fever, jaundice, and bleeding who has recently traveled to sub-Saharan Africa or tropical South America should be evaluated for yellow fever.
Nurses play a key role in public health by educating travelers about preventive measures, including vaccination with the 17D vaccine, which is the most effective way to prevent yellow fever.
What if? If a patient presented with high fever, severe headache, and muscle pain but had traveled to Southeast Asia instead of Africa, the nurse should consider Dengue fever as a strong possibility. Dengue is also caused by a Flavivirus and transmitted by Aedes mosquitoes but is more prevalent in Asia.

How to Approach the Question

This is a factual recall question testing your knowledge of microbiology and communicable diseases.
First, identify the key elements of the question: the disease is 'yellow fever' and you need to find its 'causative agent'.
Next, access your knowledge about the pathogens listed in the options.
Systematically eliminate the incorrect options. Recall that Plasmodium causes malaria, Salmonella causes typhoid fever, and Brucella causes brucellosis.
This leaves Flavivirus as the only plausible option. Confirm your knowledge that yellow fever is a viral disease and that the yellow fever virus is a member of the Flavivirus genus.

Concept Tested & Keywords

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E6 Medicine Davidson Principles Practice 24e p. 264-266

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart B (pp 202-403 of 604) p. 144-146

Practise the full MNS 2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.