Which of the following is a vector of infection?

GMCH Chandigarh - 2019

Applied Microbiology & Infection control

Easy

Appeared in: GMCH Chandigarh - 2019

Explanation

A vector is defined in epidemiology as a living carrier, most often an arthropod (like an insect or tick), that transports an infectious agent to a susceptible individual.
An infectious fly is a classic example of a mechanical vector. It can pick up pathogens on its body parts (e.g., feet, mouthparts) from a contaminated source and transfer them to food or a person.
This is distinct from a fomite, which is an inanimate object, and a reservoir, which is the natural habitat where the pathogen lives and multiplies.

Option B: A contaminated thermometer is an inanimate (non-living) object. In epidemiology, contaminated objects that transmit disease are called fomites, not vectors.
Option C: Similar to the thermometer, a contaminated ball is an inanimate object. It serves as a fomite, not a vector.
Option D: An infected person is considered a host or a reservoir of infection. They are the source where the pathogen lives and multiplies, but they are not the vector that transmits it.

Clinical Relevance

Nursing practice connection: Knowing Definition and identification of a vector in the chain of infection helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding the difference between vectors, fomites, and reservoirs is fundamental for nurses to implement appropriate infection control measures, such as environmental sanitation (for fomites), pest control (for vectors), and isolation precautions (for human reservoirs).
In community health, nurses play a vital role in educating the public about preventing vector-borne diseases. This includes advising on eliminating breeding sites (e.g., stagnant water for mosquitoes) and practicing personal hygiene and food safety to discourage flies.
What if the question asked for a 'vehicle' of transmission? The answer could then be contaminated water, food, or blood. A vehicle is a non-living substance that serves as an intermediate means to transport an infectious agent into a host.

How to Approach the Question

First, identify the core concept of the question, which is the definition of a 'vector' in the context of infection transmission.
Recall the key terms in the chain of infection. A 'vector' is a specific type of transmission mode.
Analyze each option by asking: 'Is this a living organism that transmits disease, an inanimate object, or the source of the infection itself?'
Option A, a fly, is a living insect. Options B and C, a thermometer and a ball, are non-living objects. Option D, a person, is the host/reservoir.
Based on the standard epidemiological definition, the living organism (fly) that transmits the agent is the vector. The non-living objects are fomites, and the person is the reservoir. This process of elimination identifies the correct answer.

Concept Tested & Keywords

Concept Tested: Definition and identification of a vector in the chain of infection.
Stem keywords: vector, infection
Lead-in keywords: Which
Negative lead-in flag: false

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) pp. 90-92, 89-91, 86-88