The proportion of clinical cases resulting in severe clinical manifestations is known as

RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Microbiology

Easy

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-2)

Explanation

Virulence refers to the degree of harm or severity of a disease caused by a pathogen.
It is specifically measured as the proportion of clinical cases that result in severe manifestations, including severe illness or death (e.g., case fatality rate).
A highly virulent pathogen causes severe disease in a large proportion of those who are sick, whereas a pathogen with low virulence may cause only mild illness.

Option A: Infectivity measures the ability of a pathogen to establish an infection in a susceptible host, not the severity of the disease it causes.
Option C: Pathogenicity is the ability of an organism to cause disease (i.e., produce symptoms). It doesn't describe the severity of those symptoms.
Option D: Prepathogenesis is not a measure of disease characteristics but a phase in the natural history of a disease before the agent has interacted with the host.

Clinical Relevance

Nursing practice connection: Knowing Epidemiological Measures of Disease helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding virulence helps nurses and public health professionals anticipate the potential impact of an outbreak and allocate resources, such as ICU beds and ventilators, appropriately.
Nurses use this knowledge to educate patients and communities about the seriousness of certain infections and the importance of preventive measures like vaccination and hygiene.
What if? If a new virus strain emerges with the same pathogenicity but higher virulence than the original strain, nurses should anticipate a higher rate of hospitalizations, complications, and deaths among infected patients, necessitating more intensive monitoring and care.

How to Approach the Question

First, read the question carefully to identify the key concept. The question asks for a term that describes the 'proportion of clinical cases resulting in severe clinical manifestations'.
Break down the definition: The starting group is 'clinical cases' (people who are already sick), and the outcome is 'severe manifestations'. The term must relate sickness to severity.
Evaluate each option based on this definition.
Recall or look up the definitions: Infectivity (ability to infect), Pathogenicity (ability to cause disease), and Virulence (ability to cause severe disease).
Eliminate 'Prepathogenesis' as it refers to a time period, not a measure of severity.
Compare the remaining terms. 'Virulence' is the only term that specifically measures the severity of a disease among those who are already clinically ill, which perfectly matches the question.

Concept Tested & Keywords

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E6 Medicine Davidson Principles Practice 24e p. 124-126

E6 Microbiology Essentials Sastry 4e Part 1 p. 79-81