Veterinary virology — Foot-and-mouth disease (FMD) in cloven-hoofed animals is caused by which type of pathogen?
-
ARNA virus
-
BDNA virus
-
CBacteria
-
DProtozoa
-
EFungus
Answer
Correct Answer: RNA virus
Explanation
Introduction / Context:Foot-and-mouth disease (FMD) is a highly contagious disease affecting cattle, pigs, sheep, goats, and wild ruminants. Identifying the pathogen type is foundational for understanding diagnostics, vaccine strategies, and biosecurity measures.
Given Data / Assumptions:
- FMD outbreaks spread rapidly between susceptible livestock.
- The etiologic agent is small, non-enveloped, and acid-labile.
- Control relies on vaccination, movement restrictions, and surveillance.
Concept / Approach:FMD is caused by Foot-and-mouth disease virus (FMDV), a positive-sense single-stranded RNA virus (genus Aphthovirus, family Picornaviridae). Its RNA genome encodes structural proteins (VP1–VP4) and non-structural proteins; error-prone replication leads to high diversity, complicating control.
Step-by-Step Solution:
Determine pathogen family: Picornaviridae members are RNA viruses.Recall FMDV properties: small icosahedral capsid, no envelope, ssRNA(+).Link to epidemiology: rapid spread and antigenic variation align with RNA virus behavior.Hence, the correct category is RNA virus.Verification / Alternative check:Laboratory RT-PCR is the frontline molecular diagnostic, directly indicating an RNA genome; electron microscopy and antigen ELISAs further confirm identity.
Why Other Options Are Wrong:
- DNA virus: inconsistent with picornaviral classification.
- Bacteria/protozoa/fungi: do not match clinical course, structure, or molecular tests for FMD.
Common Pitfalls:Confusing FMD with vesicular diseases of other etiologies (e.g., vesicular stomatitis, a rhabdovirus), which are also RNA viruses but distinct pathogens.
Final Answer:RNA virus.