Clinical virology — Hydrophobia (fear of water during painful spasms of swallowing) is classically associated with which viral infection?

Introduction / Context:
Hydrophobia is a dramatic clinical sign in encephalitic rabies. Painful pharyngeal spasms are triggered by attempts to drink or even by the sight/sound of water, reflecting involvement of brainstem centers and autonomic dysfunction.

Given Data / Assumptions:

• Rabies virus is a neurotropic, enveloped, negative-sense RNA virus (genus Lyssavirus).
• Clinical features include agitation, aerophobia, hydrophobia, hypersalivation, and rapidly progressive encephalitis.
• Other listed infections do not cause hydrophobia as a hallmark sign.

Concept / Approach:
Identify the one infection uniquely linked to hydrophobia. While dysphagia can accompany other neurological diseases, hydrophobia with pharyngeal spasms is a classic rabies presentation in humans.

Step-by-Step Solution:

Verification / Alternative check:
Public health manuals list hydrophobia and aerophobia as key clues in suspected rabies encephalitis.

Why Other Options Are Wrong:

• Influenza: respiratory illness with myalgias and fever; no hydrophobia.
• Polio: flaccid paralysis without hydrophobic spasms.
• Hepatitis: hepatic inflammation; unrelated neurologic syndrome.

Common Pitfalls:
Assuming any CNS infection could present similarly; hydrophobia is notably rabies-specific in classic descriptions.

Final Answer:
Rabies