For which infectious disease is passive immunization routinely used in clinical practice to provide immediate neutralization (e.g., administration of antitoxin or immunoglobulin)?

Introduction / Context:
Passive immunization involves giving pre-formed antibodies (antitoxin or immunoglobulin) to rapidly neutralize a toxin or pathogen. It provides immediate, short-term protection, unlike vaccines that induce active immunity. Diphtheria is a classic indication for passive antitoxin therapy in suspected cases.

Given Data / Assumptions:

• We seek a disease where immediate antibody-mediated neutralization is standard.
• Passive immunity does not require the host to mount a response.

Concept / Approach:
Corynebacterium diphtheriae produces a potent exotoxin causing local necrosis and systemic complications. Diphtheria antitoxin (DAT) neutralizes circulating toxin and is most effective when given early. Tuberculosis and typhoid rely on antimicrobial therapy and vaccines; passive immunization has no routine role.

Step-by-Step Solution:

Verification / Alternative check:
Clinical guidelines recommend immediate DAT administration in suspected diphtheria, alongside antibiotics, to reduce morbidity and mortality.

Why Other Options Are Wrong:

• Tuberculosis: No role for passive antibodies; management is multi-drug therapy and BCG vaccination (active).
• Enteric fever: Treated with antibiotics; vaccines used for prevention.
• Measles: Post-exposure immune globulin may be used in certain high-risk cases, but the canonical textbook answer in this set is diphtheria (antitoxin).
• All of these: Incorrect because TB/typhoid lack routine passive therapy.

Common Pitfalls:

• Confusing post-exposure prophylaxis (e.g., rabies, hepatitis B) with diseases not treated by passive immunization.

Final Answer:
Diphtheria