Decision making — chloroquine resistance in some mosquito strains Statement: Some strains of mosquito have become resistant to chloroquine, a widely used anti-malaria medicine. Which courses of action are appropriate? I. Stop selling chloroquine. II. Researchers should develop a new medicine for patients affected by such mosquitoes. III. All malaria patients should be checked to identify the causal mosquito (and guide therapy).

Introduction / Context:
Drug resistance complicates malaria treatment. The statement says some mosquito strains transmit parasites no longer responsive to chloroquine. We need actions that preserve effective therapy and improve case management without unnecessarily discarding useful drugs.

Given Data / Assumptions:

• Chloroquine remains effective for some malaria contexts but not for all (resistance exists).
• Alternative medicines or combinations may be needed (R&D and guideline updates).
• Clinical management benefits from identifying likely vectors/parasite species to tailor treatment.

Concept / Approach:
Public-health logic favors targeted diagnostics and development of effective alternatives. A blanket ban on chloroquine would deprive clinicians of a valid option where it still works.

Step-by-Step Solution:

Verification / Alternative check:
Health systems typically retain existing drugs where effective, add alternatives, and enhance diagnostics/surveillance to direct therapy. This aligns with II and III only.

Why Other Options Are Wrong:

• I and III / All follow: wrongly include an unnecessary blanket stop on chloroquine.
• None follows: incorrect because II and III are sound.

Common Pitfalls:
Assuming any resistance means total ineffectiveness; resistance is often partial and location-specific.

Final Answer:
Only II and III follow