A village in a high-malaria-burden district shows high rates of P. falciparum. The district malaria officer decides to deploy Long Lasting Insecticidal Nets (LLINs). According to NVBDCP norms, LLINs need re-treatment or replacement approximately every:
- A 3 years under field conditions
- B Every monsoon season (annually)
- C 3–5 years under WHO standard washing conditions ✓
- D 10 years — LLINs retain efficacy permanently
Explanation
LLINs are defined as factory-treated nets with insecticide incorporated into or bound to the fibres. WHO defines LLINs as nets that retain biological efficacy for at least 20 standard washes and 3 years under normal field use conditions — thus replacement/re-evaluation is recommended at 3–5 years. Regular conventional ITNs (untreated or treatment-dipped) require annual re-dipping. LLINs do not require annual treatment (option B). The claim of permanent efficacy (option D) is incorrect — physical degradation of the net and insecticide depletion occur over time. NVBDCP distributes LLINs in high-burden districts with replacement planned at 3-year intervals.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.