Why in News?
- Recent rise in dengue, Zika, and chikungunya cases across Indian cities.
- Fogging and fumigation still widely used, despite lack of evidence for effectiveness.
- Experts highlight need for integrated strategies combining personal protection, community action, and innovative top-down interventions.
Relevance :
- GS-II (Health, Governance): Vector-borne diseases, public health policy, community mobilisation.
- GS-III (S&T, Environment): Wolbachia, repellents, vaccine trials, urban resilience.
Basics:
- Aedes aegypti & Aedes albopictus → primary vectors of dengue, Zika, chikungunya.
- Breeding sites: small stagnant water collections (plastic bottles, coconut shells, plant pots, air coolers, tyres).
- Feeding habits:
- Bites during daytime and under artificial lights at night.
- Indoor feeders → vaporizers, nets, and outdoor fogging less effective.
- Range: short, 100–200 m → localised community action is crucial.
Overview:
Why Current Measures Fail
- Outdoor fumigation/fogging:
- Temporary effect; mosquitoes quickly return.
- No endorsement by national/international agencies for routine use.
- Household vaporizers:
- Aedes least active at night.
- Mosquitoes evolving tolerance to pyrethroids.
- Bed nets: ineffective, as Aedes bites during the day.
Personal Protection – First Line of Defence
- Protective clothing: loose, full-body coverage (esp. Sep–Nov peak).
- Topical repellents (WHO/CDC approved):
- DEET (20%) → gold standard; ~6 hrs protection, safe for pregnancy/lactation.
- Picaridin, IR3535, 2-undecanone → safe, effective, but not widely available in India.
- PMD (lemon eucalyptus extract) → effective but not for children <3 yrs.
- Ineffective “natural” oils (citronella, etc.) → short-lived, irritant, unsafe in undiluted form.
- Spatial emanators (transfluthrin-coated materials) → 34% risk reduction in trials.
Community Mobilisation – Bottom-Up Action
- Larval source reduction:
- Cleaning air coolers, discarded containers, indoor plants, flower vases.
- Not reusing old cooler grass, covering water storage containers.
- Randomised trials evidence:
- Camino Verde study: 29% reduction in dengue via community-led cleanups.
- Chennai study: container lids cut larval risk by 94%.
- India-specific campaign: “10 Weeks, 10 AM, 10 Minutes” → weekly neighbourhood clean-up drives.
- ASHA workers’ role: disseminating behavioural change communication.
Top-Down Innovations
- Wolbachia mosquitoes:
- Release of mosquitoes infected with Wolbachia bacteria → block viral transmission.
- Successfully deployed in 15 countries.
- Barriers in India: high cost, weak institutional push.
- Dengue vaccine trials: ongoing, but no cross-protection for Zika/chikungunya.
- Policy gaps: absence of systemic push for DEET availability and community education.
Structural Challenges
- Plastic pollution: discarded plastics → key larval habitats; waste management is directly tied to ABVD control.
- Chemical larvicides (temephos): shown to increase dengue risk due to false security + resistance development.
- Public misinformation: preference for “natural” repellents and mistrust of DEET.
- Weak urban health systems: over-reliance on municipal fogging, little investment in local community-led interventions.
Way Forward
- Integrated approach:
- Bottom-up: community-led source reduction + personal protection.
- Top-down: Wolbachia deployment, spatial emanators, vaccine development.
- Urban governance reform: link RWA initiatives with municipal corporations.
- Health communication: counter misinformation on repellents; promote safe, effective alternatives.
- Institutional support: scale up ASHA workers’ role, ensure repellents’ availability, incentivise innovations.
- Policy focus: plastic waste management, water management, and urban resilience planning.
