Climate Change and Disease Patterns

Climate's Core Impact - Health Under Heat

• Global warming ↑ average & extreme temperatures. Urban Heat Island (UHI) effect amplifies exposure.
• Direct health effects:
  • Heat cramps, heat exhaustion, heatstroke (core body temp > 40°C).
  • Dehydration, electrolyte imbalance.
• Aggravates existing conditions:
  • Cardiovascular (↑MI, CVA).
  • Respiratory (↑asthma, COPD).
  • Renal diseases (↑AKI).
• Vulnerable: Elderly, infants, outdoor workers, pre-existing illness. 📌 Mnemonic: "HEAL" (Heat, Elderly, Ailments, Labourers).

⭐ Heatstroke: core body temperature > 40°C (104°F) with CNS dysfunction; high mortality if untreated.

Vector Voyage - Bugs on the Move

• Climate change impacts vector ecology & disease patterns:
  • Temperature ↑: Accelerates pathogen development (Extrinsic Incubation Period ↓), ↑ vector activity, biting rates & potential vector competence.
  • Rainfall Δ: Alters breeding sites (e.g., Anopheles, Aedes). Floods/droughts create new or disrupt existing habitats.
  • Humidity Δ: Influences vector survival & activity.
• Major Indian VBDs affected:
  • Malaria (Anopheles): Geographic expansion (e.g., higher altitudes), longer transmission seasons.
  • Dengue/Chikungunya (Aedes): ↑ transmission intensity, urban & peri-urban spread.
  • Japanese Encephalitis (Culex): Influenced by rice cultivation, temperature, pig populations.
  • Kala-azar (Sandflies): Sensitive to temperature & humidity.
  • Scrub Typhus (Mites), KFD (Ticks): Changes in vegetation & host animal distribution.
• Overall Effects:
  • Vectors invade new geographical areas.
  • Longer periods suitable for disease transmission.

⭐ Warmer temperatures can reduce the Extrinsic Incubation Period (EIP) of pathogens like dengue virus in Aedes mosquitoes, leading to quicker transmission potential after infection.

Waterborne Worries - Tainted Tides

Climate change disrupts water cycles: ↑temperatures, extreme rainfall, floods & droughts escalate water contamination.

• Mechanisms:
  • Floods: Overwhelm sanitation, spread sewage & agricultural runoff.
  • Droughts: Concentrate pollutants in scarce water sources.
  • Warmer waters: Promote pathogen (e.g., Vibrio) & algal bloom growth.
• Key Diseases Exacerbated:
  • Cholera (Vibrio cholerae): Linked to ↑sea surface temp (optimal growth $20-30°C$), post-flood.
  • Typhoid Fever (Salmonella Typhi): Contamination after floods, sanitation issues.
  • Leptospirosis: Rodent urine in floodwaters.
  • Giardiasis & Cryptosporidiosis: Protozoal, via contaminated runoff.
  • Harmful Algal Blooms (HABs): Produce toxins, thrive in warmer, nutrient-rich waters.

⭐ Coastal flooding dramatically ↑ risk of cholera outbreaks due to favorable conditions for Vibrio cholerae (salinity changes, organic matter).

Air & Aridity Alarms - Gasping & Parched

• Air Pollution Surge: Climate change intensifies:
  • Wildfires: Release PM2.5, CO, PAHs.
  • Dust storms: ↑ PM10 from arid lands; linked to desertification.
  • Ground-level Ozone (O3): Forms from precursors (NOx, VOCs) in heat & sunlight.
  • Aeroallergens: ↑ Pollen counts, longer seasons.
• Health Impacts - Air Quality:
  • Respiratory: New/worsened asthma, COPD, bronchitis, allergic rhinitis. 📌 "Airway Alarms"
  • Cardiovascular: ↑ MI, stroke, hypertension, arrhythmias.
  • ⚠️ PM2.5: Penetrates alveoli, enters bloodstream, causes systemic inflammation.
• Aridity & Drought Stress:
  • Water Scarcity: Compromises hygiene, sanitation; risk of dehydration.
  • Heat Stress Amplification: Dry conditions worsen heat's physiological impact.
  • Food Security: Crop failures → malnutrition, stunting.
  • Dust Exposure: ↑ Respiratory infections, eye irritation (trachoma).

⭐ Increased frequency of dust storms due to desertification significantly elevates risks of respiratory diseases like silicosis and exacerbates asthma.

High‑Yield Points - ⚡ Biggest Takeaways

• Climate change escalates vector-borne diseases (Dengue, Malaria, JE) by expanding vector habitats and transmission seasons.
• Increased incidence of water-borne infections like Cholera and Typhoid due to floods and contaminated water sources.
• Rising temperatures intensify heat-related illnesses, such as heatstroke, particularly affecting vulnerable populations.
• Deteriorating air quality aggravates respiratory conditions (Asthma, COPD) and cardiovascular diseases.
• Significant threat of food insecurity and malnutrition from climate-induced agricultural disruptions.
• Shifting patterns of zoonotic diseases due to ecological disturbances and altered human-animal interactions.