Lecture 27

Extreme weather events brings about diseases
Tropical diseases are vector borne where climate change has the greatest effect
Parasite development is climate dependent
Extrinsic incubation period (EIP)
To be infectious, the EIP needs to be less than the life expectancy
Climate may affect EIP
Dv = pEIP/(-ln p)
Dv = duration of infectiousness
Dv = 0.912 / (-ln0.9) = 2.7 days
In hotter climates EIP could reduce to 6 days
Dv = 0.96 / (-ln 0.9) = 5 days – amount of days infectious
Hotter climates can also increase likeliness of survival of p (vector)
Vectorial capacity can be reduced if EID is more than life expectancy
El nino years cycle lasts 2-7 years, persisting for 12-18 months
El nino years causes weather changes around the world
El nino causes increase in rainfall which is perfct for breeding for mosquito
Temperature increases surivival of mosquitos

Dengue is a mosquito born viral infection

• Causes flu like illness
• Can develop into haemorrhage
  No specific treatment for dengue – hence why intervention is important
  Because of dengues prevalence in tropical and sub tropical areas, half of the population is at risk of it
  El nino and dengue
• They are well correlated

El nino is statistically ascoaited with malaria in some countries

• Associated with flooding in some countries (peru)
  Climate is not a fully indicator of a disease

Biological influence of blue tongue virus
Temperature – warm/hot periods in autumn/summer increases transmission potential

• Warm nights/winter increases virus persistence
  Precipitation – govern size / persistence of semi-aquatic breeding sites