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