Lecture 27. Climate Change and Disease Flashcards
What is required for a disease to be infectious?
Extrinsic incubation period (EIP) < Average adult life expectancy (L)
How might climate affect vectors?
may affect whether and for how long the average vector may be infectious Dv
Is El Niño responsible for periodic epidemic cycles?
ENSO (El Niño Southern Oscillation) statistically associated with malaria outbreaks in Columbia,
Guyana, Peru and Venezuela
ENSO associated flooding enabled epidemics in costal Peru
ENSO associated draughts preceded epidemics in Columbia and Guyana by 12 months but NOT Brazil and Ecuador
No clear evidence why ENSO-forecasting is not universal
What is bluetongue virus (BTV)?
Double stranded RNA virus of livestock
Subclinical (normally) chronic infection in cattle = reservoir host
Severe disease in some sheep/deer species
Vector-borne by midges (Diptera: Ceratopogonidae)
Competent vectors traditionally subtropical/tropical latitudes 35°S and 40°N
Traditional African/Asian midge vector is Culicoides imicola
Where are BTV midges expanding into?
Europe
How might temperature influence BTV transmission?
Warm/hot periods in autumn/summer increases transmission potential
Warm nights/winter increases virus persistence to “overwinter”
Induces competence of traditionally non-vectorial European midges
How might precipitation influence BTV transmission?
Governs size/persistence of semi-aquatic breeding sites
Moisture governs key microhabitats for adult
e.g C. imicola breeds in wet organic-matter rich soil, but pupae do not survive flooding
What explains BTV expansion into Europe?
Northern range expansion of C. imicola in southern Europe correlated with annual mean year round warmth 12°C-20°C
New outbreaks in some areas of increased minimum temperature
Less well defined for rainfall
Transmission in N. Europe by presence of indigenous European vectors following BTV introduction
Temperature rises increase competence of traditionally non-vectorial species; variable for C. obsoletus in the UK
