Vector dynamics and climate

Climate Change Affect on vectors

• the diseases are sensitive to climate change

• Host environment robust for parasite

• Environmental parasite stages are sensitive to climate due to the vectors sensitivity (breeding sites etc)

Vectorial capacity calc

• ((V/N)(ah)²p^n) / -ln p

• V = no. Vectors

• N = no. Hosts

• A² = vector biting rate per day

• H² = proportion of blood meals taken on host

• P = daily vector survival rate

• N = extrinsic incubation period

Extrinsic incubation period

• time taken for parasites to develop in vector and become transmissible

• Must be less than vector life expectancy to be infectious

Gonotrophic cycle

• how often a vector feeds

• From blood meal to laying eggs

D v

• how long a vector is infectious for

• = p^EIP (extrinsic incubation period) / -ln p

  Affected by climate due to EIP

Dengue

• mosquito borne viral infection

• In tropical and sub tropical climates

• No specific treatment but survival depends on healthcare

• Prevention and control relies on vector control

• Increasing trends in incidence

• Oscillating epidemics in El Niño due to. Climate (floods and droughts - breeding sites)

Blue tongue virus

• livestock

• Cattle = reservoir host

• Vector borne

• In tropical climates but invaded Europe due to vectors

• Due to climate (temp and precipitation induced competence of traditionally non vectorial midges)

• Some areas increased in min temp , some midges could now survive in winter

Climate

• can affect various stages of vector dynamics

• Changes characteristics of infectious disease presence and transmission