Climate change and vectorborne diseases

Many vulnerability assessments anticipate climate change will result in increased incidence of communicable diseases including vectorborne diseases (VBDs). VBDs are transmitted by the bites of infected mosquitoes and other insects (vectors). Their incidence is particularly dependent on climatic factors because:

• Insects have no internal control over their physiological temperatures and the ambient temperature determines their reproduction rate, biting behaviour and survival: their distribution may expand as the earth warms.
• Humidity and availability of water for breeding are also determinants of vectors' distribution, longevity and behaviour.
• The incubation period of pathogens inside vectors is temperature-dependent (and tends to decrease at warmer temperatures).
• Human behaviour is likely to be affected by climate change which will alter our interaction with vectors and the diseases they carry.

Climate-sensitive VBDs in the region

In the WHO Western Pacific Region, important VBDs that might be affected by climate change include: malaria, dengue, other arboviruses such as Japanese encephalitis, chikungunya and West Nile virus, lymphatic filariasis, plague, tick borne diseases including tick-borne encephalitis, lyme disease and rickettsioses, and schistosomiasis.

WHO response to climate change

WHO has taken action to reduce the health risks of climate change on vulnerable population groups and urges member states to combat the effects of climate change including by:

• Developing health measures for adaptation to climate change.
• Strengthening capacity of health monitoring and minimizing the public health impacts of climate change.
• Promoting effective engagement of the health sector to reduce risks from climate change.
• Adoption of intersectoral initiatives via assessment of the health implications of other sectors' climate change policies, such as urban planning, transport, energy supply, food production and water resources.
• Advocating for decisions that provide opportunities for improving health.