1b Physical factors Flashcards
What physical factors affect patterns of disease?
Temperature, precipitation, relief and water sources
Temperature
Determines rate of vector development and viral replication
Malaria
Warm humid conditions
Seasonal
Precipitation
Seasonal
Aquatic habitats - stagnant pools
Insects and disease vectors
Relief
Cause changes in climate
Water sources
Contaminated by sewage
Bacteria thrives - cholera
Stagnant water drinking supplies provides habitats for disease vectors
How can physical factors influence disease vectors - Dengue?
Infects 400 million
Climate control epidemiology and Aede mosquitos - thrive in warm, humid conditions
How do cold seasonal variations influence disease outbreaks?
Influenza peaks in winter due to easier transmission of the flu virus at lower temperatures
How does the rainy season influence disease outbreaks?
Vector borne diseases peak
Diarrhoeal disease
How does climate change provide conditions for emerging infectious diseases?
Increases temperature, rainfall and humidity
Vector-borne diseases and extended their geographic range
Warmer and wetter - mosquitos
West Nile virus - climate change
Climate change - higher temperatures
Spread globally from Uganda by birds
2012, 5500 cases of WNV in the USA
Ticks - climate change
Thrive in warm conditions
Lyme disease
Expanding northwards
Tsetse fly - climate change (trypanosomiasis)
Sleeping sickness
Affects 70 million
Transmitted by tsetse fly
Climate change - will increase vector growth rate and geographical distribution
Likely to spread into Southern Africa - will affect 77 million more by 2090
May disappear from East Africa - too hot
Zoonotic diseases
Spread from animals to humans
Bird flu and rabies
Conditions for zoonotic diseases more likely to be transmitted
- Movement of infected animals
- Ineffective control on movement of animals
- Urbanisation (foxes, racoons)
- Limited vaccinations
- Poor hygiene and sanitation - drink water contaminated
- Lots of contact between humans and animals
