disease and physical factors Flashcards
temperature and vector borne diseases
warm climate is beneficial for mosquito spread diseases as it increases the overall global distribution.
Also mosquitos feed more (eg: zika outbreak in 2016 had highest incidence rate in areas with temperature and drought hotspots)
However vectors that live in cool temperatures can be destroyed by increased heat. Cold weather (bellow 16) greatly diminishes survival rates of most vectors .
temperature and airborne disease diffusion
colder temperatures promote diffusion because people huddle together and stay indoors with limited ventilation.
For example influenza virus spreads more in northern countries due to favourable cool conditions.
In contrast Connecticut found lower temperatures defended against rhinoviruses because the pathogen could not survive in cooler weather.
temperature and water borne diseases
these diseases have a less direct link with temperature but have links through hot weather causing drought which increases disease and so does heavy rain.
Bangladesh cholera concentrations were up to 50% higher in dry weather drainage flow samples compared to wet weather samples from floodwater due to water shortage decreasing sanitation and hygiene
precipitation and vector borne diseases
- More rainfall causes river overflow which results in more stagnant water for larval breading. Increasing mosquito population. Eg increase in aedes aegypti will increase rates of dengue virus and yellow fever.
- However, water can destroy habitats for rodent vectors e.g rabies
- Severe flooding moves rodents into homes and densely populated areas. e.g leptospirosis ,rodent spread, rates increased after flooding in Brazil
precipitation on water borne diseases
- Contaminated water due to runoff mixing sewage and drinking water spreads cholera and e.coli combined sewage overflow event
- Extreme water shortages can lead to increased incidence in diarrhoeal disease due to improper hygine and use of contaminated water in desperation Bangladesh cholera concentrations were up to 50% higher in dry weather
influence of relief on disease
Less disease at high altitude due to decreased population density
In Ethiopia malaria is concentrated to low lands because of cool temperatures high up killing Anopheles
physical barrier to migration
climate change: where temp increases 2–4°C there will be a proliferation of the malaria-carrying mosquitoes at higher altitudes: shifting climatic bands
impact of drought on airborne disease
- Increase spread to people seeking refuge together
- Malnourishment and undernourishment diseases occur
- Respiratory (pakistan 20210) disease spread more due to decrease in hand washing
exacerbate socioeconomic vulnerability
impact of drought on water borne diseases
Less food washing leads to E.coli and salmonella
- When temperatures rise more people bathe and swim in open water and without rinsing can contract water-borne disease
- More drinking of contaminated water
- Incomplete sewage disposal spreads faecal to oral diseases like Ebola.
however sept 2015 floods in Sierra Leone were mitigated against by CDC and no new outbreak of Ebola
impacts of monsoon on vector borne disease
increases=vb disease
- Increase in specific zoonotic diseases like leptospirosis
- Malaria epidemics are often seen 6-8 weeks after floods due to increased stagnant water for breeding. Costa Rica (1991) The Dominican Republic (2004)
impacts of monsoons on other diseases
increases wb and ab disease
- Secondary effects of flooding (crowding and subsequent faecal to oral transmission) spreads diarrheal disease and airborne disease.
- Increased respiratory tract infections due to loss of shelter and exposure to flood water and rain (Pakistan floods 2010).
temporal changes of El Nino
- Every 5 years
- Increased frequency and volatility
Changes over space of El Nino
worldwide economic impacts due to lack of trade
- Mainly effects tropics between south America and Indonesia
- Effects extend somewhat North and South
global increased risk of Dengue Fever Cholera and Malaria 2015-16
hanta, virus, plague and west nile virus isolated to USA 2015-16
Effect of El Nino temperature on disease patterns
- Warmer temps decrease certain vector-borne disease like ones spread by rodents, but increase the mosquito population.
- Drought causes hunger so diseases caused from deprivation and desperation
- Cooler areas cause less diseases that are water-borne and airborne
- Cooler temps decrease immune response so increase vulnerability to disease in those areas.
Effect of El Nino precipitation on disease patterns
- Droughts cause malnourishment and undernourishment
- Droughts decrease most vector-borne disease but increase airborne and water-borne- dynamic relationship
Increased rain increases most vector borne and airborne as well as waterborne due to contamination
- Droughts decrease most vector-borne disease but increase airborne and water-borne- dynamic relationship
Effect of temperature of air borne disease immunity
cool weather supresses the immune system
a natural risk factor for disease as the body can’t fight off pathogens.
A drop in nasal tissue temperature of just 5° C reduced immune response by almost half.
