Lecture 4: Environmental basis of disease Flashcards
Epidemiology is the
Basic science concerned with the patterns of disease frequency in human population
-distribution of disease by person., place time
assumptions made by epidemiology:
- Disease does not occur randomly
- Disease has identifiable causes
Epidemiological research is used to
- Describe the health status of a population
- Explain the aetiology of disease
- Predict the disease occurrence
- Control the disease distribution
Epidemiological triangle
- Host (intrinsic factors)
- Environment (extrinsic factors)
- Agent
from triangle: HOST
- Genetic
- Age
- Sex
- Physiolocial state
- immunisiation
- behaviour
from triangle: ENVIRONMENT
- physical
- socioeconomic
from triangle: AGENT
- Nutritive
- chemical
- physical/radiation
- infectious
epidemic -
widespread disease outbreak amongst a population
pandemic -
epidemic crossing populations
importance of migrant studies:
can look between immigrants and sons of immigrants and them in native countries to see if lifestyle and environment affects potential for disease (interplay of genetic and environmental factors)
John Snow
(1813-1858)
-victorian surgeon & anaesthesiologist
Vibrio Chloera
the organism that causes cholera was discovered 25 years after john snows death by ROBERT KOCH
Cholera remains a serious problem in many countries due to
- Poor access to safe water and inadequate disposal of sewage.
- In unprepared communities fatalities to 50%.
- In well organised and prepared countries fatalities <1%
- ~6 million/yr die from diarrhoea (not all from cholera)
Associations vs causations
things can be associated such as being french, smoking and lung cancer.
-but doesn’t mean if you’re french you will definitely have lung cancer
mortality associated with smoking
- 320+ UK deaths every day from smoking, 120,000 per year
- 1/5 all deaths across all ages
- 7.5 years average loss of life expectancy
- 4 million deaths/year worldwide
Major health consequences of smoking:
- Cancer;
- -lung
- -mouth, larynx, throat, oesophagus
- -bladder, cervix, kidney, pancreas
- Respiratory disease e.g. COPD (chronic obstructive pulmonary disease)
- Vascular disease
- -Coronary heart disease
- -Stroke
- -Peripheral vascular disease
- Pregnancy and birth complications
smoking can lead to premature birth
- maternal endocrine/paracrine changes
- altered cell signalling
- restricted placental blood flow
- increased risk of membrane and rupture
- fetal hypoxia
pulmonary emphysema =
enlargement of alveolar airspaces
with destruction of elastin in walls
tobacco –> chronic chemical injury —> pulmonary emphysema
irritates –> alveolar macrophage –> neutrophil / chemotactic factors (IL8) –> proteases (inc elastase) –> tissue damage –> emphysema
anti trypsin is mainly synthesised by hepatocytes but is also r
released from macrophages and neutrophils (some people are anti-trypsin deficient)
smoking can lead to
- decrease in ciliary action
- chronic bronchitis increase excess of mucus
- -> both lead to infections –> tissue damage and emphysema
smoking is highly addictive
- 70+% of smokers want to give up
- 50- % succeed before age 65
- 40% of heart attack smokers relapse while still in hospital within 2 days of intensive care
- 50% of patients with laryngectomies try smoking again
- 50% of patients with lung removed for lung cancer smoke again
- More than half of heroin and cocaine users and alcoholics rate smoking harder to quit
in smoking whats the driving force behind addiction?
NICOTINE
critical factors in determine whether exposure leads to disease
Chemical & biological composition Shape & size of particles Dose - concentration and duration Pre-existing health or genetic status Concurrent exposure to other toxic
pneumoconioses
- Lung disease caused by inhaled dust
- Dusts may be
- -Inorganic (mineral)
- -Organic
- Reaction may be
- -Inert (coal-miner’s)
- -Fibrous (asbestosis, silicosis)
- -Allergic (extrinsic allergic alveolitis)
- -Neoplastic (mesothelioma, lung carcinoma)
- Co-existing disease may aggravate reaction
Asbestos produces several diseases
- Asbestosis
- Lung cancer
- Mesothelioma
- Cancer of
- -Stomach
- -Colon
- -Rectum
the asbestos fibre + iron and calcium ==
“ferruginous body” (iron stain)
Macrophage fibre ingestion ..
increases fibrogenic response (collage deposition by fibroblasts)
