Transcript Geographic variation in GI diseases.

Geographic variation of GI
diseases.
R. Fielding
Department of Community
Medicine, HKU
Learning objectives
• Discuss the relationship between diet & GI
disease, giving at least two examples to illustrate
this
• Give meaningful examples of relationships
between poverty & disease & realistic estimates
of the scale of the problems arising from this
• Give at least two examples of GI diseases arising
from different geographic environments
• Outline main components of the politics of
infantile gastroenteritis
• Describe the prevalence of under-nutrition, list
most common causes and those most at risk
Introduction
• Both infectious and non-infectious GI
diseases vary drastically by geographic
location
• Main influences:
– socio-economic gradients
– diet (foods, preparation & preservation)
– political economics.
• Infections contribute to number of important
neoplasms (stomach; hepatic)
Public health principle
Cancers: Upper GIT
• Oesophagus: was declining, but remains high
in France, Iran, Kashmir, Khazakstan, China.
Now increasing in west over past 20 yr:
gastric reflux
• Stomach: declines worldwide since 1970.
Most common Ca in Japan. Japan, Korea &
Sabah, Iran & Kashmir, (China: Qinghai,
Ningxia) highest (about 26-33% of ca deaths
in men).
S & SE Asia, lowest prevalence in Asia.
Incidence of gastric cancer
/100,000
250
200
Jap . M ale
Jap . F em
150
S /h ai m al
100
S /h ai fem
H K M ale
50
H K fem
0
1970
1985
1992
What has changed?
• Diet • Food preservation methods
• Increased screening, earlier detection but
survival remains poor (50% 5 yr, 21% 10 yr
Eckert etal, 1998)
• Recognition of Helicobacter pylori too
recent to impact on incidence rates.
Cancers: lower GIT
Whereas age standardized incidence of
upper GIT cancers have declined, lower
GIT cancer incidence has increased.
Colorectal cancer incidence in West has
increased (E.Europe 11% / 5 years) but
mortality declining.
GIT cancer incidence
40
35
30
O esoph
25
stomach
20
small intes
15
liver
colon
10
rectum
5
0
1974-77
1988-92
Contributing factors
•
•
•
•
•
•
•
•
Agent, vector, host changes in:
diet
activity
technology
social behaviour
living conditions
tobacco / alcohol use
persistence of infectious agents
(Opisthorciasis / Hep B/C and hepatic ca.
Infectious GI diseases
• Increasingly serious problem in developed and
well as developing world
• Oro-feacal contamination: Major infectious
GIDs are water- or food-borne.
• Resulting from
– poor hygiene / contamination
– inadequate or improperly implemented food
regulation
• Many common GI infections not problematic
unless immune-compromised
Socio-economics of infantile
diarrhoea
• 40,000 infant deaths weekly <5 years old
due to diarrhoea.
• Principally contaminated water, (not boiled).
• Baby milk formula food expensive, therefore
made more weakly than required.
• Lack of clean oral rehydration > death.
• WHO estimates 1.5 million deaths / year
avoidable by effective breast feeding
protection.
Why do poor mothers use baby formula?
• Heavily promoted to doctors and in
maternity units
• “Free samples” given (which once used
prevent baby reverting to breast feeding).
Mother then dependant on formula food,
which:
• uses significant financial resources
• cannot be administered properly as most
women are illiterate
• principle cause of infantile diarrhoea
Poverty and GIDs
Access to uncontaminated water more
difficult for poor people.
• combined with:
– under or poor nutrition
– tobacco / alcohol use
– crowded living conditions
– lack of toilets, sanitation
– exposure to toxins and other carcinogens
• greater risk of
– diarrhoeal
– parasitic diseases
Malnutrition 1: overnutrition
• Excess dietary intake: BMI >25 =
overweight
• Appears first among affluent then lower
class.
• In adults high refined protein, carbohydrate
and fat intake and too low fruit/veg.
• Predisposing factors are malnutrition during
foetal and childhood periods.
• 30% of Latin Am, Caribb, N.Africa, Pac.Is.
and urban Asia
2. Undernutrition
• Insufficient dietary intake. Protein-calorific or
trace nutrient (eg iron, zinc).
• Prevalent -Famine: war, drought, pests, floods
unemployment, dislocation.
• Primary (insufficient food); secondary (
parasitosis).
• Growth delay, cognitive impairments in children
• Risk factor for infectious GIDs, acute Ris and
other infections.
Summary
• Where people live.
– tropical / temperate, wet / dry, nomadic / rural /
urban, developed / under-developed
• What they do there…
– agriculture/ fishing/ livestock, industry / service /
homemaker
• How they can live
– trad/modern, poor/affluent, education / none,
available health care, costs, market conditions
• major determinants of their host status and
exposure to vectors and agents of GIDs