Geographic variation of GI diseases.

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Geographic variation of GI diseases.

• R. Fielding
• Department of Community Medicine, HKU

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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

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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)

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Public health principle
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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.

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Incidence of gastric cancer /100,000
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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.

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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.

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GIT cancer incidence
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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.

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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

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Socio-economics of infantile diarrhoea

• 40,000 infant deaths weekly 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.

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• 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

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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

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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

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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.

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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