BIOS 5445: Human Ecology
Dr. Stephen Malcolm, Department of Biological Sciences
•  Lecture 8. Mortality Disease:
– Infectious
diseases.
– Non-infectious
diseases.
– Pollution.
– Responses to
stress.
– Fat.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 1
2. Infectious disease - Vector-borne diseases:
•  Most common vectors are arthropods.
•  Mechanical and biological transmission.
•  Examples:
–  Malaria:
•  Largest source of human mortality.
•  Caused by Plasmodium protozoa.
•  Transmitted by Anopheles mosquitoes.
–  Onchocerciasis (river blindness):
•
•
•
•
Filarial worms migrate to eye.
Transmitted by black flies, Simulium damnosum.
Flies breed in fast-flowing water.
Conflict between needing water and incidence of parasites:
–  like schistosomiasis (caused by a fluke) with snail vector.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 2
3. Human response to malaria (Fig. 9-7):
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 3
4. Infectious disease - Direct transmission:
•  Coughs, sneezes & touch transmit droplets.
•  Respond to aggregations of humans generated
by intensive agriculture.
•  Examples:
–  Measles - viral.
–  Influenza - viral:
•  Changes in viral protein coat lead to antigenic drift & foils
host immunity.
•  Can result in global pandemics:
–  1918-20 killed 25-50 million people.
•  Animal reservoirs (pigs and birds) lead to great antigenic
variation.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 4
5. Incidence of measles (Fig. 9-8):
•  Type I waves (a) in large
island populations with
continuous incidence.
•  Type II waves (b) in
medium-sized island
populations with regular
incidence/absence
cycles.
•  Type III waves (c) in small
island populations with
irregular incidence.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 5
6. Virgin soil epidemics:
•  Introduced diseases can be especially virulent
•  Contact with highly aggregated people can be
disastrous with <90% mortality because
everyone is susceptible.
•  May have resulted in collapsed cultures in the
Americas.
•  Examples:
–  Native Americans and Pacific Islanders upon contact
with smallpox and measles carried by
explorers/immigrants from densely populated
Europe.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 6
7. Disease and sanitation:
•  Fecal-oral route through contamination of
water and food.
•  Exacerbated by mechanical vectors.
•  Problems first generated when nomadic
lifestyles were abandoned in favor of
sedentary, agricultural lifestyles.
•  Examples:
–  Hookworm in human intestine.
–  Cholera - caused by Vibrio cholerae bacterium in
fecal/body fluid-contaminated water.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 7
8. Human response to cholera (Fig. 9-10):
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 8
9. Disease and intimate contact:
•  Mostly sexually-transmitted diseases.
•  Examples:
–  Gonorrhea is caused by the gonococcal bacterium,
Neisseria gonorrhoeae.
–  Treponemal diseases caused by bacterial spirochetes:
•  Venereal syphilis:
–  Mostly horizontal by genital contact (>90%), some vertical from
mother to fetus.
•  Yaws:
–  Both direct transmission & fly vectors, mostly in poor children.
•  Pinta:
–  Mild skin disease.
•  Nonvenereal (endemic) syphilis:
–  Transmission by contact and water/food.
•  Treponemal disease - cross resistance among diseases.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 9
10. AIDS:
•  Acquired Immune Deficiency Syndrome caused
by human immunodeficiency virus (HIV) - a
retrovirus (RNA-based).
•  Extremely fast mutation rate (faster than
influenza) of both HIV-1 and HIV-2.
•  Targets immune system.
•  Transmitted horizontally in body fluids by
sexual contact (homosexual and
heterosexual), transfusions and injections
(immunizations & drug use).
•  Transmitted vertically from mother to fetus.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 10
11. Interactions among nutrition,
disease and other stressors:
•  Negative feedback:
–  Poor nutrition leads to reduced immune system
function and enhanced susceptibility to disease.
–  This in turn leads to lethargy and reduced mental
ability that results in less ability to gather nutritious
food.
•  Warfare can also generate the same negative
feedback through the disruption of food
production and distribution systems.
•  These factors can also interact with abiotic
conditions such as altitude and temperature
to generate problems from hypoxia and
cold stress.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 11
12. Non-infectious or chronic diseases and
modern stress:
•  Generating wealth in urban/suburban
environments also creates new
problems from stress, pollution and
overconsumption of resources.
•  Problems generate chronic diseases
such as cancer, hypertension, heart
disease and diabetes.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 12
13. Cancer:
•  Gene mutations that alter regulation of cell proliferation.
•  Causes:
–  Mutagens:
•  Physical or chemical agents that might affect rates of mutation and
interact with genetic susceptibility.
•  Examples include cigarette smoke, viruses and radiation.
•  Specific cancers may have specific environmental causation.
•  Incidence varies among populations:
–  Geographical variation.
–  Higher incidence in modernized than traditional societies.
•  Strong environmental influence.
•  Strong correlations with rates of urbanization, level of education,
per capita Gross Domestic product (GDP) and amount of imports.
–  Higher modern incidence not a product of greater longevity.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 13
14. Hypertension:
•  A symptom of stress.
•  Persistently high arterial blood pressure.
•  Increased risk of stroke, heart disease,
blindness & kidney failure.
•  Higher incidence in modernized
societies.
•  Characteristic rise in blood pressure with
age in modernized societies but not in
traditional societies.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 14
15. Heart disease:
•  Atherosclerosis:
–  Hard, lipid-containing deposits or plaques on wall of
coronary arteries:
–  Blockage causes heart attack.
•  Arteriosclerosis:
–  Hardening of the arteries can lead to aneurysm
(vessel ballooning) and rupture.
•  Higher incidence in modernized societies:
–  Immigrants also adopt host country incidence of
heart disease within 1 or 2 generations.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 15
16. Diabetes mellitus:
•  Inability to metabolize carbohydrates
through lack of hormone insulin or
inability to use insulin.
–  2 forms:
•  Insulin-dependent diabetes mellitus (IDDM):
–  Often in young people - juvenile diabetes caused by
autoimmune response to stop insulin production.
•  Noninsulin-dependent diabetes mellitus (NIDDM):
–  More common, with late onset.
–  Cells have few insulin receptors and respond poorly.
–  Associated with obesity and modernization.
–  Thrifty genotypes - feast-and-famine cycles select for
physiologies that promote rapid buildup or loss of fat.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 16
17. Pollution:
•  Chronic diseases both caused and influenced
by natural and anthropogenic actions:
–  Air pollution:
•  Smoke - cooking fires, energy creation, industrialization,
transport, tobacco use.
•  Smog - combination of smoke and water vapor:
–  Photochemical smog from action of sunlight on vehicular and
industrial chemicals in air pollution (SOx and NOx chemicals).
–  Water Pollution:
•  Disease and toxic chemicals from industry and agriculture.
•  Heavy metal poisoning.
•  Toxic organics & solid waste.
–  PCBs (polychlorinated biphenyls) and industrial solvent TCE.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 17
18. Physiological
response to stress
(Fig. 10-2):
• General stress is a
mediating variable
between a stimulus
and a response.
• Two forms of biological response to
general stress:
(1)  Via pituitary and
adrenal glands
(Fig. 10-2).
(2) Via sympathetic
nervous system
(Fig. 10-3).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 18
19. Physiological
response to stress
(Fig. 10-3):
• Fight-or-flight
prepares for major
physical effort.
• Loads blood with
glucose & oxygen.
• Increases blood
circulation.
adrenaline
and
noradrenaline
• But may impair
immune system.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 19
20. Urbanization and stress:
•  Situations characterized by novelty, unpredictability, or perceived
lack of control lead to increased stress responses.
•  Stress in an English village influenced epinephrine levels through
psychosocial arousal (both pleasant and unpleasant):
–  Daily activities at work and in home and travelling.
•  Modernization also appears to increase stress as measured by
excreted hormones (epinephrine and norepinephrine, Fig. 104):
–  Especially for immigrants not fully integrated.
–  Stress can also generate high cortisol bursts and lowered
immunoglobulin associated with outbreaks of infectious diseases:
•  Caused by social stress from divorce, work away from home and conflict
such as riots or warfare.
•  Children are especially susceptible.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 20
21. Hormonal response to stress in Filipino
Americans in Honolulu (Fig. 10-4):
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 21
22. Fat and chronic disease:
•  Tendency towards increased adiposity with
modernization.
•  More food calories consumed than are being
used & caloric excess is stored as fat.
•  Overnutrition is a form of malnutrition.
•  Fatness varies with genetic background, sex,
age and variables such as eating, exercise,
stress, smoking & socioeconomic status
(including modernization (Fig. 10-5).
•  Fat associated with chronic diseases:
–  Cardiovascular disease, diabetes & some cancers.
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 8: Slide - 22
23. Changes in adiposity with
modernization in Samoans (Fig. 10-5):
weight
Dr. S. Malcolm
skinfold
BIOS 5445: Human Ecology
Lecture 8: Slide - 23
13. References:
•  Kormondy, E.J., & D.E. Brown. 1998. Fundamentals of human
ecology. Prentice Hall. 503 pp. (chapters 9 & 10).
Dr. S. Malcolm
BIOS 5445: Human Ecology
Lecture 6: Slide - 24