Story by AM/CLH , Photo by ANWAR MIRZA,
REUTERS NEWS PICTURE SERVICE
Recent Awareness of How
Hong Kong killsHuman
8,300 chickens
as and LandActivities
bird flu found CHINA: February 3,
uses
are
Linked
to
Human
2003
Health and Disease
Transmission among Humans
and Animals
Ban on importing
or exporting meat
because of mad
cow disease
Stalking a Deadly Virus, Battling a Town's Fears
By SHARON LaFRANIERE and Denise Grady;
April 17, 2005 – New York Times
Evelyn Hockstein/Polaris, for The New York
Times
Evelyn Hockstein/Polaris, for The
New York Times
Soldiers in Uíge wore biohazard
suits while burying two bodies
even though dead not known to
have Marburg virus.
Health workers
decontaminate body died due to Marburg
virus & wrapped it in a
protective shroud.
Vietnamese Boy Disabled by
Agent Orange in a Ho Chi Minh
City Hospital
VIETNAM : February 28, 2005
A Vietnamese boy disabled by Agent Orange gets the attention of a
volunteer while sitting in his cot in a Ho Chi Minh City hospital,
February 25, 2005.
“On
Monday, a New York court will begin hearing
a lawsuit brought by more than 100 Vietnamese
seeking compensation and a clean-up of
contaminated areas from more than 30 firms,
among them Dow Chemical Co and Monsanto
Co, the largest makers of Agent Orange. Agent
Orange, named after the colour of its containers,
is blamed for nightmarish birth defects in
Vietnam where babies appeared with two heads
or without eyes or arms.”
Story by Adrees Latif AL/CCK, Photo by ADREES LATIF, REUTERS
NEWS PICTURE SERVICE
Forests and Human Health
1. Human Health links to Forests
2. Introduction – complex factors
interlinked to disease
3. Factors accelerating the spread of
contagious diseases
4. Two Case Studies – show forest link
to disease
Leading causes of deaths (1997)
Aids
Link between forests and source of disease? Insect
vectors very adaptable to human social systems. Used to be adapted to forest
environment and bred in tree holes but now discarded tires, drains, water cans
1997
data
FORESTS
IMPORTANT?
Important in
Forests, tropics
eg Tuberculosis
Deforestation
causes insect
vectors to move
to cities
Factors accelerating spread of contagious
diseases: Global Factors
• High human population densities
• Poor sanitary conditions - contact with water,
food contaminated with human waste
• Speed, frequency of modern travel
• Use of excess chemicals (fertilizers,
pesticides, etc) against insect vectors, increase
growth of food crops
• Climate change, climatic events
Forests and Human Health
Introduction – complex factors
interlinked to disease
Genetics – Environment –
Nutrition – Social – Political
factors - Resource uses
Nutrition, Food Security, Poverty = Human Health
• Food security - inability to obtain
sufficient food on a day-to-day basis
• Higher incidence of infectious
diseases when undernourished can’t afford medicine or medicine not
available
• Poverty greatest threat to food security &
human health
• A poor environment will
contribute to a poor diet and
negatively affect nutrition
• Poor nutrition may contribute
to diseases & their emergence
USDA
Food
Pyramid
High Health = Low
Sickness
Eating a Balanced Diet
BUT this is food in many parts of the world
if you are fortunate
What nourishment exists from eating monkeys?
Central Africa eat primates when antelopes are scarce.
In tropics, 50% of protein consumed by people from bushmeat &
war stops agriculture so more dependent on bushmeat
When and what in
forests contribute to
Human health
problems?
Forests and Human Health –
link is human behavior in landscape
Factors accelerating spread contagious diseases
• Global factors – people, sanitary conditions,
travel, chemical uses, climate change
• Land use changes
• Moving into or through interior, remote
forest areas – close contact humans to wildlife
• Wars - Hunting for bushmeat, selling animal
parts for medicinal purposes
Factors accelerating spread of contagious
diseases: Global Factors
- climate determines insect outbreaks (eg malaria, dengue fever)
•Temperature = Insects sensitive to climate affects timing, intensity of outbreaks (minimum air
temp 15-18C needed for development of malaria
parasite, threshold temps >20C set off epidemic)
[what is average room temperature??]
•Drought (combined with AIDS, poverty, war, bad
governments, corruption) – extreme starvation >
poor health > higher disease susceptibility
CLIMATIC EVENTS
- climate determines insect outbreaks
•Higher rainfall = more malaria outbreaks in
world with more rain & increases in night time
temperatures during El Nino
- El Nino 1987, malaria increased significantly
in Rwanda
- El Nino 1997/98 worst in history with
torrential rains in East Africa – malaria
epidemics in Uganda highlands
Factors accelerating spread of contagious
diseases: Land Use Changes
•Deforestation
•Replace forests with crop farming, ranching and small
animals
•Which vegetation regrows after deforestation
•Water bodies in disrupted areas
•Road construction
•Mining
WHY affect health?
- Creates supportive habitat for parasites & their vectors, increase
spread disease organisms = (cattle, pigs, chickens serve as host for
disease)
Why extensive deforestation
in tropics affect disease spread
and its vectors?
Forests:
•heavily shaded
•not have free standing water (thick
organic layers on ground) so few
breeding ground for mosquitoes
•Trees adapted to get rid of excess
water
Cleared land:
•more sunlight
•prone to water puddles
•crops (sugar cane, rice) use of
irrigation ditches – good breeding
habitats
DEFORESTATION:
- most disruptive change
affecting parasitic vector
populations. Exposed
ground becomes great
breeding habitat for
mosquitoes (e.g. increase
in incidence of malaria)
Malaysia – 50 year repeat growing of rubber had
cyclic malaria epidemics
Trinidad – 1940s cut forests, trees came back with
lots bromeliads in canopy (hold water and preferred
breeding site of malaria mosquitoes).
- Removal bromeliads, malaria prevalence decreased
Replacement of forests with
rubber plantations or other
vegetation
Aechmea chantinii (Leinbach)
http://www.charlies-web.com/bromeliads-alphalist/tex365.html
Aechmea nidularioides
Frogs die and fertilize plants but also
mosquitoes use as breeding ground
ROADS
Road Construction into previously
inaccessible forests:
•Erosion, create ponds – breeding sites disease vectors
•Roads allow construction workers, loggers, miners, tourists,
conservationists to travel to new areas – expose new diseases (no
immunity like forest dwellers); animals –exposed to new
diseases
http://www.delange.org/TucumePyramids/T
ucumePyramids.htm
http://www.webshots.com/explains/outdoors/indian-ocean.html
Bali`s rice fields...
published by nature4u2 in scenery & nature on 2001-07-31 last
update on 2003-04-29
STANDING
POOLS OF
WATER –
GREAT
HABITAT FOR
MOSQUITOES
http://it.inmagine.com/agricultureimmagini-photos/pixtal-pt055
Factors accelerating spread of contagious
diseases: Moving into or through interior,
remote forest areas – close contact humans
to wildlife
- increase contact between
wildlife and humans in
interior forest areas (e.g.
increase Ebola, AIDS)
Interior, remote forest areas:
forest dwellers no
immunity to new diseases
from outside regions
Forest dwellers immune
but NOT OUTSIDERS
• economic development (mining,
timber, water for hydro electric
plants, irrigation), legal/illegal
trade, drugs moving people with
no immunity into regions
• Outsiders exposed to new
diseases from contact with animals
or changing land-uses
Wars – factors accelerating spread disease
• Decrease food security and people’s health in
general which makes people more susceptible to
diseases and premature death
• Resettling people or people spontaneously
migrating. Example Indonesia, resettling people
from densely populated islands of Java and Bali
to more sparsely populated and densely forested
outer island where people not have immunity to
malaria and where the plasmodium thrive in
conditions created by the development project
(Prothero 1999).
• Most people who move are poorly educated
and do not know how to protect themselves
against malaria and other health risks (Prothero 1999)
Humans are also dangerous to
the Health of Forest Animals!!
Human contact with
animals makes animals
sick!!!!
Outbreaks of disease in chimpanzees, great
apes of human origin:
Polio-like virus epidemic spread from
a village; 15 chimpanzees severely
crippled or died in 1960s, Tanzania
Polio like virus & flu like epidemic
killed 11 chimpanzees in Democratic
Republic of Congo, 2003
Great Apes - Documented outbreaks
of scabies, intestinal parasites, yaws
(syphilis-like), respiratory infections
similar to measles from human
contacts
- Ebola has killed up to 90% of the
apes in central Africa
Outbreaks of disease in
chimpanzees, great apes
of human origin :
Illnesses in villages next to Park
(% people with symptoms),
Kibale National Park, Uganda:
Fever = 82%
Coughing = 64%
Respiratory distress = 26%
Diarrhea = 24%
Vomiting = 24%
General Illness = 22%
International Gorilla Conservation
Programme ask tourists:
•Keep minimum distance between tourists and gorillas
at 5 to 7 m
•Use facemasks reduce transmission airborne diseases
•Prior to visit, tourists wash hands & disinfect feet
•Construct adequate pit latrines so proper disposal
human wastes
•Refuse tourists entry if sick
Two Case Studies – show forest link to
disease
• Malaria, forests, environmental change
and people (All 4 impact: climate change,
land use change, people moving into
remote forest areas, wars)
• Acorns, white footed mouse/deer, ticks,
bacteria, Lyme disease, forest
fragmentation (impact: land use change –
others less relevant)
Malaria, forests, environmental change, people
Malaria originated in Africa – fossils of mosquitoes
30 million years old; Plasmodium parasites highly
specific - man only vertebrate host, Anopheles
mosquitoes as vectors (parasite specificity - long,
adaptive relationship with humans)
Commonly called “forest malaria”
•Reasons where found – year round rainfall, temperatures where
mosquitoes breed continuously
•Forests fringes – most malarious where ecological conditions favor
disease
??
??
Malaria in 91
countries
The map indicates current distribution of indigenous
malaria according to WHO http://www.wehi.edu.au/MalDB-www/intro.html
In 1990, 80% cases in Africa, remainder clustered in nine
countries: India, Brazil, Afghanistan, Sri-Lanka, Thailand, Indonesia, Vietnam,
Cambodia, China.
NOTE WHERE FOUND! ARE THERE NO MOSQUITOES IN
THE NORTHERN LATITUDES (BOREAL FORESTS,
TUNDRA)?
Anopheles Mosquitos http://www.wehi.edu.au/MalDB-www/intro.html
•TODAY Malaria endemic to tropics, with extensions
into subtropics but 18th century North America had
malaria in lowland forests but eradicated it
•Malaria spread by travelers flying - cause death in nonmalarious areas.
Heliconia – high
abundance after
agriculture
abandonment in
American tropics
Building Panama
Canal, found linked
to incidence of
malaria since good
mosquito breeding
ground
Left, United
Nations; Corbis
Use of DDT works as an insecticide to control
but conflicts over other effects of DDT even
though DDT only effective control of
mosquitoes
Control measures:
spraying with DDT
coating marshes with paraffin
draining stagnant water
Preventive Measures:
Safest anti-malarial drug (chloroquine) no longer
works as well since malaria parasite becoming
immune
The top photograph of
a Unicef spraying with
DDT in Paraguay was
exhibited at the 196465 World's Fair
Unicef; Ian Berry/Magnum
Bottom picture, assault
on mosquitos -- without
DDT -- in Burundi in
2003
Unicef; Ian Berry/Magnum
Lyme Disease
Slide 32
Acorns
White footed mouse/deer
Ticks
Bacteria
Lyme
Disease
Forest fragmentation
- a case study not mainly in the tropics but found
globally and significant in the temperate region
(becoming big concern even in western US)
HUMANS
and Lyme
disease =
Fatigue
Sore joints
Heart
damage
Arthritis
Center for Disease Control and Prevention
= 17,730 cases Lyme disease in 2000;
Disease found in 44 states, only 6 free
from Lyme disease
Memory loss
Animals, trees,
people health all
connected to
Lyme disease
Deer and mice
are hosts for
bacteria
White Oak acorns
http://www.bowsite.com/bowsite/features/armchair_biologist/acorns/
acorns.html; http://www.bartelart.com/acorn.htm
White footed mouse
http://animaldiversity.ummz.umich.edu/media/phil/pln1.jpg
Acorn masting high
every 2-5 years in oaks
Gypsy Moth –
an invasive
introduced silk
making in US,
great mouse
food
High food for mouse
– increase their #s
http://lucas.osu.edu/gm/tufc.htm, White footed mouse
http://animaldiversity.ummz.umich.edu/media/phil/perom
yscus_leucopus_37.jpg
More ticks with bacteria
causing Lyme
#3
Ticks bite humans – Lyme disease
#2
#1
More food =
MORE MICE
Ticks have more animals to bite
to get blood = # ticks increases
Allan et al. 2002
Ticks
Small forest patch
(< 3 acres)
Large forest
patch > 3 acres
WHY DOES FOREST SIZE AFFECT
INCIDENCE OF LYME DISEASE?
White-footed
mouse - at
home in forest,
field, your
house
Loss of predators
(foxes, weasels)
Loss of competitors
(chipmunks, squirrels)
No controls on
populations so
increase esp. forest
patch < 5 acres
http://encarta.msn.com/encnet/refpages/RefMedia.aspx?refid=461517523&artrefid=761565627&sec=1&pn=1
Conventional
Subdivision
Both plans provide 36 home
Which better
for ticks?
sites,
Cluster
Housing
(OpenSpace
Zoning)
Conventional development
strategy worst for ticks,
Lyme disease when forest
tract cut up into small
pieces with lawns
Better - cluster houses in
large area of undeveloped
forest
Future drivers of
Deforestation
http://www.sefut.uni-freiburg.de/bilder/Nassreisanbau.pdf
- most disruptive change
affecting parasitic vector
populations. Exposed
ground becomes great
breeding habitat for
mosquitoes (e.g. increase
in incidence of malaria)
- increase contact between
wildlife and humans in
interior forest areas (e.g.
increase Ebola, AIDS)