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World Health
What is the deadliest animal in the
world to humans?
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Mosquito
Asian Cobra
Australian Box Jellyfish
Great White Shark
African Lion
Australian Saltwater Crocodile
Elephant
Polar Bear
Cape Buffalo
Poison Dart Frog
Malaria
 Malaria
kills 2-3 million people annually
 Mortality rate for malaria is < 1%
 300-500 million people contract malaria
annually – almost 10% of the world’s
population!
 What is malaria & how can it be
controlled?
Malaria
 Mosquitos
carry a parasite which causes
malaria
 Mosquitos are the “vector” for malaria
 Parasite is a protozoan called Plasmodium
falciparum
 Enters human bloodstream through
mosquito saliva
Plasmodium
 Plasmodium
avoids detection by immune
system. Immune system detects a foreign
protein on the cell surface. But,
 Plasmodium avoids detection by
immediately hiding within liver cells. This
happens within 30 minutes of infection!
 Liver cells are released into bloodstream
with the parasite onboard.
Malaria Symptoms
 Messes
with metabolism causing
shivering, fever, coma and possibly death
if left untreated.
 Can be treated with anti-parasitic drugs
but they are expensive.
 Better to prevent malaria, than treat it.
 How to prevent?
Malaria Prevention
 Can’t
make a vaccine, because parasite
does not present foreign proteins.
 Kill the mosquitos – the vector for malaria!
 Malaria is only spread by a few species of
mosquito of the genus Anopheles.
 Get rid of the mosquitos and you can
largely get rid of the disease.
 Don’t get bitten to begin with – quinine
Malaria Eradication in the U.S.
How do you kill the mosquitos?
 Swamp
Drainage
 DDT
 This
occurred through a massive New
Deal effort in the 1930s-1950s to protect
soldiers at training camps
 By 1952, disease largely eradicated in
U.S. Now just a few cases each year.
DDT

DDT interferes with the action potential of the
insect’s neurons.
 DDT causes all of the sodium channels in an
insect’s nerve cells to spontaneously open.
 Sudden and extreme firing of every neuron in
the insect’s body leading to spasm and death.
 Chemist who discovered its insecticidal
properties was awarded the Nobel Prize in 1948.
DDT in the Environment
 Persistent
 Moves
up food chain in ever increasing
concentrations
 Weakening of bird eggshells – decline in
bald eagle populations
 Detectable levels of DDT in human blood
and tissues
DDT in the Human Body
 May
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cause
Nausea, headaches
Nervous system abnormalities
Convulsions
Increased infant mortality
Developmental delays in children
Cancer
DDT in the Environment
– U.S. government banned the use
of DDT as a pesticide
 2001 – Stockholm Convention called for
an international ban on its use
 Convention ratified by 98 countries
 But, in many developing countries, DDT is
the only cost effective way to control
malarial infection.
 1972
Question
 Should
there be a global ban on DDT?
Switching Gears Slightly…HIV

Human Immunodeficiency Virus has a group of
cells that it prefers to attack (as all viruses do)
 In the case of HIV, the virus attacks T-cells and
cytotoxic cells
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Remember from a couple of weeks ago that these
start the immune response, and that immune
response destroys infected cells
Most people with HIV don’t die of AIDS, they die of
pneumonia and other diseases that are not fought off
by the immune system
History of AIDS
 Probably
has existed in Africa for at least
100 years
 First recognized in the early 1980s
 Has grown into an epidemic
The AIDS Epidemic
http://www.time.com/time/2001/aidsinafrica/
map_flash.html
http://www.aidsinafrica.net/map.php
http://www.countdeath.com/aids.shtml
Tonight’s Assignment
 Read
“Thirdworldization”, about the
urbanization of African cultures and the
subsequent spread of HIV
 Write a reaction to the reading
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What about it surprised you?
Angered you?
Concerned you?