Transcript Malaria has Been Significant Enough to Make the

Malaria Facts
• Where malaria is common the average
life span is 30 YOA. This is not all due to
malaria but malaria and trypanosomiasis
do play their part!
Malaria Facts
• Where malaria is common the average life span is 30
YOA. This is not all due to malaria but malaria and
trypanosomiasis do play their part!
• Malaria has protected Western Africa
from European colonization!
Malaria has Been Significant Enough
to Make the World Different!
• Being sent to Gambia, Serra Leon, etc. was
considered a death sentence because of the
probability of contracting malaria!
Malaria has Been Significant Enough
to Make the World Different!
• Being sent to Gambia, Serra Leon, etc. was considered
a death sentence because of the probability of
contracting malaria!
• 1880 was when Plasmodium was fist discovered.
Malaria has Been Significant Enough
to Make the World Different!
• Being sent to Gambia, Serra Leon, etc. was considered
a death sentence because of the probability of
contracting malaria!
• 1880 was when Plasmodium was fist discovered.
• 1897: the vector host was discovered by Ronald
Ross. But it did not matter since there was no
attempt to control it!
Malaria in History
• Ancient references
– China, Assyria, India
– 500 BC Hippocrates gives first clinical
description
Malaria in History
• Ancient references
– China, Assyria, India
– 500 BC Hippocrates gives first clinical description
• Historical Impacts
– 413 BC Fall of Greek empire
– 323 BC Alexander the Great died of malaria
– The Roman Empire: Malaria is generally
considered to have played a role in the decline
of Rome, a city located in marshland, where
malaria is transmitted
History
• 1800’s 20-40% of people hospitalized in
New Orleans had malaria
History
• 1800’s 20-40% of people hospitalized in New Orleans had
malaria
• 1861-1865 Civil War. Savannah, GA 878
men had 3313 cases of malaria in a 14
month period.
History
• 1800’s 20-40% of people hospitalized in New Orleans had
malaria
• 1861-1865 Civil War. Savannah, GA 878 men had 3313
cases of malaria in a 14 month period.
• 1880 Plasmodium discovered as etiological
agent
History
• 1800’s 20-40% of people hospitalized in New Orleans had
malaria
• 1861-1865 Civil War. Savannah, GA 878 men had 3313
cases of malaria in a 14 month period.
• 1880 Plasmodium discovered as etiological agent
• 1900’s Sir Ronald Ross discovers
mosquitoes are vectors
History
• 1800’s 20-40% of people hospitalized in New Orleans had
malaria
• 1861-1865 Civil War. Savannah, GA 878 men had 3313
cases of malaria in a 14 month period.
• 1880 Plasmodium discovered as etiological agent
• 1900’s Sir Ronald Ross discovers mosquitoes are vectors
• 1930’s malaria diminished in U.S. except for
southeast. Conversion of swamp to
agriculture.
1882
1912
1934
History
• World War II. In 1942, 2678 cases from
1,000 men; Ran out of drug for treatment.
History
• Gen. Douglas MacArthur in May 1943: "Doctor,"
he said, "this will be a long war if for every
division I have facing the enemy I must count on a
second division in hospital with malaria and a
third division convalescing from this debilitating
disease!" The general was not at all worried about
defeating the Japanese, but he was greatly
concerned about the failure up to that time to
defeat the Anopheles mosquito.
History
• Lost five times more men to malaria than
in Battle!
History
• Lost five times more men to malaria than in Battle!
• Brought about chemical insecticides.
– DDT was a result of WWII
– And a few year later there were only 50/1000
History
• Lost five times more men to malaria than in Battle!
• Brought about chemical insecticides.
– DDT was a result of WWII
– And a few year later there were only 50/1000
• So after the war there was a false hope of
eradicating malaria from the world!
History
• 1946. WHO initiates program to “eradicate
malaria”.
•
History
• 1946. WHO initiates program to “eradicate malaria”.
• 1961: A parasitology textbook is quoted as
saying “with present prospects, malaria
WILL soon be treated as an
uncommon/non-existent disease.
History
• 1946. WHO initiates program to “eradicate malaria”.
• 1961: A parasitology textbook is quoted as saying “with
present prospects, malaria WILL soon be treated as an
uncommon/non-existent disease.
• 1970. Malaria decreased dramatically.
Eradication of Malaria
• So why did the campaign fail?
• 1) Insecticides (DDT)
– Environmental damage!
Eradication of Malaria
• So why did the campaign fail?
• 1) Insecticides (DDT)
– Environmental damage!
Pesticide Resistance
• Rapid Reproduction
• Selection
DDT
Pesticide Resistance
• Rapid Reproduction
• Selection
DDT
Eradication of Malaria
• 2) Plasmodium
– Wide use of chloroquine has led to drug
resistant strains!
Eradication of Malaria
• 3) Social/Political Reasons
– Emerging nations in Africa were trying to be
free from external (Western European
nations) domination; much of the monetary
resources stopped flowing in!
There are some general genotypes that
are resistant to malaria
• Genetic resistance to Plasmodium
• 2 examples
Duffy Blood Group
• Noticed in military groups in Vietnam.
• African Americans had less severe cases
or no cases of malaria!
Genetic Resistance
• Plasmodium vivax
• Duffy blood groups
– Proteins on cell surface
– 3 alleles
• A Dominant
• B Dominant
• y recessive
A=
B=
y = no proteins
Genetic Resistance
• Plasmodium vivax
• Duffy blood groups
– Proteins on cell surface
– 3 alleles
A=
B=
y = no proteins
By
• A Dominant
• B Dominant
• y recessive
AA
BB
AB
Ay
yy
Genetic Resistance
• yy genotype has advantage
– P. vivax malaria resistance
– Only advantageous if P. vivax malaria
endemic
• 40% people of W. African decent
• 0.1% people of non-African decent
• P. vivax keeps the allele common in
Africa.
Genetic Resistance
• Sickle celled anemia
• Codominant trait (Allele “A” and “B”)
– AA have sickle celled anemia
– AB have both types of cells
• Sickle cells don’t support species of Plasmodium
well.
• Resistance to infection
Genetic Resistance
• AA selected against
– Sickle celled anemia
• AB selected for
– Both sickle and normal cells
• BB selected against
– Normal cells
• If malaria is not endemic, what alleles will be
selected for? Against?
• Allele for sickle cells maintained in the
population even though strongly
disadvantageous to have both alleles.
Genetic Resistance
Sickle Celled Anemia
• In the US, 10% of African Americans
have this allele!
Other forms of Resistance to Malaria
• Babies get antibodies from their moms
breast milk; they are protected until
weaned.
• Once weaned becomes susceptible again!
• What you need to have malaria spread
within a population!
Epidemiological Models
Habitat
Behavior
Infected
People
contact
Mosquitoes
contact
Source of
Plasmodium
Uninfected
People
Source of
New Hosts
Climate
Habitat
Food
Breaking the Chain
Habitat
Behavior
Infected
People
contact
Mosquitoes
contact
Source of
Plasmodium
Uninfected
People
Source of
New Hosts
Climate
Habitat
Food
Eliminating Mosquitoes
• Mosquito
Life Cycle
Eliminating Mosquitoes
Eliminating Mosquitoes
• Destroy habitat
• Insecticides
• Biological control
Eliminating Mosquitoes
•
•
•
•
Destroy habitat
Insecticides
Biological control
Why don’t these methods work?
Pesticide Resistance
• Rapid Reproduction
• Natural selection
Getting rid of the source of
Plasmodium
Getting rid of the source of
Plasmodium
• Drug treatment
• Transgenic mosquitoes
Getting rid of the source of
Plasmodium
• Drug treatment
• Transgenic mosquitoes
• Why don’t these work?
Getting rid of the source of
Plasmodium
• Drug treatment
• Transgenic mosquitoes
• Why don’t these work?
– Availability of drugs
• Money
• Medical staff
–
–
–
–
–
Recrudescense
Drug resistance
Reservoir hosts?
Transgenic mosquitoes not a reality
Expensive
How can we protect the uninfected
population?
• Vaccines
• Prophylactic drugs
How can we protect the uninfected
population?
• Vaccines
• Prophylactic drugs
• Why don’t these work?
How can we protect the uninfected
population?
• Vaccines
• Prophylactic drugs
• Why don’t these work?
– Vaccines unsuccessful
– Prophylactic drugs expensive
– Prophylactic drugs unpleasant
How can we prevent contact between
people and mosquitoes?
•
•
•
•
•
Insecticides
Mosquito nets
Long clothing
Behavior
Avoid mosquito
habitat
• Screens on houses
How can we prevent contact between
people and mosquitoes?
•
•
•
•
•
Insecticides
Mosquito nets
Long clothing
Behavior
Avoid mosquito
habitat
• Screens on houses
• Why don’t these
work?
How can we prevent contact between
people and mosquitoes?
•
•
•
•
•
Insecticides
Mosquito nets
Long clothing
Behavior
Avoid mosquito
habitat
• Screens on houses
• Why don’t these
work?
– Money
– Availability of
materials
– Human behavior
difficult to change
• "Everything about malaria is so molded
by local conditions that it becomes a
thousand epidemiological puzzles."
Hackett (1937)
Roll Back Malaria (RBM) Strategy
• Early diagnosis and prompt treatment
Roll Back Malaria (RBM) Strategy
• Early diagnosis and prompt treatment
• Prevention
– insecticide-treated materials
– vector control measures
• indoor spraying
• larvicide
• environmental management
Roll Back Malaria (RBM) Strategy
• Early diagnosis and prompt treatment
• Prevention
– insecticide-treated materials
– vector control measures
• indoor spraying
• larvicide
• environmental management
• Prevention of malaria in pregnancy
Roll Back Malaria (RBM) Strategy
• Early diagnosis and prompt treatment
• Prevention
– insecticide-treated materials
– vector control measures
• indoor spraying
• larvicide
• environmental management
• Prevention of malaria in pregnancy
• Monitoring for epidemics
– Rapid response
Roll Back Malaria (RBM) Strategy
• Early diagnosis and prompt treatment
• Prevention
– insecticide-treated materials
– vector control measures
• indoor spraying
• larvicide
• environmental management
• Prevention of malaria in pregnancy
• Monitoring for epidemics
– Rapid response
• New methods and tools
Roll Back Malaria (RBM) Strategy
• Early diagnosis and prompt treatment
• Prevention
– insecticide-treated materials
– vector control measures
• indoor spraying
• larvicide
• environmental management
• Prevention of malaria in pregnancy
• Monitoring for epidemics
– Rapid response
• New methods and tools
• Improvement in existing tools through
research and development
Roll Back Malaria (RBM) Strategy
• Early diagnosis and prompt treatment
• Prevention
– insecticide-treated materials
– vector control measures
• indoor spraying
• larvicide
• environmental management
• Prevention of malaria in pregnancy
• Monitoring for epidemics
– Rapid response
• New methods and tools
• Improvement in existing tools through research and development
• Coordinated action through establishing
partnerships that utilize an optimal mix of
measures adapted to local situations.