malaria facts where malaria is common the average life span is 30 yoa. this is not all due to...

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!



• 1880 was when Plasmodium was fist discovered.



• 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


• 1861-1865 Civil War. Savannah, GA 878 men had 3313 cases of malaria in a 14 month period.

History



• 1880 Plasmodium discovered as etiological agent

History




• 1900’s Sir Ronald Ross discovers mosquitoes are vectors

History




• 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

• 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

History

• Lost five times more men to malaria than in Battle!

History


• Brought about chemical insecticides.– DDT was a result of WWII– And a few year later there were only 50/1000

History


• 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!

• 1946. WHO initiates program to “eradicate malaria”.

History


• 1961: A parasitology textbook is quoted as saying “with present prospects, malaria WILL soon be treated as an uncommon/non-existent disease.

History


• 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.

History

Eradication of Malaria

• So why did the campaign fail?

• 1) Insecticides (DDT)– Environmental damage!

Pesticide Resistance

• Rapid Reproduction

• Selection

DDT

DDT

Pesticide Resistance

• Rapid Reproduction

• Selection


• 2) Plasmodium– Wide use of chloroquine has led to drug

resistant strains!


• 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!

• Genetic resistance to Plasmodium

• 2 examples

There are some general genotypes that are resistant to malaria

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 Dominant

• B Dominant

• y recessive

A =

B =

y = no proteins

AB yyAA BB Ay

By

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!

malaria facts where malaria is common the average life span is 30 yoa. this is not all due to...

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