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Malaria, Mosquitoes, and DDT The Toxic War Against a Global Disease

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Majority women and children. Competitor with AIDS, however very low priority ... As parasite multiplies in red blood cells, produces gametocytes. ... – PowerPoint PPT presentation

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Title: Malaria, Mosquitoes, and DDT The Toxic War Against a Global Disease


1
Malaria, Mosquitoes, and DDT The Toxic War
Against a Global Disease
  • ByAnne Platt McGinn

2
Malaria
  • In a Single Year
  • 300-500 million cases of malaria
  • 1-3 million people will die
  • Majority women and children
  • Competitor with AIDS, however very low priority
  • Only 5 (150 million) of the 12.8 billion
    funding that AIDS receives

3
Malaria Process
  • Caused by 4 protozoan parasite species.
  • Female mosquitoes bite humans.
  • Parasites moves from the saliva of mosquitoes to
    human blood. (sporozoite)
  • Invades bodys immune system and makes way to
    liver (less than an hour). (merozoites)
  • Moves from liver back into blood invading the red
    blood cells, destroys red blood cells.
  • Symptoms convulsion, difficulty breathing,
    coma, death.

4
Malaria Process cont.
  • As parasite multiplies in red blood cells,
    produces gametocytes.
  • Occurs when parasites moves back into the
    mosquitoes.
  • Mosquitoes can ingest the gametocytes, by feeding
    on an already infected person.
  • Causes more sporozoites to invade the mosquitoes
    salivary glands.
  • Cycle begins all over again.

5
History of Malaria
  • 1897 British physician Ronald Ross proved
    mosquitoes carried malaria.
  • T. Roosevelt recognized malaria and yellow fever
    as the most serious obstacles in the construction
    of the Panama Canal.
  • Prior French attempt to build canal lost between
    10,000-20,000 men to malaria/yellow fever.
  • U.S. used mosquito netting, filled in/drained
    swamps.
  • Prevention tactics worked
  • 1906- 80 of workers had disease
  • 1913- 7 had disease.

6
Prevention
  • Only about a dozen anti-malarial in use.
  • Instead of focusing on killing the parasite,
    policy focused on killing the mosquitoes that
    carried the malaria parasites.
  • Dichlorodiphenyl Trichloroethane (DDT).

7
The Beginning of DDT
  • 1939- Swiss Chemist Paul Muller discovered DDT as
    a potent pesticide.
  • First used in World War II.
  • Cheap and long lasting.
  • Most insecticides stopped working after a few
    days.
  • DDT lasted up to 6 months.

Paul Muller
8
The Beginning of DDT cont.
  • 1955- World Health Organization (WHO) launched
    Global Malaria Eradication Program.
  • 65 nations joined the cause.
  • Funding for DDT factories donated to poorer
    countries.
  • DDT production increased greatly.
  • 1961- Program reached peak.
  • Malaria eliminated/dramatically reduced in 37
    countries.

9
Impacts of DDT
  • 1962- Silent Spring, by Rachel Carson
    published.
  • Explained ecological damage caused by the
    widespread use of DDT and other pesticides.

10
Process of DDT Exposure
  • Bioaccumulates.
  • Animal ingests DDT by eating vegetation
    contaminated with DDT.
  • Pesticide collects in the animals fat instead of
    being excreted.
  • Larger animal eats the infected animal, and the
    larger animal absorbs its preys DDT.
  • Process leads to increase of DDT in higher
    animals in food chain.
  • DDTs high chronic toxicity leads to various
    physiological abnormalities.

11
Previous Attitude Towards Malaria and DDT
  • Main focus was getting rid of Malaria and not the
    toxicity of DDT.
  • Eventually resistance occurred.
  • Continual exposure to insecticide leads to a new
    breed of insect populations that are partially
    immune to the poison.
  • DDT resistance occurred from 4-7 years.
  • Took 3 years to clear malaria from human
    population.
  • 1969- Campaign was abandoned.

12
Current Attitude Towards DDT
  • DDT resistance still very widespread.
  • Finally recognized DDT will not prevail against
    mosquitoes.
  • Most countries have banned this chemical.
  • Finally asked the question In order to control
    disease why must we poison our soils, our waters,
    and ourselves?

13
Questions?
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