World Health

What is the deadliest animal in the world to humans? 1. Mosquito 2. Asian Cobra 3. Australian Box Jellyfish 4. Great White Shark 5. African Lion 6. Australian Saltwater Crocodile 7. Elephant 8. Polar Bear 9. Cape Buffalo 10. Poison Dart Frog

Malaria  Malaria kills 2-3 million people annually  Mortality rate for malaria is < 1%  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 cause Nausea, headaches Nausea, headaches Nervous system abnormalities Nervous system abnormalities Convulsions Convulsions Increased infant mortality Increased infant mortality Developmental delays in children Developmental delays in children Cancer Cancer

DDT in the Environment  1972 – 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.

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 Remember from a couple of weeks ago that these start the immune response, and that immune response destroys infected cells 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 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 map_flash.html map_flash.html

Tonight’s Assignment  Read “Thirdworldization”, about the urbanization of African cultures and the subsequent spread of HIV  Write a reaction to the reading What about it surprised you? What about it surprised you? Angered you? Angered you? Concerned you? Concerned you?