Malaria: Coming soon to an airport near you! Tropical Diseases in the Global Village

You too can get tropical diseases without leaving the comfort of your own home.

What accounts for the geographic restriction of some diseases? How do diseases move into new areas? Are tropical diseases really diseases of economic underdevelopment?

Malaria has been with us for a long time now 10,000 BC mummiesDNA evidence The A- African variant of G-6-PD may date as far back as 11,760 years ago

When did malaria come to the New World? with Columbus or the slave trade –no documented blood polymorphisms associated with malaria resistance in the Amerindians, so malaria is recent –Ravenels extinction hypothesis: eradication of the original natives of the Caribbean islands and coastal plain was caused by malaria

Did malaria arrive twice? P. simium in New World monkeys looks like Asian P. vivax New World P. vivax is distinct from both –DNA –vector specificity

Conclusion: malaria entered the New World twice –once > stable transmission in monkeys –once > stable transmission in man

How is transmission established? mosquito man bite first host bite second host

Factors that influence transmission mosquito man bite first host bite second host susceptible vector species

Factors that influence transmission mosquito man bite first host bite second host vector longevity

Factors that influence transmission mosquito man bite first host bite second host biting preferences

Factors that influence transmission mosquito man bite first host bite second host infected reservoir

Factors that influence transmission mosquito man bite first host bite second host available to vector

Colonial America malaria was well established in Connecticut by 1650 Charleston, SC, was almost abandoned in 1680 because of the intensity of malaria transmission

Eradication in the north 1900: Staten Island, NY, one in five residents has malaria 1901: Port Authority gives $50,000 to Alvah Doty to drain the marshes 1908: Staten Island is malaria-free

Malaria and the New Deal ecological degradation of major river basins in the South –deforestation –erosion –uncontrolled floods 1933: 150,000 cases of malaria, 5,000 deaths annually in Tennessee R. basin

TVA: Power and Public Health 21 dams, 600,000 acres of lakes mosquito control teams –periodically raise and lower water levels –speed water flow in canals –clear aquatic vegetation 1942: 50,000 malaria cases annually, 600 deaths

DDT 1943: widescale aerial application 1952: malaria eradicated 1962: Silent Spring

Will malaria return? reappearance of infected hosts –immigrants from endemic regions –returning military personnel transmission from a single marine to 35 campers in the California Sierras

Will malaria return? introduction of new efficient vectors –1930: Anopheles gambiae introduced into Brazil by a French naval vessel; epidemic malaria, 16,000 deaths –malaria vectors brought to Guam by military aircraft during WWII and Viet Nam war; outbreaks in 1966 and 1969

Airport Malaria: The case for disinsection between 1969 and 1999 –26 cases in France –17 cases in Belgium –14 cases in the UK –4 cases in Germany –4 cases in the US