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Nevertheless the reduction of the number of malaria deaths is one of the main reasons for the dramatic increase of the

Nevertheless the reduction of the number of malaria deaths is one of the main reasons for the dramatic increase of the world population since the end of WWII. Mosquitoes: basic biology. Larvae and pupae always found in water. Adult mosquitoes of both sexes feed on nectar.

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Nevertheless the reduction of the number of malaria deaths is one of the main reasons for the dramatic increase of the

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  1. Nevertheless the reduction of the number of malaria deaths is one of the main reasons for the dramatic increase of the world population since the end of WWII.

  2. Mosquitoes: basic biology • Larvae and pupae always found in water. • Adult mosquitoes of both sexes feed on nectar. • Females of most species need a blood meal for egg development. • In temperate climate: diapause (adults in dormant state) or produce dormant eggs.

  3. Mosquitoes: basic biology II • Three major breeding groups: • Permanent water breeders: Anopheles and many Culex in swamps, ponds, lakes, and ditches. • Floodwater breeders: salt marsh, inland flood water, and rice field mosquitoes. • Artificial container/tree hole breeders: Aedes aegypti and Aedes albopictus.

  4. Mosquitoes as vectors • Aedes: filaria, viruses (e.g. Aedes aegypti for dengue and yellow fever). • Anopheles: malaria, filaria (Wuchereria bancrofti) , viruses. • Culex: filaria, viruses (e.g. Culex pipiens for SLE).

  5. Aedes aegypti • Worldwide within the 20°C isotherms. • Vector of yellow fever and dengue. • Urban mosquito. • Daytime biting mosquito. Goddard J. 2003. CRC Press

  6. Aedes albopictus • Asian Tiger Mosquito. • Agressive, daytime biting mosquito. • Associated with used automobile tires. • Vector of yellow fever, dengue and Lacrosse encephalitis virus. Goddard J. 2003. CRC Press

  7. Aedes albopictus • Asian Tiger Mosquito. • Agressive, daytime biting mosquito. • Associated with used automobile tires. Goddard J. 2003. CRC Press

  8. Aedes albopictus • Asian Tiger Mosquito. • Agressive, daytime biting mosquito. • Chikungunya outbreak in Réunion, a French “overseas département”. • Arboviral disease. • Fever and arthralgias. Eurosurveillance. 2006. Volume 11. Issue 1, at http://www.eurosurveillance.org/

  9. Aedes albopictus • Chikungunya fever in the province of Ravenna, Italy: A. albopictus is the most likely vector … • A. albopictus in … Belgium, the Netherlands, … Eurosurveillance. 2007. Volume 12. Issue 9, at http://www.eurosurveillance.org/ • A. albopictus in NL: via “lucky bamboo” from SE-China. Ned Tijdschr Geneeskd. 2007. 151:1333-1338.

  10. Anopheles labranchiae atroparvus • Ziet gij muggen lang van poot? Aarzelt niet, maar slaat ze dood. • Main malaria vector in the Low Countries. • Lived in pig stables (Vapona strip) and attics (Sprays). • The larvae are found in brackish water along the coast from the southern Baltic to Spain.

  11. Anopheles gambiae • Most important vector in Africa. • < 1000 m • 2 (7) km • 0 – 4 h maximal activity. • Endophilic species.

  12. Anopheles gambiae • 1930: Brazil. • 1937-1938: large fatal epidemics associated with A. gambiae in Brazil. • 1939-1941: eradicated from Brazil. • 1943-1945: eradicated from Egypt. The Lancet Infectious Diseases. 2002. 2:618-627.

  13. UK NEQAS Parasitology on the web Approximately 60 different species of Anopheles mosquitoes can transmit malaria.

  14. Malaria transmission Mosquito to man Blood transfusion Mother to child

  15. American Civil War (1861-1865): patients with mosquito nets, Washington D.C. 50% of the white soldiers got malaria annually

  16. Alphonse Laveran(1845-1922) • Physician of the French Army. • 1880: Constantine, Algeria, The malaria parasite: Laveriana, Plasmodium. • Nobel Prize in 1907.

  17. Sir Ronald Ross (1857-1932)20 August 1897: mosquito day • Surgeon-Major in the British Indian Medical Service wrote to his wife: “I know that this little thing a million men will save”. • Studied bird malaria. • Nobel Prize in 1902.

  18. Battista Grassi • 1899 • Only female mosquitoes are able to transmit malaria. • Blood is necessary for oogenesis.

  19. Courtesy CDC

  20. Plasmodium falciparumlimited to (sub-) tropical areas (summer isotherm of 20°C, altitude < 2000 m).

  21. Sporogony in the mosquito • Plasmodium falciparum • 8 days at 30°C • between 20 (18) and 33°C • Plasmodiumvivax • development occurs at 16°C M. Wéry, 1995.

  22. Developmental period in mosquito • Plasmodium falciparum: 22 days at 20°C, 10 days at 27°C (minimal temperature (18) 2O°C) • Plasmodium malariae: 30-35 days at 20°C, 25 days at 24°C (minimal temperature 16°C) • Beaver et al. 1984.

  23. Developmental period in mosquito • Plasmodium ovale: 16 days at 25°C, 14 days at 27°C (minimal temperature (18) 2O°C) • Plasmodium vivax: 30+ days at 16°C, 16 days at 20°C, 10 days at 30°C (minimal temperature 16°C) • Beaver et al. 1984.

  24. Malaria: Vector Control • Source reduction (larval control) • Historically most effective campaign in Brazil and Egypt (1930s and 1940s). • Bacillusthurigiensis var. israelensis (Bti toxins). • Mosquito fish (Gambusia affinis): larger bodies of water. CDC, www.cdc.gov/malaria/

  25. New strategy against Aedes aegypti in Vietnam Kay B., Nam V. 2005. Lancet: 365:613-617. • Major sources of A. aegypti are large water storage containers. • 1998-2003: Elimination from 32 of 37 communes with Mesocyclops spp. (cyclopoid copepods) (309730 people). • No dengue cases since 2002.

  26. New strategy against Aedes aegypti in Vietnam Kay B., Nam V. 2005. Lancet: 365:613-617. • Mesocyclops spp. (cyclopoid copepods) • WHO: only in countries free of Guinea worm (Mesocyclops spp. are intermediate host) • Gnathostoma and Diphyllobothrium ?

  27. Malaria: Vector Control • Indoor residual spraying • DDT, dieldrin • more expensive insecticides • failure of eradication (1955-1969) • environmental concerns • Insecticide-treated bed nets • pyrethroid insecticides • nets retreated at 6-12 months CDC, www.cdc.gov/malaria/

  28. DDT • Dichloro-diphenyl-trichloroethane. • 1874: German chemist: Othmer Zeidler. • 1939: Paul Hermann Müller (1899-1965) in Switzerland (J.R. Geigy A.G., Basle). • WWII: louse-borne typhus, malaria. • 1948: Nobel Prize Medicine.

  29. Parasitology • orphan parasites • orphan drugs • The disaster of the ban of DDT. • The Lancet. 2000. 356: 265 and 1189. • 2001: indoor residual spraying with DDT resumed in S. Africa and malaria cases fell. • The Lancet. 2007. 369:1922. • (orphan reimbursement, B)

  30. DDT indoor residual spray, … • Still an effective tool to control Anopheles fluviatilis – transmitted Plasmodium falciparum in India. Gunasekaran K. et al. 2005. Trop Med Int Health, 10:160-168.

  31. Eradication of malaria 1934: Hans Andersag at Bayer discovers chloroquine 1939: Paul Müller at Geigy discovers DDT 1951: Sardinia malaria free 1955: WHA (WHAssembly): goal of global eradication 1955-1969: WHO uses DDT and chloroquine 50’s: DDT-resistance 1962-1970: chloroquine-R 1955-1965: expenditure of $ 1.4 billion 1969: WHO back to malaria control 1975: Europe free of malaria for first time in history Courtesy of C.D.C

  32. Recent history of the World Bank's work on malaria The World Bank co-founded the Roll Back Malaria (RBM) Partnership in 1998. Since July 2000, the Bank has committed about US$100-150 million in funds earmarked for malaria control. This includes only health sector investment credits and grants, as well as commitments through broad programmatic operations such as Sector-Wide Approaches (SWAps). Total World Bank support for malaria control was higher, due to financing through debt relief, multisectoral operations such as Poverty Reduction Support Credits (PRSCs), Emergency Recovery Credits and Social Funds. However, it is difficult to quantify exactly how much of these programmatic operations went to malaria control, since such operations do not track details of inputs into specific disease control programs.

  33. RBM is enabling countries to take effective, sustainable action against malaria by focusing on • preventing and controlling malaria during pregancy • promoting the use of insecticide-treated mosquito nets as a means of prevention • dealing effectively with malaria in emergency and epidemic situations. • providing prompt access to effective treatment

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