Epidemiology of Malaria


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Epidemiology of Malaria by Dr Nikhil Bansal

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Epidemiology of Malaria

  1. 1. Epidemiology of Malaria Dr Nikhil Bansal J.N.M.C.,W ardha
  2. 2. Malaria Vector borne infectious disease Caused by protozoan parasite Very common infectious disease Transmitted by female anopheles mosquito No vaccines available Can be treated easily with derivatives of quinine and artemisinin (drug resistance common)
  3. 3. History First record of “periodic fevers” from China in 2700 BC Term “malaria” derived from Italian for “bad air” – mala aria Also known as “ague” or “marsh fever”
  4. 4.  First effective treatment was the bark of the cinchona tree (contains quinine) Grows in the Peruvian Andes Used by the locals to control malaria Jesuits introduced it to Europe in 1640s Active ingredients (quinine) isolated from the bark Named by French chemist Pierre Pelletier and Jean Caventou
  5. 5.  The blood stage of malaria life cycle was recognized in 19th and early 20th century The latent form of the disease (in the liver) was only recognized in 1980s Explained why apparently “cured” people could have recurrent episodes years later in the absence of new exposure
  6. 6. Estimation of mortality and DALYs lostdue to malaria world wide (2002)Region Mortality DALYs (000) lost(000)Africa 1136 40855Americas 1 111East Medi- 59 1196terraneanEurope 0 21SEAR 65 2777Western Pacific 11 371Total 1272 46481
  7. 7. Epidemiology Precise statistics unknown - most cases are rural 400-900 million cases of fever per year Affects about 515 million people per year Kills between 1 – 3 million per year Most deaths occur in children less then 5 years in Sub Saharan Africa (pregnant women also vulnerable) One death every 30 seconds
  8. 8. State-wise distribution of malaria in India in 2005 and 2006 2005 2006State Malaria P.F. deaths Malaria P.F. deaths cases cases cases casesJharkha 192334 51484 21 33288 8707 1ndHaryana 33262 238 0 7558 7 0Punjab 1883 28 0 58 2 0Assam 67885 45453 113 85070 60885 271Orissa 391261 337934 249 63690 55365 49Uttar 105303 3149 0 14590 219 0Pradesh
  9. 9. Malaria parasite Malaria is caused by protozoan parasite of the genus plasmodium In humans the causes include  P. Falciparum  P. malariae  P. ovale  P. vivax
  10. 10.  P. vivax is the most common infection (80% of the cases) P. falciparum causes most deaths (15% of infections and 90% of deaths) Other Plasmodium species also infects birds, reptiles, rodents, monkeys and apes
  11. 11. Mosquito vectors Primary hosts and transmission vectors are the female Anopheles mosquito Only the female feed on blood Mosquito ingests parasite from infected human blood whilst feeding Carry sporozoites in the salivary glands There is a complex life cycle within the mosquito
  12. 12.  Parasite relatively protected from the human immune system because it hides in the red blood cells or in the liver. Circulating infected cells can be destroyed in the spleen Parasite infected cells stick to blood vessel walls (to avoid the spleen) – can cause strokes in cerebral malaria.
  13. 13. Exogenous phase(in mosquito) Sexual cycle (sporogony) Human phase` Sporozoites reach Oocyst grows salivary glands Outer layer of Sporozoites fromstomach wall and mosquito encysts enter human Human blood Ookinete enters mosquito Microgamete Zygote (fertilization) Macrogamete
  14. 14. Endogenous phase(in human)Mosquito asexual cycle (schizogony) phase Exo-erythrocytic stage Sprozoites Mature Merozoites Schizont Immature Erythrocytic Enter trophozoite cycle RBC Microgamete Mature Ring (differntiation) trophozoites trophozoites Macrogamete
  15. 15. References Essentials of Medical Pharmacology - K.D. Tripathi 6th edition Principles of Pharmacology - Sharma and Sharma 1st edition 2007 Textbook of Preventive and Social Medicine - K .Park 15th edition