Epidemiology of Malaria by Dr Nikhil Bansal

1. Epidemiology of Malaria
Dr Nikhil Bansal
J.N.M.C.,W ardha

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. 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.  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.  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. Estimation of mortality and DALYs lost
due to malaria world wide (2002)
Region Mortality DALYs
(000) lost(000)
Africa 1136 40855
Americas 1 111
East Medi- 59 1196
terranean
Europe 0 21
SEAR 65 2777
Western Pacific 11 371
Total 1272 46481

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. State-wise distribution of malaria in India in
2005 and 2006
2005 2006
State Malaria P.F. deaths Malaria P.F. deaths
cases cases cases cases
Jharkha 192334 51484 21 33288 8707 1
nd
Haryana 33262 238 0 7558 7 0
Punjab 1883 28 0 58 2 0
Assam 67885 45453 113 85070 60885 271
Orissa 391261 337934 249 63690 55365 49
Uttar 105303 3149 0 14590 219 0
Pradesh

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.  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. 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.  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. Exogenous phase(in mosquito)
Sexual cycle (sporogony) Human
phase`
Sporozoites reach
Oocyst grows salivary glands
Outer layer of Sporozoites from
stomach wall and mosquito
encysts enter human
Human blood
Ookinete
enters mosquito
Microgamete
Zygote (fertilization)
Macrogamete

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. 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