Malaria

Communicable Disease Epidemiology
Malaria

1. MALARIA Dr. P I Muhammed Safeer Assistant Professor Department of PG Studies in Swasthavritta & Yoga VPSV Ayurveda College , Kottakkal 1

2. Mala – Bad , Aria – Air Caused by Protozoal parasite – Plasmodium . Transmitted from person to person by the bite of infected female anophelin mosquito. Fever with rigors, profuse sweating & headache. Repeated episodes with intermittent periodicity 2

3. Results in Splenomegaly and secondary anaemia Mortality is not high, incapacitation of affected human resources. 3

4. History Hippocrates BC 5 th Century Caraka & Susruta  diseases spread by mosquitoes 1880 – discovered malarial parasite 1987 – Ronald Ross illustrated the devpt of parasite in the mosquito 1953 – NMCP 1958 – NMEP 4

5. 1977 – Modified Plan of Operation 1999 – National Antimalaria Programme 2003 -04, included under National Vector Borne Disease Control Program. 5

6. Agent factor Pl. vivax  70% cases Pl. falciparum  25-30% Pl. malaria  less than 1% Pl. ovale  rarely affect human being Mixed infection  4-8% Pl. malariae is endemic to Hassan & Tumkur Dt of Karnataka 6

7. Life history of Agent Development in 2 hosts, man & mosquito Man, intermediate host, asexual phase of dvpt . Female anopheline mosquito  sexual phase. 7

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9. Reservoir of infection Only human reservoir, case or carrier Criteria of a carrier Should have both sexes of gametocyte in blood Gametocytes must be matured, viable and in sufficient numbers 9

10. Host factors Age incidence: young children at high risk Sex incidence: more in men (outdoor work& less clothed) Pregnancy: increases the risk & severity Occupation: more in rural, agricultural society 10

11. Predisposing factors Poor standard of housing – ill lighting, ill ventilation  mosquito resting Industrialization, urbanization, irrigation & agriculture activities, deforestation ‘man made malaria’ Out door sleeping habits 11

12. Environmental factors Season: high incidence, July – Nov (low temp, high humidity) Atm temperature: favourable for parasitic devpt  20 – 30 C Humidity: Relative humidity 60% and above Rainfall: increase humidity, breeding places Altitude: mosquito won’t survive above 2500m 12

13. Vector: Anopheles mosquito Breeding habits: freshwater as in ponds, wells, cisterns, over-head tanks, pools etc Resting habit: mostly indoor, after blood meal. Density: above critical level is needed for active disease transmission 13

14. Mode of transmission: from person to person by the bite of infected mosquito Accidentally through contaminated syringes Vertical transmission can occur but very rare 14

15. Incubation period Period between the bite of mosquito and the onset of the first symptom, i.e. fever Pl. vivax  14 days Pl. falciparum  12 days Pl. malaria  28 days Pl. ovale  17 days 15

16. Clinical features Clinically 4 types of malaria Benign tertian malaria ( Vivax malaria) 3 stages; A. Cold stage B. Hot stage C. Sweating stage 16

17. Cold stage – Sudden onset of acute fever with rigors & sensation of extreme cold Teeth chatter Desires to cover with several blankets Severe head ache, vomiting Lasts for 15 – 30 minutes 17

18. Hot stage – high fever 103 -104 F Feels burning heat, removes blankets & clothes Headache persists, vomiting can occur Lasts for 2 – 6 hours 18

19. Sweating stage – Fever comes down by itself with profuse sweating Feels comfortable and falls asleep due to exhaustion Lasts for 2 –4 hours Next day the patient feels normal and attends to duties 19

20. In vivax malaria Fever reappears every third day Rupture of RBCs & release of merozoite is associated with rigors. Repeated episodes results in spleenomegaly & secondary anaemia. 20

21. 2. Malignant tertian malaria ( Falciparum malaria) Gradual rise of temperature, increasing daily, becomes high and almost continuous Cold, hot & sweating stages rarely occur Vomiting & Headache are common 21

22. Highly fatal because of following complications Cerebral malaria – convulsions, paralysis Black water fever – black coloured urine Algid malaria – with shock Septicemic malaria – septicemia & circulatory failure 22

23. 3. Quartan malaria Caused by Pl. mlaria Fever appears once in 4 days 23

24. 4. Ovale malaria Caused by Pl. Ovale common only in Africa 24

25. Investigations Blood smear for malarial parasite 25

26. Measurement of Malaria/ Malariometry To know the magnitude of the problem By prevalence and incidence rates and entamological parameters ( vector indices ) together known as malariometric indicators 26

27. Prevention & Control Elimination of reservoir Breaking the channel of transmission Protection of susceptibles 27

28. Elimination of reservoir Presumptive treatment Mass treatment Chemoprophylaxis Revised National Policy 28

29. Breaking the channel of transmission Antiadult measures Antilarval measures 29

30. Antiadult measure Residual spraying – spraying DDT, malathion , fenitrothion in indoor surfaces like houses, cattle sheds etc Space spraying - outdoor spraying in the form of fog, mist 30

31. Antilarval measures – bioenvironmental control 1. Source reduction – elimination of nonessential water bodies. 2. Environmental modification & manipulation – levelling of land, filling of depression. 3. Biological control – natural enemies like fish, bacteriae 31

32. Personal protection – 1. bed nets 2. use of mosquito repellents 3. malaria vaccines 32