1

Epidemiological exercises:Malaria indices

Dr. Rizwan S AAsst. Professor (Community Medicine)

VMCH & RI, Madurai

2

Three major types

• Rates and proportions• Measures of association• Diagnostic test validity

3

RATE AND PROPORTIONS

4

Rate and Proportions

• Demographic indices (CBR, CDR, MYP)• MCH indicators• Disease related indices (AR, SAR)• Filarial indices • Malarial indices• TB indices• Fertility indices (TFR, GFR, GMFR)

5

INTRO TO MALARIA BURDEN

6

WORLD

7

8

Global disease burden in 2015

• New cases: 214 million (149–303)– Africa (88%), South-East Asia (10%)

• Deaths: 438 000 (236 000–635 000)• Between 2000 and 2015, – malaria incidence fell by 37% globally– malaria mortality fell by 60% globally

• Global Technical Strategy for Malaria 2016-2030– reducing incidence by 90%; reducing mortality 90%;

eliminating malaria in at least 35 countries;

9

Countries with malaria

10

Trends in incidence and deaths

11

INDIA

12

Malaria endemic areas in India (API 2004)

13

P. falciparum distribution in India

14

High risk towns for malaria in India

15

Pf%, API and Deaths (1995-2014)

16

ABER, API, SPR, SFR, Deaths (2001-14)

17

Trends in incidence

18

Trends in cases and deaths (2001-14)

19

Controversies in malaria burden

• India’s true malaria burden is a matter of intense debate

• Different estimates of malaria deaths– WHO: 15,000 – Million Deaths Study: 1.2-2.7 lakh– ICMR committee: 40,297

20

MALARIA INDICES

21

Learning objectives

• To assess the burden of disease in a community in terms of morbidity and mortality wrt malaria

• To calculate indices to monitor and evaluate national health programs wrt malaria

22

Malarial indices – 1/3• Annual blood examination rate

= X 100• Annual parasite incidence

= X 1000

23

Malarial indices – 2/3

• Annual falciparum incidence

= X 1000

• Slide positivity rate

= X 100

24

Malarial indices – 3/3

• Slide falciparum rate

= X 100

• Percentage of falciparum

= X 100

25

Malaria control in India

26

Objective and indicators

• To achieve API <1 by 2017• At least 80% of those suffering from malaria

get complete treatment within 24 hours• At least 10% of the population in high-risk

areas is surveyed annually (ABER >10%)• At least 50% reduction in mortality by 2017

(2010 baseline)

27

28

EXAMPLE PROBLEMS

29

Ex. Problem 1

1. In a Community health centre, with a population of 1,00,000, the health workers collected 3725 blood smears from fever cases during their home visits. In the same year, 3275 blood smears were collected from Outpatient departments. On examination 185 slides were positive for P. vivax and 15 slides were positive for P. falciparum. Calculate the all-possible malarial indices.

30

Ex. Problem 1

Given:– Population = 100000– Blood smears collected from fever cases home visits = 3725– Blood smears collected from Outpatient departments = 3275– Slides positive for P. vivax = 185– Slides positive for P. falciparum = 15

• Annual blood examination rate = (3725+3275)/100000 X 100 = 7%• Annual parasite incidence = (185+15)/100000 X 1000 = 2 per 1000 population• Annual falciparum incidence = 15/100000 X 1000 = 0.15 per 1000 population• Slide positivity rate = 200/7000 X 100 = 2.8%• Slide falciparum rate = 15/7000 X 100 = 0.2%• Percentage of falciparum = 15/200 X 100 = 7.5%

31

Ex. Problem 2

2. Population of a PHC is 25000. A total of 200 peripheral blood smears were made. 38 of them tested positive for P.vivax, 40 for P.Falciparum and 10 showed both. Calculate the indices for malaria control in the area.

32

Ex. Problem 2

• API= 88/25000*1000= 3.5 per 1000 population

• ABER= 200/25000*100= 0.8%• SPR = 88/ 200*100= 44%• SFR= 40/200 *100= 20%

33

Work out on your own 1

The following are the data available for Madurai district with population 10,00,000 regarding Anti malaria activities during the year 2010. Blood smear examined = 80000 positive cases detected PV = 2592, PF = 308. Calculate ABER, API, AFI, SPR and Percentage of falciparum. Interpret the results and mention remedial measures.

34

Work out on your own 2• The following are the data from a Primary Health Centre

for the year 2015• Total population = 30,000• Blood slides collected by active surveillance =260• Blood slides positive for parasite in above = 80• Blood slide collected by passive surveillance = 140• Blood slides positive for parasite in above = 40• Among the positive slides, falciparum was seen in 9

Calculate the malaria indices and comment on them