Epidemiology module of practical skills for mbbs student

Q.. If 600 hundred person worked in the factory what is the attack rate of the disease ?

Exercise 2

There was an out break of Typhoid Fever in Pondicherry . Few cases occurred in JIPMER campus and some from various part of the town . Secondary cases with in 30 days of onset were also reported .Data are given below -----

Typhoid fever in household pondicherry secondary cases in houses with two types of sanitary facilities .

	Household with Privy & Well			Houses with public water supply & sever system
Age in years	No. of contact exposed to primary cases	No. of sec.cases	Attack rate	No. of contact exposed to primary cases	No of sec.cases	Attack rate
0-4	173	41		143	9
5-14	196	37		216	10
15&above	245	24		361	14
Total	614	102		720	33

Q1 – Calculate the secondary attack rate in each category.

Q2- What inference do you draw from this result?

2. 
   Prevalence: The total number of all individuals who have an attribute or disease at a particular time or during a particular period divided by the populations at risk of having the attribute or disease at this point of time or midway through the period. Although referred as rate, prevalence is really a ratio.
   

Types of Prevalence

1. 
   Point Prevalence: The data have been collected for one point of time. The point in, point prevalence may for all practical purposes consist of a day, several days or even a few weeks depending upon the time taken to examine the population sample.
   
2. 
   Period Prevalence: It measures the frequency of all current cases (Old & New) existing during a defined period of time (e.g. annual prevalence) expressed in relation to a defined population. It includes cases arising before but extending into or through the year as well as those cases arising during the year.
   

No. of existing cases (old & new) of a specified disease

During a given year (period of time interval)

Prevalence = -------------------------------------------------------------X1000

Estimated mid year (interval) population

3.