Question

During 1966, a total of 126 cases of St. Louis encephalitis (SLE) were reported from a community having a population of 20,000. Calculate the incidence rate of SLE in the community per 1,000 population during 1966? 3. Further investigation of the 126 cases (in question #2) revealed that 67 cases were males and the rest were females. The number of males in the community is 9,200. (a) Calculate the sex-specific incidence rates per 10,000 population; (b) Calculate the proposal distribution of the cases by sex; and (c) Determine the ratio of male rate to female rate (using the preferred methods, that is, the smallest number in the ratio is 1).

Answer 1

Explanation:

(2)

Incidence Rate / 1000 =
`(Total\;Cases)/(Population\;at\;risk) * 1000`

Incidence Rate / 1000 =
`(126)/(20000) * 1000`

Incidence Rate / 1000 = 6.3

(3)

As there are 9,200 males in the population of 20,000, the number of females are (20,000-9,200) 10,800. Similarly, as there are 67 male cases from a total of 126, therefore, (126-67) 59 are female cases.

Male Incidence Rate / 10,000 =
`(67)/(9200) * 10,000`

Male Incidence Rate / 10,000 =
`72.83`

Female Incidence Rate / 10,000 =
`(59)/(10800) * 10,000`

Female Incidence Rate / 10,000 =
`54.63`

(b)

For proposal distribution we will simply use the incidence rates as the minimum threshold for each sexes as their acceptance rates to be regarded as affected (by the disease).

(c)

Male to Female Ratio =
`(72.83)/(54.63)`

Male to Female Ratio = 1.333