Night blood survey is done in?

Night blood survey is done in ?
a) Filaria
b) Typhoid
c) Malaria
d) Kala-azar
Correct Answer - A
Ans. is ‘a’ i.e., Filaria
The microfilariae of W. bancrofti and B. malayi occuring in India
display a nocturnal periodicity, i.e., they appear in large number at
night and retreat from the blood stream during the day.
This is a biological adaptation to the nocturnal biting habits of vector
mosquitoes.
The maximum density of microfilariae in blood is reported between
10 pm and 2am.
When the sleeping habits of the host are altered, a reversal in
periodicity has been observed