It is found recently that incidence of Malaria is increasing because

Of poor sanitary conditions

with increase in population it has become impossible to mainatain cleanliness everywhere

The mosquitoes have become DDT-resistance

Explanation

Answer::

A single gene mutation results in resistance to DDT and pyrethroids, a class of pesticides used in bed nets. According to a new study in the journal Geno Mosquitoes (Anopheles funestus), Geno Mosquitoes (Anopheles funestus) is a malaria vector, and most strategies for controlling disease epidemics focus on controlling mosquito populations with pesticides. I'm guessing. The spread of resistance genes can delay efforts to prevent disease.