The number of people diagnosed with dengue fever ( which is contacted from the bite of an infected mosquito ) in Bangladesh this year is twice the number diagnosed last year . The authorities have concluded that measures to control the mosquito population have failed in the region. All of the following , if true , would cast doubt on the authorities' conclusion EXCEPT-

More case are now reported because of increased administrative efficiency

A more effective diagnostic test was introduced about nine month ago

The disease is prevalent only in some industrialised areas which have shown a dramatic increase in population due to migration

The incidents (number of cases per thousand) of malaria, also contacted from mosquito bites has increased