[maxerickson]

The period with many less mosquitoes can still have a dramatic impact on future disease transmission. During the limited population period, the number of reservoir hosts also decreases dramatically (they either get over the illness or die). So later when the mosquito population rebounds, there is much less virus for them to spread.

For the diseases mentioned at the link there are animal hosts (other primates) so it won't be as effective, but for something like malaria where humans are the primary reservoir species, the effect can be very large.

It can also be effective in lowering the rates of transmission in urban areas.