Is Dengue fever a problem in Cebu city in April and how can it be avoided?

How do you keep the mozzies away, i ve read that the locals use patches with thiamine in,is this true and do they work? Whats the worst time of the day for mosquitoes. Ive been to Hong Kong and Taipei where they have dengue awareness, but you never even see any mosquitoes hardly let alone get bitten.Is cebu like this or should dengue be taken seriously there