Use topical repellents that have the four proven active compounds within their chemical structures, but most importantly at the appropriate chemical concentrations. They include the likes of DEET at a 20-50%) concentration and PMD at a 30% concentration.
DEET is a good choice, some guidelines are available with the World Health Organisation.
Importantly, reapply repellents at least 6 to 8 hours after using DEET or 4 to 6 hours for PMD. You need to supervise the application as kids tend to miss places!
Also remove topical agent at bedtime where possible. Your baby or kid should be in the most important device available to protect them during the night, namely a Mosquito NET. I cannot describe the value in taking NETs for yourselves and your babies and kids!
Some research has showed that DEET 33.5% reduces Sun Protection Factor (SPF). Another interesting point is that when sunscreen is applied over repellent it could reduce the effect by 1 hour or so. So remember to reapply earlier if this is the case.
Mosquito infection preventions key points are (1.) good clothing cover at the correct times of day and (2.) good safe WHO approved topical repellents for babies and kids.
See http://www.baby2day.co.za for the full story.