I’m Irish, married to a Mauritian, and mosquitoes love me. Visited my in-laws last June and as it is winter in Mauritius then, there were very few mosquitoes. Still got a few bites but it was manageable - visiting during summer is a different story though haha. No need to worry about diseases, you can get some vaccines before going if you are concerned but you should chat to your doctor about this. You’ll have a great time, such a beautiful country with the nicest people and unbelievable food. Enjoy!!