Generally, mosquito bites simply appear as a small itchy bump, but some people can have more intense reactions to the bites if they are allergic. Although a mosquito bite itself is harmless, mosquitoes are capable of transmitting serious diseases through these bites, such as malaria, yellow fever and West Nile virus. Because of the risk, it is always smart to use insect repellant when outside in order to prevent mosquito bites. If at any time you feel that the bite is serious, seek medical help as soon as possible.