How long does it take after the bite of an infected mosquito, for someone to feel the effects of malaria?

8-25 days. The incubation period is usually 8-25 days but sometimes it can be much longer, up to 4 years in one case.
1 week to few months. Malaria symptoms show up a week to a few months after being infected by a mosquito bite. Fevers, chills, fatigue, swelling of the spleen, etc... Usually occur. With medical treatment, the symptoms should go away in a couple of weeks. However, without treatment, and depending on the strain of malaria parasite, an infected person can have symptoms for a few years, up to a few decades.