Using of mosquito net can only prevent mosquito from attacking you at night but cannot prevent a mosquito from attacking you outside , that means staying outside in a location that has a population of female anopheles mosquito might be risky because the chance of you getting infected by the mosquito will be very high..
Sometimes the symptom of malaria can be so different depending on who is infected by the disease but generally the symptom of malaria is always headache, stomach pains, general weakness. Lost of appetite and when the symptom is observed i suggest that malaria should be treated as soon as possible..
However there are other disease that may present the same symptoms as malaria and we can not be so sure of what might be wrong with us until we are tested., A medical doctor will ask you to carry out a malaria test to confirm the present of malaria in your bloodstream..after the confirmation you have to take a malaria drugs.
Malaria if left untreated can be dangerous because it can kill, most especially children and people with weak immune system which is the older people.. however there are some certain tribe of children in South Africa that are resistant to malaria.. but I understand very little about them.