Hello, thanks for the query & I am sorry to hear all your troubles. Briefly, can you tell me what medications he is on for bipolar disorder? considering the change in behavior from cheerful to aloof which is labelled as autistic by you; this might be a new episode of depression triggered due to irregular drug compliance, stress of illness (malaria) or de novo. So we will need to adjust the dose of his mood stabilizer medications for prompt relief from depressive symptoms; Secondly when was he diagnosed as malaria? is there any any documented fever or other symptoms? and whether he is receiving any treatment for same? Considering his recent trip & return from a malaria & other infectious disease endemic area; it will be a good option for a peripheral blood smear (PBS) to identify malaria parasite & start treatment with artesunate, lumefantrine or other appropriate group of antimalaria drug. Lastly, as some of mood stabilizer medications like divalproate sodium, carbamazepine etc. tend to react with medications resulting in change in blood drug levels; your primary health care doctor should be informed about your friends medications of bipolar disorder. If you need any extra help, kindly revert back. Dont worry; act promptly...good luck