During malaria, a mother can give breast feeds to the child if she is not very sick and is physically fit.
The mother should normally breastfeed her child for atleast one year but she can feed upto 2 years of childs age. Preferably, she should try to feed from both the breasts, if she is offering only one breast for feeds, she may develop engorgement in that breast which can cause discomfort to the mother and also gradually milk production in that breast will stop. Otherwise it is not likey to have any long term effects.