MALARIA consists of a set of 16 separate variables, covering each year from 2000 to 2015. The variables report the mean clinical Plasmodium falciparium malaria cases per person within a 10 kilometer circular buffer around each DHS cluster location, by year. MALARIA is available for a subset of the IPUMS-DHS samples with GPS data.
By adding MALARIA to your data cart, you are in effect adding 16 separate variables (MALARIA_2000 - MALARIA_2015), one variable for each year.
Please see the User Note on Using IPUMS-DHS Contextual Variables: Malaria [URL omitted from DDI.] for more information about these variables, including data sources and methodology.