Residue Rendezvous

Professor Putricide has been holed up in his foul laboratory, experimenting and refining increasingly lethal strains of blight to be used against us. If only we could obtain pure samples of the toxins, our researchers could concoct an antidote that would save countless lives.$B$BBut there's a catch -- a proper sample will need to mix two active strains within a living host. Should you have the... misfortune... of becoming such a host, please return here immediately so that we can harvest you for study.