Population dynamics of a mixed Plasmodium vivax-P. falciparum infection, in which P. vivax first appears in the blood (from relapse or superinfection) 150 days after the appearance of P. falciparum. P. falciparum stabilizes at approximately 11,600 parasites/μl prior to the appearance of P. vivax, falls to nearly sub-detectable levels following the appearance of P. vivax, then recrudesces to levels nearly three times (32,900 parasites/μl) its level prior to the appearance of P. vivax. Here, x = y = 0, cs = 0.001, cn = 0.01, ss = sn = 0.001.