Chloroquine kills the "Plasmodium" in the blood. But the "Plasmodium" in the liver is not killed by chloroquine. "P. vivax" and "P. ovale" both stay in the liver a "long" time. This is the "dormant phase". Another medicine must be given with chloroquine for "P. vivax" and "P. ovale". This is to kill the "Plasmodium" in the liver. The medicine used to kill malaria in the liver is "primaquine". In southeast Asia, some "P. vivax" is resistant to primaquine. Most other places, "primaquine" works very well.