That's not what that paper says. That paper says that the parasite can itself be infected with certain viruses, and maybe we should look into how those viruses affect hosts infected with malaria.

The condition Malaria is caused by the parasite.

Nope.

That paper just reports the discovery of a virus that is a parasite of the plasmodium parasite that causes malaria in humans.

Plasmodium and all its relatives have become parasites a very long time ago, causing a variety of diseases in many animals.

How the Apicomplexa, including the plasmodia, have become parasites has nothing to do with the viruses that may be parasites of these parasites (a.k.a. hyperparasites), which are most likely to diminish the speed of the multiplication of the plasmodia.

That is not at all what that paper is looking at.