Relexive Verb - Enfermarse

I am confused in using the reflexive verb "enfermarse". ¿Cómo se dice: "Ana is sick"? I read in a Beginner's Spanish book as "Ana está enferma". I thought, it should be "Ana se enferma". As per Rocket Spanish Beginner's Manual (6.3), the verb "enfermarse" is ALWAYS a reflexive verb. Could you please clarify? Muchas gracias! EMB :?

I'm not sure, but I think that enfermarse means "to become sick, to get sick" rather than "to be sick." Thus, if you want to say Maria became sick yesterday, you could say *Maria se enfermó ayer*, but if you want to say that Maria is sick, you would say *Maria está enferma*, and if you want to say that Maria was sick yesterday, you'd say *Maria estuvo enferma ayer*. If I'm mistaken, I hope someone will correct me.