Learn Spanish (Spain): El tratamiento ya ha curado la enfermedad. - The treatment has already cured the disease.

Ha curado is the present perfect tense, which connects a past action to the present. In Spain, this tense is used very often, especially for things that have a result right now, like a treatment successfully curing a disease.

Could I put ya between ha and curado, like in English "has already cured"?

No, in Spanish you can never put a word between the helping verb (ha) and the main verb (curado). Extra words like ya (already) must go before the helping verb or at the end of the sentence.

Is there a trick to remember that enfermedad is feminine?

Yes! Spanish nouns ending in -dad (like la enfermedad, la ciudad, la verdad) are almost always feminine.

Is there a similar rule to know the gender of tratamiento?

Yes! Nouns ending in the suffix -miento are masculine, so it takes el. This is a very common ending for nouns made from verbs, like getting el tratamiento (the treatment) from tratar (to treat).