From 1895 to 1902, he attended mental illness courses and internships and visited many asylums in Germany, England, France, Italy, and Scotland.

When the disease got worse, he took a new license and traveled to Europe for better treatment and later went to a sanatorium in Cairo, where he met Augusta Peick, a German nurse from Hamburg.

Moreira spoke against the pseudoscientific racist beliefs espoused at the time, such as that racial miscegenation caused mental illnesses; he defended that they were due to physical and situational factors such as poor hygiene and lack of access to education.

[5] Moreira was the first researcher to identify mucosal cutaneous leishmaniasis and sought to prove that the racial issue did not motivate the disease.

Despite opposing racism, Moreira was a member of eugenist organizations and defended practices such as the sterilization of criminals and alcoholics.