Dengue Fever: Given the patient's origin from Puerto Rico, where dengue fever is endemic, and the presentation of fever, leukopenia, and thrombocytopenia, dengue fever is a highly plausible diagnosis. These symptoms are classic for dengue, especially during the febrile phase.

Viral Infections (e.g., HIV, EBV, CMV): These infections can cause fever, leukopenia, and thrombocytopenia. The patient's age and potential exposure history make these considerations relevant.
Malaria: Although less common in Puerto Rico, travel history or exposure to infected mosquitoes could lead to malaria, which can present with similar symptoms.
Ehrlichiosis/Anaplasmosis: These tick-borne illnesses can cause fever, leukopenia, and thrombocytopenia, and their incidence can vary by geographic location.

Sepsis: Any patient presenting with fever and signs of bone marrow suppression (leukopenia and thrombocytopenia) must be evaluated for sepsis, as it is a life-threatening condition requiring immediate intervention.
Meningococcemia: Although less common, this condition can present with fever and signs of bone marrow suppression, and it is critical to diagnose early due to its high mortality rate if untreated.
Hantavirus: While rare, hantavirus infection can cause severe disease, including hemorrhagic fever with renal syndrome or hantavirus pulmonary syndrome, both of which can present with fever, leukopenia, and thrombocytopenia.

Lymphoma/Leukemia: Although less likely, these malignancies can cause bone marrow suppression leading to leukopenia and thrombocytopenia, along with systemic symptoms like fever.
Aplastic Anemia: A rare condition characterized by bone marrow failure, which could explain the patient's cytopenias, though fever would be an atypical presenting symptom.
Thrombotic Thrombocytopenic Purpura (TTP): A rare blood disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, renal failure, and neurological symptoms, which could be considered in the differential diagnosis due to the thrombocytopenia.