On March 30, 2001, CDC was notified by Pennsylvania Department of Health (PDH) of an acute respiratory febrile illness in 44 students from two colleges who traveled to Acapulco, Mexico, for spring break vacation during March 3-18. Within 7-14 days of their return from Acapulco, 21 students presented to health-care providers with illness characterized by fever, chills, dry cough, chest pain, and headache. Two students were hospitalized. On the basis of clinical symptoms and chest radiographs that revealed bilateral, nodular patchy infiltrates, acute pulmonary histoplasmosis was the suspected illness. While in Acapulco, most of the students stayed at the Calinda Beach Hotel and participated in group activities at other recreational locations.