5558
The sample includes all the HIV - infected - patients continuously referred to the Outpatient Service of the Infectious Diseases dept . of Bologna ' s " Ospedale Maggiore " General Hospital during some five days ( 19 - 23rd , July 1993 ) .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 None