what are the causes of throat ulcers?
['Epstein-Barr virus (EBV)', 'Herpes simplex virus.', 'Human immunodeficiency virus (HIV)', 'Oral thrush (Candida albicans fungal infection)', 'Other bacterial and viral infections.', 'Tonsillitis caused by group A beta-hemolytic Streptococcus (most common cause)']