In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: A man , 25 years old , was admitted to hospital with high fever , chill , vomiting , jaundice .
### Output Text:
A man , 25 years old , was admitted to hospital with high fever , chill , vomiting , jaundice . 