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: Five cases of encephalitis during treatment of loiasis with diethylcarbamazine .
### Output Text:
Five cases of encephalitis during treatment of loiasis with <span class="chemical">diethylcarbamazine</span> . 