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 total of 350 patients ( 215 [ 61 . 4 % ] < 5 years of age and 135 [ 38 . 6 % ] > 5 years of age ) were followed - up after treatment with injectable artesunate for severe malaria in hospitals and health centers of the Democratic Republic of the Congo .
### Output Text:
A total of 350 patients ( 215 [ 61 . 4 % ] < 5 years of age and 135 [ 38 . 6 % ] > 5 years of age ) were followed - up after treatment with injectable <span class="chemical">artesunate</span> for severe malaria in hospitals and health centers of the Democratic Republic of the Congo . 