Shame about this illness thing because the lad was doing okay and appearing regularly for Hereford.
Glandular fever apparently. He'd be quarantined from other players and convalescing for some weeks:
Medical Dictionary: "As glandular fever is caused by a virus there is no specific treatment and antibiotics are of no benefit. It is considered to be a self-limiting infection which resolves with time. Getting plenty of rest and drinking lots of fluid is very important during recovery...
http://bullsnews.blogspot.co.nz/2013/03/musa-returns-to-fulham.html
http://www.herefordunited.co.uk/news/article/musa-returns-to-fulham-26032013-735119.aspx
Author: Mark Farmer

Left-back James Musa has returned to parent club Fulham due to illness.
His loan spell was extended for a third and final month on March 1st, but he has now returned to Craven Cottage.
"We threw James into the deep end a bit, but he's quietly got on and done his job," Bulls boss Martin Foyle told the Official Hereford United Website on March 1st.
Musa suffered defeat in just four of his 15 Hereford games, against Wrexham, Ebbsfleet, Newport and Gateshead, and finished on the winning side on five occasions against Braintree, Lincoln, Cambridge, Stockport and Barrow.
