He added: "I went away with the national team and they gave me some pills, which I took.
"But I stayed on in Ghana for a while after the football was finished and I didn't have any more pills to take so it seems my protection ran out."
The 21-year-old recovered sufficiently to join United on their pre-season tour of Ireland, although he has not returned to full training.
The former Ajax youngster added: "I was feeling dizzy then one minute I would be feeling hot, the next I was freezing cold.
"I played in a friendly against Stirling last weekend and had to come off before half-time because I had no energy and felt sick.
"It is a serious disease and I hear you can die from it but now we know what it is and I have the correct tablets I will be fine."