A 35 year old man is brought in semi-conscious, around 15 minutes after he suddenly collapsed in front of his family. He had complained of 'feeling ill' since waking up today.

He developed an extremely high fever with chills around 5 days ago, in association with a headache and arthralgia. This was self-medicated with Ibuprofen alone, and subsided completely last evening.

His medical, surgical, and family histories are unremarkable, and he is not on any medications. He only drinks socially, and has never smoked.

Close questioning reveals that he returned from a month's vacation to Sri Lanka around a week ago.