Possible Clues:

• Disease caused by lack of vitamin B
• At end of last four months, one doubled up with illness
• Disease caused by thiamine deficiency
• Asian disease affecting the nerves and limbs
• One might get sick of a couple of fruit, by the sound of it
• You might get sick of only two such fruit, by the sound of it
• Result of thiamine deficiency
• Sounds as if a couple of fruit's enough to make one sick
• Lack-of-vitamin-B disease
• Tropical vitamin deficiency disease