13.—(1) The following provisions apply to a person receiving
(a)regular weekly treatment by way of haemodialysis for chronic renal failure or peritoneal dialysis for chronic renal failure;
(b)treatment by way of plasmapheresis, by way of parenteral chemotherapy with cytotoxic drugs, anti-tumour agents or immuno-suppressive drugs or by way of radiotherapy; or
(c)regular weekly treatment by way of total parenteral nutrition for gross impairment of enteric function.7
(2) A person referred to in paragraph (1) shall be treated as incapable of work on any day on which he is engaged in that treatment.
(3) A person who works during any week in which he receives treatment referred to in paragraph (1) shall be treated as capable of work for the purposes of regulation 16 only on the actual day or days on which he works in that week.
(4) Section 167B(3) (which defines a spell of incapacity) shall have effect in relation to a person referred to in paragraph (1) as if the period of 4 days mentioned in that section were a period of 2 days, whether consecutive or not, within a period of 7 consecutive days.