Waikato DHB, which has used the procedure with the greatest number of patients, 10 by late last year, introduced it in 2012, the year after Counties Manukau, which was the first, in 2011.
As gross as it sounds, infusions of poo "donated" by a healthy family member, have proved remarkably effective at quickly treating a nasty problem: recurrent or treatment-resistant diarrhoea infection caused by clostridium difficile bacteria.
The patient acquires clostridium or it may have been in their bowel for some time without any symptoms.
They will have been taking antibiotics for some other condition, septic arthritis for instance. As well as curing that condition, the medicine kills healthy bacteria that live in the gut - but not the clostridium.
In the absence of competing bacteria, the clostridium grows rapidly. It produces a toxin which stimulates the bowel to produce fluid and causes inflammation, leading to diarrhoea.
The idea behind faecal transplants is to reintroduce healthy bacteria to the bowel. They quickly grow in numbers and crowd out the clostridium.
"It's not new; it's just being looked at more systematically now," said infectious diseases physician Dr David Holland, of Counties Manukau DHB. "There was a report in 1958 of faecal enema for diarrhoea in someone quite unwell, with success.
"It got forgotten, and perhaps the other reason is it's not aesthetically pleasing."
He notes most patients would prefer a pill, but after the misery of recurrent diarrhoea they are more likely to consider "faecal microbiota treatment" (FMT).
He recalls the first patient he treated with this after hearing of the procedure at a London conference. She had already learned of it on the internet and said to him when he suggested the treatment: "I was afraid you might mention that."
Once a patient's healthy spouse or other family member agrees to be the donor, he or she is screened to ensure they are not carrying illnesses.
The faeces is processed into a slurry with water or saline and put into a short tube that drains into the patient's rectum. Some hospitals use colonoscopy.
A Dutch trial infused the slurry into the first part of the small intestine, via nasal/gastric tube. An analysis of side-effects found 19 per cent of patients reported belching.
A Boston hospital last year reported its trial of faecal capsules. The processed poo - from unrelated donors - was sealed inside two medicine capsules, frozen and then swallowed by the patients.
Dr Holland said the efficacy of faecal transplants was 90 to 98 per cent in various trials in the small group of patients with recurrent or resistant diarrhoea infections.
The cure rate at New Zealand hospitals reflects this, being at or near 100 per cent, although Auckland DHB withheld the data. "The cure seems to be long-lasting," Dr Holland said. "They don't seem to come back with recurrences or if they do, a second infusion will do the trick."
Faecal transplants - since 2011, by DHB
