Here are some references on B. hominis which may be useful.  It was
generally  considered a harmless intestinal commensal but there are reports
suggesting it may be pathogenic.  I agree with Barbara Wilson-Clay that
breastfeeding must not be stopped especially if the child has diarrhoea
from the blastocystis. And what's wrong with bananas?  Give the kid some
fresh yogurt for the diarrhoea too.  David, paediatrician, Trinidad, West
Indies, where we have lots of diarrhoea!

Lancet,1:1233-1234, 1984. Clinical relevance of Blastocystis hominis.
Garcia, LS et al

Am. J. Trop. Med. Hyg. 35:1023-11026, 1986. Blastocystis hominis presenting
as recurrent diarrhoea.  Vanatta, JB. et al

West Indian Med. J. 39:57-58, 1990. Blastocystis hominis in Two children of
one family. D.E. Bratt & E.S. Tikasingh