Infection with H. diminuta: (i) activates the intrinsic apoptotic pathway in the small and large intestine of the host; (ii) triggers apoptosis via the activation of a caspase cascade, such as with caspase-3 and caspase-9; (iii) enhances apoptosis in the small and large intestine of the host by increasing the expression of the gene and pro-apoptotic protein Bax and by decreasing the gene and protein expression of anti-apoptotic Bcl-2. This evidence concerns the gene CASP9 and infection.