Increased mucosal damage during parasite infection in mice fed an elemental diet

We have examined the effects of parasite infection on the mucosal architecture of mice maintained on an elemental diet (Vivonex). Techniques used were conventional histology, micro-dissection and measurement of individual villi and crypts, and measurement of crypt cell proliferation rate by a metaphase accumulation technique. In normal, non-parasitised mice the elemental diet caused no change in villus height, crypt depth, or crypt cell proliferation. Likewise, the only effects of chronic protozoal infection or Nippostrongylus brasiliensis infection on the intestine of mice fed a normal diet have been a slight crypt hypertrophy and an increase in crypt cell proliferation rate without villous atrophy. However, the combination of elemental diet and parasite infection resulted in increased mucosal damage when compared with infected mice on a normal diet. Elemental diet mice infected with the nematode Nippostrongylus brasiliensis had significantly reduced villus height and correspondingly raised crypt length and metaphase accumulation rate. Elemental diet mice infected with the protozoan Giardia muris did not have villous atrophy but there was a significant increase in crypt length and metaphase accumulation when compared with infected normal diet mice. These experiments show that in two animal models of enteric infection, elemental diet has altered the host parasite relationship to the detriment of the host.