The gastrointestinal tracts, lungs, and urinary bladders from 77 Bufo microscaphus, 61 Bufo woodhousii, and 8 of their hybrids were examined for helminths. One species of trematode (Glypthelmins quieta), 1 species of cestode (Distoichometra bufonis), and 5 species of nematodes (Aplectana incerta, A. itzocanensis, Rhabdias americanus, Physaloptera sp., and Physocephalus sp.) were found. The greatest prevalence (41%) and mean intensity (231.7) were recorded for Aplectana incerta in Bufo woodhousii. It appears hybrids harbor fewer parasites than either parent species.
Goldberg, Stephen R.; Bursey, Charles R.; Malmos, Keith B.; Sullivan, Brian K.; and Cheam, Hay
"Helminths of the southwestern toad, Bufo Microscaphus, Woodhouse's toad, Bufo woodhousii (Bufonidae), and their hybrids from central Arizona,"
Great Basin Naturalist: Vol. 56
, Article 11.
Available at: http://scholarsarchive.byu.edu/gbn/vol56/iss4/11