A University of Colorado (Boulder) study found that high levels of nutrients from farming and ranching activities increase parasitic infections that lead to frog deformities in ponds and lakes across the United States.

According to this study, increased levels of nitrogen and phosphorous (nutrients used in farming and ranching activities) can cause sharp hikes in the reproduction and presence of a snail species that host microscopic parasites, called trematodes. In turn, these parasites form cysts in the developing limbs of tadpoles causing deformities.

This research is relevant as a decline in the amphibian population can potentially lead to the spread of diseases such as cholera, malaria, West Nile virus, and other diseases affecting coral reefs.

Another study of more than 6,000 amphibian species worldwide concluded that 32% were threatened and 43% were declining in population. The causes identified included habitat loss and emerging diseases.