Sludge Watch ==> Bullfrog as host and vector for sludge/manure based Ecoli O157 infection

[Maureen Reilly]

Bullfrogs to serve as hosts for E. coli O157:H7
20.jun.07
Huliq.com

http://www.huliq.com/25178/bullfrogs-to-serve-as-hosts-for-e-coli-o157-h7

For the first time researchers have identified American bullfrogs as 
potentially suitable hosts for E. coli O157:H7, a common source of 
food-borne illness. They report their findings in the June 2007 issue of the 
journal Applied and Environmental Microbiology.

Escherichia coli O157:H7 is a major food safety concern worldwide. Cattle 
are known reservoirs of the bacterium and researchers are now suggesting 
transmission to aquatic vertebrates, such as amphibians, occurs when 
infected cattle defecate in water sources. Infected tadpoles could then shed 
the pathogen and infect cattle drinking the contaminated water as well as 
vegetables if the water is used for irrigation.

In the study researchers orally inoculated American bullfrog tadpoles and 
metamorphs with E. coli O157:H7 and tested for infection after 14 days. 
Tadpoles, which were housed in flowthrough aquaria, did not become infected, 
however 54% of metamorphs tested positive after being housed in stagnant 
aquaria.

“Our results suggest that American bullfrog metamorphs could function as a 
‘spill-over’ reservoir for E. coli O157:H7 and thus contribute to its 
persistence in aquatic environments,” say the researchers. “Further, given 
that metamorphs are capable of dispersal, they may have a role in the 
epidemiology of this pathogen.”-American Society for Microbiology