Ichthyophonus-like infection in wild amphibians from Quebec, Canada

Myositis associated with infection by Ichthyophonus-like organisms was diag nosed in 35 of 260 (13%) wild amphibians collected in Quebec, Canada, from 1959 to 1964 (n = 30), and 1992 to 1999 (n = 230). Infection was diagnosed in 17 green frogs Rana clamitans, 9 wood frogs R, sylvatica, 4 red-spotted newts Notophthalmus viridescens, 3 bullfrogs R. catesbeiana, 1 spring peepe r Pseudacris crucifer, and 1 pickerel frog R. palustris. The spring peeper and one of the bullfrogs were collected in 1964 from the Mont Saint-Hilaire Biosphere Reserve, indicating long-term presence of the organism. Spores o f the organisms invaded striated muscle fibers and were associated with var iable degrees of granulomatous and eosinophilic inflammation. Infection was considered fatal in 2 green frogs, 1 wood frog, and 1 red-spotted newt. It was considered potentially significant in 3 additional green frogs in whic h up to 100% of the fibers of some muscles were replaced by spores associat ed with a severe granulomatous reaction. Ultrastructural features of Ichthy ophonus-like spores included a thick trilaminated wall, a paramural cytopla sm, multiple nuclei, oval mitochondria with short tubulo-vesicular cristae and numerous ribosomes. This report represents 4 new host records and shows that ichthyophonosis is enzootic in amphibians from Quebec.