The river, not being able to flow freely across the barriers composed of vegetation and weeds which the current of the water carries and deposits in the more shallow places, forms there extensive and infectious swamps, amid which the fever does not spare even the negroes.
"In Desert and Wilderness"
Henryk Sienkiewicz
Even the dogs caught the infectious enthusiasm.
"My Attainment of the Pole"
Frederick A. Cook
For you, who are satisfied with everything around you, and who greet every new day for its fresh pleasures, I am a dangerous companion, for my discontent is infectious.
"The Mystery of the Locks"
Edgar Watson Howe