The word disinfested is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 17
Highest Scoring Words With Friends™ Plays In The Letters disinfested
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Seven Letter Word Alert: (24 words)
defends, defined, defines, deified, deifies, deities, densest, destine, dieties, dietine, dissent, distend, edified, edifies, finesse, fitness, indited, indites, infests, insides, seitens, sestine, snidest, teddies