The word disinfestation 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: 20
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (89 words)
adonise, anodise, anoints, asinine, attends, daftest, daisies, defiant, dentins, dentist, destain, detains, dietist, dissent, distant, ditties, dittoes, donates, dotiest, edition, enfants, fadeins, fainted, fastens, fastest, fatness, fattens, fatties, fiestas, fission, fitness, foisted, fondant, fondest, indents, indians, indites, infants, infests, inosine, inosite, insides, instant, instate, instead, intends, intents, intoned, intones, iodines, iodises, iodites, ionised, ionises, nations, nondate, nondeaf, nondiet, nonfast, noseans, nosiest, notated, notists, sainted, seitans, sestina, setfast, siennas, sinoids, snidest, snotted, softens, softest, softies, sonnets, stained, statins, station, stetson, stinted, tainted, tannest, taoists, tenants, tendons, tension, tidiest, tiniest, toasted