The word helminthiasis 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: 22
Highest Scoring Words With Friends™ Play In The Letters helminthiasis
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Seven Letter Word Alert: (50 words)
ailment, aimless, aliment, animist, anthems, ashiest, atheism, elastin, elitism, enlists, entails, haemins, halites, hamlets, hastens, hatless, healths, ileitis, inhales, initial, inmates, inseams, laments, liaises, listens, manless, mantels, mantles, messiah, militia, miniate, misseat, missile, nailset, netmail, salient, salines, seitans, seminal, sestina, sheaths, silanes, silents, simians, similes, stamens, stimies, theisms, thiamin, tinsels