水疱瘡 (hiragana みずぼうそう, romaji mizubōsō, historical hiragana みづばうさう)
/midu bausau/ > /mizu bɔːsɔː/ > /mizu boːsoː/. Compound of 水 (mizu, “water”) + 疱瘡 (bōsō, “smallpox”).