**Question:** Concentration of diethylcarbomazine in DEC medicated salt in endemic filariasis is -

A. 250 ppm
B. 333 ppm
C. 500 ppm
D. 1000 ppm

**Core Concept:** Diethylcarbamazine (DEC) is an antiparasitic drug used for the treatment of lymphatic filariasis, a parasitic infection caused by worms. DEC is commonly combined with iodine to form DEC-iodine salt, which is known as DEC-medicated salt. This salt is used in endemic areas to prevent and control filariasis.

**Why the Correct Answer is Right:** The correct answer is 333 ppm (parts per million). DEC-medicated salt contains diethylcarbamazine at a concentration of 333 ppm, specifically 333 ppm iodine + 1.06 ppm DEC. This concentration is effective in preventing lymphatic filariasis transmission.

**Why Each Wrong Option is Incorrect:**

A. 250 ppm: This option is too low for DEC's effective concentration, which is required to prevent filariasis transmission.
B. 1000 ppm: This option is too high, potentially causing adverse effects, and exceeding the recommended therapeutic dose.
C. 500 ppm: Although higher than the correct answer, this option is still not the exact concentration of DEC-medicated salt, which is 333 ppm of iodine and 1.06 ppm of DEC.

**Clinical Pearl:** DEC-medicated salt (333 ppm iodine + 1.06 ppm DEC) is an essential component of mass drug administration (MDA) programs in endemic areas for the control of lymphatic filariasis. The correct concentration ensures the preventive efficacy without causing severe adverse effects.

**Correct Answer:** 333 ppm (parts per million)

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The correct answer, 333 ppm, represents the concentration of iodine and DEC in DEC-medicated salt, which is crucial for its preventive efficacy against lymphatic filariasis. The combination of iodine and DEC in this concentration is essential for mass drug administration programs in endemic regions to control and prevent filariasis transmission without causing severe adverse effects.