**Question:** The DEC-medicated salt for mass treatment in lymphatic filariasis was shown to be safe, cheap and effective in

A. Africa
B. Asia
C. South America
D. Europe

**Core Concept:** Lymphatic filariasis is a mosquito-borne parasitic infection caused by filarial worms. The disease is prevalent in tropical and subtropical regions, particularly in Africa, Asia, and South America. Diethylcarbamazine citrate (DEC) is an effective drug used for mass drug administration (MDA) in lymphatic filariasis control programs, as it is safe, cost-effective, and can reduce microfilaraemia and disease progression.

**Why the Correct Answer is Right:** DEC is a benzimidazole derivative that targets the microfilariae (immature worms) of Wuchereria bancrofti, Brugia malayi, and Brugia timori, the most common species causing lymphatic filariasis in different regions. In this context, the correct answer is B. Asia, as it encompasses countries like India, Indonesia, Nigeria, and many others where lymphatic filariasis is endemic.

**Why Each Wrong Option is Incorrect:**

A. Africa: While some filarial infections are present in Africa, the prevalence is generally lower compared to Asia and South America. The answer is incorrect due to the lower prevalence of filariasis in this region.

B. Europe: Lymphatic filariasis does not occur in Europe as it is a tropical disease transmitted by mosquitoes native to the tropics and subtropics.

C. South America: Although filarial infections are present in South America, the prevalence is generally lower compared to Asia. The answer is incorrect due to the lower prevalence of filariasis in this region.

**Clinical Pearl:** Mass drug administration (MDA) with DEC and albendazole is a key component of the Global Programme to Eliminate Lymphatic Filariasis (GPELF). This program aims to reduce the transmission of filarial worms by treating a high number of individuals in endemic areas. The combination of DEC and albendazole is considered safe and effective for MDA, but the focus here is on DEC's role in eliminating microfilariae and preventing disease progression.