NTD preventive chemotherapy — DTM&H MCQ

Correct answer: D — LF, onchocerciasis, STH, schistosomiasis, and trachoma

The correct answer is D, LF, onchocerciasis, STH, schistosomiasis, and trachoma. These five neglected tropical diseases (NTDs) form the WHO preventive chemotherapy (PC) platform because they can each be controlled by mass drug administration (MDA) using a small number of safe, oral medicines given periodically to whole at-risk communities without individual diagnosis. The regimens overlap and can be co-administered: albendazole or mebendazole for STH, albendazole plus ivermectin or diethylcarbamazine for lymphatic filariasis, ivermectin for onchocerciasis, praziquantel for schistosomiasis, and azithromycin (within the SAFE strategy) for trachoma. This integration is the basis of WHO's NTD roadmap, which co-packages delivery to cut costs and raise coverage across endemic districts, particularly in sub-Saharan Africa where several of these diseases are co-endemic. Why the other options are wrong: E. Malaria, dengue, yellow fever, and chikungunya: these are vector-borne viral or parasitic infections controlled by vector control, vaccination, or case management, not by mass preventive chemotherapy; there is no shared oral drug platform for periodic community-wide dosing. A. HIV, TB, and hepatitis B: these require individual diagnosis, prolonged or lifelong multidrug regimens, and in the case of hepatitis B and TB, vaccination or directly observed therapy, none of which fits the MDA model. C. Leishmaniasis, sleeping sickness, and Chagas: these are vector-borne protozoal diseases needing case detection and targeted, often toxic, individualised treatment rather than population-wide chemoprophylaxis. B. Cholera, typhoid, and shigellosis: these are enteric bacterial infections managed through water, sanitation and hygiene (WASH) measures, vaccination, and antibiotics for confirmed cases, not periodic mass drug administration. Key point: preventive chemotherapy is defined by WHO specifically for the five NTDs (LF, onchocerciasis, schistosomiasis, STH, trachoma) because their treatments can be safely combined and delivered en masse without individual diagnosis.

Reference: WHO, Preventive chemotherapy strategy page and Global update on implementation of preventive chemotherapy against neglected tropical diseases in 2024 (Weekly Epidemiological Record), who.int