Lymphatic filariasis — DTM&H MCQ

Correct answer: E — Community mass drug administration

The correct answer is E, community mass drug administration. The presentation, recurrent fever with lymphangitis, chronic unilateral leg lymphoedema in a patient from coastal East Africa, together with sheathed microfilariae on night blood film, is classic for bancroftian lymphatic filariasis (Wuchereria bancrofti), transmitted by night-biting Culex mosquitoes with nocturnal periodicity of microfilaraemia. Individual chemotherapy treats the single patient, but the public health priority in endemic coastal Tanzania is interrupting ongoing transmission at community level. WHO established the Global Programme to Eliminate Lymphatic Filariasis (GPELF) to stop transmission of infection by mass drug administration (MDA) of anthelminthics and to alleviate the suffering of people affected by the disease through morbidity management. Annual community-wide MDA with albendazole plus ivermectin or diethylcarbamazine reduces microfilarial reservoirs enough to break vector transmission, which is why it constitutes the correct prophylactic strategy for this endemic setting rather than any individual measure. Why the other options are wrong: C. Yellow fever vaccination: this prevents a flavivirus infection transmitted by Aedes mosquitoes; it has no bearing on filarial transmission and the vignette shows no features of yellow fever. B. Avoid raw fish: this is prophylaxis for fish-borne trematodes or nematodes such as Anisakis or Clonorchis, not for a mosquito-transmitted filarial nematode. D. Dog vaccination: dogs are not the reservoir for W. bancrofti, which is an anthroponotic infection with humans as the only significant reservoir, so veterinary intervention is irrelevant. A. Household boiling of water: this prevents waterborne or ingested infections (for example dracunculiasis or cholera), but W. bancrofti is transmitted by mosquito bite, not by contaminated water. Key point: sheathed, nocturnally periodic microfilariae with lymphoedema in an African patient indicate W. bancrofti, and control depends on interrupting mosquito-borne transmission through community mass drug administration, not individual dietary, water, or animal measures.

Reference: WHO. Global programme to eliminate lymphatic filariasis: progress report, 2023. Weekly Epidemiological Record, 2024. https://www.who.int/publications/i/item/who-wer-9940-565-576