Which parasite causes lymphatic filariasis and which genera of mosquitoes serve as vectors?

• A. Plasmodium falciparum; Anopheles
• B. Wuchereria bancrofti (and Brugia species); Culex, Anopheles, and Aedes depending on species
• C. Dirofilaria immitis; Aedes
• D. Loa loa; Aedes

Answer: (B)

Lymphatic filariasis is caused by filarial nematodes, most commonly Wuchereria bancrofti, with Brugia species also contributing in some regions. The disease is transmitted by mosquitoes, but which mosquito genera pass the infection along varies by geography and parasite species. In many areas, Culex mosquitoes are important vectors; in others, Anopheles; and in still others, Aedes can be responsible. The life cycle involves microfilariae circulating in human blood, taken up by a mosquito during a blood meal, developing into infective larvae inside the mosquito, and then being transmitted to humans to inhabit the lymphatic system and cause disease. The other options mix a different parasite or a different vector pair that does not cause lymphatic filariasis—for example, the malaria parasite is transmitted by Anopheles, heartworm is a different filarial species, and loa loa is transmitted by deer flies, not mosquitoes.