Which anthelmintic agent is effective against filarial infections?

Ivermectin is the anthelmintic agent effective against filarial infections, which include diseases such as lymphatic filariasis and onchocerciasis. It works by binding to specific ion channels in the parasites, leading to paralysis and death of the organism. Ivermectin is particularly effective against the microfilariae stage of filarial worms, and its use has significantly contributed to the control and elimination of filarial diseases worldwide.

The other options, while effective against various types of parasites, do not target filarial infections specifically. Praziquantel is primarily used to treat schistosomiasis and infections caused by cestodes (tapeworms). Albendazole is effective against a range of nematodes and some cestodes, but it is not the first choice for filarial infections. Levamisole, although an anthelmintic, primarily targets certain nematode infections and is not effective against filariae. Therefore, Ivermectin stands out as the correct choice for treating filarial infections.