Introduction:
Filariasis is a parasitic disease caused by thread-like nematodes of the superfamily Filarioidea. The causative agent of filariasis is transmitted to humans through the bite of infected mosquitoes.

Location of multiplication:
The causative agent of filariasis, such as Wuchereria bancrofti or Brugia malayi, multiplies in the lymph nodes of humans. Once the infective larvae enter the human host through the bite of an infected mosquito, they migrate to the lymphatic vessels and lymph nodes where they mature and reproduce.

Life cycle:
- The adult worms reside in the lymphatic vessels, where they release microfilariae into the bloodstream.
- The microfilariae circulate in the bloodstream, where they can be ingested by mosquitoes during a blood meal.
- In the mosquito, the microfilariae develop into infective larvae, which migrate to the mosquito's proboscis and can be transmitted to humans during subsequent mosquito bites.

Manifestation of disease:
As the adult worms and microfilariae block the lymphatic vessels and cause inflammation, individuals infected with filariasis may develop symptoms such as lymphedema (swelling of limbs), hydrocele (fluid accumulation in the scrotum), and elephantiasis (severe swelling and thickening of the skin).

Prevention and control:
Preventive measures for filariasis include mosquito control measures (such as bed nets and insect repellents) to reduce mosquito bites, mass drug administration with antiparasitic medications, and proper management of lymphedema to prevent complications.