Filariasis is a parasitic disease caused by a roundworm of the family Filarioidea. The filarial worms are transmitted and spread by blood-feeding black flies and mosquitoes. Upon entering the body, the larvae of the worm accumulate in an organ of the body and multiply where they cause the chronic inflammation of that organ. Depending on the infecting parasite there are two different kinds of filariasis that affect different parts of the body.
Types of Filariasis
- Lymphatic filariasis: It is caused by the worms Wuchereria bancrofti, Brugia malayi and Brugia timori. These worms affect the lymphatic system especially the lymph nodes. Chronic cases of lymphatic filariasis lead to the disease Elephantiasis.
- Subcutaneous filariasis: It is caused by the Loa loa worm which burrows themselves in the subcutaneous fat layer right under the skin. These worms are responsible for river blindness.
The symptoms can be rather large and unseemly. This is very true in the case of Lymphatic filariasis, the victims of which experience the thickening of the skin and the tissues underneath. These tissues over time engorge and harden. Elephantiasis mostly affects the lower parts of the body such as the legs, genitals etc. The parasites take up residence in the lymph nodes where they block the flow of lymph fluid. This results in the accumulation of fluid which is responsible for the enlargement of body parts. More than 120 million people worldwide are infected with lymphatic filariasis with most victims from Africa and Asia. Enlargement of body parts adversely affects the social life and economic well-being of the individual.
Life cycle of a Filarial worm
Mosquitoes act as carriers for the disease. The larvae of the parasite enter the bloodstream, consume the resources that we need and grow into adults. Once again it is important to mention that the growth occurs in the lymphatic system. The larvae then mature and the adult filarial worms release smaller worms called microfilariae covered in a protective coating of the blood. The next time a mosquito bites the person, these microfilariae enter into the mosquito with the blood. In the mosquito, the microfilariae shed the covering and begin to grow. This mosquito is now contaminated with filarial larvae which can then infect another human.
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