Lymphatic mosquito. The culex mosquito sucks the blood

Lymphatic filariasis is an insect borne disease caused by certain nematodes of the family Filaridae, and is a major public health problem in India. It is found in almost all states of India.

Causative Agent:

Lymphatic filariasis is caused by two organism’s i.e: (i) Wucheresia (Filaria) bancrofti, and (ii) Brugia malayi Out of these two organisms W. bancrofti is more common in causing the infection. They are long thread like tape worms with tapering ends and are easily visible with naked eye.

The adult male worms measure about 2.5 cm x 1.0 mm whereas female worms measure about 8 to 10 cm x 0.3 mm in length.

Man is the definite host in whose lymphatic system the adult worms live and the culex mosquito is the intermediate host in which the embryos (microfilariae) undergo further development after which they become infective to man.

Mode of Spread:

It is spread through bites of infective female culex mosquito. The culex mosquito sucks the blood of an infected person during the night and transmits the disease. Infection is more common during hot and humid climate which is favourable for mosquito breeding and their development.

Incubation Period:

Incubation period is 6-18 months (average 9 months).

Signs and Symptoms:

The clinical symptoms are fever, lymphangitis, lymph adenitis, elephantiasis of scrotum, legs and arms due to blockage of lymphatic vessels. Lower extremities are affected more than rest of the parts. Though this disease is not fatal but it causes great suffering, deformity and disability especially due to swelling of the legs and the external genitalia, a condition termed as elephantiasis.

Prevention and Control:

For prevention and control of lymphatic filariasis the measures discussed under malaria for protection from mosquito bite and anti- mosquito measures should be followed.


Diethylcarbamazine (DEC) is the drug of choice for treating filariasis. It is available in the market under the name Hetrazan in the form of tablets. Due to its side effects it is not used on mass scale.


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