Filaria Nematode worm Disease of Lymphatic Systems Transmitted by Mosquitoes




  • Massive swelling, esp. of the genitalia and lower extremities, resulting from obstruction of lymphatic vessels, for example by filarial parasites, malignancies, neurofibromatosis, or a familial congenital disease (Milroy’s disease).
  • Prolonged swelling can cause an increase in interstitial fibrous tissue and skin puckering or breakdown. In patients with  the filarial diseases

Filaria 2
Filaria Nematode worm Disease of Lymphatic Systems Transmitted by Mosquitoes

Filaria can occur due to three nematode worms.


  • 1. Wuchereria bancrofti
  • 2. Brugia malayi
  • 3. Brugia timori.
Wuchereria bancrofti 32
Wuchereria bancrofti
  • All three infections are transmitted to man by the bite of mosquitoes.
  • A parasitic worm that is the causative agent of elephantiasis.
  • Adults of the species live in human lymph nodes and ducts.
  • Females give birth to sheathed microfilariae, which remain in internal organs during the day but at night are in circulating blood, where they are sucked up by night-biting mosquitoes,
  • Inside the mosquitoes microfilariae larva are continue their development, and becoming infective larvae in about 2 weeks
  • All have similar life cycles with the adult worms living in the lymphatic vessels whilst the microfilaria circu­late in peripheral blood.
Culex mosquito2
Vector of Filaria Culex mosquito


Vector of Filaria


  • The microfilaria are taken in by the mosquito when they feed on the host.
  • The vector for W. bancrofti is Culex mosquito.
  • The vector for B. malayi is Mansonia mosquito. The vector for B. timori is Anopheles mosquito
  • Filaria is transmitted by the bite of infected mosquito. The parasite is deposited at the site of puncture and passes through the skin and reaches the lymphatic system.
  • The incubation period is 8 – 12 months or longer.


Clinical Features of FILARIASIS :


  • · The disease may be asymptomatic or acute or chronic.
  • · The important features are lymphangitis, lym­phadenitis, elephantiasis of genitals, legs and arms.
  • · It may also present as tropical pulmonary eosi­nophilia or filarial arthritis.
  • · Filaria can cause great deformity and disability.



  • There may be no symptoms inspite of micro-filaria in the blood. The host acts as carrier.
  • There may be recurrent episodes of acute inflamma­tion in lymph nodes and lymphatics.
  • There is periodic high grade fever, lymphangitis, lym­phadenitis, lymphedema of various parts of body and even epididymoorchitis in males.
  • The chronic stage may develop 10 years after the first attack. There is fibrosis and obstruction of lym­phatic vessels causing permanent structural changes.
  • There is hydrocele, elephantiasis and chyluria. Elephantiasis affects the legs, scrotum, arms, penis, vulva and breasts.
  • Other causes of elephantiasis are tuberculosis, tumors, irradiation, silica poisoning.





  • There are no clinical manifestations of the parasite and microfilaria are not found in the blood e.g. tropi­cal pulmonary eosinophilia.


Diagnosis of FILARIASIS:


  • · A thick film made from capillary blood between 8.30 pm and 12.00 midnight is prepared on the glass slide and examined for microfilaria.
  • · Membrane filter concentration (MFC) method is a sensitive method for detection of microfilaria.
  • · Blood is collected from a vial and filtered to de­tect microfilaria.
  • · DEC provocation test – Diethyl carbamazine (DEC) 100 mg is given orally to induce microfi­laria to appear in blood within 15 minutes to 2 hrs.
  • · Serological tests to detect antibodies to microfi­laria using immunoflourescent and complement fixing techniques.


Treatment of FILARIASIS:


  • Diethyl carbamazine (DEC) is safe and effective. 6 mg/kg body weight of DEC is given orally for 12 days in divided doses after meals.
  • DEC kills the microfilaria. DEC can cause serious side effects like headache, nausea, vomiting and dizziness.
  • Ivermectin is a broad spectrum macrolide anti­biotic (microfilaricidal agent). It is given in doses of 200-400 µg/kg body weight.
  • Other measures are control of vector by antilarval measures, removal of pistia plant and larvicidal (to kill the larvae) operation.
  • DDT, HCH and Dieldrin can be sprayed. Pyrethrum is a new anti-vector spray.


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