Filaria Nematode worm Disease of Lymphatic Systems Transmitted by Mosquitoes

Filariasis

• 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 Nematode worm Disease of Lymphatic Systems Transmitted by Mosquitoes Filariasis

Filaria can occur due to three nematode worms.

• 1. Wuchereria bancrofti
• 2. Brugia malayi
• 3. Brugia timori.

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.

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.

LYMPHATIC FILARIASIS

LYMPHATIC FILARIASIS

• 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.

OCCULT FILARIASIS

OCCULT FILARIASIS

• 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.