BRUGIA PAHANGI & BRUGIA BEAVERI

ZOONOTIC BRUGIAN FILARIASIS

Several sp. of natural parasites of wild and domestic mammals cause accidental infection in man.

Transmitted by blood sucking arthropods which feed on both animals and humans( eg: Aedes aegypti mosquito).

Infective larvae develop into adults but do not mature to produce microfilariae.

Following death of worm, chronic inflammatory reaction occurs around dead worm and that causes clinical manifestations.

GENERAL CONCEPTS.

ETIOLOGIC AGENTS: Brugia pahangi, Brugia beaveri, Brugia leporis etc.,

CLINICAL MANIFESTATIONS: Enlarged lymph nodes.

COMPLICATIONS: Typically none. MODE OF TRANSMISSION: Inoculation

of microfilaria from the salivary glands of a mosquito.

DIAGNOSIS: Observation of worm in the histological section following excision of infected lymph node.

TREATMENT: Excision of infected lymph node.

DRUG OF CHOICE: None. RESERVOIR HOSTS: Raccoons &

rabbits(B. beaveri in North America); cats & dogs(B. pahangi in Malaysia).

CONTROL MEASURES: Take precaution to avoid mosquito bite.

SCIENTIFIC CLASSIFICATION

KINGDOM: Animalia PHYLUM: Nematoda CLASS: Secernentea ORDER: Spirurida FAMILY: Onchocercidae GENUS: Brugia SPECIES: B. pahangi & B. beaveri

BRUGIA PAHANGI

ETYMOLOGY: Brugia from Dr.Brug and pahangi from Pahang, Malaysia.

HISTORY: Discovered by Buckley and Edeson in 1956 from dogs and cats of Malaysia.

GEOGRAPHICAL DISTRIBUTION

Aedes aegypti and Armigeres obturbans (vectors of B. pahangi)

RESERVOIR HOSTS(cats and dogs)

LIFE CYCLE OF BRUGIA PAHANGI

MORPHOLOGY

Adult male:17.4-20 mm, Adult female:38-63 mm.

Distinguishing feature: spicules shortest among Brugia sp.(B. pahangi<B. malayi).

Microfilariae: -280 μm(when collected in 2% formalin-Knott’s technique), -189 μm(in thick blood smear).

PATHOGENESIS

From cats and dogs; in Malaysia. Implicated in cases of lymphangitis and

lymphadenitis. Pathology restricted to affected lymph

node. Worms are located in lymph nodes and

lymphatic tissue. Worms are immature and infertile.

Worms are often dead and surrounded by a necrotizing granuloma.

It is very difficult to differentiate between B. pahangi infection and endemic B. malayi infection because-i. Both have same mosquito vectors.ii. Microfilaria of both have similar

appearance.

BRUGIA BEAVERI

Parasite of raccoon in North America. Mosquitoes may accidentally transmit

the infective stage by feeding on an infected animal and then on a human approximately 2 week later.

Rarely exhibit any symptoms. Patient presents with a tender mass in

the cervical, axillary or inguinal region.

GEOGRAPHICAL DISTRIBUTION(North & South America)

RESERVOIR HOST(Raccoon)

Gravid female Brugia (H&E stain)

34-transverse section through male B. beaveri 35-transverse section through female B. beaveri

(Trichrome stain)

Differential DiagnosisEnlarged lymph nodeLymphomaLipomaPapilloma

If the worm is dead, it is surrounded by a granulomatous reaction.

Once the mass is removed no further treatment is required.

CLINICAL MANIFESTATIONS AND COMPLICATIONS OF ZOONOTIC

BRUGIAN FILARIASIS Local lymphadenopathy. Infected node generally not tender. Lesions are non erythematous. Most common sites are

Groin(34%)Neck(21%)Axilla(10%)

But in case of immunodeficient patients, disease may progress to severe lymph edema and worm may become patent and produce microfilaria.

DIAGNOSIS

Typically made by examination of worms in histological section from surgically excised lymph node.

TREATMENT AND CONTROL MEASURES

Removal of infected lymph node or lymphatic tissue provide complete cure.

The only realistic control measure is to avoid being bitten by mosquitoes.

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