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Lymphacytic Filarial Worms

(Brugia malayi, Brugia pahangi)

Brugia malayi and Brugia pahangi are nematodes that cause lymphatic filariasis in humans. Dogs are suspected to be reservoirs of human infection and rarely show clinical signs when infected.

Parasite: Brugia malayi, Brugia pahangi
Common name: Lymphatic filarial worms
Hosts: Humans, dogs, cats
Location in host: Free in bloodstream
Distribution: Indonesia, Malaysia, Thailand, India
Transmission route: Mosquitoes
Zoonotic: Yes


Brugia malayi and B. pahangi are restricted to Southeast Asia and India.

Clinical signs

Dogs infected with B. malayi and B. pahangi are a rare occurrence and mostly remain asymptomatic. There have been limited reports of infected dogs developing lymphadenopathy and lymphedema. Studies have shown that genetically inherited traits determine the clinical outcome of infection in dogs.


The diagnosis of Brugia spp. infection can be made upon detection of the microfilariae in wet blood mounts and thin blood smears via light microscopy. Serological assays such as ELISA can also be used to confirm a diagnosis through the detection of antibodies or antigen. PCR with sequencing are useful for detection of low parasitaemia and for species determination.


Brugia infection in dogs can be treated with moxidectin, selamectin, doramectin and ivermectin.


Minimizing dog contact with vectors by using topical repellents and insecticides such as collars and spot-on formulations (e.g. permethrin, flumethrin, deltamethrin).

Public health considerations

Brugia malayi and B. pahangi are both zoonotic and there have been several reports in humans in endemic areas.