Brugia malayi: Agent of Lymphatic Filariasis

Introduction

Brugia malayi is one of three nematodes that cause lymphatic filariasis. Lymphatic filariasis is neglected tropical disease that is most easily recognized by the symptom elephantiasis. This symptom is the swelling of the lower extremities.[5] B. malayi is only found in south and southeast Asia. The parasite is transmitted by a mosquito vector and humans are its definitive host.

Symbiont Description

Brugia malayi are long, thread-like roundworms. Male worms are capable of growing to 2cm length while females can grow up to 8cm in length when they reach the adult stage.[3]

Host Description

B. malayi reaches sexual maturation in the definitive host which can be human, monkey, domestic cats, or forest carnivores. The parasite is transmitted to the definitive host by the species of Mansonia, Aedes, Anopleles, and Culex mosquitoes. While the mosquito is taking its blood meal the larvae enter the wound.[2]

Life Cycle

http://dpd.cdc.gov/DPDx/images/ParasiteImages/A-F/Filariasis/B_malayi_LifeCycle.gif

B. malayi larvae are transmitted to a definitive host by a mosquito vector. The larvae develop into adults in the lymphatic tissue. The adults produce microfilariae that enter the bloodstream and are taken up by a mosquito vector. The cycle continues again with transmission to another host.[4]

Ecology 

B. malayi is a causative agent for lymphatic filariasis. The nematodes nest in the lymph nodes stretching them until lymph fluid can only drain downward. This causes excessive pain and swelling. Both of these symptoms can be treated but there is currently no cure for filariasis. The World Health Organization hopes to eradicate the disease through the use of deworming drugs.[1]

Example of a vector-borne transmission

B. malayi is transmitted by a mosquito vector, specifically the mosquitoes of the genera Mansonia, Aedes, Anopleles, and Culex. These mosquitoes are found in the swamps and irrigated fields of Asia. The parasite resides in the stomach, thorax muscles, and the proboscis of the mosquito until it is transmitted to the definitive host.[2]

References 

1.  http://www.nytimes.com/2006/04/09/world/americas/09lymph.html?ex=1160884800&en=f67aded46f031e62&ei=5070

2. http://eol.org/pages/2921743/details#ecology

3. http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=6279

4. http://dpd.cdc.gov/DPDx/HTML/Frames/A-F/Filariasis/body_Filariasis_b_malayi.htm 

5. http://www.who.int/mediacentre/factsheets/fs102/en/