Areas of the world in which mosquitoes breed are the primary places in which Brugia malayi can be found.These include the Philippines, Indonesia, Sri Lanka, New Guinea, Vietnam, Thailand and Japan, Korea and China.Although humans are considered the primary definite host, Brugia malayi is also known to infect felines and monkeys.
Morphology of Brugia malayi
The typical Brugia malayi microfilaria ranges from 200 to 280 μm in length. Like Wuchereria bancrofti, this organism has a sheath, a rounded anterior end and numerous nuclei.The characteristic that distinguishes it from the other sheathed organisms is the presence of two distinct nuclei at the tip of the slightly pointed tail. These two nuclei are separate and separate from the other nuclei in the organism.
The adult worms of Brugia malayi resemble those of Wuchereria bancrofti, because the members of both species are white in color and thready in appearance. The typical adult female worm measures 53 mm in length, while the adult male measures 24 mm in length.
Life Cycle of Brugia malayi
Brugia malayi can be transmitted by the mosquito genera Aedes, Anopheles or Mansonia, depending on the location and animal reservoirs present.The Anopheles mosquito can also transmit Wuchereria bancrofti, so that co-infection can be theoretically possible.All other aspects of Brugia Malayi ‘s life cycle are similar to that of Wuchereria bancrofti.
Clinical symptoms of Malayan Filariasis
Brugia malayi infections are often asymptomatic, even with the presence of microfilaria in the blood.Fevers can take months to years to develop after the initial infection.Additional symptoms include the formation of granulomatous lesions following a microfilarial invasion of the lymphatics, chills, lymphadenopathy, lymphangitis and eosinophilia.Finally, the result is elephantiasis of the legs.Genital elephantiasis is possible, but less common.
Laboratory Diagnosis of Malayan Filariasis
Although a limited number of documented Brugia malayi microfilariae have been recovered, the examination of stained blood films is the best diagnostic method.Because Brugia malayi usually has nocturnal periodicity, specimens collected during nighttime hours are most likely to produce large numbers of circulating microfilaria.Subperiodic organisms may appear, and this possibility should be considered when determining the protocol for specimen collection.The Knott technique can also be used. Serological methods have also been developed and are now available.
Treatment of Malayan Filariasis
Treatment for Brugia malayi is similar to that for Wuchereria bancrofti, the most useful medication being diethylcarbamazine( DEC). Inflammatory reactions are more common and can be severe after treatment. Anti- inflammatory drugs may therefore be necessary.
Prevention and Control of Malayan Filariasis
The prevention and control measures for Brugia malayi are the same as those for Wuchereria bancrofti.
Notes of Interest and New Trends
In addition to Brugia malayi, Malayan filariasis may also be caused by another Brugia species, Brugia timori, first isolated on Timor Island in 1964. Readily distinguishable from Brugia malayi, Brugia timori microfilariae measure approximately 310 μm.The organism has a sheath that is difficult to observe with Giemsa stain and distinct nuclei in the tip of the tail. The body tissue of this organism does not bulge around the two nuclei like Brugia malayi.A condition called tropical eosinophilia or occult( meaning hidden or not apparent) filariasis is known to occur in people living in areas of the world where both Brugia malayi and Wuchereria bancrofti are endemic. These patients have a number of pulmonary and asthmatic symptoms.On a thorough examination of infected patients, no microfilaria is found in their blood. It is suspected that a filarial parasite is present and responsible for this condition but remains hidden deep in the body, such as the lungs.The signs and symptoms may be due to the inflammatory response of the body. Successful resolution of symptoms with DEC therapy confirms the diagnosis of filarial infection, but failure to respond to DEC suggests another cause of symptoms.
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