Adventure Doc
keeping you healthy for life's adventures
Erik McLaughlin MD, MPH
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WUCHERIA BANCROFTI
Basics:
Mosquito transmitted infection that is known to cause lymphatic blockages secondary to accumulation of adult stages in lymphatic channels. Capable of being carried by Culex, Aedes and Anopheles species, W. Bancrofti is most common (90%) but other important species include Brugia malayi and Brugia timori. Fever and asthma are common manifestations.
Location:
W. Bancrofti is most common, worldwide. B. Timori is found on Timor and areas of Indonesia. B. Malayi is found in SE Asia.
Transmission/ Incubation:
Acquired from the bite of an infected female mosquito. Adult worms can take 8-12 months to mature from infective stage.
Prevention:
Mosquito/Vector control (see malaria section), mass treatment in endemic areas with DEC (diethylcarbamazine)
Diagnosis:
Demonstration of filariae in blood smear. Certain species are more active in bloodstream during different times of day, depending on geographic location. W. Bancrofti in S. Pacific and sections of SE Asia are “day active” and blood samples should be taken at several times during the day/night to ensure proper demonstration. Filtration of blood through membranes (Nucleopore) may assist in identification. ELISA and commercially available test-cards are also available. Filariae may take 3-12 months to appear in bloodstream, after infection.
PRODUCT REVIEWS
Treatment:
DEC (diethylcarbamazine) is the drug of choice but must be used with caution in areas with concurrent Onchocerciasis due to a Mazotti reaction. DEC or ivermectine, in combination with albendazole is used to eradicate all microfilariae. However, not all adult worms may be eradicated. This is why monthly treatment is advised for 1-2 years to ensure no new microfilariae appear.
W. Bancrofti collected with pore filtration
images from
Note the pointed tip and the cells do not extend to the end of the tail.
Wuchereria Bancrofti in hematoxylin stained blood smear
Elephantiasis of lower extremities
This causes elephantiasis (swelling of the leg due to lymphatic blockage). This is an infection that effects the lymphatic channels of people’s legs and hips. The person gets bitten by a mosquito, that carries the disease, from the Culex, Anopheles or Aedes species to get infected. The mosquito deposits microfilaria (tiny, tiny worms) into the blood stream. These tiny worms move to the lymphatic channels in the hips and legs, where they grow into adults. The adults block the return of the lymph from the legs, causing them to swell, over many years. Lymph is not blood, but your body’s fluid it uses transport harmful and infectious material. W. Bancrofti is found in South America, Africa, Asia and the Pacific Islands. The damage and swelling that occurs from the blockage of the lymph channels is irreversible and can never be fixed. Surgery to remove the adult filarial worms will only produce scarring and further block the channels, making the problem worse. The “filarial dance sign” can show the live, adult worm moving in the lymphatic channels of infected persons, when examined with ultrasound. Infections of the skin are common in the swollen limbs. Treatment is with a drug called Diethylcarbamazine (DEC). The WHO (world health organization) conducts massive efforts to eradicate this from areas of the planet where it causes major morbidity (illness without death). This eradication is with low-dose DEC, given monthly for 1-2 years, after initial treatment dose. DEC is even being placed into the salt, in endemic areas. On the pictures, note that W. Bancrofti has a sheath and the cells are loosely packed.
