- slide 1 of 1
Wuchereria bancrofti is the filarial worm that causes lymphatic filariasis, commonly called elephantiasis. The disease is characterized by the enlargement of body parts (e.g. breasts, scrotum, legs, and arms) because the movement of fluids in the lymphatic system is blocked by filarial worms, resulting in the accumulation of the fluids in the body parts. People will acquire filariasis if they are infected by W. bancrofti microfilariae (juveniles) contained in the saliva of common mosquito species such as Anopheles, Aedes, Mansonia, and Culex. Not all infected with the filarial worms develop elephantiasis; some of them may just experience microfilaremia, a condition of having microfilaria in the blood. These microfilaremic individuals, however, may experience painful inflammations and in due time still develop elephantiasis; it depends on how strong the immunity of those individuals is. Filariasis is still a misunderstood disease in many parts of Africa and Asia. Ignorance combined with the absence of proper healthcare contributes to the prevalence of filariasis in those areas. The disease can now be diagnosed and treated with different medical techniques.
Diagnosis of Wuchereria bancrofti Infection
One simple and practical technique in detecting W. bancrofti in the blood is microscopic technique. It is important that blood smear should be collected during a period where microfilariae (juviniles) are concentrated in the peripheral blood vessels, usually during night time. This will ensure that the blood sample has a considerable number of filarial worms to observe. It is also necessary that the medical technician who will study the blood is able to distinguish W. bancrofti worms from other worms that may be present in the blood (Hoegaerden 1986).
Another diagnostic technique is detecting W. bancrofti DNA in the blood through the use of Polymerase Chain Reaction (PCR), which is capable of amplifying filarial DNA to many copies. One percent filarial DNA in a blood sample is enough to be detected using PCR. If in cases that an infected individual is amicrofilaremic (no microfilariae in the blood), technicians use techniques to detect antigens from the adult filarial worm (Nicolas 1997).
The vigorous movement of adult filarial worms in the body creates a pattern of noises called “filarial dance sign (Amaral et al. 1994)." The noises can be detected by ultrasonography. It is however necessary that the diagnostician is knowledgeable about the pattern of the noises so that he can determine if indeed filarial worms are present in the blood. Another emerging technique is the use of x-ray examinations to detect dead, calcified W. bancrofti worms.
Treatment of Wuchereria bancrofti Infections
For the past four decades, the drug of choice has been diethylcarbamazine (DEC, Hetrazan) which is capable of killing both microfilariae and adult worms (Eberhard et al. 1997). The drug is administered to a patient in a dosage of 6 mg/kg given over a period of 7 to 12 days. There are reports of side effects that dissuade patients from continuing to take the drugs (Kimura et al. 1996). Prevalence of filariasis is controlled in areas where the inhabitants take 6mg/kg dosage annually; side effects are fewer and logistically easier. If DEC is taken together with Ivermectin or albendazole, the result is better than just taking one kind of drug.
Edematous limbs can be treated using a pressure bandage to force lymph out of the swollen area. This treatment can decrease the size of the swollen limb to nearly normal, but connective tissues that have already proliferated cannot be removed. One good option to treat elephantoid limbs, breasts, scrota, and legs is surgery. Surgery of African patients has been successful through the years, thanks to numerous medical volunteers there who have helped relieved the pain and shame of many Africans suffering from the debilitating effects of elephantiasis
Amaral FG, Dreyer J, Figueredo-Silva J, Noroes A, Cavalcanti SC, Samico A, Santos, and A Coutinho. 1994. Live adult worms detected by ultrasonography in human bancroftian filariasis. Am. J. Trop. Med. Hyg. 50:753-757.
Eberhard ML, Hightower AW, Addiss DG, Lammie PJ. 1997. Clearance of W. bancrofti antigen after treatment with diethylcarbamazine or ivermectin. Am. J. Trop. Med. Hyg. 57:483-486
Hoegaerden M, and B Ivanoff. 1986. A rapid, simple method for isolation of viable microfilariae. Am. J. Trop. Med. Hyg. 35:148-151.
Kimura E, and Mataika JU. 1996. Control of lymphatic flariasis by annual single-dose diethylcarbamazine treatments. Parasitology Today 12:240-244
Nicolas L. 1997. New tools for diagnosis and monitoring of bancrofian filariasis parasitism: The Polynesian experience. Parasitology TOday 13:370-375.