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Clinical Characteristics

Filarial infection results in a wide spectrum of clinical findings that is dependent to some degree on worm species and geographic location. At one extreme, people living in endemic regions demonstrate a microfilaremia, or are filarial antigen positive but are asymptomatic. At the other end of the spectrum there are patients showing chronic manifestations which, in their most severe form, result in massive lymphedema and elephantiasis (Figs. 26.6-26.8). Clinical reports of affected soldiers returning from the Pacific during the Second World War showed that the first symptoms appeared in 3-4 months, with severe clinical manifestations after about 8 months. The hallmarks of the disease (lymphangitis, lymphadenopathy, scrotal swelling, and inflammation) responded to treatment and all the treated soldiers showed gradual and complete remission.

Lymphatic filariasis has both an acute and a chronic phase. In the acute phase, patients suffer from malaise and fever due to acute lymphangitis and lymphadenitis, with inflammatory episodes which are recurrent and variable in intensity. Males with bancroftian filariasis may also present with acute epididymo-orchitis. Although these initial events are known to be an important cause of lymphatic damage, the sequence of events and the time course is imprecisely known. The chronic phase of lymphatic filariasis is characterized by hydrocele, lymphedema, elephantiasis, and chyluria (Fig. 26.8). Lymphedema is classified as follows:

Grade I: pitting edema that is spontaneously reversible with limb elevation
Grade II: nonpitting edema that is not spontaneously reversible on limb elevation
Grade III: gross lymphedema with dermatosclerosis and papillomatous lesions (elephantiasis)

Moderate to severe lymphedema becomes progressively more debilitating over months to years and is often associated with secondary bacterial or fungal infection. There is an important distinction between the limb lymphedema caused by W. bancrofti and that caused by B. malayi. In the former, swelling involves the thigh and lower leg while in the latter, the swelling is confined to below the knee. Hydrocele (usually containing clear and straw-colored fluid) is very common in bancroftian, but rare in brugian filariasis. Scrotal fluid accumulation is due to lymphatic obstruction in the retroperitoneum. Rarely, this fluid may be chylous. Funiculitis and lymphedematous thickening of the scrotal skin are chronic genital manifestations in men while equivalent lesions involve the fallopian tubes and vulva in women.

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Fig. 26.6A-G. Filarial lymphedema progressing to gross elephantiasis in patients from Samoa (A-C) and India. A, B Edema of the left foot, ankle, and lower leg. In this patient the full length of the left leg is swollen, compared with the right.C More advanced edema of the left lower leg in another patient, with verrucal reaction over the foot and beginning over the left tibia. D Although this patient is still a young woman, the right lower leg is markedly swollen and heavy, and will make walking difficult. E Gross edema and deformity of the right lower leg up to the knee: above this the leg is not badly swollen and the left lower leg and foot are normal. F As the swelling gets worse there is an increased risk of injury and secondary infection, which may be pyogenic or fungal. G Severe lymphedema of both lower legs, making it almost impossible to walk. (D from Marty and Anderson 1995).

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Fig. 26.7 A-E Male genital elephantiasis due to filarial infection. A A 59-year-old Samoan with hydroceles and mild penile elephantiasis. B The penis is submerged within the scrotum. C The penis is partially submerged due to large bilateral hydroceles. D A large lymphocele along the right spermatic cord in association with hydroceles. The penis is not affected.E Gross scrotal enlargement or "wheelbarrow scrotum" - a term that reflects the burden of filariasis in some patients. F Massive scrotal and penile elephantiasis. In this African patient, the urethral orifice is at the level of the knees. (B-F are patients from West Africa).

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Fig. 26.8 A, B. Filarial elephantiasis of the foot and ankle in a 32-year-old West African male. The markedly thickened and nodular soft tissue due to chronic lymphatic obstruction is an easily recognized but nonspecific finding.

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