AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

Filariasis is a disease group affecting humans and animals that is caused by nematode parasites of the order Filariidae, commonly called filariae. Filarial parasites may be classified according to the habitat of the adult worms in the vertebral host. The cutaneous group includes Loa loa, Onchocerca volvulus, and Mansonella streptocerca. The lymphatic group includes Wuchereria bancrofti, Brugia malayi, and Brugia timori. The body cavity group includes Mansonella perstans and Mansonella ozzardi.

Of the hundreds of described filarial parasites, only these 8 species cause natural infections in humans. The parasites of the cutaneous and lymphatic groups are of the most significant clinical interest. Other species of filariae may cause incomplete infections because they are unable to reach adult maturity in human hosts and, therefore, cannot produce microfilaria (eg, Dirofilaria immitis [dog heartworm], Dirofilaria [Nochtiella] repens, and Dirofilaria tenuis [raccoon heartworm]).

Pathophysiology

The filarial life cycle, like that of all nematodes, consists of 5 developmental or larval stages in a vertebral host and an arthropod intermediate host and vector. Adult female worms produce thousands of first-stage larvae or microfilariae that are ingested by a feeding insect vector. Some microfilariae have a unique circadian periodicity in the peripheral circulation over a 24-hour period. The arthropod vectors, mosquitoes and flies, also have a circadian rhythm in which they obtain blood meals. The highest concentration of microfilariae usually occurs when the local vector is feeding most actively. Microfilariae then undergo 2 developmental changes in the insect. Third-stage larvae then are inoculated back into the vertebral host during the act of feeding for the final 2 stages of development.

Frequency

United States

No form of human filariasis currently is endemic to the United States. W bancrofti once was prevalent in Charleston, South Carolina because of the presence of suitable mosquito vectors. Immigrant populations and persons who have traveled long-term to the tropics are potential reservoirs of infection. Returning missionaries and Peace Corps volunteers are at particular risk for lymphatic filariasis and onchocerciasis because of the long prepatent period and relatively high intensity of exposure required between exposure to infective insect bites and the development of sexually mature adult worms.

International

Lymphatic filariasis affects more than 90 million people worldwide and is found throughout the tropics and subtropics. At least 21 million people are infected with O volvulus in equatorial Africa and foci in Central and South America. Approximately 3 million people in Central Africa are infected with L loa. In 1997, the World Health Organization (WHO) initiated a program to globally eliminate lymphatic filariasis as a public health problem.

Mortality/Morbidity

• Filarial diseases rarely are fatal, but the consequences of infection can cause significant personal and socioeconomic hardship for those who are affected.
• The WHO has identified lymphatic filariasis as the second leading cause of permanent and long-term disability in the world after leprosy.
• The morbidity of human filariasis mainly results from the host reaction to microfilariae or developing adult worms in different areas of the body.

Race

No racial predilection is known.

Sex

Both sexes are equally susceptible to infection. Because of different local, cultural, and social work practices, as well as differences in exposure to insect vectors, one sex or the other may be exposed to infection more often.

Age

• Individuals of all ages are susceptible and potentially microfilaremic.
• Microfilaremia rates increase with age through childhood and early adulthood, although clinical infection may not be apparent.
• The manifestation of acute and chronic filariasis usually occurs only after years of repeated and intense exposure to infected vectors in endemic areas.

CLINICAL

Section 3 of 11  

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• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

Symptoms for filariasis are species-dependent and body-site–dependent and can be acute or chronic in nature.

• Lymphatic filariasis
• • The symptoms of lymphatic filariasis predominantly result from the presence of adult worms residing in the lymphatics.
  • Symptoms include fever, inguinal or axillary lymphadenopathy, testicular and/or inguinal pain, skin exfoliation, and limb or genital swelling.
  • Patients with microfilaremia generally are asymptomatic, although subjects with heavy microfilarial loads may develop acute and chronic inflammatory granulomas secondary to splenic destruction.
  • Passage of cloudy milklike urine may denote chyluria.
• Tropical pulmonary eosinophilia
• • Tropical pulmonary eosinophilia (TPE) is a form of occult filariasis.
  • Presenting symptoms include a paroxysmal dry cough, wheezing, dyspnea, anorexia, malaise, and weight loss.
• D immitis infection
• • Symptoms are respiratory in nature, with chest discomfort, cough, fever, and hemoptysis.
  • Immature forms of the worm also may cause breast and subcutaneous abscesses.
• D repens infection: Symptoms usually are a subcutaneous, submucosal, or eyelid lump.
• Onchocerciasis
• • This also is known as hanging groins, leopard skin, river blindness, or sowda.
  • Symptoms result from the presence of microfilariae in the skin and include pruritus, subcutaneous lumps, lymphadenitis, and blindness.
• Loaiasis
• • The symptoms of L loa infection usually are confined to subcutaneous swellings on the extremities, localized pain, pruritus, and urticaria.
  • Microfilaremia tends to be asymptomatic.
• M ozzardi, M perstans, and M streptocerca infection
• • Infections from Mansonella species usually are asymptomatic.
  • If symptoms are present, they may include fever, pruritus, skin lumps, lymphadenitis, and abdominal pain.

Physical

Signs of filariasis present on examination are species-dependent and may be acute or chronic.

• Lymphatic filariasis
• • Acute manifestations of lymphatic filariasis usually are referred to as adenolymphangitis (ADL). ADL is characterized by episodic attacks of fever associated with inflammation of the inguinal lymph nodes, testis, spermatic cord, lymphedema, or a combination of these. Skin exfoliation of the affected body part usually occurs with resolution of an episode.
  • Repeated episodes of inflammation and lymphedema lead to lymphatic damage; chronic swelling; and elephantiasis of the legs, arms, scrotum, vulva, and breasts.
  • Hydrocele is the most common manifestation of chronic W bancrofti infection in males in endemic areas but is rare with B malayi and B timori infection.
  • Chyluria also may be present in chronically infected persons.
• Tropical pulmonary eosinophilia
• • Scattered wheezes and crackles are heard in both lung fields.
  • Lymphadenopathy and hepatomegaly may be present.
• D immitis infection: Reduced localized air entry may be detected upon chest auscultation.
• D repens infection: Signs usually are a painless subcutaneous, submucosal, or eyelid lump.
• Onchocerciasis
• • The clinical triad of infection is dermatitis, skin nodules (ie, onchocercomas), and ocular lesions.
  • Skin lesions include edema, pruritus, erythema, papules, scablike eruptions, altered pigmentation, and lichenification.
  • Skin nodules tend to be common over bony prominences.
  • Eye lesions usually are related to the duration and severity of infection and are caused by an abnormal host immune response to microfilariae. The common eye findings are punctate keratitis, pannus formation, corneal fibrosis, iridocyclitis, glaucoma, choroiditis, and optic atrophy.
• Loaiasis
• • The diagnostic feature of disease is a Calabar swelling, ie, a large transient area of localized nonerythematous subcutaneous edema. This is most common around the joints.
  • Other rare manifestations of infection include arthritis, breast calcification, meningoencephalopathy, endomyocardial fibrosis, peripheral neuropathy, pleural effusions, and retinopathy.
• M ozzardi, M perstans, and M streptocerca infection: Subcutaneous or conjunctival nodules and lymphadenopathy may be detected in symptomatic persons.

Causes

• Lymphatic filariasis
• • Mosquitoes of the genera Aedes, Anopheles, Culex, or Mansonia are the intermediate hosts and vectors of all species that cause lymphatic filariasis.
  • Acute lymphatic filariasis is related to larval molting and adult maturation to fifth-stage larvae. Adult worms are found in lymph nodes and lymphatic vessels distal to the nodes. Females measure 80-100 mm in length and males are 40 mm.
  • The most commonly affected nodes are in the femoral and epitrochlear regions.
  • Abscess formation may occur at the nodes or anywhere along the distal vessel.
  • Infection with B timori appears to result in more abscesses than infection with B malayi or W bancrofti.
  • Cellular invasion, with plasma cells, eosinophils, and macrophages, together with hyperplasia of the lymphatic endothelium, occurs with repeated inflammatory episodes. The consequence is lymphatic damage and chronic leakage of protein-rich lymph in the tissues, thickening and verrucous changes of the skin, and chronic streptococcal and fungal infections, which all contribute to the appearance of elephantiasis.
  • B malayi elephantiasis is more likely to affect the upper and lower limbs, with genital pathology and chyluria being rare.
• Occult filariasis
• • Occult filariasis denotes filarial infection in which microfilariae are not observed in the blood but may be found in other body fluids and/or tissues.
  • The occult syndromes are TPE, D immitis or D repens infection, filarial arthritis, filarial breast abscess, and filarial-associated immune-complex glomerulonephritis.
  • TPE most likely results from a hyperresponsiveness to W bancrofti or B malayi antigen.
  • Human infection with D immitis may result in pulmonary lesions of immature Dirofilaria worms in the lung periphery. If D immitis larvae lodge in branches of the pulmonary arteries, they can cause pulmonary infarcts.
• Onchocerciasis
• • Microfilariae from the skin are ingested by the Simulium species of blackflies.
  • Chronic onchocerciasis cases are hyporesponsive to parasite antigen, have increased eosinophilia, and result in the presence of high levels of serum immunoglobulin E (IgE).
  • Patterns of onchocercal eye disease also are associated with parasite strain differences at the DNA level.
• Loaiasis
• • Mango flies or deerflies of Chrysops transmit loaiasis.
  • Response to L loa infection appears to differ between residents and nonresidents in endemic areas. Nonresidents with infection appear to be more prone to symptoms than residents, despite lower levels of microfilaremia. Eosinophil, serum IgE, and antibody levels also are higher in nonresidents with infection.
• L loa meningoencephalopathy
• • Meningoencephalopathy is a severe and often fatal complication of infection.
  • The syndrome usually is related to diethylcarbamazine (DEC) administration to individuals with high-density microfilaremia, but it may occur without drug therapy. DEC causes a large influx of microfilariae into the cerebrospinal fluid, leading to capillary obstruction, cerebral edema, hypoxia, and coma.
  • Localized necrotizing granulomas also are present in response to microfilariae.

DIFFERENTIALS

Section 4 of 11  

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• Miscellaneous
• Multimedia
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Other Problems to be Considered

Lymphatic filariasis

Bacterial or fungal lymphadenitis (eg, sporotrichosis resulting from Sporothrix schenckii infection)
Recurrent streptococcal lymphadenitis (ie, relapsing erysipelas)
Congenital or hereditary lymphedema (eg, Milroy syndrome)
Nonfilarial elephantiasis (highlands of East Africa)
Congenital hydrocele
Epididymal cysts
Carcinoma of testis and/or scrotum
Lymphosarcoma

Occult filariasis

Asthma
Bacterial monoarthritis
Bacterial breast abscess
Idiopathic or poststreptococcal glomerulonephritis

Onchocerciasis

Vitiligo
Trachoma
Lepromatous leprosy

Loaiasis

Hereditary and/or localized idiopathic angioedema

WORKUP

Section 5 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Detection of microfilariae: The traditional diagnostic method is to demonstrate microfilariae in the peripheral blood or skin.
• Detection of microfilariae in blood
• • The microfilariae of all species that cause lymphatic filariasis and the microfilariae of L loa, M ozzardi, and M perstans are detected in blood.
  • Capillary finger-prick or venous blood is used for thick blood films. Venous blood also can be concentrated or passed through a Nuclepore filter before being examined microscopically. The species of infection then can be determined by the microscopic appearance.
  • Microfilaria may be periodic in appearance in the peripheral circulation, and the blood should be examined at different intervals over a 24-hour period to achieve the best chances of detection.
  • Provocation of nocturnally periodic microfilariae may be achieved with a daytime dose of DEC at 1-2 mg/kg.
  • Microfilariae also may be observed in chylous urine and hydrocele fluid.
  • Microfilariae may be absent in patients with ADL or late chronic lymphatic disease.
  • Microfilariae typically are absent in patients with loaiasis, unless the infection has been present for many years.
• Detection of microfilariae in skin
• • O volvulus and M streptocerca infections are diagnosed when microfilariae are detected in multiple skin snip specimens from different body sites from both sides of the body.
  • In suspected cases of African onchocerciasis, the recommended sites for skin snips are the gluteus and calf. For American onchocerciasis, the scapula and deltoid skin is preferred.
• Detection of microfilariae in the eye: Microfilariae of O volvulus may be detected in the cornea or anterior chamber of the eye using slit-lamp examination.
• Detection of filarial antigen: The presence of circulating filarial antigen in the peripheral blood, with or without microfilariae, now is considered diagnostic of patent filarial infection and is used to monitor the effectiveness of therapy. Commercial kits are available to test venous blood.
• Detection of filarial antibodies: Use of recombinant antigens for the diagnosis of onchocerciasis immunoglobulin G4 (IgG4) antibodies has improved the sensitivity and specificity of serological assays.
• Urine examination and microscopy: If lymphatic filariasis is suspected, urine should be examined macroscopically for chyluria and then concentrated to examine for microfilariae.
• Complete blood cell count: Eosinophilia is marked in all forms of patent filarial infection.
• Serum immunoglobulins: Elevated serum IgE and IgG4 may be observed in patients with active filarial disease.

Imaging Studies

• Chest radiograph: Patients with TPE show diffuse pulmonary infiltrates.
• Ultrasound
• • Lymphatic obstruction of the inguinal and scrotal lymphatics can be demonstrated and monitored by ultrasound.
  • Deep onchocercomas and vitreous changes in the eye sometimes can be detected by ultrasound.

Other Tests

• The Mazzotti test allows a presumptive diagnosis of cutaneous filariasis when skin snip results are negative for microfilariae. An intense pruritus is elicited within hours after a single small dose of DEC (50-100 mg). Steroids may be necessary to control this inflammatory reaction. The test must be used with caution in individuals who may be heavily infected because a severe systemic reaction can be provoked. A DEC patch test that causes a localized skin reaction may be used in such patients.

Procedures

• Lymph node or skin nodule biopsy: Obtaining these biopsy specimens is recommended only in patients with cutaneous filariasis because excising nodes may further impede lymphatic drainage in patients with lymphatic filariasis. Adult worms of O volvulus and L loa are found in the nodules and fibrotic tissue of the skin. L loa worms occasionally can be dissected from the conjunctiva of the eye or bridge of the nose as they migrate through the subcutaneous tissues.

Histologic Findings

Lymphatic filariasis

Affected lymph nodes fibrose. Lymphatics stenose and obstruct with the creation of collateral channels. The skin of individuals with elephantiasis is affected with hyperkeratosis, acanthosis, lymph and fatty tissue, loss of elastin fibers, and fibrosis.

Onchocerciasis

Two areas are evident in onchocercomas: a central stromal and granulomatous inflammatory region where the adult worms are found and a peripheral fibrous section. Microfilariae in the skin incite a low-grade inflammatory reaction with loss of elasticity and fibrotic scarring.

TREATMENT

Section 6 of 11  

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• Follow-up
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• References

Medical Care

The medical management of a filarial infection should be specific and based on the microfilariae isolated or antigenemia detected.

• Lymphatic filariasis
• • Patients with asymptomatic microfilaremia can be treated on an outpatient basis.
  • Supervision of oral DEC therapy and provocation with postadministration observation is recommended for patient compliance with therapy and for the management of febrile reactions in heavily infected patients.
  • Inpatient care initially may be required for ADL and chronic filariasis and includes antihistamines, steroids, pain relief, and intravenous antibiotics for secondary infections.
  • Bed rest, limb elevation, and compression bandages traditionally have been used for the management of chronic lymphedema.
  • Steroids can be used to soften and reduce the swelling of lymphedematous tissues.
• Onchocerciasis: If DEC and suramin are used, inpatient care is recommended to monitor for reactions and complications of therapy.

Surgical Care

• Lymphatic filariasis
• • Large hydroceles and scrotal elephantiasis can be managed with surgical excision.
  • Correcting gross limb elephantiasis with surgery is less successful and may necessitate multiple procedures and skin grafting.
• Onchocerciasis: Nodulectomy with local anesthetic is a common treatment to reduce skin and eye complications.

Consultations

• Infectious diseases specialist
• Urologist
• Ophthalmologist
• General surgeon
• Plastic surgeon

Diet

Fatty foods are restricted in individuals with proven chyluria that is associated with lymphatic filariasis.

Activity

Individuals with chronic lymphatic filariasis are encouraged to mobilize (with compression bandage support) the affected limb.

MEDICATION

Section 7 of 11  

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The goals of pharmacotherapy are to eradicate the infestation, reduce morbidity, and prevent complications.

Drug Category: Anthelmintics

Recent studies have validated the use of single-dose regimens of ivermectin and DEC or albendazole for large-scale control and elimination programs and to reduce W bancrofti microfilaremia, antigenemia, and clinical manifestations.

Drug Name	Diethylcarbamazine (Hetrazan)
Description	Microfilaricide. The precise mechanism is not understood. Shown to induce immobilization of microfilariae by decreasing muscle activity because of hyperpolarization effects. Alteration of surface membrane also occurs, with enhanced destruction by the host's immune system. Evidence exists that DEC may enhance adhesion of granulocytes via antibody-dependent and independent mechanisms. Hypotheses also include interference by microfilarial intracellular processing and transport of specific macromolecules by DEC. To decrease risk of adverse effects, low doses (approximately 2-3 mg/kg/d) usually are recommended for the first 3 d of treatment. Higher doses (9 mg/kg/d) are recommended for L loa from days 4-21. Concurrent administration of corticosteroids should be considered with DEC treatment to minimize the allergic manifestations secondary to the disintegration of microfilariae, particularly O volvulus and L loa infections. To avoid adverse effects, doses for the treatment of onchocerciasis and loaiasis start at 50 mg and are increased slowly in frequency and amount.
Adult Dose	6 mg/kg PO qd for 12 d to 3 wk
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity; DEC provocation
Interactions	None reported
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Caution in individuals with potential heavy infections of lymphatic filarioids because a DEC dose of 2 mg/kg may provoke a febrile and inflammatory reaction secondary to worm death; antipyretics and steroids may decrease the risk of these symptoms; adjust in patients with renal failure

Drug Name	Suramin (Germanin, Antrypol, Naganinum, Naganol)
Description	Antitrypanosome and antihelminthic. Currently the only drug in clinical use for onchocerciasis that is effective against adult worms, but use is restricted because of frequency of associated complications and intrinsic toxicity. WHO has advised that it should only be considered for the curative treatment of individuals in areas without transmission of onchocerciasis, in individuals leaving an endemic area, and in individuals with severe hyperreactive onchodermatitis whose symptoms are not adequately controlled with ivermectin. WHO also recommends that suramin should not be used to treat onchocerciasis in individuals who are elderly or infirm, in patients with severe liver or renal disease, in children <10 y, in totally blind persons (unless they require relief from intensely itchy lesions), in lightly to moderately infected people with no symptoms and whose eyes are not at risk, or in pregnant women (who should be treated after delivery).
Adult Dose	66.7 mg/kg/d IV in 6 weekly doses
Pediatric Dose	<10 years: Not recommended >10 years: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	None reported
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Monitor CBC; perform coagulation tests; evaluate for neuropathy during therapy; caution in patients with hepatic and renal failure; urine should be tested before treatment starts and at weekly intervals during treatment, reduce dosage if moderate proteinuria develops and discontinue if it becomes severe or if casts appear; adverse effects include abdominal pain, mouth ulceration, and skin reactions (eg, urticaria, pruritus); later reactions include paraesthesia, polyneuropathy, hyperesthesia of the palms and soles, skin eruptions, fever, polyuria, increased thirst, elevated liver enzymes, photophobia, and lacrimation; occasional reports of adrenal insufficiency exist

Drug Name	Mebendazole (Vermox, Banworm)
Description	Causes worm death by selectively and irreversibly blocking uptake of glucose and other nutrients in susceptible adult intestine where helminths dwell.
Adult Dose	100 mg PO bid for 3 d; second course if patient not cured in 3 wk
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Carbamazepine and phenytoin may decrease effects; cimetidine may increase levels
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Adjust dose in patients with hepatic impairment; it is poorly absorbed and requires multiple doses; adverse effects include nausea and diarrhea

Drug Name	Flubendazole (Fluvermal)
Description	Benzimidazole carbamate antihelminthic that is an analogue of mebendazole.
Adult Dose	100 mg PO bid for 3 d
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Coadministration with carbamazepine may decrease efficacy; dexamethasone, cimetidine, and praziquantel may increase toxicity
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Ulceration at injection site may occur; adjust dose in patients with hepatic impairment

Drug Name	Albendazole (Albenza, Eskazole, Zentel)
Description	Broad-spectrum antihelminthic. Decreases ATP production in worms, causing energy depletion, immobilization, and, finally, death.
Adult Dose	400 mg PO single dose
Pediatric Dose	Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Coadministration with carbamazepine may decrease efficacy; dexamethasone, cimetidine, and praziquantel may increase toxicity
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Mild-to-moderate elevations of liver enzymes reported, especially with high-dose regimens, but enzymes usually normalize upon discontinuation of treatment; rare reports exist of severe hepatic abnormalities associated with jaundice and histological hepatocellular damage, which may be irreversible; caution if patient is pregnant or may become pregnant

FOLLOW-UP

Section 8 of 11  

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Further Inpatient Care

• Observation for complications of therapy, especially if DEC is used

Further Outpatient Care

• Posttreatment follow-up for 12 months, with examination of peripheral blood and skin snips for microfilariae

In/Out Patient Meds

• Oral therapeutic plans involving DEC should be monitored because compliance with therapy is poor and patients usually do not complete it.

Deterrence/Prevention

• Avoid bites from insect vectors.

Complications

• Secondary bacterial infection resulting in elephantiasis blindness

Prognosis

• Prognosis is good if infection is recognized and treated early.

Patient Education

• Protect against insect vectors.
• Refrain from self-treatment regimens, especially with DEC.

MISCELLANEOUS

Section 9 of 11  

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Medical/Legal Pitfalls

• Incorrect diagnosis
• • Initially missing the diagnosis of filariasis certainly is possible because cases in the developed world and the western hemisphere are infrequent.
  • Major complications in this scenario are a late diagnosis resulting in a greater degree of individual patient morbidity and a failure in the timely epidemiologic notification of a case.
  • To avoid this pitfall, obtain and document a travel history from patients with suspicious lesions.
• Inappropriate treatment
• • Although this scenario is much less likely than incorrect or delayed diagnosis, inappropriate treatment may be a potential pitfall, even if the diagnosis was made correctly.
  • The risk of adverse reactions is high, especially in patients with heavy microfilaremic burdens.
  • To prevent inappropriate treatment, consult an infectious disease specialist in all cases of suspected filariasis outside of endemic nations.
• Reaction to treatment
• • Care must be taken to ascertain whether a patient with filariasis has ever had any antiparasitic drugs and if the drugs were noted to cause problems.
  • Failure to do this and a resultant adverse reaction to the prescribed medication is a clear-cut legal pitfall that should be eliminated by following the standards of care and obtaining an appropriate patient history.

Special Concerns

• Patients with filariasis are, by default, at risk for other parasitic infections because areas endemic for bancroftian filariasis also are endemic for other parasites. After treatment, patients should be monitored for other symptomatology characteristic of parasitic infections.

MULTIMEDIA

Section 10 of 11  

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• Differentials
• Workup
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• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Filariasis. This figure displays the life cycle of Wuchereria bancrofti in humans and mosquito vectors (ie, Aedes, Anopheles, Culex, Mansonia species). Life cycles of other lymphatic nematodes (ie, Brugia malayi, Brugia timori) are identical, while the life cycles for other filariae differ in the body location of adult worms, the microfilariae present, and the arthropod intermediate hosts and vectors.
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Media file 2:  Filarial abscess scar on the left upper thigh in a young male who is positive for Wuchereria bancrofti microfilariae
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Media file 3:  Lymphatic filariasis resulting from Wuchereria bancrofti infection, which is causing limb lymphoedema, inguinal lymphadenopathy, and hydrocele. Photograph taken by Professor Bruce McMillan and donated by John Walker, MD.
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Media file 4:  Filariasis. Unilateral left lower leg elephantiasis secondary to Wuchereria bancrofti infection in a boy.
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Media file 5:  Filariasis. This is a close-up view of the unilateral lower leg elephantiasis shown in Image 4. Note the lymphedema and typical skin appearance of depigmentation and verrucosities (warty changes).
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Media file 6:  Filariasis. Lateral view of the right outer aspect of a leg affected by gross elephantiasis secondary to Wuchereria bancrofti infection.
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Media file 7:  Filariasis. Inner aspect of the lower leg of the male patient in Image 6, showing gross elephantiasis secondary to Wuchereria bancrofti infection.
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Media file 8:  Filariasis. Unilateral left hydrocele and testicular enlargement secondary to Wuchereria bancrofti infection in a man who also was positive for microfilariae.
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Media file 9:  Filariasis. Bilateral hydrocele, testicular enlargement, and inguinal lymphadenopathy secondary to Wuchereria bancrofti infection in a man who also was microfilaremic.
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Media file 10:  Filariasis. Adult worms of Wuchereria bancrofti in cross section isolated from a testicular lump.
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Media file 11:  Filariasis. Microfilaria of Wuchereria bancrofti in a peripheral blood smear.
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Media file 12:  Filariasis. Appearance of microfilariae after concentration of venous blood with a Nuclepore filter.
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Media file 13:  Filariasis. Onchocercomas of the forearm skin (sowda) in a Sudanese man.
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Media file 14:  Filariasis. Adult Onchocerca volvulus contained within onchocercomas of the skin.
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Media file 15:  Filariasis. Microfilariae of Loa loa detected in skin snips.
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Media file 16:  Filariasis. Microfilariae of Mansonella perstans in peripheral blood.
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REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

• Babu BV, Swain BK, Rath K. Impact of chronic lymphatic filariasis on quantity and quality of productive work among weavers in an endemic village from India. Trop Med Int Health. May 2006;11(5):712-7.
• Baird JK, Neafie RC, Lanoie L, Connor DH. Adult Mansonella perstans in the abdominal cavity in nine Africans. Am J Trop Med Hyg. Nov 1987;37(3):578-84. [Medline].
• Bazi T, Finan R, Zourob D. Filariasis infection is a probable cause of implantation failure in in vitro fertilization cycles. Fertil Steril. May 3 2006.
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Article Last Updated: Jun 9, 2006