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Infectious Diseases

Lymphatic Filariasis

A parasitic disease caused by tissue-dwelling filarial nematodes (primarily Wuchereria bancrofti in Africa), transmitted by mosquito bites. Damages the lymphatic system, leading to lymphoedema and hydrocele.

Also known as: Elephantiasis

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Referral and warning signs

When to refer

Refer patients with hydrocele for surgical assessment. Refer patients with severe or complicated lymphoedema/elephantiasis for specialist MMDP guidance and potential reconstructive surgery consult. Refer if diagnosis uncertain.

Red flags

  • Signs of severe secondary infection (rapidly spreading cellulitis, high fever, sepsis).
  • Rapidly progressing lymphoedema.
  • Suspicion of malignancy mimicking lymphoedema.

Signs and symptoms

  • Many infections are asymptomatic but cause subclinical lymphatic damage.
  • Acute Episodes (Adenolymphangitis - ADL):
  • - Recurrent episodes of fever, chills.
  • - Inflammation of lymph nodes (lymphadenitis) and lymphatic vessels (lymphangitis), often tracking along limbs.
  • - Localized pain, tenderness, redness, swelling (limb, genitalia).
  • - Acute epididymo-orchitis.
  • - Episodes typically last 3-7 days, resolve spontaneously, recur periodically.
  • Chronic Manifestations (Develop after years of repeated infection/inflammation):
  • - Lymphoedema: Chronic swelling, usually of legs, sometimes arms, breasts, genitalia. Initially pitting, becomes hard, non-pitting, skin thickens.
  • - Elephantiasis: Gross enlargement and thickening/hardening of skin and subcutaneous tissues, primarily of legs and scrotum, due to severe chronic lymphoedema.
  • - Hydrocele: Fluid collection in the scrotum.
  • - Chyluria (milky urine - rare).
  • - Impaired immune function in affected limbs -> increased susceptibility to secondary bacterial/fungal infections.

Risk factors

  • Living in endemic areas.
  • Repeated exposure to bites from infected mosquitoes (Culex, Anopheles, Aedes, Mansonia - vectors vary geographically).
  • Lack of protective measures against mosquito bites.

Diagnosis

Clinical assessment

Chronic stages (lymphoedema, hydrocele, elephantiasis) diagnosed clinically in endemic areas. Acute ADL episodes are suggestive. History of recurrent attacks.

Differential diagnosis

  • Lymphoedema: Podoconiosis (non-filarial, related to soil exposure), Post-surgical/radiation, Congenital, Venous insufficiency, Cardiac failure, Malignancy.
  • Hydrocele: Other causes (infection, tumour, trauma, hernia).
  • Acute ADL: Cellulitis, Erysipelas, DVT, Orchitis from other causes.

Investigations

  • Microfilariae Detection in Blood: Definitive diagnosis. Requires timed blood sample (usually night-time blood smear between 9pm-3am for W. bancrofti due to nocturnal periodicity). Thick blood film stained with Giemsa/Field's stain.
  • Antigen Detection Tests: Immunochromatographic card tests (ICT) detect circulating filarial antigens (W. bancrofti). Can use daytime blood sample, highly sensitive/specific. Used in mapping/surveillance.
  • Ultrasound: Can detect live adult worms ('filarial dance sign') in lymphatic vessels (scrotal US for hydrocele/worms).
  • Antibody tests (less useful for active infection).

Diagnostic criteria

Clinical signs in endemic area +/- Laboratory confirmation (Microfilariae on blood smear OR Positive antigen test).

Management

Non-pharmacological management

  • Management of Lymphoedema/Elephantiasis (Morbidity Management and Disability Prevention - MMDP): Focuses on hygiene, preventing secondary infections, reducing swelling.
  • - Limb Hygiene: Meticulous washing and drying of affected limb daily.
  • - Skin Care: Use emollients, treat entry lesions/cracks promptly with antiseptic/antibiotic ointment.
  • - Elevation: Elevate limb when resting.
  • - Exercise: Gentle exercises to promote lymphatic drainage.
  • - Compression Bandaging: May help reduce swelling (specialist guidance).
  • - Treat Acute ADL Episodes Promptly: Bed rest, limb elevation, analgesics, cooling, antibiotics if secondary bacterial infection suspected.
  • Hydrocele Management: Surgical excision (hydrocelectomy) is curative.
  • Psychosocial Support.

Pharmacological treatment

  • Antifilarial Drugs (Kill microfilariae, may affect adult worms slowly):
  • - Used primarily for interrupting transmission in Mass Drug Administration (MDA) programs.
  • - Individual Treatment: May be given to reduce microfilarial load, potentially slow progression (benefit for established lymphoedema debated).
  • - Standard MDA Regimen (Annual): Diethylcarbamazine (DEC - not used in areas co-endemic with Onchocerciasis) OR Ivermectin (150-200 mcg/kg single dose) PLUS Albendazole (400mg single dose). (LOC: Public Health Programs)
  • - Doxycycline: 100-200mg daily for 4-6 weeks. Targets Wolbachia endosymbiont bacteria within adult worms, leading to worm sterility and eventual death. May have benefit for lymphoedema/ADL frequency (specialist use).
  • - Note: Anti-parasitic treatment generally NOT given during acute ADL attack.
  • Antibiotics: For secondary bacterial infections complicating lymphoedema.

Monitoring

Monitor frequency of ADL attacks. Monitor progression of lymphoedema/hydrocele. Monitor adherence to hygiene measures.

Complications

  • Severe chronic lymphoedema / Elephantiasis -> disability, disfigurement, social stigma.
  • Recurrent secondary bacterial/fungal infections -> worsening lymphoedema.
  • Hydrocele -> discomfort, cosmetic issues, potential infertility.
  • Chronic pain.
  • Reduced mobility, inability to work.

Prevention

  • Mass Drug Administration (MDA): Annual treatment of entire eligible population in endemic areas with Ivermectin + Albendazole (or DEC+Albendazole where appropriate) for 4-6 years to interrupt transmission.
  • Vector Control: Reduce mosquito breeding sites, use of insecticide-treated bed nets (ITNs).
  • Morbidity Management and Disability Prevention (MMDP) for those already affected.

Patient education

  • Explanation of LF cause (mosquito-borne worms damaging lymphatics).
  • Chronic nature of lymphoedema/elephantiasis.
  • Critical importance of lifelong meticulous limb hygiene and skin care to prevent ADL/infections.
  • Limb elevation and exercise techniques.
  • Hydrocele surgery option.
  • Role of MDA in community transmission control.

Uganda-specific notes

Lymphatic filariasis is endemic in several districts. W. bancrofti is the cause, transmitted by Anopheles and Culex mosquitoes. National control program utilizes MDA with Ivermectin + Albendazole. MMDP activities focus on hygiene and hydrocele surgery.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 2, Section 2.4.4

  • National Lymphatic Filariasis Elimination Programme Guidelines, MOH Uganda

    (Specific program documents)

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