The document summarizes the pathogenesis and clinical manifestations of filariasis caused by Wuchereria bancrofti. It describes two main types: classical filariasis caused by blockage of lymph vessels by adult worms, leading to lymph stasis and elephantiasis; and occult filariasis caused by hypersensitivity to microfilarial antigens without lymphatic involvement, presenting with eosinophilia and pulmonary symptoms. Classical filariasis presents as asymptomatic microfilaremia, acute adenolymphangitis, lymphedema or elephantiasis of limbs. Occult filariasis manifests as tropical pulmonary eosinophilia.

1. PATHOGENESIS OF FILARIA
PREPARED BY : - KAUSHIK GHOSH

2. INTRODUCTION
• INFECTION CAUSED BY W. BANCROFTI IS TERMED AS WUCHERERIASIS
• DISEASE PRESENT AS
• CLASSICAL FILARIASIS
• OCCULT FILARIASIS

3. CLASSICAL FILARIASIS
Occurs due to blockage of lymph vessels and lymph nodes by the
adult worm.
Blockage could be due to mechanical factors/allergic inflammatory reaction to worm antigens
and secretions
Affected lymph nodes and vessels are infiltrated with macrophages , eosinophils,
lymphocytes and plasma cells
The vessel wall gets thickened and the lumen narrowed / occluded leading to lymph stasis and
dilatation of lymph vessels
Leads to granuloma formations with subsequent severity and even
calcification

4. Inflammatory changes damage the valves in lymph vessels , further
aggravating lymph stasis
Increased permeability of lymph vessel wall lead to leakage of protein rich lymph into
tissues leading to typical hard pitting / browny Edelman of filariasis
Invading fibroblast lay down fibrous tissues , producing non pitting gross oedema
of elephantiasis .
Recurrent secondary bacterial infections cause further damage

5. CLINICAL MANIFESTATION
• MOST COMMONLY MANIFESTATION
• ASYMPTOMATIC (SUB CLINICAL),MICROFILAREMIA
• ACUTE ADENOLYMPHANGITIS (ADL)
• CHRONIC LYMPHATIC DISEASE .
• ASYMPTOMATIC MICROFILAREMIA
• PATIENTS APPEAR ASYMPTOMATIC BUT HAVE
• SUBCLINICAL DISEASE
• MICROSCOPIC HEMATURIA / PROTEINURIA
• DIALATED LYMPHATICS
• IN MEN WITH W.BANCROFTI INFECTION SCROTAL LYMPHANGIOVARIX

6. ACUTE ADENOLYMPHANGITIS
• CHARACTERISED BY HIGH GRADE FEVER
• SUDDEN IN ONSET
• WITH RIGORS
• LAST FOR 2/3DAYS
• LYMPHATIC INFLAMMATION (LYMPHANGITIS AND LYMPHADENITIS)
• TRANSIENT LOCAL EDEMA
• LYMPHANGITIS IS INFLAMED LYMPH VESSELS SEEN
• AS RED STREAKS UNDERNEATH THE SKIN
• FREQUENTLY INVOLVED LYMPHATICS ARE THAT OF TESTES AND SPERMATIC CORD .MAY ALSO BE
ASSOCIATED WITH STREPTOCOCCAL INFECTION

8. • LYMPHADENITIS
• INFLAMMATION OF LYMPH NODES
• MOST COMMON AFFECTED BEING INGUINAL NODES FOLLOWED BY AXILLARY NODES
• LYMPH NODE BECOME ENLARGED ,PAINFUL AND TENDER.
• LYMPH EDEMA
• FOLLOWS SUCCESSIVE ATTACKS OF LYMPHANGITIS AND STARTS AS SWELLING
AROUND THE ANKLE , SPREADING TO THE BACK OF FOOT AND LEG
• MAY ALSO AFFECT THE ARMS, BREAST, SCROTUM, VULVA AND ANY OTHER PART OF
BODY .

9. LYMPHANGIOVARIX
• DILATATION OF LYMPH VESSELS COMMONLY OCCURS IN INGUINAL , SCROTAL
TESTICULAR AND ABDOMINAL SITES
• THE LYMPHANGITIS AND LYMPH ADENITIS CAN INVOLVE BOTH THE UPPER AND
LOWER EXTREMITIES IN BOTH BANCROFTIAN AND BRUGIAN FILARIASIS BUT
INVOLVEMENT OF GENITAL LYMPHATIC OCCURS EXCLUSIVELY WITH W.
BANCROFTI INFECTION.

10. HYDROCELE
• COMMON MANIFESTATION
• ACCUMULATION OF FLUID OCCURS DUE TO OBSTRUCTION OF LYMPH VESSELS
OF SPERMATIC CORD AND BY EXUDATION FROM INFLAMED TESTES AND
EPIDIDYMIS.
• FLUID IS USUALLY CLEAR OR STRAW COLOURED BUT MAY BE CLOUDY,MILKY /
HEMORRHAGIC.

11. LYMPHORRHAGIA
• RUPTURE OF LYMPH VARIES LEADING TO RELEASE OF LYMPH OR CHYLE
RESULTING IN CHYLURIA ,CHYLOUS DIARRHOEA,CHYLOUS ASCITES AND
CYCLOTHORAX DEPENDING ON THE INVOLVED SITE.

12. ELEPHANTIASIS
• DELAYED SEQUEL TO REPEATED LYMPHANGITIS, OBSTRUCTION AND
LYMPEDEMA.
• THERE IS NON PITTING BROWNY EDEMA WITH GROWTH OF NEW ADVENTITIOUS
TISSUE AND THICKENED SKIN, CRACKS AND FISSURES WITH SECONDARY
BACTERIAL OR FUNGAL INFECTION.

13. OCCULT FILARIASIS
• OCCURS AS A RESULT OF HYPERSENSITIVITY REACTION TO MICROFILARIAL
ANTIGENS, NOT DIRECTLY DUE TO LYMPHATIC INVOLVEMENT
• MICROFILARIAE ARE NOT FOUND IN BLOOD , AS THEY ARE DAMAGED BY THE
ALLERGIC INFLAMMATION IN THE TISSUES .

14. CLINICAL MANIFESTATION
• MASSIVE EOSINOPHILIA (30-80%)
• HEPATOSPLENOMEGALY
• PULMONARY SYMPTOMS LIKE NOCTURNAL COUGH , DYSPNOEA AND
ASTHMATIC WHEEZING
• ALSO HAS BEEN REPORTED TO CAUSE ARTHRITIS, GLOMERULONEPHRITIS ,
THROMBOPHLEBITIS, TENOSYNOVITIS ETC.
• CLASSICAL FEATURES OF LYMPHATIC FILARIASIS ARE ABSENT
• MEYERS KOUWENAAR SYNDROME IS A SYNONYM FOR OCCULT FILARIASIS

15. TROPICAL PULMONARY EOSINOPHILIA
• MANIFESTATION OF OCCULT FILARIASIS PRESENTS WITH
• LOW GRADE FEVER ,
• LOSS OF WEIGHT AND
• PULMONARY SYMPTOMS SUCH AS DRY NOCTURNAL COUGH ,DYSPNNEA AND ASTHMATIC WHEEZING
• THERE IS A MARKED INCREASE IN EOSINOPHIL COUNT , WHICH MAY GO UP TO 50,000/MORE
• CHEST X-RAY SHOWS MOTTLED SHADOWS SIMILAR TO MILIARY TUBERCULOSIS
• ASSOCIATED WITH A HIGH LEVEL OF SERUM IMMUNOGLOBULIN (IGE) AND FILARIAL
ANTIBODIES
• CHILDREN AND YOUNG ADULTS ARE MORE COMMONLY AFFECTED IN AREAS OF ENDEMIC
FILARIASIS INCLUDING THE INDIAN SUB CONTINENT
• CONDITIONS RESPONDS TO TREATMENT WITH DIETHYLCARBAMAZINE (DEC) WHICH ACTS ON
MICRO FILARIAE.