Filariasis - Year 3 - 2009 -10 Batch

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BANCROFTIAN

FILARIASIS

Rumala Morel

Department of Parasitology

Peradeniya

Y3S2



South East Asia - ½ the global burden



1.Describe the geographical distribution in SL

2.Describe the pathogenesis & clinical features

3.Evaluate the laboratory methods of diagnosis

4.Name the antifilarial drug(s) used in Sri Lanka

5.State the principles underlying the prevention and control

6.Describe the preventive and control measures used in theNational Filariasis Control Programme in Sri Lanka

OBJECTIVES - Bancroftian filariasis



Distribution of Bancroftian

filariasis in Sri Lanka

Confined to urbanizedcoastal belt:

3 provinces - 9.5 million

(50% of SL population)

exposed

inland foci:

Gampaha,Warakapola

Veyangoda



life span 7-16 yrs

Revision of Life Cycle



Immunopathogenesis:as yet unclear, associated with

location of adult worms in lymphatics Basic lesion

Dilatation of lymphatics = Lymphangiectasia

Granuloma

(host inflammatory reaction)

Not due to blockage by adult worm



PATHOLOGY

Adult worms induce

endothelial cell proliferation

lymphatic dilatationDeath of adult worms – antigen leakage

formation of granulomatous nodules

activation of host inflammatory responses

Obliterative peri/endolymphangitis in dilated

lymphatics

Episodes of ACUTE FILARIAL LYMPHANGITIS [AFL]

Lymphangiectasia = dilated lymphaticsImpairs lymphatic function

Predisposes to bacterial & fungal infections

ACUTE DERMATOLYMPHANGIOADENITIS [ADLA]

leads to CHRONIC LYMPHOEDEMA



Pathogenesis of lympoedema

Acute Dermatolymphangioadenitis[ADLA]

Lymphoedema

Pitting [Grade 1]

Non pitting [Grade 2]

Elephantiasis [Grade 3]

Obstruction &

Dilatation of lymphatics

Granuloma

Death of adult worms

Acute Filarial Lymphangitis [AFL]

11ry bacterial & fungal infections

Repeated attacks of

ADLA

No mechanical blockage by worms



Death of adult worm causes

granuloma formation

Obliterative peri/endolymphangitisin dilated lymphatics



Clinical – ACUTE FILARIASIS1. Acute Filarial Lymphangitis [AFL]

Due to death of adult worms

Mild Residual lymphoedema - rare

2. Acute Dermatolymphangioadenitis [ADLA]

Due to 11ry bacterial infections in limbs with

compromised lymphatics

2-6 attacks / year

Diffuse subcutaneous inflammation & oedema

Males - acute funiculitis- acute epididymo – orchitis

Extra lymphatic disease - filarial monoarthritis - KJ

- filarial fevers



•Clinical – CHRONIC FILARIASIS

LymphangiectasiaDue to adult worms

lymphoedema

elephantiasis

Males: hydrocoele

11ry

bacterial& fungal

infections

11ry bacterial

infectionsRecurrent ADLA

&



Non pitting

[Grade 2]

Pitting oedema

[Grade 1]

Lymphoedema



Elephantiasis

[Grade 3]



Clinical manifestations of lymphoedema

depend on site of obstruction

lympoedema –

Grade 1- pitting

Grade 2- non pitting

Grade 3- elephantiasis

lymph leakage into urinary tract-

chyluria

(obstruction in cisterna chyli)

lymph leakage into

peritoneal cavity

chylous peritonitis

Common sites

limbs

genitalia

breast

Kidney damage: proteinuria & /or haematuria



CLINICAL MANIFESTATIONS IN

MALE GENITALIA

- acute funiculitis

- acute epididymo – orchitis

- hydrocoele

-Scrotal elephantiasis,

-lymph scrotum(skin vesicles)



Tropical Pulmonary Eosinophilia - TPEOCCULT FILARIASIS

common in India, Sri LankaPathogenesis: immune destruction of mf in lungs

due to host response

to human mf / mf of animal filaria

Eosinophilic granulocytes in lung



X’ray- broncho vascular markings

serum IgE levels (> 1000 kU/L)

filarial Ag/Ab+

peripheral blood mf - veand

clinical response to diethylcarbamazine

Diagnostic criteria for TPE

Clinical Syndrome: cough, bronchospasm (worse at night)

With eosinophila >3000/µl

& history of exposure to lymphatic filariasis

Bilaterally diffusebronchopneumonia.

Early treatment canprevent interstitialfibrosis

http://www.isradiology.org/tropical_deseases/tmcr/chapter26/large26/26-36A.jpg



Bilaterally diffuse

milliary nodules

Tropical Pulmonary Eosinophilia- TPE

OCCULT FILARIASIS

ANTI-FILARIAL TREATMENT

Diethylcarbamazine 6mg/kg tds

3 weeks

http://www.isradiology.org/tropical_deseases/tmcr/chapter26/large26/26-36B.jpg



Clinical manifestations in endemic areas

mf +subclinical

lymphangiectasia

but non reversible40% kidney

damage

mf +/- AFD-filarial fevers

lymphangitis

lymphadenitisCFD-chronic

obstructive mf -

TPEAsymptomatic Symptomatic

mf - ve

Filarial Ag +/-

Ab +

Occult

filariasis

AFD = Acute Filarial Disease

CFD = Chronic Filarial Disease



Laboratory Diagnosis of Filariasis:

Direct- detection of microfilaria in blood

Thick film- 10pm-2 am (20-60µl)wet mount/ stain Giemsa

Not sensitive!

Concentration-

•Knott’s method (old)•Membrane filtration- pore size 5µm

Detection of adults in biopsy- rare

Indirect1. Circulating Filarial Antigen [CFA] - BEST daytime

2. Filarial Specific Antibody – won’t differentiate

from past infection



Useful in occult filariasis - TPE

Indirect immunofluorescent test- IFA/FAT

ELISA (enzyme linked immunosorbent assay)

Disadvantage: Can’t diagnose acute

lymphatic disease.

Antibodies long lasting. May be past infection.

Detection of filarial

antibodies in serum



Now WHO recommends :-www. who.int. lymphatic_filariasis/epidemiology

Antigen detectionImmunochromatographic [ICT] card

test

high sensitivity [100% sensitive in mf +ves ]

high specificity

100 μl of fingerprick blood drawn at any time, day

or night.

simple, no equipment required

quick results <15 min



Antigen detection strip (card) tests- RDTs

Sample origin

(whole blood

serum/plasma)

polyclonal Ab

+ colloidal gold

Mab

W bancrofti

T C

absorbent pad

test control

Immunochromatographic [ICT] card test

Detects specific

circulating W bancrofti Ag

in serum/whole bloodusing monoclonal antibody



A. Ultrasound scan – scrotum – filarial dance sign

B. Radionucleotide lymphoscintigraphy

- assessment of lymphatic damage

Imaging techniques



The Global Programme to Eliminate

Lymphatic Filariasis (GPELF) - 2000

--• Global Alliance to Eliminate Lymphatic Filariasis - 2000

– public-private partnership

– WHO & national Ministries of Health,

–

Private drug companies donating albendazole & ivermectin(Mectizan®)

– NGOs

• 1 billion at risk population

• > 120 million people are already infected

• > 40 million incapacitated or disfigured



RAGFIL: Rapid Assesment of Geographical distribution of

bancroftian FILariasis. - Map endemic foci of lymphatic

filariasis - to decide on mass treatment programs.

>60%



Filariasis in Sri Lanka-

1937-39: Brugia malayi predominant1947: Anti Filariasis Campaign

1960’s: Brugian filariasis eradicated

control of larval breedingresidual action of DDT on adults

treatment with DEC

Bancroftian filariasis is the ONLY lymphaticfilariasis in SL now

Fil i i t l i S i L k



Filariasis control in Sri Lankaby

Anti Filariasis Campaign

Vector control: prevent mosquito breeding

clear drains, cess pits, sealing of septic tanks

larviciding with insecticides, larvivorous fish

Selective treatment of mf + cases

2-weeks diethylcarbamazine [DEC] (6 mg/kg)

Mass Drug Administration- eradicate parasite bykilling mf and disrupting transmission - continued for 4-5 years

MOST EFFECTIVE

Morbidity control – disability management training

M D Ad i i t ti



started in Oct/1999 in SL

covering endemic area-3 provinces.

In 2004 - coverage 80% compliance 71% (WHO)

Exclude infants & pregnant females

Pregnancy- treat 1 month after delivery

Mf + and clinical filariasis treated with full course DEC

Effect on intestinal geohelminths

– Gunawardena NK et al - Ceylon Med J. 2008 Mar;53(1):13-6

Treat all persons in endemic areas with

Diethylcabamazine [DEC] +albendazole

annually

Mass Drug Administration-



Motivate & train pts & care givers on :-washing

elevation

preventing & treating entry lesions

-topical antibiotics & antifungals using proper footwear

WHO morbidity control strategy

Community Home Based Care

by Filariasis Morbidity Control Clinics



Washing with soap

Proper footwear



1. Regarding lymphatic filariasis

A. Adult worms block lymphatics

B. Wucheraria bancrofti microfilaria show nocturnal periodicity

C. Immunochromatographic card test is used to detect

circulating filarial antigensD. Secondary bacterial infections are important

co-factors in pathogenesis

E. Treatment is with diethylcarbamazine [DEC]

True BCDE

MCQ

Documents

Filariasis - Year 3 - 2009 -10 Batch