This document discusses several filarial worms including Brugia malayi, Loa loa, Onchocera volvulus, and Mansonella species. It provides information on the epidemiology, morphology, life cycle, clinical features, laboratory diagnosis, and treatment for each parasite. B. malayi causes lymphatic filariasis and its microfilariae can be detected by microscopy of blood or antibodies detected by ELISA. Treatment involves diethylcarbamazine. L. loa causes Calabar swellings and can infect the eye. It is transmitted by deer flies and its microfilariae circulate in blood.

1. Other Filarial Worms
Ms. Clemencia Tjazuko
MSc. Medical Microbiology
Filaria

2. Brugia malayi
 Epidemiology
 Eastern India, Indonesia, Malaysia and Philippines
 In India, major states involved: Kerala, Odisha and
West Bengal
 Two types of periodicity:
I. Nocturnal form transmitted in areas of coastal
rice fields
II. Sub-periodic form rare, found in forests of
Malaysia and Indonesia
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3.  Morphology
 Adult worms- similar to W.bancrofti but smaller in
size. Males3.5 cm by 0.1 mm and Females5-6
cm by 0.1 mm
 Microfilariae 175-230 µm by 5-6 µm and is
sheathed
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4.  Life Cycle
 Vector:
 For nocturnal strains  Mansonia. (Sometimes
Anopheles and Aedes)
 For sub-periodic B.malayi strains Coquillettidia
and Mansonia
 Reservoir:
 Humans (sub-periodic B.malayi- cats, dogs,
monkeys)
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6.  Clinical features
 Lymphatic filariasis
 Pulmonary eosinophilia
 More frequent episodes of acute
adenolymphangitis and filarial abscesses
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7.  Lymphydema and elephantiasis occur less
frequently
 No genital involovement
 Elephantiasis swelling limited to leg below knee
 Chyluria
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9.  Laboratory Diagnosis
 Microscopy
 Detect microfilaria in blood by staining with Giemsa
stain
 Antibody detection
 ELISA and ICT  detect IgG-4 against
recombinant BmR1 antigen of B.malayi
 Ultrasound
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10.  Molecular Method
 PCR differentiate between W. Bancrofti and B.
Malayi
 Treatment
 Diethylcarbamazine (DEC)
drug of choice
given 6 mg/kg daily for 12 days
 Prophylactic Measures
 Vector control- destruction of mosquitoes
 Protection against mosquito bite
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11. Brugia timori
 David and Edison in 1965
 Timor islands of southeastern Indonesia
 Microfilariae: 265-325 µm
 Cephalic space- length to width ratio 3:1
 5-8 nuclei in tail region, 2 nuclei in tail tip
 Sheath does not stain with Giemsa stain
 Transmitted by: Anopheles barbirostris
 Clinical features, lab diagnosis and treatment
same as B. malayi
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12. Loa loa
 African eye worm
 West Indies 1770
 Argyll-Robertson 1895described adult worm
from subcutaneous swelling of the eye of woman
residing in Calabar, West Africa. Named
Calabar swelling
 Epidemiology
 Rain forests of West and Central Africa
 1.3 million people infected
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13.  Morphology
 Adult worms:
females [50-70 mm by 0.5 mm]
males [30-35 mm by 0.3 mm]
 Live in subcutaneous tissues
 Microfilariae circulate in blood
 Sheathed, measure 250-300 µm, have column of
nuclei
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15.  Life Cycle
 Same as that of W.bancrofti except vector is female
Chrysops species (deerflies, mangoflies)
 Mode of transmission
 Infective (L3) larvae transmitted by bite of Chrysops
species during blood meals in daytime
 Larvae adult worm (6-12 months) and migrate in
subcutaneous tissues and eyes.
 Microfilariae released blood, ingested by deer
flies during blood meal, loose, sheath, penetrate
gut wall fat body  become L3 in 10-12 days of
time
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16.  Pathogenesis and Clinical Features
 Calabar Swellings
 Fugitive swelling
 Subcutaneous swelling on knee or wrist
 Develops rapidly in few hours, starts with pain,
pruritus and uriticaria, lasts for 2-4 days
 Occurs due to inflammatory response to migrating
adult worm (speed of 1 cm/min) or metabolic
products
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18.  Ocular Manifestations
 Conjuctival granuloma
 Edema of eye lid leading to proptosis (bulging)
 Complications
 Nephropathy, encephalopathy and cardiomyopathy
 Hypergammaglobulinemia
 Elevated serum IgE
 Elevated leukocyte and eosinophil counts
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19.  Laboratory Diagnosis
 Microscopy
 Detection of microfilariae in peripheral blood
 Isolation of adult worm from eye/biopsy of swelling
 Molecular Methods
 Nested PCR-based assays to detect DNA of Loa loa in
blood
 Antibody Detection
 Done by using recombinant antigen
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20.  Treatment
 Diethylcarbamazine (DEC)
 Glucocorticoids
 Albendazole/Ivermectin
 Surgical removal of the worms
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21. Onchocera volvulus
 Epidemiology
 37 million people infected worldwide
 Endemic arearural poor region of Sub Saharan
Africa, Yemen and central and South America
 Morphology
 Adult worm
 Long thin, tapering at both the ends
 Bear transverse striations on cuticle with annular
and oblique thickening
 Female worms longer than males
 Adult worms coiled within subcutaneous nodules
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22.  Microfilaria
 Found mostly in skin dermis, rarely subcutaneous
nodules, blood, sputum or urine
 200-360 µm long, pointed tail with no nuclei
 Unsheathed
 Life Cycle
 Same as W.bancorfti but Simuluim is vector
 Mode of transmission
 Infective form is larva transmitted by Simuluim flies
during blood meal
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23.  Larvae transform to adult worms and migrate in
subcutaneous tissues and eyes
 Microfilariae released after 15 months by female
worms
 Microfilariae are ingested by black flies during blood
meal, penetrate the gut wall and transform to
infective larva
 Clinical features
 Dermatitis
 Intense pruritus and generalized papular rashes
 Prolonged infection  loss of elastic fibers,
epidermal atrophy
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24.  Leopard Skin: hypo to hyperpigmented
 Sowda: chronic hyper reactive of dermatitis due to
formation of auto antibodies against defensins
 Onchocercoma (Subcutaneous Nodules)
 Firm, non tender nodules containing coiled adult
worms
 Ocular involvement
 Bilateral blindness/river blindness
 Lesions develop in all parts of eye
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25.  Conjuctivitis with photophobia
 Punctate keratitis
 Lymph Nodes
 Enlarged nodes
 Lab Diagnosis
 Detection of microfilariae in skin snip smear
 Detection of Adult Worm from biopsy of
subcutaneous nodules
 Serology mixture of recombinant antigens of
O.volvulus used to detect specific antibodies
 PCR detecting onchocercal DNA in skin strips
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28.  Mazzoti Skin Test (DEC Patch Test)
 Topical application of DEC on skin leads to reaction
erythema and icthing, to dead worm
 Done only in light infection as the reaction with
heavy infection is severe
 Treatment
 Ivermectin active against microfilariae but not
adult worms
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29. Mansonella perstans
 Found in center of Africa and North-Eastern South
America
 Transmission
 Culicoides
 Life Cycle
 Same as other filarial worms.
 Clinical features
 Nonpathogenic but can cause urticaria and pruritus
 Lab diagnosis
 Microfilariae non-sheathed, with straight tail with
blunt end
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31. Mansonella streptocerca
 Epidemiology: tropical forest of Africa – Ghana,
Nigeria, Uganda
 Transmission: biting of midges – Culcoides
granhami
 Life cycle: same as other worms
 Clinical feature: infected individuals are
asymptomatic. Some develop lymphadenopathy,
chronic dermatitis with pruritus
 Lab diagnosis: detection of microfilariae in skin
snips.
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33. Mansonella ozzardi
 Epidemiology and transmission
 M.ozzardi –Central and South America
transmiited by Culcoides
 Caribbean islands transmitted by Simuluim
amazonicum (blackflies)
 Life cycle: similar to other worms
 Clinical features: asymptomatic but can cause
lymphadenopathy, uriticaria, pruritus
 Detection: peripheral blood
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35.  Assignment
1. What are the clinical features of B. Malayi?
Discuss lab diagnosis and treatment
2. Draw life cycle of Loa loa. What disease(s) does
it cause?
Submit on 4 April
No submission = No attendance
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