Wuchereria bancrofti

Wuchereria bancroftiis a human parasitic roundworm that is the major cause of lymphatic filariasis.

Superfamily: Filariodea Subfamily: Acanthocheilonematinae

Genus: WuchereriaSpecie: W. bancrofti

Otto Wucherer Joseph Bancroft

W. bancrofti was named after physician Otto Wucherer and parasitologist Joseph Bancroft.

Morphology

Adult worms (dioecious): Female 80- 100 mm in lengthovoviviparousMale 40 mm by 0.1 mm

MorphologyMicrofilariae:

244- 296 um by 7.5- 10 um Nuclei not reaching tail end No terminal nuclei Nuclei regularly spaced,

dispersed Bigger, wider than B. MalayiGraceful sweeping curves Short head space (as long as

broad) Sheath unstained with

GiemsaBluntly rounded anteriorly and

pointed caudally

Microfilaria- is a miniature adult that retains the egg membrane as a sheath.

Characteristics

Habitat of Adult worm : Lymphatic systemHabitat of Microfilaria: BloodIntermediate Host : Anopheles minimus

var. Flavirostris- principal vector for malaria in Philippines- bite indoors, night- biters Others: Aedes poecilus ( in axils of plants)

Definitive Host : Man

Characteristics

Periodicity: Nocturnal periodicity, EXCEPT South Pacific microfilariae

Nocturnal periodicity: 8 PM- 4 AM = best time to collect

Microfilariae may not be demonstrable in peripheral blood if:- low intensity of infection- dead worms- obstructed lymphatics

Life Cycle

Epidemiology

Tropical areas worldwide

India SEA Pacific Islands Africa South America Central America

Epidemiology

Philippines Camarines Sur/ Norte Albay Sorsogon Mindoro Masbate Romblon Marinduque Bohol Samar Leyte Palawan Mountain Province All provinces of Mindanao

Pathogenesis

Lymphedema • abnormal

accumulation of lymph in tissues causing swelling of arms, breasts, or genitals.

Pathogenesis

Elephantiasis• disabling and

disfiguring lymphedema of the limbs, breasts, and genitals, accompanied by marked thickening of the skin.

Pathogenesis

Hydrocoele• fluid- filled balloon-

like enlargement of the sacs around the testes.

Diagnosis

Direct methods (visualization of larval stage or microfilaria and adult worm)

Microfilaria can be seen on peripheral blood or other body fluids (eg. urine, ascitic, hydrocoele, or lymph fluid).

Wet smear examination under the microscope where motility can also be seen

Examination of stained peripheral blood smear which is also useful in species identification based on morphologic features of organism, especially the tail end

Thick or concentrated blood smears concentration smears are useful in patients with low

parasetimia blood sample is taken during the period in the day when

the juveniles are in the peripheral circulation.

Diagnosis

Direct Methods

X- ray adult worms can be demonstrated in lymph node biopsy calcified adult worms are visualized

Doppler Ultrasonography detect presence of motile adult worms in dilated

lymphatics

Diagnosis

Indirect Methods Peripheral blood eosinophilia Elevated serum IgE concentration Presence of antifilarial serum antibody Intradermal complement fixation tests

Treatment

diethylcarbamazine (DEC) ivermectinoralbendazole

Prevention and Control

Insect repellantsUse of mosquito netsPublic education

END