L2: Bancroftian filariasis Flashcards
What is the definition of Bancroftian filariasis?
- It is caused by a slender “thin” white filarial worm called Wuchereria bancrofti, transmitted by mosquitoes bite, lives in lymphatics, periodically shedding larvae into peripheral bloodstream
- often causes elephantiasis by blocking lymphatic drainage.
What is the morphology of adult of wuchereria bancrofti?
“Female is double the male”
- Male: 4 cm long, curved posterior end.
- Female: 8 cm long, tapered tail.
What is the morphology of the microfilaria of wuchereria bancrofti?
- About 300 x 10 μ.
- Has lose sheath, rounded anterior end, and tapered posterior end devoid of nuclei.
What is the lifecycle of wuchereria bancrofti?
- Habitat: adults live in lymph vessels and lymph nodes especially those draining lower part of the body, and microfilariae are in peripheral blood.
- Definitive host (D.H.): man.
- Intermediate host (I.H., vector): mainly female Culex, also female Anopheles and Aedes mosquitoes.
- Infective stage: infective filariform larvae in mosquito mouth.
- Mode of infection: through the skin, during the bite of infected female mosquito.
- Infected insect bites human→infective filariform larvae actively enter through bite wound→migrate to lymphatics→transform to adult worms.
- Fertilized females lay microfilariae→migrate to peripheral blood→ sucked by insect vector.
- In the insect midgut, microfilariae moult “peel” →infective filariform larvae →migrate to the mosquito mouth.
And what causes the clinical manifestations of wuchereria bancrofti?
“Like entamoeba”
❑ Results from a complex interplay of:
- Pathogenic potential of the parasite.
- Tissue response of the host.
- External bacterial and fungal infections.
what are the types of pathology caused by wuchereria bancrofti ?
Classical filarias
Occult filariasis
Compare between classical filariasis and occult filariasis according to:-
Cause Lesions Pathology C/P MF in blood Diagnosis
“Adult in lymphatics —–> microfilaria in peripheral blood ——-> infective filariform larva in mosquito midgut”
Cause:
- Adult worm
- Microfilaria (Microfilaria usually non-pathogenic)
Lesions:
- LNs & Lymphatics
- Lung, Liver and Spleen
Pathology C/P:
- Inflammation, Fibrosis ands classical manifestations
- esinophilic granuloma, cough, Dyspnea and asthma
MF in blood:
- Present
- Pbsent in blood (present in affected tissues)
Diagnosis:
- Blood film - Serology is less effective
- Serology
What is the incubation period of wuchereria bancrofti??
8 - 16 months
What are the clinical manifestations of wuchereria bancrofti?
Asymptomatic filariasis
Symptomatic filariasis
What are the characteristics of asymptomatic Filariasis?
- in people living in endemic areas, and they are source of infection
What are the types of symptomatic filariasis?
Acute inflammatory manifestations “in nearly 6 months”
Chronic obstructive manifestations (10-15 years)
Tropical pulmonary eosinophilia (TPE, diffuse filarial lung disease)
What are Acute inflammatory manifestations of lymphatic filariasis?
- Lymphangitis
- Lymphadenitis
- Filarial fever
What are the characteristics of lymphangitis in lymphatic filariasis?
- dilated, inflamed and thickened lymphatic vessels.
What are the symptoms of lymphangitis of lymphatic filariasis?
- red, tender & swollen.
What are the causes of lymphangitis of lymphatic filariasis?
a. Mechanical irritation by moving worms.
b. Metabolites of living worms.
c. Toxic products of living and dead worms.
d. Secondary bacterial infection.
What are the symptoms of lymphadenitis of Lymphatic filariasis?
- enlarged, tender and matted lymph nodes
What causes lymphadenitis of Lymphatic filariasis?
- due to fibrosis and necrosis & obstruction of proximal lymphatic vessels.
What is the site of lymphadenitis of lymphatic filariasis?
inguinal lymph nodes.
What are the symptoms of filarial fever?
- high fever, chills and excess sweating.
