Filariasis

Question 1

Describe the life cycle of the filarial worm Wucheria Bancrofti, giving the stage names also

Answer 1

First bite! L3 larval stage enter body. Go to lymphatic system and mature into adults. Pair off and migrate to lymph and blood vessels, producing MICROFILARIAE (sheathed). Second bite! Burrow into mozzie midgut to the thoracis muscles and mature through stage 1-3 larvae. Migrate to mozzie head and proboscis. CYCLE BEGINS AGAIN.

Question 2

What are the three immune response stages of a filariasis infection?

Answer 2

1) initial asymptomatic stage 2) inflammatory response stage, Th1 cytokines involved 3) Obstructive chronic stage, Th2 response to parasite antigens.

Question 3

Give me the overall breakdown for the immune response

Answer 3

Initially, Th1 response dominates. However it is then downregulated, TLRs 1,2,4,9 downregulated. Letting Th2 responses dominate, allowing microfilariae to be killed by the degranulation of eosinophils and mast cells.

Question 4

Describe the immune evasion of the filarial parasite

Answer 4

L3 stages interact with LC’s and suppressing them. This allows L3s to move to lymphatics. Microfilariae confront the immune system and impair DCs by inducing apoptosis or suppressing Th1 cytokine production.

Question 5

What has IgG4 got to do with anything?

Answer 5

There are increased levels. This blocks IgE mediated degranulation of eosinophils and protects the microfilariae.

Question 6

What are the main pathologies of wucheria bancrofti?

Answer 6

1) hydrocele and scrotal elephantiasis 2) febrile lymphangitis 3) Onchoceriasis - subcutaneous nodules, lymphadenopathies, ocular lesions leading to blindness

Question 7

What is a pathology found in Asia?

Answer 7

TPE - tropical pulmonary eosinophilia - nocturnal cough/wheezing and fever, prolonged leads to lung damage

Question 8

What is the difference in pathologies between Wucheria bancrofti and Brugia malayi?

Answer 8

No big scrotum

Question 9

Give 5 methods of diagnosing filariasis

Answer 9

1) MF in blood film 2) DE provocation test, causes MF to appear 30-60 mins post treatment 3)Ultrasonography of adult scrotum for wiggly worms 4) Chyluria 5) Filarial antigen test (ELISA)

Question 10

Vaccines?

Answer 10

Targets - stage specific microfilarial chitinase (essential for desheathing) effective pre-infection