Helminths

Question 1

Name three helminth phyla

Answer 1

Nematode
Platyhelminths
Acanthocephalans

Question 2

Give charcteristic features of helminths and their diseases

Answer 2

Complex migration route 
Slow maturation time 
Multiplication opportunities limited
Slow to induce an immune response 
Overt pathology limited but can eventually become overt and lead to death

Question 3

Describe the distribution of helminth infections

Answer 3

Very young not infected
Infection accumulates with increasing age and the stabilies or declines
Infection intensity: lower at youger ages,increasing with age until ~20, then stabilising or decreasing

Question 4

How do helminths persist

Answer 4

Gut helminths: Oral infection route, lives in colon or caecum,penetrates epithelium forming tunnels. Epilthelium under contant renewal (epithelial escalator)

Question 5

What is the epithelial escalator?

Answer 5

In susceptible mice: Slow turnover, Crypt hyperplasia (long crypts), incrased cell prolif. Mediated by Th1, IFN y, CXCL10
Resistant mouse: High cell turnover, No crypt hyperplasia (short crypts),limited cell prolif. Mediated by Th2, IL-13`

Question 6

Describe human stage of helminth life cycle

Answer 6

Blackfly bite, adults form in subcutanoues nodule,. Adults produce unshealthed microfilariae (found in skin, lymphatics etc.)

Question 7

Problems with chemotherapy for helminths

Answer 7

drugs that kill worms often toxic to host
dead worms accumulate in host
risk of over use of insecticides in trying to kill intermediate host

Question 8

Describe action and problems with Ivermectin

Answer 8

broad spectrum activity against experimental nem infections
active against microfilariae
found to reduce presence of Onchocerca in non-treated animals
acts by blocking glutamate-gated channels (blocking neurotransmission)

Problems: Only kills microfilariae, used in combination with albendazole, appears to make female worms less fecund

Question 9

Give another potential approach to treating helminths

Answer 9

Worms have endosymbionts (oocytes and larvae)

Treatment with tetracycline or doxycycline stops embryogenesis

Question 10

Describe the chronic and acute immune reponse against helminths

Answer 10

Chronic: Th2 type reponses (helps host and parasite by removing late comers which may overload the host, leading to death - not cool!)

Acute: Th1 response

Question 11

Do helminths directly interfere with the immune response?

Answer 11

People experiencing worm infections have reduced incidence of allergy and autoimmunity
Patients given pig whip ova had a 75-100% remission rate in Crohn’s and colitis. Relapse when worms gone and some side effects
Multiple sclerosis -patients given t.suis. fewer lesions in CNS but relapse after helminth expelled

Question 12

Desribe ES-62 as an anti-inflammatory helminth product

Answer 12

Secreted by filiarial nems, modulates b&T cell, dendritic cell, and macrophage proliferation.
Can cause B cells to produce IL-10, whichstops B1 cells from producing immunoglobulin and macrophages from activating
Inhibits mast cells preventing signalling for histamine release
reduces airway allergy
active against collagen induced arthritis