Parasitic diseases Flashcards
(43 cards)
what are parasites?
organisms that live feed and can reproduce in a host organism
where are parasitic helminths most prevelent?
helminths live in warm, moist shaded soil so are endemic in tropical areas
why are helminth infection still so prevelent in tropical regions?
Neglected tropical disease-
they do not recieve funding and lack of eradication
so helminth infection remain highly prevelent
what are the 2 major classes of parasitic helminth infection (affect humans)
roundworms/nematodes e.g hookworm
flatworms e.g tapeworm, schistosoma
which human helminth is most clinically relevant?
Schistosoma infections cause the most morbidity and mortality.
this is because consequence of infection can be liver remodelling. fibrosis, megly and can result in liver failure
which helminth uses mosquitos as a host?
A) Schistosoma
B) Hookworm
C) Filaria
D) Ascaris
Filaria
they can cause lymphatic filaris as the microfilarae migrate to blood and lymph nnodes
this alters lymph flow causing swelling and disfigurement (elephantisis)
does filaria infection have higher or lower mortality than schistosoma infection?
Why?
Lower mortality but has a much greater MORBIDITY
as the elephantisis disfigures body
filaria infection and a different Filaria infection can result in river blindness
name 3 examples of soil transmitted helminths
Hookworms
whipworms
ascaris
how to STH establish infection?
they establish infection in intestine causing diarrhea, abdominal pain
can also influence cognitive function and lung emphysema
why are rodents useful models for helminth infection?
despite size difference, there is similar immune response is observed as in humans
why can’t other models like dogs or hamsters be used to model helminth infection?
these animals NATURALLY aqquire immunity to helminth whereas humans do not
why is there no human helminth vaccine despite some existing for cattle?
vaccines are tightly regulated and need to meet a ‘‘preferred product characteristic’’
so efficacy of vaccine needs to be very high and reduce worm and egg burden by 75% and no such vaccine has reached that criteria yet
what are some vaccine considerations?
need to be able to be effective
is there an antigen response
can the protein be scaled up?
how can we treat those already infected with helminths?
use antihelminthics
these are drugs targeting diffrent aspects of helminth membrane permeability
what is the issue with drug administeratieve programmes against helminths?
they are very expensive, can become easily disrupted (e.g covid19) and rural areas are often neglected from these programmes as hard to access
side effects with these anti-helminthics or drug resistance can occur to
how can genomics help with anti-helminth drug development?
able to identify mutations in those resistant to treatment and exploit that
able to target metabolism of helminth (drug)
Target the blood feeding pathway too (vaccine)
how does the body naturally try and rid of a helminth infection?
> later
a type 2 immune response is initiated
IL4,5,13 are secreted
this is a distinct signature for parasitic disease
how does the body naturally try and rid of helminth?
> initially?
level 1 immune system barriers like goblet cell hyperplasia ans mucus production as part of
‘‘weep and sweep’’
what do cytokines produced bt Type 2- tcells do?
> specifically
they activate mast cell, eosinophil and basophils in innate immune response
activate smooth muscle cell to help with weep and sweep response
activate b-cell and IgE production in adaptive
what do cytokines produced bt Type 2- tcells do?
> generally
amplify the type-2 immune response
which receptor is the type 2 immune response driven by?
A IL-1B
B TNF-al
C IL-4al
D IgE
OPTION C
ubiquitously expressed on non-haematopoetic cells
essential for helminth expulsion
what is a danger of IL-4alpha
Where is evidence for that?
despite its necessity for helminth expulsion ir can exacerbate liver fibrosis in schitosoma infected mice
other than IL-4alpaha receptor what other Receptors can be targeted to eradicate helminths?
tuft cells can release IL-25 to activate innate lymphoid cells which produce type 2 cytokines independent of IL-4aR signalling
so could target IL-25 receptor to amplify this type 2 immune response
what is the hygeine hypothesis?
immune systems are less exposed to organisms in childhood so experience high incidence of inflammatory disorders in later life
