pathogenesis of parasitic infections

Question 1

describe helminths - schistomsomiasis

Answer 1

three main species:

1. schistosoma mansoni
2. s.haematobium
3. s.japonicium

key feature = granuloma formation. egg becomes organised into granulomas and repeated insults and tissue repair lead to fibrosis and organ damage

Question 2

cercarial dermatitis

Answer 2

exposure to cercariea from animal or bird schistosomes
requires pre-sensitization
allergic type reaction

Question 3

urinary schistosomiasis

Answer 3

haematuria = urinating blood
bladder can have long term damage due to inflammation
nodular carcinoma and papillomas

Question 4

describe onchocerciasis and symptoms

Answer 4

caused by worm
cause of blindness, major blinding disease by filarial parasite, transmitted by back flies

vector = simulium, digs holes into skin
caused by repeated episodes of inflammation to presence of microfilariae leads to permanent damage and scarring in skin and eyes

onchocercal nodules
skin disease = acute paula onchodermatitis
eye disease

Question 5

ectoparasites = ticks

Answer 5

buries head within skin
forms layer of cement between mouth and skin
hard ticks and soft ticks
can cause mechanical injury by bite
ticks toxin produces block in motornerve fibres

Question 6

examples of hard ticks and soft ticks

Answer 6

hard = tick typhus, viral encephalitis, viral fevers

soft ticks = q fever, relapsing fever

Question 7

medication to treat parasties

Answer 7

protozoa = trinidazole, metronidazole

helminths = albendazole, praziquantel

ectoparasites = ivermectin, benzyl