Parasitology Flashcards
What type of parasite is schistosomiasis?
→helminths
→flukes
What are the three main species of schistosomiasis?
→• Schistosoma mansoni
→S. haematobium
→ S. japonicum
Describe the life cycle of schistomiasis
→Eggs shed from infected human
→eggs hatch and release miracidia
→miracidia penetrate snail tissue
→sporocysts develop in snail
→free swimming cercariae released from snail into water
→cercariae penetrate skin
→cercariae lose tails during penetration and become schistosomulae
→circulation
→migration to portal blood in liver and maturation into adults
→paired adult worms migrate to bowel, liver, bladder
→eggs shed in urine
What is the presentation of schistosomiasis cercarial dermatitis?
→Allergic-type reaction
What is a key feature of immune response in schistosomiasis?
granuloma formation
eggs become organised in granulomas
What damage can granulomas do in schistosomiasis?
tissue repair leads to fibrosis and
organ damage
Which schistosomiasis strains result in hepato-intestinal symptoms?
S.mansoni
S.
japonicum
What type of parasite if onchocerciasis?
helminths
What is a major disease in onchocerciasis?
blinding disease
What is onchocerciasis caused by?
filarial parasite
onchocerca volvulus
What is onchocerciasis transmitted by?
blackfires
Describe the geographical distribution of onchocerciasis
Africa
South America
Describe the life cycle of onchocerciasis
→blackfly takes a blood meal
→subcutaneous tissues
→adults produce unsheathed microfilariae found in skin and lymphatics, urine
→blackfly takes blood meal
→microfilarie penetrate blackfly’s midgut and migrate to thoracic muscle
→migrate to head
Why is there damage and scarring in the skin and eyes in onchocerciasis?
→ repeated episodes of inflammation to microfilariae
Describe the clinical presentations of skin disease in onchocerciasis
→Acute papular onchodermatitis
→Chronic onchodermatitis
→ sowda
What are the clinical eye presentations in onchocerciasis?
→• Punctate keratitis • Acute iridocyclitis • Sclerosing keratitis →Optic neuritis/atrophy • Chorioretinopathy
What are the different molecules involved in acute or chronic onchocerciasis?
Acute
→dendritic cell
→natural or adaptive TReg
→eosinophil
What are the different molecules in chronic immune response of onchocerciasis?
→activated macrophages
→IgG
→B2 cells
What causes progressive tick paralysis?
→failure of acetylcholine release in neuromuscular junction
→toxin blocks motor nerve fibres
What is the difference in disease between hard bodied ticks and soft-bodied ticks?
→hard bodied= rickettsal, bacterial, protozoan diseases
→soft bodied= fever, Q-fever
Where do body lice lay their eggs?
→on clothing
What are the two types of sucking lice?
→crab lice
→public lice
How does suckling lice spread?
→close contact
Describe the life cycle of botfly
→fly bites cow
→produces larvas
Where is botfly disease endemic to?
→South America
What are some treatments for protozoa?
→Tinidazole
→metronidazole
→nitazoxanide
What are some treatments for helminths?
→albendazole
→praziquantel
→Ivermectin
What are some treatments for ectoparasites?
→ivermectin
→benzyl
What are the three ways of controlling parasites?
→behaviour
→environmental interventions
→poverty reduction
What are some environmental interventions?
Spraying of residual insecticides for household vectors • Mosquito nets for malaria • Improved housing • Sewage disposal and potable water • Drainage of swamps
Why must treatment be given periodically over long periods?
→re-infections are rapid or
→treatment kills larval rather than adult stages
