Pathogenesis Of Parasitic Infections Flashcards
What are the three main species of schistosomiasis?
S. Mansoni
S. Haematobium
S. Japonium
What can schistosomiasis result in?
Cercarial dermatitis
What is a key feature of immune response to schistosomiasis?
Granuloma formation
What is hepatointestinal schistomiasis caused by?
Immune response to eggs
What causes cercarial dermatitis?
Allergic-type reaction to cercariae from animal or bird schistomes
What causes urinary schistosomiasis?
Repeated inflammatory episodes resulting in neoplastic changes
What is onchocerciasis?
Major blinding disease
What is onchocerciasis caused by?
Filarial parasite
What is onchocerciasis transmitted by?
Black flies
What is the vector of onchocerciasis?
Simulium
How do black flies transmit onchocerciasis?
Takes a blood meal and transmits larvae to the skin
How does simulium act as a vector for onchocerciasis?
Digs a hole in the skin and creates a pool of blood which it then feeds from
What is the pathology of onchocerciasis?
Repeated inflammatory episodes caused by microfilariae -> permanent damage and scarring of skin and eyes
What are the skin disease types of onchocerciasis?
Acute papular onchodermatitis
Chronic onchodermatitis
Sowda
What are the anterior segment eye diseases caused by onchocerciasis?
Punctuate keratitis
Acute iridocyclitis
Sclerosing keratitis
What are the posterior segment eye diseases caused by onchocerciasis?
Optic neuritis/atrophy
Chorioretinopathy
What is the immune pathogenesis of onchocerciasis?
Acute infection -> stimulation of Th2 cells -> eosinophil and B cell activation-> inflammatory response
What are some examples of hard tick bourne disease?
Tick typhus Viral encephalitis Viral fevers Viral haemorrhagic fevers Tularaemia Tick paralysis Human babesiosis
What are some examples of soft tick bourne disease?
Q fever
Relapsing fever
What happens in tick paralysis?
Progressive flaccidity due to a failure of acetylcholine liberation in the neuromuscular junction
What do head lice do?
Suck blood from scalp and lay eggs on hair
How are head lice spread?
Close contact
What do body lice do?
Suck blood from body and lay eggs on clothing
How are body lice spread?
Bodily contact, sharing of clothing or bedding
How do botflies spread disease?
Catches mosquito mid flight and lays its eggs
When the mosquito lands on the animal it brushes its eggs
How can you control parasitic infections?
Behaviours
Environmental interventions
Poverty reduction
What types of behaviour control parasitic infections?
Education, hand washing and hygiene behaviours
What types of environmental interventions control parasitic infections?
Spraying of residual insecticides for household vectors Mosquito nets Improved housing Sewage disposal Potable water Swamp drainage
Why must parasitic treatment be given periodically over long periods of time?
Re infections are rapid or the treatment kills larval rather than adult stages
