SCHISTOSOMIASIS Flashcards
What is the organism that causes schistosomiasis? What are the three main species?
Trematode called Schistoma
S. mansoni
S. japonicum
S. haematobium
In what parts of the world is schistosomiasis endemic?
Sub-Saharan Africa
Southern China
Brazil
Phillipines
What is the intermediate host of schistoma species?
Mollusc
What is the cause of the pathology seen in schistosomiasis?
A type IV hypersensitivity to the schistoma eggs. The healing post inflammation leads to fibrosis, which is what causes the clinical problems.
What is the initial clinical feature of schistosomiasis infection?
Local dermatitis at the cercarial invasion site - known as swimmer’s itch
What are the initial clinical features of schistosomiasis after the incubation period?
Fever
Malaise
Myalgia
Known as Katayama fever
How long is the incubation period of schistosomiasis?
1-3 weeks
As well as Katayama fever, what are the clinical features of infection by Schistoma mansoni and S. japonicum?
Abdominal pain
Diarrhoea (sometimes bloody) - can mimic IBD
Wheeze and cough - more likely with S. japonicum
Hepatosplenomegaly
Transverse myelitis - more likely with S. mansoni
What is the underlying mechanism of pathology caused by Schistoma mansoni and S. japonicum?
Worm passes from skin into blood stream
Settle in veins supplying bowel
Trapped egg results in inflammation and fibrosis in portal vein which leads to portal hypertension.
As well as Katayama fever, what are the clinical features of infection by Schistoma haematobium?
Increased frequency of passing Dysuria Haematuria Haematospermia Incontinence Hydronephrosis Renal failure Transverse myelitis
What is the underlying mechanism of pathology caused by Schistoma haematobium?
Worm passes from skin into blood stream
Settle in veins supplying bladder
Trapped eggs result in inflammation and fibrosis resulting in obstruction of ureters, hydronephrosis and renal failure.
How is the diagnosis of schistosomiasis made?
Travel history
Isolating characteristic eggs from faeces or urine depending on species
Liver biopsy will show inflammation and fibrosis
Eosinophilia on FBC during Katayama fever
How are patients diagnosed with Schistosomiasis managed?
Praziquantel - 1 dose for S. haematobium, 2 for other two species
