Platyhelminths - Schistosomiosis Flashcards
Importance of schistosomiosis
- Blood flukes (vessels - portal, mesenteric, bladder and other)
- Human pathogens; not in Aus
- Affecting 200-300 million people
Adult body
Schisto = split; soma = body
0.5-2cm
Dioecius
In-copula
(male split with female in groove)
Lifecycle of Schistosoma
Oriental schistosomiasis
S. japonicum
Risk factors for oriental schistosomiasis
Rice farming
fishing
swimming
Where is oriental schistosomiasis
Philippines, Indonesia, SE China
Acute schistosomiosis
Self-limiting cercarial dematitis
Delayed hypersensitivity response (3-4 wk)
- TH1 pro-inflammatory response
- Hypereosinophilia
- Fever, arthralgia, bronchiopneumonia and urticaria or angio-oedema
Chronic schistosomiosis eggs
- eggs laid within venules of urinary bladder/distol colon and rectum
- eggs penetrate venule and intestinal / bladder wall using spine and proteolytic enzymes to enter lumen and be passed
- some eggs lodge in organs causing granulomas esp. intestines, liver, liver, bladder ectopic sites e.g. brain
Chronic schistomsomiosis
Portal and pulmonary hypertension, ascites
Dysuria, haematuria, calcification
Worm antigens in circulation (Ab-mediated glomerulonephritis) -> nephrotic syndrome
Anaemia, stunting children
HIV/AIDS co-infection complications
Diagnosis of schistosomiosis
History/clinical signs
eggs in faeces/urine (sedement urine to see the eggs)
Serology
Control of schistosomiasis
Treat with praziquantel
- improve household sanitation and access to clean water
- educating fishermen and boatmen about the dangers of infested waters
- molluscicidal treatment
- vaccines? -> decrease worm burden by 40%
Cercarial dermatitis
swimmers itsch common in Aus
- Austrobilharzia or Trichobilharzia (aquatic birds)
- skin penetration of ‘wrong host’
- self limiting hypersensitivity reaction
Visceral schistosomiasis
pathophysiology, treatment, control similar to humans
low to mod burden - subclinical, production loss
high burdens, younger animals -> diarrhoea, haematuria, ascites, wasting. Severely affected animals deteriorate rapidle and usually die within a few months of infection
