Schistosoma: Difference between revisions

Latest revision as of 10:15, 23 September 2024

Background

Infection with a species of the genus Schistosoma

Microbiology

Schistosoma mansoni: liver and gut
Schistosoma haematobium: GU/pelvis
Schistosoma japonicum: liver and gut
Schistosoma mekongi: Mekong basin

Risk Factors

Fresh water exposure in endemic countries

Epidemiology

Seroprevalence in migrants by region of origin1
- Latin America and the Caribbean (20%; 9-34)
- Middle East and north Africa (6.4%; 0.3-19.5)
- Sub-Saharan Africa (24.1%; 16-33)
- South Asia (0%; 0-69)
- East Asia and the Pacific (5.4%; 2-10)

Clinical Manifestations

Swimmer's Itch

Cercariae penetrate exposed skin and cause prickling sensation and occasionally urticaria, followed hours later by a macular rash
Caused by schistosomes that do not cause systemic illness
Common in Great Lakes region of North America, New England in the US, and other parts of North America and Europe

Katayama Fever

Syndrome of acute schistosomiasis that follows 4 to 8 weeks (range 2 to 12 weeks), after the flukes have migrated, developed into adults, and have started producing eggs
The syndrome represents a hypersensitivity reaction to the eggs produced by adult worms
More common with Schistosoma japonicum and Schistosoma mansoni, and less common with Schistosoma haematobium
Symptoms include abrypt onset of fever, chills, fatigue, headache, myalgias, abdominal pain, diarrhea, and occasionally bloody stool
Most also develop cough, dyspnea, chest pain, and diffuse infiltrates on chest x-ray
- Lung nodules contain granulomas around eggs
Hepatomegaly, splenomegaly, and lymphadenopathy are common
Eggs may not be seen in stool until later in the course of the disease
Symptoms usually resolve within 2 to 10 weeks
Can involve symptoms anywhere the worms migrate and deposit eggs: CNS, genital tract, and skin
- However, an induced small-vessel vasculitis can also cause neurological symptoms

Chronic Schistosomiasis

Can be asymptomatic or paucisymptomatic
Chronic granulomatous inflammation causes weight loss, anemia, stunted growth
Eosinophilia is common

Investigations

Labs
- CBC, showing eosinophilia
- Schistosoma serology (only positive 6 weeks after infection)
- Egg detection in stool, urine, semen, or tissue biopsy
Imaging
- Eggs can cause granulomatous disease in various organs
- Bladder polyps and obstruction may be seen on ultrasound

Diagnosis

Usually based on serology
- Can cross-react with other helminth co-infections, including trichinosis and filariasis
- Can remain positive and even fluctuate for years after cure2

Management

Acute
- Praziquantel 40mg/kg given over one day split into 3 doses
Chronic
- Praziquantel 20-40 mg/kg or 40-60 mg/kg (if at risk for S. japonica)
- Given over one day split into 3 doses
- May be repeated 6 weeks later, though this practice is not universal
- No role for test-of-cure serology

Prognosis

Increased risk of squamous cell carcinoma, which increase with young age at infection, duration of infection, high burden of infection, and bladder wall fibrosis

References

^ Archana Asundi, Alina Beliavsky, Xing Jian Liu, Arash Akaberi, Guido Schwarzer, Zeno Bisoffi, Ana Requena-Méndez, Ian Shrier, Christina Greenaway. Prevalence of strongyloidiasis and schistosomiasis among migrants: a systematic review and meta-analysis. The Lancet Global Health. 2019;7(2):e236-e248. doi:10.1016/s2214-109x(18)30490-x.
^ Michelle K. Yong, Carolyn L. Beckett, Karin Leder, Beverley A. Biggs, Joseph Torresi, Daniel P. O’Brien. Long‐Term Follow‐Up ofSchistosomiasisSerology Post‐Treatment in Australian Travelers and Immigrants. Journal of Travel Medicine. 2010;17(2):89-93. doi:10.1111/j.1708-8305.2009.00379.x.

@@ Line 1: / Line 1: @@
+==Background==
-* Infection with a species of the genus ''Schistosoma''
+*Infection with a species of the genus ''Schistosoma''
-== Species ==
+===Microbiology===
-* ''[[Schistosoma mansoni]]'': liver and gut
-* ''[[Schistosoma haematobium]]'': GU/pelvis
-* ''[[Schistosoma japonicum]]'': liver and gut
-* ''[[Schistosoma mekongi]]'': Mekong basin
+*''[[Schistosoma mansoni]]'': liver and gut
-== Risk Factors ==
+*''[[Schistosoma haematobium]]'': GU/pelvis
+*''[[Schistosoma japonicum]]'': liver and gut
+*''[[Schistosoma mekongi]]'': Mekong basin
+===Risk Factors===
-* Fresh water exposure in endemic countries
+*Fresh water exposure in endemic countries
-== Clinical Presentation ==
-== Investigations ==
+=== Epidemiology ===
+* Seroprevalence in migrants by region of origin[[CiteRef::asundi2019pr]]
-* Labs
+** Latin America and the Caribbean (20%; 9-34)
-** CBC, showing eosinophilia
+** Middle East and north Africa (6.4%; 0.3-19.5)
-** Schisto serology (only positive 6 weeks after infection)
+** Sub-Saharan Africa (24.1%; 16-33)
-** Egg detection in stool, urine, semen, or tissue biopsy
+** South Asia (0%; 0-69)
-* Imaging
+** East Asia and the Pacific (5.4%; 2-10)
-** Eggs can cause granulomatous disease in various organs
-** Bladder polyps and obstruction may be seen on ultrasound
+==Clinical Manifestations==
-== Management ==
+===Swimmer's Itch===
-* Acute
-** Praziquantel 40mg/kg/d
-*** Can cause nausea, dizziness, and fever
-* Chronic
-** Prevention
+*Cercariae penetrate exposed skin and cause prickling sensation and occasionally urticaria, followed hours later by a macular rash
-== Prognosis ==
+*Caused by schistosomes that do not cause systemic illness
+*Common in Great Lakes region of North America, New England in the US, and other parts of North America and Europe
+===Katayama Fever===
-* Increased risk of squamous cell carcinoma, which increase with young age at infection, duration of infection, high burden of infection, and bladder wall fibrosis
+*Syndrome of acute schistosomiasis that follows 4 to 8 weeks (range 2 to 12 weeks), after the flukes have migrated, developed into adults, and have started producing eggs
-{{DISPLAYTITLE:''Schistosoma'' species}}
+*The syndrome represents a hypersensitivity reaction to the eggs produced by adult worms
+*More common with [[Schistosoma japonicum]] and [[Schistosoma mansoni]], and less common with [[Schistosoma haematobium]]
+*Symptoms include abrypt onset of fever, chills, fatigue, headache, myalgias, abdominal pain, diarrhea, and occasionally bloody stool
+*Most also develop cough, dyspnea, chest pain, and diffuse infiltrates on chest x-ray
+**Lung nodules contain granulomas around eggs
+*Hepatomegaly, splenomegaly, and lymphadenopathy are common
+*Eggs may not be seen in stool until later in the course of the disease
+*Symptoms usually resolve within 2 to 10 weeks
+*Can involve symptoms anywhere the worms migrate and deposit eggs: CNS, genital tract, and skin
+**However, an induced small-vessel vasculitis can also cause neurological symptoms
+===Chronic Schistosomiasis===
+*Can be asymptomatic or paucisymptomatic
+*Chronic granulomatous inflammation causes weight loss, anemia, stunted growth
+*[[Eosinophilia]] is common
+==Investigations==
+*Labs
+**CBC, showing eosinophilia
+**Schistosoma serology (only positive 6 weeks after infection)
+**Egg detection in stool, urine, semen, or tissue biopsy
+*Imaging
+**Eggs can cause granulomatous disease in various organs
+**Bladder polyps and obstruction may be seen on ultrasound
+== Diagnosis ==
+* Usually based on serology
+** Can cross-react with other helminth co-infections, including [[trichinosis]] and [[filariasis]]
+** Can remain positive and even fluctuate for years after cure[[CiteRef::yong2010lo]]
+==Management==
+*Acute
+**[[Is treated by::Praziquantel]] 40mg/kg given over one day split into 3 doses
+*Chronic
+**[[Is treated by::Praziquantel]] 20-40 mg/kg or 40-60 mg/kg (if at risk for ''S. japonica'')
+**Given over one day split into 3 doses
+**May be repeated 6 weeks later, though this practice is not universal
+**No role for test-of-cure serology
+==Prognosis==
+*Increased risk of squamous cell carcinoma, which increase with young age at infection, duration of infection, high burden of infection, and bladder wall fibrosis
+{{DISPLAYTITLE:''Schistosoma''}}
 [[Category:Protozoa]]