References:
- Global Infectious Diseases and Epidemiology Online Network: Infectious Diseases of the Philippines, 2013 eBook Edition, ISBN 978-1-61755-582-4, by Stephen Berger. Accessed here.
Schistosomiasis Japonicum
| Agent | |
| Reservoir | |
| Vector | |
| Vehicle | |
| Incubation Period | |
| Diagnostic Tests | |
| Typical Adult Therapy | |
| Typical Pediatric Therapy | |
| Clinical Hints | |
| Synonyms |
WHO Case Definition for Surveillance
This definition is applicable to all types of intestinal schisotomiasis.
- Endemic areas (moderate or high prevalence)
- Suspected: A person with chronic or recurrent intestinal symptoms (blood in stool, bloody diarrhea, diarrhea, abdominal pains) or, at a later stage, hepatosplenomegaly.
- Probable: A person who meets the criteria for presumptive treatment, according to the locally applicable diagnostic algorithms.
- Confirmed: A person with eggs of S. mansoni, or S. japonicum/mekongi in stools (microscope).
- Non-endemic areas and areas of low prevalence
- Suspected: A person with chronic or recurrent intestinal symptoms (blood in stool, bloody diarrhea, diarrhea, abdominal pains) or, at a later stage, hepatosplenomegaly.
- Probable: Not applicable.
- Confirmed: A person with eggs of S. mansoni or S. japonicum in stools (microscope). A person with positive reaction to immunoblot test.
The clinical features caused by Schistosoma species infecting man are similar.
Acute Infection
Within 24 hours of penetration by cercariae, the patient develops a pruritic papular skin rash known as swimmer’s itch.
- One to two months after exposure, an overt systemic illness known as Katayama fever (named for Katayama district, Hiroshima, Japan) begins, heralded by acute onset of fever, chills, diaphoresis, headache, and cough.
- The liver, spleen, and lymph nodes are enlarged, and eosinophilia is present.
- Although deaths have been described at this point (notably in S. japonicum infection) these findings subside within a few weeks in most cases.
Chronic Infection
The likelihood of progression to chronic schistosomiasis is related to the extent of infestation.
- Chronic schistosomiasis caused by S. mansoni, S. japonicum, or S. mekongi is characterized by fatigue, abdominal pain and intermittent diarrhea or dysentery.
- Colonic polyposis is has been associated with infection by S. mansoni, S. japonicum, and S. intercalatum. Retroperitoneal fibrosis has been reported with S. japonicum infection.
- Blood loss from intestinal ulcerations may lead to moderate anemia.
- In S. mansoni, S. japonicum, and S. mekongi infections, ova remain in the venous portal circulation and are carried to the liver where they produce granulomata and fibrosis, and block portal blood flow.
- Portal hypertension and portosystemic collateral circulation result.
- Although liver function tests remain normal for a long time, hepatosplenomegaly and variceal hemorrhage develop.
- The spleen is firm and may reach massive size.
- Fatal hematemesis is unusual.
- Laboratory tests reveal moderate eosinophilia and anemia related to blood loss and hypersplenism.
- Eventually, hepatic function deteriorates, with late ascites and jaundice.
In S. haematobium infection, ova are located in the bladder and ureters, leading to granuloma formation, inflammation, hematuria, ureteral obstruction, secondary infection and often carcinoma of the bladder. Ova are also commonly present in the seminal vesicles and prostate.
- Genital lesions may present a risk factor for acquisition of HIV infection 10 ; and schistosomal co-infection may accelerate
HIV disease progression and facilitate viral transmission to sexual partners.
- Terminal hematuria and dysuria are common symptoms.
S. intercalatum infection is characterized by abdominal pain and bloody diarrhea.
S. mekongi is an important cause of hepatomegaly in endemic areas.