History
Symptoms of schistosomiasis depend on the species of the schistosome and the stage of disease. Most infected individuals are asymptomatic or have only mild nonspecific symptoms. Only 5-10% of infected individuals develop severe clinical symptoms, which are usually associated with heavy infestations.
Edema and pruritus are symptoms of cercarial dermatitis and are rarely observed in primary exposure (see the image below).
Cercarial dermatitis secondary to avian schistosomes is shown. Photography taken by A. Joseph Bearup and provided by John Walker, MD.
High fever or Katayama fever is described in heavy primary infections. Nausea is observed in acute schistosomiasis and at the onset of fevers. Vomiting may be experienced in acute schistosomiasis. Generalized lymphadenopathy is described as part of the Katayama fever syndrome. Profuse diarrhea or dysentery is associated with Katayama fever.
Hematemesis or melena is the usual presenting symptom of chronic schistosomiasis due to S japonicum and S mansoni. Abdominal pain may be observed with acute and chronic schistosomiasis secondary to liver and splenic enlargement (see following image).
Two 10-year-old boys with abdominal distension secondary to chronic Schistosoma japonicum infection.
Urticaria may occur with cercarial dermatitis or may be more extensive, affecting large body areas in acute schistosomiasis. Malaise, generalized fatigue, and weakness are sometimes observed with acute schistosomiasis.
Focal epilepsy is a recognized complication of chronic S japonicum infection in East Asia (see the image below). Spinal cord lesions due to S mansoni or S haematobium can cause a myelopathy.
CT scan of the brain reveals a right cerebral hemisphere lesion due to Schistosoma japonicum. The patient presented with focal motor seizures.
A dry cough (with or without hemoptysis) secondary to inflammation in the lungs can be experienced in acute schistosomiasis and is associated with migration of schistosomula through the lungs. Cough is also a symptom of cor pulmonale resulting from chronic pulmonary schistosomiasis. The subsequent pulmonary hypertension may lead to hemoptysis.
Palpitations may be felt as a complication of cor pulmonale in chronic pulmonary schistosomiasis. Shortness of breath may be observed in both acute and chronic pulmonary schistosomiasis as a result of cor pulmonale in chronic cases. Acute pulmonary symptoms of cough and dyspnea may occur 3-6 weeks after exposure and occur without fever.
Weight loss may be experienced as a consequence of vomiting and profuse diarrhea.
Urinary frequency is regularly associated with acute S haematobium infection. Dysuria is a common feature of acute S haematobium infection. Terminal hematuria is also a regular presenting symptom for S haematobium infection or bilharzia. Referred suprapubic or perineal pain may be associated with S haematobium infection.
Physical Examination
Physical findings vary with the species and the stage of the disease.
Urticaria may be observed in cases with cercarial dermatitis or acute schistosomiasis with Katayama fever. Papular lesions may develop from cercarial dermatitis and remain for 5-7 days and up to 10 days after water exposure. However, this is more often observed with avian schistosomiasis.
General enlargement of lymph nodes may be detected in acute schistosomiasis with Katayama fever.
Areas of moist crackles may be heard over both lung fields in acute schistosomiasis.
Hepatosplenomegaly is often detected in acute and chronic schistosomiasis with S japonicum and S mansoni. Jaundice is a rare clinical finding. Purpura resulting from thrombocytopenia is observed with hypersplenism.
Hematuria with S haematobium typically progresses from microscopic to frank bloody urine as the bladder mucosa ulcerates.
A transverse myelitislike syndrome may be observed with S mansoni or S haematobium disease. Focal neurologic deficits may be found due to cerebral granulomas in cases with seizures and chronic S japonicum infection.
Clinical signs of right ventricular hypertrophy are observed in cases with cor pulmonale and chronic schistosomiasis. This includes palpable sternal heave and increased and delayed pulmonary second heart sound.
Complications
Possible complications of schistosomiasis include fibro-occlusive disease secondary to the immune stimulus of schistosome eggs, end-organ damage, end-stage liver disease, and others.
Possible complications of female genital schistosomiasis (defined as the presence of schistosome eggs or worms in the upper or lower genital tract) include hypogonadism, retarded puberty, infertility (primary and secondary), ectopic and tubal pregnancy, tubal abortion, hemoperitoneum, anemia due to chronic blood loss, metaplasia, miscarriage and preterm delivery, carcinoma, increased risk for sexually transmitted diseases, destruction of the hymen or clitoris, and vesicovaginal fistula.
Persistent bacteremia with Salmonella typhi and other Salmonella species has been reported in persons chronically infected with S mansoni, S japonicum, S intercalatum, and S haematobium. Chronic Salmonella bacteria may be noted in patients infected with S haematobium.
Immune complexes formed in response to schistosomal infection may be deposited on glomerular capillaries and renal basement membranes, leading to mesangioproliferative glomerulonephritis, nephrosclerosis, and renal failure. The severity of renal disease is related to the worm burden and to the extent and duration of hepatic fibrosis and collateral circulations.
Schistosomiasis has been associated with high HIV viral loads and a theoretical risk of increased progression of HIV disease. [6]
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Cercarial dermatitis secondary to avian schistosomes is shown. Photography taken by A. Joseph Bearup and provided by John Walker, MD.
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Two 10-year-old boys with abdominal distension secondary to chronic Schistosoma japonicum infection.
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CT scan of the brain reveals a right cerebral hemisphere lesion due to Schistosoma japonicum. The patient presented with focal motor seizures.
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Egg of Schistosoma japonicum from a fecal smear is shown. Note lateral umbilicated spine on the right side of the egg.
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Egg of Schistosoma mekongi (53 X 45 μm) in the feces of a woman from Laos.
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Egg of Schistosoma mansoni from a fecal smear.
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Egg of Schistosoma haematobium from a fecal smear.
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Eggs of Schistosoma japonicum within the intestinal mucosa.
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Liver granulomata secondary to Schistosoma japonicum infestation.
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Granuloma within the intestinal mucosa secondary to Schistosoma mansoni infestation.
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Eggs of Schistosoma haematobium isolated from urinary sediment.
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Eggs of Schistosoma haematobium detected in the bladder.
