Schistosomiasis laboratory findings

Methods for diagnosing schistosomiasis include visualization of Schistosoma eggs in stool, urine, and crushed biopsy tissues. serologic assays and urinary antigen testing have also been used. Laboratory findings consistent with the diagnosis of schistosomiasis include detection of circulating antibodies to schistosomes and schistosomal antigen in serum.

Visualization of Schistosoma eggs in stool, urine, and crushed biopsy tissues is diagnostic of schistosomiasis. Laboratory findings consistent with the diagnosis of schistosomiasis include detection of circulating antibodies to schistosomes and schistosomal antigen in serum. Diagnostic tests for schistosomiasis include the following:^[1][2][3]

• Microscopic examination of stool
• Urine testing for schistosome eggs
• Serologic testing
• Schistosomal antigen testing (urine or serum)
• Microscopic examination of tissue
• PCR to detect schistosomal DNA

• The classic and most commonly used method for identification of schistosome eggs in stool is a modified Kato-Katz thick smear.^[4]
• Testing should be done on formed stool, as schistosomiasis typically does not cause diarrhea.
• Several areas of a stool specimen should be evaluated independently, as eggs are not deposited uniformly throughout. In addition, eggs are not deposited uniformly throughout the day, and, thus, three different stool specimens should be evaluated.
• One to 99 eggs/g is suggestive of mild infection, 100 to 299 eggs/g indicate moderate infection, and more than 300 eggs/g are indicative of high-intensity infection.
• Kato Katz smears are not sufficiently sensitive for detection of low-intensity infections. Other techniques may be superior but often are unavailable or more difficult to use.

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Other laboratory tests

Other diagnostic tests that are helpful in diagnosis of schistosomiasis include:

• Urinalysis, including dipstick testing and microscopic analysis for leukocytes, erythrocytes, and casts.
• Measurement of blood urea nitrogen (BUN) and serum creatinine to test renal function.
• Liver function tests
• Complete blood count (CBC)
  • Anemia
  • Eosinophilia