Schistosomiasis has three clinical states.
The first stage is characterized by dermatitis and is caused by the cercariae.
The second stage is marked by fever and constitutional complaints (Katayama fever)
The third stage results in chronic fibro-obstructive disease which is caused by the eggs.
Acute Clinical Presentation
Dermatitis at the site of penetration
Fever results in S. mansoni and S. japonicum lasting 4-8 weeks
Acute onset: fever, headache, and cough
Heptosplenomegaly and Lymphadenopathy
Symptoms resolve in weeks but death may occur.
Eosinophilia
Chronic Clinical Presentaion
-Often asymptomatic
-Fatigue, colicky abdominal pain
-Intermittent diarrhea
-Effects on
the liver and intestines or bladder in S. haematobium
-Liver pre-sinusoidal blockage and increased portal pressure. Earliest sign
Hepatomegaly
-Intestinal granuloma, CNS (3%), Pulmonary (with patent portosystemic collateral circulation)
The first step in diagnosing Schistosomiasis is to take a thorough history and physical, and assess any possible history of exposure to contaminated water in endemic areas. Additionally, the doctor can look for acute symptoms such as cercarical dermatitis (an itchy, red rash) or fever.
Definitive diagnosis is confirmed by testing for the presence of eggs in the feces or urine of the individual. Stool or urine specimens can be filtered and the eggs per unit of liquid can be assayed in order to make a diagnosis. Additionally, visualization of the eggs may allow differentiation between the various species. A biopsy of rectal tissue can also reveal the presence of eggs.
More sophisticated techniques may use a blood test to look for Eosinophils, but this test should be cautioned for possible differential diagnoses. Other blood tests are also available, and serological immunodiagnostics are sometimes applicable. An ELISA can test for the presence of specfic antigenic sequences, and antibody staining may also reveal the presence of specific antigens. Much of the new research is focused on discovering the antigens presented by the schistosomes, and by understanding these protein sequences, new immunodiagnostic techniques might become available.