Schistosomiasis (cont.)

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What are the symptoms and signs of schistosomiasis?

Although a few patients may have minor skin irritation when the cercariae enter the skin, most people do not develop symptoms until the eggs develop (about one to two months after initial skin penetration). Then, fever, chills, cough, and muscle aches can begin within one to two months of infection. However, most people have no symptoms at this early phase of infection. Unfortunately, a few patients develop acute schistosomiasis (Katayama fever) during this one- to two-month period, and their symptoms resemble those for serum sickness and are as follows:

  • Fever
  • Abdominal pain (liver/spleen area)
  • Bloody diarrhea or blood in the stools
  • Cough
  • Malaise
  • Headache
  • Rash
  • Body aches

The majority of people who develop chronic schistosomiasis have symptoms develop months or years after the initial exposure to the parasites. The following is a list of most symptoms associated with chronic schistosomiasis. Patients usually have a few of these symptoms.

  • Abdominal pain
  • Abdominal swelling (ascites)
  • Bloody diarrhea or blood in the stools
  • Blood in the urine and painful urination
  • Shortness of breath and coughing
  • Weakness
  • Chest pain and palpitations
  • Seizures
  • Paralysis
  • Mental status changes
  • Lesions on the vulva or the perianal area

How is schistosomiasis diagnosed?

The presumptive diagnosis of schistosomiasis is based on the medical caregiver's history and physical examination of the patient. It is important to know that a person has inhabited or visited areas of the world where the disease is endemic, especially if the person has had skin exposure to freshwater lakes and streams. If the patient has that history and has symptoms that are described above, a presumptive diagnosis may be made. However, because symptoms of schistosomiasis resemble those of serum sickness and other diseases, definitive diagnostic tests are usually required. Thick fecal smears and urine concentration tests are used to determine if any Schistosoma spp. eggs are present. If eggs are found, the patient is definitively diagnosed with schistosomiasis. In addition, most eggs from each species are shaped differently so it is possible to determine which Schistosoma spp. is infecting the patient. Sometimes the definitive diagnosis is made by examination of biopsy samples of tissue; the eggs are visualized in the infected tissue.

Blood tests and, more recently, polymerase chain reaction (PCR) tests can help confirm the diagnosis, but positive results may only indicate past exposure. However, these tests are not usually positive until the patient has been infected for about six to eight weeks because it takes time for the eggs to develop and stimulate the human immune response. The PCR test is available from the U.S. Centers for Disease Control and Prevention.

Many other tests and procedures may be necessary to establish the diagnosis, especially if no eggs are found in the feces or urine, which is often the situation in chronic schistosomiasis. Colonoscopy, cystoscopy, endoscopy, and liver biopsy are all methods that can be used to obtain tissue biopsy material. In addition, ultrasound, chest X-rays, CT, MRI, and echocardiograms may be used to determine the extent of the infection in various organ systems. Most physicians will run additional blood tests (CBC, liver function tests, renal function tests) to determine if organs have been damaged by the parasites.

Medically Reviewed by a Doctor on 1/16/2014

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