Trematode Infection Clinical Presentation

Updated: Feb 19, 2019
  • Author: Subhash Chandra Parija, MD, MBBS, PhD, DSc, FRCPath; Chief Editor: John L Brusch, MD, FACP  more...
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Acute manifestations

Cercarial dermatitis, also known as swimmer's itch, is an allergic reaction caused by the penetration of cercariae in persons who have been exposed to cercariae in fresh water. Cercarial dermatitis manifests as petechial hemorrhages with edema and pruritus, followed by maculopapular rash, which may become vesicular. The process is usually related to avian schistosomal species of the genera Trichobilharzia,Gigantobilharzia, and Orientobilharzia, which do not develop further in humans.

Katayama syndrome corresponds to maturation of the fluke and the beginning of oviposition. This syndrome is caused by high worm load and egg antigen stimuli that result from immune complex formation and leads to a serum sickness–like illness. This is the most severe form and is most common in persons with S mansoni and S japonicum infections. Symptoms include high fever, chills, headache, hepatosplenomegaly, lymphadenopathy, eosinophilia, and dysentery. A history of travel in an endemic area provides a clue to the diagnosis.

Chronic manifestations

Symptoms depend on the Schistosoma species that causes the infection, the duration and severity of the infection, and the immune response of the host to the egg antigens.

Terminal hematuria, dysuria, and frequent urination are the main clinical symptoms of urinary schistosomiasis.

The earliest bladder sign is pseudotubercle, but, in longstanding infection, radiography reveals nests of calcified ova (sandy patches) surrounded by fibrous tissue in the submucosa.

Dysentery, diarrhea, weakness, and abdominal pain are the major symptoms of intestinal schistosomiasis.

A reaction to schistosomal eggs in the liver causes a periportal fibrotic reaction termed Symmers clay pipestem fibrosis.

Hemoptysis, palpitation, and dyspnea upon exertion are the symptoms of schistosomal cor pulmonale that develops as a complication of hepatic schistosomiasis.

Headache, seizures (both generalized and focal), myeloradiculopathy with lower limb and back pain, paresthesia, and urinary bladder dysfunction are the noted symptoms of CNS schistosomiasis due to S japonicum infection.

Neuroschistosomiasis is a severe manifestation of schistosomal infection. The neurological symptoms result from the inflammatory response of the host to the deposition of eggs in the brain and spinal cord. Myelopathy is the most common neurological complication of Smansoni infection. [18]


Acute manifestations include acute pulmonary infection is characterized by low-grade fever, cough, night sweats, chest pain, and blood-stained rusty-brown sputum.

Chronic manifestations can include lung abscess or pleural effusion. [19] Fever, hemoptysis, pleurisy pain, dyspnea, and recurrent attacks of bacterial pneumonia are the common symptoms. The condition mimics pulmonary tuberculosis.

Fever, headache, nausea, vomiting, visual disturbances, motor weakness, and localized or generalized paralysis are the symptoms of cerebral paragonimiasis.

Pulmonary paragonimiasis has been found to mimic metastatic pulmonary tumors on evaluation with imaging methods such as computed tomography (CT) and positron emission tomography (PET) scanning. [20]

Paragonimiasis can affect all parts of the human body, and reports have described cerebral paragonimiasis in the last few years. The rate of cerebral paragonimiasis has been found to be about 0.8% of all active cases of paragonimiasis. [21]

Liver fluke infections

Acute manifestations

Fascioliasis is mostly subclinical. Acute manifestations are due to migration of larva through lung parenchyma. Malaise, intermittent fever, night sweats, and pain in the right costal area are early symptoms of acute infection.

Clonorchiasis is frequently asymptomatic. A serum sickness–like illness with symptoms of high fever, eosinophilia, and rash occurs in individuals with acute infection.

Chronic manifestations

Chronic fascioliasis is frequently asymptomatic. In symptomatic patients, irregular fever, anemia, hepatobiliary manifestations (colicky pain, jaundice), and secondary bacterial infections are present.

In its end stage, chronic clonorchiasis may be complicated by recurrent pyogenic cholangitis and jaundice associated with cholangiocarcinoma.

Intestinal fluke infections

These infections are frequently asymptomatic. Diarrhea and abdominal pain are common symptoms in individuals with acute infection.

Generalized abdominal pain; ascites; and edema of the face, abdomen wall, and lower limbs are the main symptoms.




Acute infections manifest hepatosplenomegaly, lymphadenopathy, and rashes.

Chronic schistosomiasis manifests anemia, pedal edema, ascites, and abdominal distension with distended abdominal veins. Patients may also have intestinal polyposis and signs of malnutrition.


Abdominal mass, pain in the abdomen, and mucosanguineous diarrhea characterize abdominal paragonimiasis.

Liver fluke infections

Patients with chronic clonorchiasis may have tender hepatomegaly, progressive ascites, catarrhal cholecystitis, progressive edema, and jaundice.

Intestinal fluke infections

Patients with mild infection are usually asymptomatic. Patients with severe infections may have ascites and edema of the face, abdomen wall, and lower limbs.



See Pathophysiology.



Schistosomiasis complications can include the following:

  • Cor pulmonale

  • Portal hypertension

  • Urinary bladder carcinoma

  • Neurological complications: Cerebral and cerebellar tumour–like neuroschistosomiasis can present with increased intracranial pressure, headache, nausea and vomiting, and seizures. Myelopathy (acute transverse myelitis and subacute myeloradiculopathy) is the most common neurological complication of S mansoni infection. Schistosomal myelopathy tends to occur early after infection and is more likely to be symptomatic than cerebral schistosomiasis. The conus medullaris and cauda equina are the most common sites of involvement. Severe schistosomal myelopathy can provoke a complete flaccid paraplegia with areflexia, sphincter dysfunction, and sensory disturbances. [18]

Lung fluke complications can include the following:

  • Lung abscess

  • Pleural effusion

  • Ectopic lesions in the brain

Liver fluke complications can include the following:

  • Intercurrent bacterial infections

  • Less commonly, pancreatitis in fascioliasis [22]

  • Anemia

  • Recurrent pyogenic cholangitis and cholangiocarcinoma in clonorchiasis

Intestinal fluke complications can include asthenia with ascites in fasciolopsiasis.