Paragonimiasis Clinical Presentation

  • Author: Seth D Rosenbaum, MD; Chief Editor: Russell W Steele, MD  more...
Updated: Jun 17, 2016


About 20% of patients with paragonimiasis are asymptomatic. Abdominal pain, diarrhea, and urticaria occur during the acute phase, which corresponds to the period of invasion and migration of immature flukes. These initial symptoms are followed a few days later by fever, cough, dyspnea, chest pain, malaise, and sweats. The acute phase usually persists for several weeks. During the chronic phase, manifestations may be pulmonary or extrapulmonary. Chronic pulmonary symptoms consist of dry cough followed by a cough productive of tenacious and rusty or golden sputum. Pulmonary symptoms begin approximately 6 months after infection and are often mistaken for symptoms of tuberculosis (TB). The American College of Chest Physicians has established clinical practice guidelines for chronic due to TB and other infections.[5]

Eosinophilia and lack of fever suggest the true diagnosis. Peripheral eosinophilia is present in as many as 25% of patients.[6] Patients frequently report vague chest discomfort, dyspnea on exertion, or wheezing. Life-threatening hemoptysis may occur in some cases. Extrapulmonary paragonimiasis can be divided into cerebral, abdominal, subcutaneous, and miscellaneous forms of the disease.[7]

Extrapulmonary paragonimiasis can occur either from the migration of young or mature flukes to various organs or from eggs that enter the circulation and are carried to the following sites:

  • Liver
  • Spleen
  • Kidney
  • Brain
  • Intestinal wall
  • Peritoneum
  • Mesenteric lymph nodes
  • Muscle
  • Testis/ovary
  • Subcutaneous tissues
  • Spinal cord

Although cerebral paragonimiasis occurs in fewer than 1% of symptomatic patients, it is the most common extrapulmonary site of infection and is responsible for 50% of all extrapulmonary disease.[1] Moreover, it is seen in as many as 25% of patients requiring hospitalization. This form of the disease is also particularly common in children. Early symptoms resemble meningoencephalitis and may persist 1-2 months. Chronic phase symptoms include headache, vomiting, seizures, or weakness.

Eggs and worms may also cause surrounding cysts, abscesses, or granulomas to form. Cysts may occur in the intestinal wall, liver, spleen, abdominal wall, peritoneal cavity, or mesenteric lymph nodes. Symptoms may include bloody diarrhea or abdominal pain.

Xia et al conducted a retrospective analysis of clinical characteristics and treatment of recently diagnosed cases of cerebral paragonimiasis.[8] Their study cohort consisted of 27 patients who were diagnosed between September 2008 and September 2013. These diagnoses were confirmed by IgG enzyme-linked immunosorbent assays. Follow-up was performed for 24 patients during a period of 6 to 56 months. Cerebral paragonimiasis accounted for 27 of 125 cases (21.6%) of paragonimiasis. The average duration from onset to treatment with praziquantel was 69 days. All patients resided in rural areas. Positive lung results were found in 20 patients; of these patients, visible lung lesions were found in 14. The lesions were surgically removed in 8 of these cases. High eosinophil counts were found in 24 patients, and eosinophilic meningitis was noted in 17. The rate of misdiagnosis and missed diagnosis was 30.4%. Most symptoms markedly improved aftertreatment, but mild movement disorders in conjunction with impaired memory and personality changes persisted in a small number of patients. The investigators advised that clinicians be alert to the possibility of cerebral paragonimiasis in young patients (aged 4-16 years) who have primary symptoms of epilepsy and hemorrhage. Liquid-based cytologic examination of cerebral spinal fluid and peripheral blood eosinophil counts can aid in differentiating cerebral paragonimiasis from similar diseases.[8]



Physical findings are usually not impressive in pulmonary paragonimiasis, but may include the following:

  • Clubbing of the fingers occasionally occurs.
  • Lungs are normally clear but rales, egophony, or dullness to percussion may occur with complications such as pneumonia or pleural effusion.
  • Cough begins as dry and progresses to productive with blood-tinged sputum. [1] The late clinical picture is similar to chronic bronchitis or bronchiectasis with profuse expectoration, pleuritic chest pain, dyspnea, cough, and occasional hemoptysis.
  • Signs of cerebral paragonimiasis include facial palsy, hemiplegia, seizures, and paraplegia.
  • Ocular signs include impaired visual acuity because of optic atrophy, papilledema, and hemianopsia.
  • Spinal involvement may produce monoplegia, paraplegia, lower extremity paresthesias, or sensory loss.
  • Findings in cases of abdominal involvement may include palpable masses.
  • Hematuria may be observed with kidney involvement, and eggs may sometimes be detected in the urine.
  • Patients with subcutaneous paragonimiasis can present with migratory swelling or subcutaneous nodules containing immature flukes. These firm, mobile, and tender subcutaneous nodules are often found in the lower abdominal and inguinal region.
  • Scrotal paragonimiasis may mimic epididymitis or an incarcerated hernia.


Factors that facilitate the life cycle of the flukes and subsequent transmission of infection to humans include the following:

  • Large numbers of reservoir and intermediate hosts
  • Behaviors such as spitting
  • Culinary habits

In Asia, raw and undercooked crab or crayfish are popular foods. In Korea and Japan, raw crayfish are used to treat measles, diarrhea, and skin conditions. Some tribes in Africa eat raw crustaceans to cure infertility. Peruvians eat raw crab with vegetables and lemon juice. Paragonimiasis may also be acquired by consuming raw meat from a paratenic host that contains young flukes (eg, wild boar as "sashimi"). Raw crawfish is also popular in the Mississippi Basin.[9] Infection may also be transmitted via contaminated kitchen utensils (eg, cutting boards, knives) or from cloths used to squeeze and strain juices from crabs for the preparation of soup.

Contributor Information and Disclosures

Seth D Rosenbaum, MD Attending Physician in Infectious Diseases, Medical Specialty Associates, PA

Seth D Rosenbaum, MD is a member of the following medical societies: American College of Physicians, American Medical Association, American Society for Microbiology, Infectious Diseases Society of America

Disclosure: Nothing to disclose.


Annette C Reboli, MD Professor of Medicine, University of Medicine and Dentistry of New Jersey; Head, Division of Infectious Diseases, Department of Medicine, Cooper University Hospital and University Medical Center

Annette C Reboli, MD is a member of the following medical societies: Infectious Diseases Society of America

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Chief Editor

Russell W Steele, MD Clinical Professor, Tulane University School of Medicine; Staff Physician, Ochsner Clinic Foundation

Russell W Steele, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Immunologists, American Pediatric Society, American Society for Microbiology, Infectious Diseases Society of America, Louisiana State Medical Society, Pediatric Infectious Diseases Society, Society for Pediatric Research, Southern Medical Association

Disclosure: Nothing to disclose.


Leslie L Barton, MD Professor Emerita of Pediatrics, University of Arizona College of Medicine

Leslie L Barton, MD is a member of the following medical societies: American Academy of Pediatrics, Association of Pediatric Program Directors, Infectious Diseases Society of America, and Pediatric Infectious Diseases Society

Disclosure: Nothing to disclose.

Jennifer Patterson, DO Fellow, Department of Infectious Diseases, Cooper University Hospital, Robert Wood Johnson School of Medicine

Jennifer Patterson, DO is a member of the following medical societies: American Osteopathic Association

Disclosure: Nothing to disclose.

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This micrograph depicts an egg from the trematode parasite Paragonimus westermani. Eggs range in size from 68-118 µm x 39-67 µm. They are yellow-brown and ovoidal or elongated, with a thick shell. They are often asymmetrical, with one end slightly flattened. At the large end, the operculum (ie, lid or covering) is visible. Photo courtesy of The Centers for Disease Control and Prevention.
This is an illustration of the life cycle of Paragonimus westermani, one of the causal agents of paragonimiasis. Photo courtesy of The Centers for Disease Control and Prevention.
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