What is the recommended treatment for a patient with paragonimiasis presenting with abdominal enlargement?

Treatment of Paragonimiasis with Abdominal Enlargement

For a patient with paragonimiasis presenting with abdominal enlargement, treat immediately with praziquantel 25 mg/kg orally three times daily for 2-3 days, and strongly consider adding corticosteroids to prevent pulmonary fibrosis and manage the inflammatory response during the migration phase. 1

Understanding the Clinical Context

Paragonimiasis characteristically presents in two distinct phases that directly inform your treatment approach:

• Early abdominal phase (weeks 1-2): Epigastric or abdominal pain, diarrhea, and urticaria occur as parasites migrate through the intestinal wall—this is when abdominal enlargement may be observed 1
• Pulmonary phase (week 2 onwards): Cough with sputum, pleuritic chest pain, and characteristic "chocolate" (foul-smelling) hemoptysis develop as flukes reach the lungs 1
• Abdominal pain and diarrhea commonly precede the classic respiratory symptoms 2

Your patient with abdominal enlargement is likely in the early migratory phase, making prompt treatment critical before pulmonary complications develop.

Definitive Pharmacologic Treatment

Primary Anthelmintic Therapy

Praziquantel is the drug of choice for all Paragonimus species, including P. westermani and P. kellicotti 1:

• Dosing: 25 mg/kg orally three times daily for 2-3 days 1
• This regimen achieves cure rates of 87-100% depending on total dose administered 3, 4
• Higher total doses (75 mg/kg/day for 2 days) achieve superior cure rates approaching 97-100% 3, 4

Adjunctive Corticosteroid Therapy

Corticosteroids should be strongly considered in symptomatic cases to prevent long-term pulmonary complications 1:

• The rationale is to prevent establishment of pulmonary fibrosis during the inflammatory migration phase 1
• While specific dosing regimens are not standardized in guidelines, corticosteroids are recommended based on expert opinion for patients with significant symptoms 1
• This is particularly important in your patient with abdominal symptoms, as they are in the active migration phase when inflammatory damage occurs

Diagnostic Confirmation Strategy

Do not delay treatment while awaiting diagnostic confirmation in a patient with compatible clinical presentation and epidemiologic exposure 2, 1:

• Eosinophilia is present in only about 50% of cases, so its absence does not exclude the diagnosis 1
• Elevated serum IgE is common 1
• Sputum or bronchoalveolar lavage microscopy to identify eggs is confirmatory, but eggs may not be detectable until the pulmonary phase is well-established 1, 5
• Serology (antibody detection) is the most promising early diagnostic approach, detectable as early as 2-3 weeks after infection 5
• Specialized serology can be performed at reference laboratories 1

Common Pitfalls to Avoid

Critical diagnostic error: Paragonimiasis often mimics tuberculosis or lung cancer, leading to delayed diagnosis and inappropriate treatment 1, 6, 7:

• Always inquire about consumption of raw or undercooked freshwater crabs or crayfish 6
• This is particularly important in immigrants from Asia, travelers returning from endemic areas, or individuals exposed to U.S. freshwater river systems where P. kellicotti is endemic 6

Treatment tolerance issue: One patient in a case series could not tolerate the standard 75 mg/kg daily dose due to nausea, and spreading the same total dose over 4 days resulted in treatment failure 4:

• If nausea occurs, consider antiemetics rather than dose reduction or prolongation
• Adverse effects include nausea, headache, and urticaria (possibly from antigen release from dying parasites) 4

Monitoring and Follow-up

Clinical and parasitological monitoring is essential:

• Most patients become ova-negative by day 90 post-treatment, though some may require up to 120 days 4
• Ongoing respiratory management by a pulmonologist may be helpful for patients who develop significant respiratory symptoms 1
• Repeat stool and sputum examination at 90 days to confirm cure 4

Special Consideration for Abdominal Enlargement

While abdominal enlargement is mentioned as a potential presentation, the specific etiology (hepatosplenomegaly, ascites, or other causes) should be evaluated:

• Visceral larva migrans can present with abdominal pain and hepatosplenomegaly, though usually with concurrent respiratory symptoms 2
• If hepatosplenomegaly is present, consider imaging to exclude other causes such as hydatid disease, which also presents with abdominal enlargement and eosinophilia 2

The treatment regimen remains the same regardless: praziquantel 25 mg/kg three times daily for 2-3 days with consideration for corticosteroids 1.