What is the recommended treatment for a patient infected with Paragonimus westermanii, considering their medical history and potential respiratory complications?

Treatment of Paragonimus westermani Infection

The recommended treatment for Paragonimus westermani infection is praziquantel 25 mg/kg three times daily for 2-3 days, with consideration for corticosteroids in severe cases to prevent pulmonary fibrosis. 1

First-Line Treatment Regimen

Praziquantel is the drug of choice for paragonimiasis caused by P. westermani and other Paragonimus species. 1, 2

• Standard dosing: Praziquantel 25 mg/kg orally three times daily for 2-3 days 2
• Alternative dosing from clinical trials: 3 doses of 25 mg/kg body weight on a single day achieved 71.4% cure rate, while the same dose for 2 consecutive days achieved 85.7% cure rate, and 3 consecutive days achieved 100% cure rate 3
• Cure rates exceed 90% in most case series when adequate dosing is used 4, 5

Adjunctive Corticosteroid Therapy

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

• The rationale is to prevent establishment of pulmonary fibrosis (expert opinion) 1
• Specific dosing regimens are not standardized in guidelines, but corticosteroids have been used based on expert opinion 1
• Ongoing respiratory management by a pulmonologist may be helpful for patients with significant respiratory symptoms 1

Symptomatic Management

Bronchodilators may be responsive for dyspnea in patients with respiratory symptoms (expert opinion). 1

Alternative and Adjunctive Therapies

Seek expert advice regarding doxycycline and diethylcarbamazine as these have theoretical benefit but require specialist consultation. 1

• These agents are mentioned in guidelines but their use requires caution and specialist input 1
• Relapses may occur, necessitating retreatment 1

Severe or Refractory Cases

In severe infections, a second course of praziquantel may be needed if initial treatment fails. 2

• For cerebral paragonimiasis (which occurs in approximately 1% of all paragonimiasis cases and 45% of extrapulmonary cases), praziquantel remains the treatment of choice at the same dosing 2
• Triclabendazole at 10 mg/kg twice daily has been used for some Paragonimus species (P. uterobilateralis, P. mexicanus, P. skrjabini), but its efficacy in P. westermani infection, particularly cerebral infections, remains unclear 2

Clinical Presentation to Recognize

Paragonimiasis presents in two phases that guide timing of diagnosis and treatment. 1

• Early phase (weeks 1-2): Epigastric or abdominal pain, diarrhea, and urticaria as parasites migrate through the intestinal wall 1
• Pulmonary phase (week 2 onwards): Cough with sputum, pleuritic chest pain, and characteristic "chocolate" (foul-smelling) hemoptysis 1
• Fever is rare, which helps distinguish it from other infections 1
• The presentation may mimic tuberculosis or lung cancer, requiring careful diagnostic workup 1, 5

Diagnostic Confirmation

Eosinophilia is present in only about half of cases, so its absence does not exclude the diagnosis. 1

• Elevated serum IgE is common 1
• Confirmation is by sputum or bronchoalveolar lavage microscopy to identify eggs 1
• Serology can be performed at specialized laboratories such as the Swiss Tropical and Public Health Institute 1
• Bronchoscopic examination is very useful for accurate diagnosis when sputum examination is negative 5

Special Considerations

Praziquantel is generally well tolerated with minimal side effects. 3, 5

• Common side effects include mild and transient headache and dizziness 3
• Anaphylactic reactions to praziquantel are rare but have been reported 4
• In cases of praziquantel allergy, rapid desensitization protocols have been successfully used 4
• Extended hematological and biochemical tests typically reveal no abnormal findings related to the drug 3

Monitoring Treatment Response

Follow-up should include both parasitological and radiological assessment. 3

• Disappearance of eggs in sputum/stool examination confirms parasitological cure 3
• Resolution of abnormal shadows on chest X-ray provides additional confirmation of cure 3
• Disappearance of precipitating bands on immunoelectrophoresis can also indicate successful treatment 3
• Monthly follow-up examinations for up to 4 months post-treatment are recommended 3

Potential Complications Requiring Surgical Intervention

Empyema may develop and require surgical decortication despite appropriate praziquantel treatment. 5

• This complication occurred in at least one reported case despite effective antimicrobial therapy 5
• Surgical consultation should be considered for patients with pleural complications 5