The patient was a 13-year-old male from Yun County, Lincang City, Yunnan province. He went to the local city hospital on October 20, 2023, for treatment due to “Fever with right upper abdominal pain for over 2 days”. The abdominal CT showed uneven enhancement of the liver parenchyma with multiple patches of slight hypoenhancement, suggesting an infectious lesion. He was given ceftriaxone with other anti-infection treatments (dosage course of treatment was unknown) and praziquantel against helminth infections, but the symptoms did not improve. He was transferred to Kunming Children’s Hospital on November 9 for inpatient treatment. The physical examination showed a slight bulge below the xiphoid, pressure pain in the right epigastric region, a mass about 3 cm × 2.5 cm in size palpable at the outer edge of the rectus abdominis muscle on the right side, and the liver palpable 4 cm below the right costal margin and 5 cm below the xiphoid. Routine blood tests showed an elevated eosinophil count (1.02 × 10⁹/L) and elevated C-reactive protein (CRP) (68.54 mg/L). The other blood tests showed elevated alanine aminotransferase (90 U/L), aspartate aminotransferase (51 U/L), γ-glutamyltransferase (296 U/L), alkaline phosphatase (794 U/L), and immunoglobulin G (34.55 g/L), with accelerated sedimentation rate (67 mm/h). The blood cultures were negative. No eggs were found in stool under microscopy. Abdominal CT scan and enhancement showed multiple hypodense foci in the liver parenchyma, intrahepatic bile duct dilatation and possible cholangitis. The result of enzyme-linked immunosorbent assays for serum antibody against Fasciola hepatica was positive. Five sequences of F. hepatica and eight sequences of Pseudomonas aeruginosa were detected in the venous blood by metagenominext-generation sequencing, and no sequences of other pathogens were detected, such as fungi and viruses. The patient lived in a rural area and had a history of consuming cold watercress and drinking unboiled water. Epidemiological investigation, physical examination and relevant auxiliary test results led to the final diagnosis of F. hepatica combined with P. aeruginosa infection. Triclabendazole (500 mg/d once daily) was given for 2 days for deworming and meropenem [60 mg/(kg•d), three times a day)] was given as anti-infection treatment for 2 weeks, and he was discharged from the hospital without further fever and abdominal pain. After 3 months of follow-up and reexamination after discharge, no abdominal mass was touched, and the blood eosinophil count was normal. The abdominal CT scan showed that most of the lesions were smaller than before.