Background: Three reported Swedish cases of hepatitis C in patients receiving an intravenous immunoglobulin (Gammagard, Baxter Healthcare, Deerfield, IL) were among the first to bring to light a worldwide outbreak of hepatitis C associated with non-solvent/detergent (SD)-treated Gammagard. In February 1994, all implicated batches of Gammagard were recalled and exposed patients traced.
Study design and methods: Sera from all identified and hepatitis C-viremic Swedish and Danish patients (n = 14) exposed to the implicated batches underwent hepatitis C virus genotyping and sequencing of the core region and hypervariable region 1 of E2. Genomic amplification was also done on 15 non-SD-treated batches of Gammagard.
Results: Twelve patients were infected with subtype 1a and surprisingly, two with subtype 2b. Analysis of the core region showed identical sequences in four patients and the only consistently positive batch. Five patients shared another sequence, whereas three other subtype 1a patients each manifested unique sequences. The two subtype 2b isolates were identical. Genomic fingerprinting of the hypervariable region confirmed identity within each group with great stringency. Amplification with isolate-specific primers showed mixed infection in one patient whose exposure was confined to a single batch.
Conclusion: The few batches implicated presumably were contaminated with several strains.