A case of varicella caused by co-infection with two different genotypes of varicella–zoster virus

We describe for the first time a case of varicella caused by co-infection with 2 genotypes of Varicella–zoster virus in a 19 month old child 3 days post-immunization with the varicella live vaccine. The presence of 2 different wild-type viruses in vesicular fluid was confirmed by amplification from single virus genomes and genotyping of single nucleotide polymorphisms (SNPs) known to distinguish the 5 different genotypes of VZV. The finding has important implications for recombination of wild type VZV.