Wild poliovirus type 3 (WPV3)-shedding event following detection in environmental surveillance of poliovirus essential facilities, the Netherlands, November 2022 to January 2023.

On 21 November 2022, a wild poliovirus type 3 (WPV3) was isolated from an environmental surveillance sample of poliovirus essential facilities in the Netherlands. All 51 employees with access to this strain were screened for ongoing or recent poliovirus infection. One employee shedding WPV3 was identified on 8 December and placed in isolation; monitoring and contact tracing were initiated. WPV3 shedding continued for 4 weeks and stopped 5 January 2023. Isolation was lifted 11 January and no further transmission was detected.

Cytochrome oxidase c subunit 1 polymorphisms show significant differences in distribution between a laboratory maintained population and a field isolate of Cooperia oncophora.

A 474 bp fragment of the mitochondrial cytochrome oxidase c subunit 1 (cox1) of Cooperia oncophora was cloned and sequenced. The overall nucleotide diversity of the cox1 fragment varied from 0.5 to 2.0% between individuals. Two nucleotide substitutions were found within two RsaI endonuclease restriction sites and were used in a PCR-based restriction fragment length polymorphism (PCR-RFLP) assay to asses the intra-population variation of C. oncophora. Testing 816 individuals revealed the existence of three different haplotypes, having either both (type I) or only one (types II and III) RsaI site. Laboratory maintained individuals obtained at different time points after infection showed no significant difference in the distribution of the three haplotypes. Neither was there a difference in the distribution between male and female worms, confirming that the mitochondrial genome of C. oncophora is also maternally inherited. Nevertheless, there was a significant difference in the prevalence of the RsaI point mutation in the cox1 gene between the laboratory maintained population of C. oncophora and a Dutch field isolate, indicating that these RFLPs can be used to study genetic variation within or among C. oncophora populations.