Eradicated wild polio surfaced last year during routine wastewater monitoring in the Netherlands. This offers a cautionary tale about the importance of persistent virus monitoring.
Sewage samples proved positive for infectious poliovirus in mid-November, and genome sequencing revealed a strain of wild poliovirus type 3 declared globally eradicated in 2019 . Permanently highly contagious and potentially paralyzing bacteria.
As a brief background, there are three types of wild poliovirus. Types 2 and 3 have been eradicated, the former he eradicated in 2015. Wild poliovirus type 1 continues to circulate in Afghanistan and Pakistan. There have also been occasional outbreaks of vaccine-derived poliovirus in communities with low vaccination coverage, such as the recent outbreak in New York.
Last year’s positive wastewater sample was the first and only indication of a previous strain of polio in the Netherlands. It occurred among employees at a vaccine manufacturing facility run by Bilthoven Biologicals, which manufactures inactivated polio vaccines. The Netherlands had set up regular wastewater monitoring around production sites to monitor for such virus spills.
Genome sequencing revealed that the virus was an active infection rather than a case of somehow being dumped down the drain. Viral isolates had two to three mutations, suggesting human shedding. So officials worked to identify which employee had access to her polio type 3 in the weeks before the positive samples. They narrowed it down to 51 employees, testing blood and stool samples for each. Only one person tested positive.
It is unknown how this employee became infected. The person was fully vaccinated against polio and had no symptoms. Yet, they were excreting infectious virions of otherwise eradicated viruses in their faeces, which could spread them to others. lived in
On December 8, the employee agreed to quarantine under daily supervision from local health workers. Bilthoven Biologicals placed the infected employee in a house designed for isolation. This home is located in a community where vaccination coverage is over 90% of his. Local health workers confirmed that the person was following strict hygiene measures while shedding the virus. The person’s faeces were collected in a single-use system and incinerated. The person was only allowed to see people outside without physical contact.
Infected employees were quarantined for 33 days, including holidays, until three consecutive negative stool samples were obtained. Overall, she shed virus for 51 days. However, contact tracing and further employee testing found no evidence of other infections. Also, no other positive samples were found in wastewater sampling.
Overall, local health officials stressed the importance of surveillance in this case. “This incident shows that incidents leading to containment breaches and even infections can go unnoticed and go unreported if regular surveillance is not in place,” they concluded.
