An eradicated type of wild polio surfaced in routine wastewater monitoring within the Netherlands final yr, providing a cautionary story on the significance of monitoring for the tenacious virus, researchers report this week within the journal Eurosurveilance.
The sewage pattern got here up constructive for infectious poliovirus in mid-November and genome sequencing revealed a pressure of untamed poliovirus kind 3, which was declared globally eradicated in 2019. Its potential revival can be a devastating setback within the decades-long effort to stamp out extremely infectious and doubtlessly paralytic germ for good.
For transient background, there are three sorts of wild polioviruses: kind 2 and kind 3 have been eradicated, with the previous being knocked out in 2015. Wild poliovirus kind 1 continues to flow into in Afghanistan and Pakistan. There are additionally occasional vaccine-derived polioviruses that flow into in communities with low vaccination charges, which lately occurred in New York.
The constructive wastewater pattern final yr was the primary and solely indication of a polio an infection with the bygone pressure within the Netherlands. It occurred in an worker of a vaccine manufacturing facility run by Bilthoven Biologicals, which makes inactivated polio vaccines. The Netherlands had arrange routine wastewater surveillance across the manufacturing website to watch for such a viral escape.
The genome sequencing made clear it was an lively an infection quite than a case of the virus being dumped down the drain in some way. The virus isolates had two to 3 mutations, suggesting human shedding. As such, officers labored to establish which staff had entry to kind 3 polio within the weeks earlier than the constructive pattern. They narrowed it right down to 51 staff and examined blood and stool samples from every. Just one got here up constructive.
It is unclear how this worker grew to become contaminated. The individual was absolutely vaccinated towards polio and had no signs. Nonetheless, they have been shedding infectious virions of an in any other case eradicated virus of their stool, which might doubtlessly unfold to others. Furthermore, the individual lived in a group with vaccination protection of lower than 90 p.c.
On December 8, the worker agreed to enter isolation with day by day supervision from native well being employees. Bilthoven Biologicals positioned its contaminated worker in a home designed for isolation, located in a group with greater than 90 p.c vaccination protection. Native well being employees made certain the individual adopted strict hygiene measures whereas they have been nonetheless shedding viruses. The individual’s feces have been collected in a disposable system and incinerated. The individual was solely allowed to see individuals exterior, with no bodily contact.
The contaminated worker spent the following 33 days in isolation, together with over the vacations, till they’d three consecutive damaging stool samples. Total, the individual shed the virus over 51 days. However contact tracing and additional worker testing discovered no proof of different infections, and wastewater sampling didn’t flip up another constructive samples.
In all, native well being officers emphasised the significance of surveillance on this case. “This occasion exhibits that incidents that result in a breach of containment and even an an infection can stay unnoticed and never reported if routine monitoring is just not in place,” they concluded.
