Detection of two different polio virus strains in wastewater samples from Cape Town has prompted a public health response, but the national Department of Health says there is no need for panic as no human cases have been identified.

The National Institute for Communicable Diseases (NICD) informed the department that the strains, identified as VDPV3 and nOPV2-L, were detected during routine environmental and wastewater surveillance in the Western Cape.

The department said in a statement, the testing forms part of proactive disease monitoring aimed at detecting emerging outbreaks and viral variants before clinical cases appear.

Officials stressed that the detections are classified as “vaccine events” because the viruses were not found in any person.

“No outbreak has been declared and no additional vaccination campaign is required,” read the statement.

Polio is a vaccine-preventable disease, and South Africa was officially declared polio-free by the World Health Organization’s African Regional Certification Commission in September 2019.

According to the department, the viruses detected are likely linked to imported cases involving people vaccinated with different vaccines from those used in South Africa.

The department said it is working with the NICD and has since strengthened surveillance measures and increased the frequency of wastewater sampling as part of ongoing monitoring and outbreak preparedness.

It said the detections do not translate into an outbreak and reassured the public that there is no need for panic.

However, residents are encouraged to remain vigilant and report any suspected symptoms to healthcare providers.

Symptoms associated with polio can include progressive muscle or joint weakness and pain, fatigue, muscle wasting, breathing or swallowing difficulties, and sleep-related breathing disorders, although these symptoms may also be linked to other medical conditions.

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