Fresh threat to polio eradication as patient sheds immune disease for 28 years
A study published on August 27 in PLOS Pathogens reports results from an individual in the United Kingdom (UK) with an immune disease whose stool samples have contained large amounts of live polio virus for over 20 years. Patients like this one, the authors suggest, could start new polio outbreaks and complicate polio eradication as currently planned.
Until now, with all but two countries worldwide, Pakistan and Afghanistan, declared polio-free, the eradication of the devastating viral disease in the near future is a real possibility.
Nigeria, on July 24, 2015, for the first time, celebrated without recording any confirmed case of the Wild Polio Virus (WPV) and hopes to be certified polio-free if the momentum is sustained for another two years.
According to the latest edition of Weekly Polio Update published by the Global Polio Eradication Initiative (GPEI), published yesterday: “No new Wild Poliovirus Type 1 (WPV1) cases were reported in the past week. No cases have been reported in 2015. Nigeria’s total WPV1 case count for 2014 remains six. The most recent case had onset of paralysis on 24 July 2014 in Sumaila Local Council, Kano State.
“No new cases of type 2 circulating vaccine-derived poliovirus (cVDPV2) were reported in the past week. The most recent case had onset of paralysis in Kwali Local Council, Federal Capital Territory (FCT), Abuja, with onset of paralysis on May 16; this is the only cVDPV2 case reported in Nigeria in 2015.
“The Expert Review Committee met in Nigeria last week to review the progress made in Nigeria, identify ways to strengthen the gains of the last few years and identify the major risks to stopping polio across the country.
“In line with the National Emergency Action Plan for polio eradication, aggressive and rapid vaccination activities are conducted in response to any detected virus. Three case response ‘mopping-up campaigns’ using trivalent oral polio vaccine (tOPV) have taken place in the FCT and Kaduna and Kogi states, as well as in adjacent local councils of Niger and Nasarawa states to stop transmission of the persistent strain of cVDPV2. Sub-national Immunisation Days (SNIDs) are planned in the North of Nigeria on September 5 and October 17 using trivalent OPV.”
Also, according to the PLOS study, Javier Martin from the National Institute for Biological Standards and Control, Potters Bar, UK, and colleagues, analysed more than 100 stool samples collected between 1995 and 2015 from a white male. The individual received a full course of childhood immunisation, including OPV at five, seven and 12 months, with a booster at about seven years of age. He was later diagnosed with an immunodeficiency, which can affect the ability of the immune system to kill viruses in the digestive tract.
The researchers conclude that “enhanced surveillance including sewage sampling and stool surveys to search for the presence of iVDPV strains and the development of efficient anti-viral treatments to interrupt virus replication in immune-deficient individuals are needed to be able to identify and manage the possible risks of iVDPV strains spreading and causing disease in patients and the general population, particularly in the light of changes in vaccination strategies as part of the polio eradication endgame and the absence of an established outbreak response strategy”.
They added: “New polio vaccines such as those based on non-infectious virus-like particles or even new genetically designed stable live-attenuated versions with no associated risk of producing VDPVs, might be required to complete polio eradication.”