Role of environmental poliovirus surveillance in global polio eradication and beyond

Abstract

SUMMARYEnvironmental poliovirus surveillance (ENV) means monitoring of poliovirus (PV) transmission in human populations by examining environmental specimens supposedly contaminated by human faeces. The rationale is based on the fact that PV-infected individuals, whether presenting with disease symptoms or not, shed large amounts of PV in the faeces for several weeks. As the morbidity :infection ratio of PV infection is very low, this fact contributes to the sensitivity of ENV which under optimal conditions can be better than that of the standard acute flaccid paralysis (AFP) surveillance. The World Health Organization has included ENV in the new Strategic Plan of the Global Polio Eradication Initiative for years 2010-2012 to be increasingly used in PV surveillance, supplementing AFP surveillance. In this paper we review the feasibility of using ENV to monitor wild PV and vaccine-derived PV circulation in human populations, based on global experiences in defined epidemiological situations.

Surveillance of poliomyelitis in Northern Italy: Results of acute flaccid paralysis surveillance and environmental surveillance, 2012–2015

“…Although AFPS remains the gold standard for PV control, systematic ES has been recognized as a powerful tool to detect PV in the absence of AFP cases, especially in polio-free countries. 5,[7][8][9] According to Centralized Information System for Infectious Diseases (CISID), Italy -as several European countriesachieves barely the WHO target of AFPS performance indicators, 16 probably because of the low priority given to AFPS by national public health authorities and because Italy was declared "polio-free" in 2002 and since then PV has not been considered a health hazard anymore.…”

“…5 For these reasons, ES is currently recognized as a powerful tool for PV surveillance, especially in polio-free countries. 7,9 Since Non-Polio Enteroviruses (NPEVs) are widespread worldwide and -like PVs -can be transmitted by fecal-oral route, NPEVs detection is expected in ES and epidemiological field study on these viruses are encouraged. 5,[10][11][12][13][14] In Italy, nationwide AFPS was established in 1997, 15 whereas ES was set up in 2005 only in Milan and other 5 Italian cities (Bolzano, Parma, Sassari, Napoli and Palermo).…”

Polioviruses and other Enteroviruses

“…The advantage of ENVS is that it can detect PV circulation in the absence of clinical cases since virus is excreted into sewage during asymptomatic infections as well as symptomatic infections. Moreover, results can be semi quantitative as well as qualitative (Hovi et al, 2012;Hovi et al, 2001;Lodder et al, 2012;Manor et al, 2014).…”

“…ENVS and AFP surveillance will be critically important during the end stage of eradication and post eradication for documenting eradication and ensuring very early detection of any reemergence. ENVS will be especially important for populations with high IPV vaccine coverage, since the ratio of AFP cases to asymptomatic infections would be orders of magnitude lower than for under-vaccinated populations (Hovi et al, 2012 Live attenuated polio vaccine can be transmitted from person-to-person, a trait considered advantageous when WPV infections were endemic, but which is now problematic as the eradication endgame approaches (Dowdle et al, 2003). Specifically, like wild poliovirus, the OPV genome evolves during circulation.…”

Should Enteroviruses Be Monitored in Natural Recreational Waters?

“…EVs are not included in this monitoring program. The EV-surveillance in SR includes sampling of waters from the sewage treatment plants as a part of the screening of acute flaccid paralysis (AFP) cases for poliovirus (PV), and a part of the PV-surveillance according to the new strategic plan of the Global Polio Eradication Initiative (GPEI) supplementing surveillance of AFP (7). The EVs cause a wide spectrum of diseases ranging from sub-clinical mild flu-like illness to serious manifestations such as meningo-encephalitis, paralysis, myocarditis, and in neonates a fulminant sepsis-like syndrome.…”