History of the Wastewater Assessment of Polio and Non-Polio Enteroviruses in the Slovak Republic in 1963-2019

Abstract

We describe the genesis of poliovirus (PV) and non-polio enterovirus (NPEV) surveillance program of sewage wastewaters from its inception to the present in the Slovak Republic (SR). Sampling procedures and evolution of the methodology used in the SR for the detection of PVs and NPEVs are presented chronologically. For statistical data processing, we divided our dataset into two periods, the first period from 1963 to 1998 (35 years), and the second period from 1999 to 2019 (21 years). Generalized additive models were used to assess temporal trends in the probability of occurrence of major EV serotypes during both periods. Canonical correspondence analysis on relative abundance data was used to test temporal changes in the composition of virus assemblages over the second period. The probability of occurrence of major viruses PV, coxsackieviruses (CVA, CVB), and Echoviruses (E)) significantly changed over time. We found that 1015 isolated PVs were of vaccine origin, called "Sabin-like" (isolates PV1, PV2, PV3). The composition of EV assemblages changed significantly during the second period. We conclude that during the whole period, CVB5, CVB4, and E3 were prominent NPEVS in the SR.

Keywords: enterovirus; non-polio enteroviruses; polio surveillance in Slovak Republic; wastewater assessment.

Figure 1

(a) Generalized additive models (GAM) showing temporal trends in the probability of enteroviruses (EV) strains, coxsackievirus A (CVA), CVB, echoviruses (E), and polioviruses (PV) occurrence during the first period (1963–1998). (b) Temporal trends in the probability of EV groups occurrence during the second period (1999–2019). GAM-based estimates (lines) are displayed along with their 95% confidence intervals.

Figure 2

Temporal trends in the probability of enterovirus (EV) strains, coxsackievirus A (CVA), CVB, echoviruses (E) and polioviruses (PV) occurrence during the second period (1999–2019). Generalized additive models (GAM)-based estimates (lines) are displayed along with their 95% confidence intervals.

Figure 3

Canonical correspondence analysis (CCA) ordination plot showing temporal changes in the assemblage composition of enterovirus (EV) strains, coxsackievirus A (CVA), CVB, echoviruses (E), polioviruses (PV), and vaccine-derived poliovirus (VDPV) during the second period (1999–2019). Only the most frequent strains with the best fit to the long-term temporal trend (first axis) are displayed (in italics). Sample scores are labelled by years (in blue), and the strain scores, representing the maxima of relative abundances, are shown in red. The ordination plot is scaled symmetrically; variation explained by the ordination axes is displayed in parentheses.