Thanks to the polio vaccine, the crippling and potentially deadly infectious disease has virtually disappeared in most of the world since the late 1970s.
However, “wild polio” virus outbreaks can be triggered by an infected person from a country such as Afghanistan, Pakistan or Nigeria, where the disease has not been eradicated and many people aren’t vaccinated.
Environmental surveillance (ES) data collected from wastewater following such an outbreak in Israel in 2013 has provided the basis for a new model to detect and assess polio outbreaks and help eradicate them completely.
In the March 29, 2017 issue of Science Translational Medicine, industrial engineering and management Prof. Yakir Berchenko from Ben-Gurion University of the Negev and his colleagues describe how their model enables detecting outbreaks earlier, determining the extent of the outbreaks more quickly and eliminating much of the guesswork in managing outbreaks and declaring them over.
There are two ways to assess a polio outbreak, the researchers explain. One is to wait for a case of paralysis to be reported. The other is environmental surveillance — regular checks of sewage or wastewater to test for poliovirus.
Until now, scientists did not think that environmental surveillance data was sensitive enough to be trustworthy, and therefore this alternative was not applied globally.
Following the detection of three pediatric cases of wild polio in Nigeria in summer 2016, the World Health Organization recommended that “all countries, in particular those with frequent travel and contacts with polio-affected countries and areas, strengthen surveillance for acute flaccid paralysis (AFP) cases in order to rapidly detect any poliovirus and to facilitate a rapid response” and further suggested that “any country infected by poliovirus should declare the outbreak as a national public health emergency and consider vaccination of all international travellers.”
A model to apply anywhere in the world
Berchenko and his colleagues developed a model that not only establishes the sensitivity of environmental surveillance data but actually proves it to be much more reliable than the alternative.
And while the data is derived specifically from the Israeli case, the model is applicable all over the world, say the scientists.
“These results will be valuable in monitoring future outbreaks with ES, and this approach could be used to certify poliovirus elimination or to validate the need for more containment efforts,” the Israelis wrote in their journal report, titled “Estimation of Polio Infection Prevalence from Environmental Surveillance Data.”
Berchenko’s coauthors on the polio study include Itamar Grotto from BGU’s department of public health; Yossi Manor from the Central Virology Laboratory of the Ministry of Health at Chaim Sheba Medical Center in Tel Hashomer; Laurence S. Freedman of the Biostatistics Unit of the Gertner Institute for Epidemiology and Health Policy Research at Tel Hashomer; Ehud Kaliner of Public Health Services in Jerusalem; Ella Mendelson from the Central Virology Laboratory and Tel Aviv University’s School of Public Health; and Amit Huppert of the Gertner Biostatics Unit and the TAU School of Public Health.