By Kemo Cham
Health authorities in Sierra Leone have cautioned parents to ensure children are vaccinated against polio, after a Type 2 poliovirus was detected in a sewage system in Freetown.
The discovery of the virus in the sewage system in Mabela, one of the city’s most populated slum communities, came a day after confirmation of a human case of type 3 poliovirus in a child in the northern district of Kambia.
The National Public Health Agency (NPHA) said both cases were vaccine derived poliovirus. These are attenuated or the weakened form of the virus which were used to manufacture the vaccine.
The samples were tested in Abidjan, Ivory Coast and confirmed in South Africa, in line with international public health protocol, the Agency said in separate statements.
“The child was extremely malnourished and shedding vaccine derived poliovirus, a rare occurrence,” the NPHA said in the first statement issued on Friday, March 8.
Polio is an illness caused by a virus that mainly affects nerves in the spinal cord or brain stem. In its most severe form, polio can lead to a person being unable to move certain limbs, also called paralysis. It can also lead to trouble breathing and sometimes death. The disease also is called poliomyelitis.
Mr Harold Thomas, Communications Lead at the NPHA and head of the Public Health Education Programme in the Ministry of Health, said the case in Mabela was discovered as part of a routine environmental surveillance system.
The sample was taken from water under a popular bridge in the community, he told ManoReporters.
“It is concerning because if it is under the sewage, it means somebody is shedding it there. At least one persons is shedding the virus. It could be an adult, it could be a child. If it is an adult, it won’t likely show sign of polio, but it could infect children under five years and they could get paralysis,” Thomas said in a telephone interview.
According to the World Health Organization (WHO), of the three strains of wild poliovirus (type 1, type 2 and type 3), wild poliovirus type 2 was eradicated in 1999 and wild poliovirus type 3 was eradicated in 2020. As at 2022, endemic wild poliovirus type 1 remains in only two countries – Pakistan and Afghanistan.
Vaccine derived polio virus are rare, and experts say they circulate only due to low vaccination rate.
Thomas said this has been the case in the Mano River Basin.
According to WHO, 23 countries in the WHO Africa Region recorded cases of the circulating cVDPV2 between 2020 and 2021.
In Sierra Leone, between December 2020 and June 2021, a total of 34 confirmed cases were recorded.
But Thomas pointed out that the fact that these viruses have been detected shows that Sierra Leone’s public health surveillance system is sharp and working.
The risk communication expert however warned that there is no room for complaisance even with this form of the virus, as both have potential to cause paralysis.
“We usually don’t underestimate them because a virus is a virus,” he said.
“If we don’t do something about it, we fear that it could be a problem,” he added.
The NPHA said together with the Ministry of Health, it is collaborating with neighbouring countries on cross border surveillance.
“The NPHA, MOH and WHO along with technical partners, are actively educating the public about polio and vaccination, strengthening national surveillance systems and implementing a robust response plan,” it said.
