Kenya’s hopes of being certified as a polio-free country have been dashed after the discovery of live polio viruses in sewage samples from Nairobi’s Eastleigh estate.
On April 6, 2018, Kenya Medical Research Institute personnel found the samples in the area during a routine investigation.
In a letter to county directors of health signed by Director of Medical Services Jackson Kioko, the Health ministry said the viruses could infect individuals and cause paralysis.
Polio is a crippling and potentially deadly infectious disease caused by the poliovirus.
The virus spreads from person to person and can attack an infected person's brain and spinal cord, causing paralysis, a condition in which a person cannot move parts of the body.
“On Friday, April 6, the ministry was notified by Kenya Medical Research Institute (Kemri) of isolation of polio virus type 2 from an environmental sample collected on March 21 from one of the sites in Eastleigh, Kamukunji sub County," said the government alert.
"Genetic sequencing of the isolate in CDC Atlanta laboratories subsequently confirmed it is circulating vaccine-derived polio type 2(CVDPV2),” read the ministry alert.
Kenya has been carrying out sample surveillance in targeted areas for possible polio outbreaks since 2013 after the large wild polio virus outbreak in Somalia which resulted in 14 cases.
The exercise is ongoing in nine locations spread across the four counties: Garissa, Kisumu, Mombasa and Nairobi.
“This type of virus has the capacity to cause paralysis in un-protected or un-immunised persons just like the wild polio viruses,” read Dr Kioko’s statement.
He confirmed that the type found in Eastleigh was a vaccine derived polio virus type 2, which comes from the oral polio vaccine mostly administered to children and contains a live but weakened virus.
In cases where the children are not properly immunised, the weakened vaccine virus can change its genetic structure or mutate in their intestines before being removed through human waste as a wild or naturally occurring virus.
The virus is then able to attack non-vaccinated individuals who may come into contact with the stool or respiratory discharges of the infected person like cough sputum, causing polio in the process.
Currently, Kenya is engaged in the process of replacing the weakened virus vaccine with the inactivated polio variety, which partly consists of a dead virus.
Dr Kioko said the ministry has conducted surveillance in Kamukunji sub-County for cases of active acute flaccid paralysis (AFP), assessment of population immunity, searching for viral infection cases in health facilities.
“A vaccination campaign has been planned in Nairobi County and will start from May 5, 2019 and end on May 9, 2018,” the ministry document stated.
Health care workers have subsequently been advised to remain on high alert for cases of patients with symptoms of AFP.
“Two stool samples should be collected (24 hours apart) from suspected cases and sent to Kemri polio laboratory for testing,” said Dr Kioko.
In February 2016, Kemri destroyed the remaining stockpiles of one of the poliovirus type 2 strain.
Prior to the discovery, Kenya was hoping to be certified polio-free this year.
National plans to apply for certification will now have to be postponed since the World Health Organisation does not view a country as being polio-free until 12 months pass without a reported case or positive environmental sample.
Dr Kioko said the last positive polio cases reported in Kenya were the 14 individuals who crossed over the country’s border from Somalia in 2013.