On 18 June 2014, Brazil reported to the World Health Organization (WHO) that wild poliovirus type 1 (WPV1) had been detected in a sewage sample collected in March 2014 at Viracopos International Airport in Sao Paolo state. Genetic sequencing indicates that this virus is most closely related to the virus that is circulating in Equatorial Guinea.
Four wild poliovirus type 1 (WPV1) cases have been reported in Equatorial Guinea in 2014. The index case – Equatorial Guinea’s first case to be reported since 1999 – had onset of paralysis on 28 January 2014; the country’s most recent case occurred on 3 April 2014. Genetic sequencing indicates these cases are linked to an ongoing WPV1 outbreak in Cameroon (Cameroon’s most recent case was on 31 January 2014).
Back in March 2014, the World Health Organization elevated the risk assessment of the international spread of polio from central Africa, particularly Cameroon, to very high. An analysis of immunity levels across central Africa found important immunity gaps in most countries in 2014, prompting the large-scale polio immunization campaigns that are ongoing in the area.
To date, no one in Brazil has been paralyzed by the virus nor is there evidence of transmission within the population of that country, but the discovery of poliovirus in Brazil demonstrates that the risk of international spread from central Africa remains very high.
“This importation event in Brazil demonstrates that all regions of the world continue to be at risk of exposure to wild poliovirus until polio eradication is completed globally,” stated the WHO. “It is important that all countries, in particular those with frequent travel and contacts with polio-affected countries and areas, strengthen surveillance for polioviruses in order to rapidly detect any new virus importations and to facilitate a rapid response.”
Given Brazil’s high levels of population immunity, reflected in the high routine immunization coverage (>95%) and periodic vaccination campaigns, the lack of evidence so far of WPV1 transmission and the response being implemented, WHO assesses the risk of spread of this virus within or from Brazil as low.
Source: World Health Organization, adapted.