Seven cases of vaccine-derived poliovirus type 2 confirmed in DR Congo outbreak

The European Center for Disease Control (ECDC) says three different types of vaccine-derived poliovirus type 2 (cVDPV2)) outbreaks are circulating in the eastern Democratic Republic of Congo (DRC).

By July 9, seven cases were confirmed in four provinces of the eastern DRC. The ECDC said three strains of poliovirus type 2 were detected in cases of acute flaccid paralysis (AFP) in Ituri Province close to the border with Uganda.

“The cVDPV2 (poliovirus type 2) strain, which was previously detected in Haut Lomami, Tanganyika and Haut Katanga provinces, spread to Ituri Province in June 2018. The virus was confirmed in an acute flaccid paralysis (AFP) case, with onset of paralysis on 5 May 2018,” the ECDC said.

In April, the same poliovirus strain was isolated in stool specimens taken from two healthy community contacts in the same area, which was affected by outbreak in 2016 and 2017.

Due to the proximity of the affected provinces to neighbouring countries, the World Health Organization (WHO) and its emergency response partners have elevated the risk of cross-border transmission to ultra-high.

“This risk is magnified by population movements between the affected areas of the DRC and Uganda, Central African Republic and South Sudan, as well as the upcoming rainy season. The rainy season is associated with increased intensity of virus transmission.

“The detection of cVDPV2 underscores the importance of maintaining high routine vaccination coverage everywhere to minimise the risk and consequences of poliovirus circulation. These events also underscore the risk posed by any low-level transmission of the virus,” the analysis said.

The ECDC said the ongoing spread of the cVDPV2 in DRC demonstrated ‘significant gaps in population immunity’ at a critical time in the fight against polio.

The report also noted that the lack of polio vaccination programs in countries neighbouring the DRC heightened the risk of international spread at a time when overall population immunity is rapidly waning.

Like Kenya, Syria, Nigeria and Somalia, the DRC is considered as a cVDPV2 infected state with a higher potential for the outbreak spreading internationally.