Uganda on high alert after polio outbreak in South Sudan

HEALTH

The Ministry of Health has urged all districts countrywide to intensify polio surveillance following the outbreak of a vaccine-derived poliovirus disease in South Sudan. 

In a letter dated November 17, 2020, the ministry's director-general of health services, Dr Henry Mwebesa, instructed all districts to undertake urgent risk mitigation measures by intensifying active surveillance and routine immunisation through daily vaccination services. 

THREE CASES 

Mwebesa noted that with three cases confirmed from Jur River County in Western Bahr el Ghazal state, Tonj North County in Warrap state and Torit County in Eastern Equatoria state close to the Uganda border, the risk of importation of the virus is high. The cases were reported between June and September last year. 

"The risk of importation (of polio virus)  into Uganda and failure to detect is high on account of the proximity of the latest case to northern Uganda and large-scale population movements across the two countries," he said. 

Mwebesa noted that the risk is also high because of the 90% coverage of polio Type 2 containing vaccine and the weak Acute Flaccid Paralysis (AFP) surveillance in Uganda, where 25 out of the 135 districts are silent and 78 have not reached the required threshold of two AFP cases per 100,000 persons. 

NEW POLIO VARIANT 

In August last year, the World Health Organisation (WHO) announced that wild polio had been eradicated in Africa, but two weeks later, the new polio variant outbreak was announced in Sudan. The outbreak has also been recorded in Chad, Central Africa Republic and DR Congo. 

The WHO has linked the virus to the oral polio vaccine that uses a weakened form of the virus. It warned that the risk of spread of the virus to other parts of the continent is high. The vaccine-derived polio virus is, therefore, a strain of the weakened poliovirus that was initially included in the oral polio vaccine and has changed over time. 

According to scientists, it behaves more like the wild or naturally occurring virus. 

The WHO said two children, one from South Darfur and the other from Gadarif state, were paralysed  in March and April. Both had been recently vaccinated against polio. It said that sequencing of viruses isolated in Sudan indicated that they are related to those reported earlier in Chad, from where there were multiple separate introductions into Sudan from Chad. 

RISK ASSESSMENT 

The WHO said their risk assessment found that transmission is high across central Africa and the Horn of Africa. 

"It is important that all countries, in particular those with frequent travel and contacts with polio-affected countries and areas, strengthen surveillance for AFP in order to detect any new virus importation and to facilitate a rapid response. Countries, territories and areas should also maintain uniformly high routine immunisation coverage at the district level to minimise the consequences of any new virus introduction," WHO advised. 

The WHO said all travellers to polio-affected areas should be vaccinated against the virus, while residents and visitors from polio-affected areas should receive an additional dose of polio vaccine or inactivated polio vaccine within four weeks to 12 months of travel.