Namibian polio outbreak puzzles experts
Polio has resurfaced in Namibia after a ten-year absence, but this time it is targeting adults. According to the Namibian health permanent secretary, ten had died from the disease on 14 June and there are at least 60 suspected cases.
The country's health authorities are now racing to vaccinate Namibia's entire population of two million. The first campaign will begin on 21 June and at least two more are scheduled later in the year.
Outbreaks among adults are very rare as most have either been vaccinated or been exposed to infected children and have gained immunity in this way.
The genetic sequence of the Namibian virus suggests it originally came from India and recently crossed the border from Angola where only a handful of cases were reported, but scientists are puzzled by its rapid spread in Namibia.
Researchers assume the infected adults were not immunised as children but this does not explain how they escaped being exposed to the virus before 1996, when the last case of native poliovirus was reported.
But tackling Namibia's outbreak may not be the biggest polio challenge. Some feel Angola is not doing enough to stop transmission. Meanwhile, Nigeria — where some have opposed vaccination — has had 438 reported cases this year alone.