Officials in Burundi have detected an outbreak of vaccine-related polio

LONDON — Health officials in Burundi have declared an outbreak of vaccine-linked polio, the first time the paralytic disease has been seen in the East African country in more than three decades.

Polio has been diagnosed in an unvaccinated four-year-old child in the western part of the country, as well as in two other children who had contact with the child, the Burundian authorities confirmed in a statement on Friday. Officials also found traces of the virus in sewage samples, confirming the spread of polio.

The virus that sickened the children turned out to be a mutant strain of polio that originally came from an oral vaccine.

Burundi’s government has declared the polio outbreak a national public health emergency and is planning an immunization campaign within weeks to protect all children under the age of seven.

“We support national efforts to accelerate polio vaccination so that no child is left behind or faces the debilitating effects of polio,” said WHO Africa Director Dr Matshidiso Moeti.

The outbreak marks another setback in the global effort to end polio, led by the World Health Organization and its partners, which first began in 1988 and originally aimed to eradicate the disease within a dozen years.

Polio is a highly contagious disease that is spread mostly through water and usually affects children under the age of five. There is no treatment. Although the oral vaccine used in global efforts to eradicate the disease is highly effective, four doses are required.

The oral vaccine can cause polio in about 2 to 4 children per 2 million doses. In extremely rare cases, the weakened virus can sometimes mutate into a more dangerous form and cause outbreaks, especially in places with poor sanitation and low vaccination rates.

In recent years, the oral polio vaccine has caused far more cases of polio than the wild polio virus. Last year saw the first cases of oral vaccine-related cases in wealthy countries, including Britain, Israel and the United States.

Last year, officials began rolling out a new oral polio vaccine that they hope will be less likely to mutate into a version capable of triggering new outbreaks. But it turned out that the Burundi epidemic – along with six cases in the Congo – was caused by the new oral vaccine.

More than 400 cases of polio were linked to the oral vaccine across Africa last year, including in Congo, Nigeria, Ethiopia and Zambia.

The disease is stubbornly rooted in Pakistan and Afghanistan, where its spread has never been stopped.