Papua New Guinea has experienced its first outbreak of polio in 18 years, the National Department of Health of Papua New Guinea and the World Health Organization have confirmed.
The presence of polio was first suspected on April 28, when a 6-year-old boy was presented to doctors with lower limb paralysis in the nation’s northern Morobe Province. In May, the diagnosis of vaccine-derived poliovirus type 1 was confirmed.
The subsequent outbreak was declared when the US Centers for Disease Control and Prevention discovered the same strain of polio in the stool samples of two children from the boy's neighbourhood.
"We are deeply concerned about this polio case in Papua New Guinea and the fact that the virus is circulating," Papua New Guinea's Health Secretary Pascoe Kase said in a statement.
“Our immediate priority is to respond and prevent more children from being infected,” Kase said.
Vaccine-derived poliovirus varies significantly from wild poliovirus, a highly infectious disease that most commonly affects children under the age of 5. Vaccine-derived poliovirus, the strain of virus located in the province, is an extremely rare, mutated variety of the weaker polio virus used in vaccinations.
According to the Global Polio Eradication Initiative, between 2000 and 2011, only 580 cases of the vaccine-derived virus were recorded, despite over 10 billion doses of the oral vaccine given.
“The oral polio vaccine contains a live, attenuated (weakened) vaccine-virus,” the Global Polio Eradication Initiative said in a statement. “When a child is vaccinated, the weakened vaccine-virus replicates in the intestine and enters into the bloodstream, triggering a protective immune response in the child. Like wild poliovirus, the child excretes the vaccine-virus for a period of six to eight weeks. Importantly, as it is excreted, some of the vaccine-virus may no longer be the same as the original vaccine-virus as it has genetically altered during replication.”
In areas with poor sanitation, unsuitable access to clean water, and very low immunisation rates, the disease can spread through the accidental consumption of faeces — normally via contaminated water or food.
In Morobe Province, polio immunisation rates are low, with only 61% of children having received the endorsed three doses. The area also has challenges with appropriate water, sanitation, and hygiene levels.
In the immediate aftermath of the outbreak announcement, various large scale measures were put in place in an attempt to prevent the disease from spreading. The National Department of Health, World Health Organisation, and the Global Polio Eradication Initiative have launched a widespread immunisation campaign that targets children under the age of 15.
House-to-house surveys, community sample collections, contact tracing, and a strengthened awareness system to help detect the presence of the virus have also been employed.
.@WHO and partners are supporting national authorities to stop a new #polio outbreak in #PapuaNewGuinea. The emergence of cVDPV strains underscores importance of maintaining high levels of routine vaccination coverage and effective surveillance systems: https://t.co/6XJsXZY7fd— Peter Salama (@PeteSalama) July 2, 2018
“The WHO has been working with the Government on the investigation, laboratory confirmation, enhanced surveillance and response activities," Luo Dapeng, the WHO representative in Papua New Guinea, announced in a statement.
"We will continue to support the Government to ensure children are protected."