In a follow-up on the polio outbreak in Papua New Guinea,  the Global Polio Eradication Initiative (GPEI) reports an additional case of circulating vaccine-derived poliovirus type 1 (cVDPV1) in the past week, from East Sepik.   Onset of paralysis was on 1 August.

Image/CDC-/ Meredith Boyter Newlove, M.S., James Archer, M.S.
Image/CDC-/ Meredith Boyter Newlove, M.S., James Archer, M.S.

This brings the total number of cases in 2018 to 15.

In addition, two VDPV1 positive environmental samples, both collected on 5 September, were reported from Port Moresby.

GPEI says:

Vaccine-derived polioviruses (VDPVs) are rare strains of poliovirus that have genetically mutated from the strain contained in the oral polio vaccine. The oral polio vaccine contains a live, attenuated(weakened) vaccine-virus. 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.

Emergency Operations Centres are established and operational in all affected provinces; environmental surveillance is functional in five sites in two major cities.

Three Supplemental Immunization Activities (SIAs) of expanding scope have taken place since late July, from three provinces to nine, to nation-wide. The most recent was aimed at children under the age of 15, due to the large numbers of poorly-immunized older children.

In addition to the cases in Papua New Guinea, 46 other VDPV cases have been reported this year, all in Africa–Democratic Republic Of The Congo (15), Niger (3), Nigeria (16) and Somalia (12).

There have also been 19 wild poliovirus type 1 (WPV1) cases reported from two countries–Afghanistan (15) and Pakistan (4).