There were 21 new cases of wild poliovirus type 1 (WPV1) reported out of the polio endemic countries, according to the latest data from the Global Polio Eradication Initiative (GPEI).

Poliovirus  Image/CDC
Poliovirus Image/CDC

Afghanistan saw a jump in 6 WPV1 cases during the past week, bringing their total to 18 for 2014.  Of these, 4 are from Kandahar province (2 in Kandahar district, and 1 in each of the previously uninfected districts of Shahwalikot and Arghandab); 1 is from the Bermel district of Paktika province, and 1 from the previously uninfected province of Ghazni, in Giro district.

Afghanistan saw nine WPV1 cases this time last year.

Neighboring Pakistan’s polio numbers continue their rise as they report 15 additional cases during the past week. Of these, 8 are from the Federally Administered Tribal Areas (FATA) (1 from South Waziristan, 1 from Frontier Region Bannu and 6 from Khyber Agency); 3 from Balochistan province (2 from Killa Abdullah district and 1 from Quetta); and 4 from Khyber Pakhtunkhwa (KP) province (3 from Peshawar district and 1 from Charsada district, previously uninfected in 2014).

This brings the total number of WPV1 cases in 2014 to 235 compared to 56 in 2013 by this date.

Although the 3rd endemic country, Nigeria, did not report any WPV1 cases, One new type 2 circulating vaccine-derived poliovirus (cVDPV2) case was reported in the past week in Bindawa district of Katsina province. The total number of cVDPV2 cases for 2014 is now 21.

On the Horn of Africa, two new cases of circulating vaccine derived poliovirus type 2 (cVDPV2) have been reported in South Sudan this week. According to GPEI, this constitutes an outbreak. Immunization activities are planned in November and December in order to stop the spread of cVDPV.

The Global Polio Eradication Initiative (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. This is called a vaccine-derived poliovirus.

In the Middle East, there has not been a WPV1 case reported in almost 7 months. The most recent case occurred  in Iraq in April 2014.

To date, there has been 278 WPV1 cases in nine countries.

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