Poliovirus rokote OPV tyypit 1, 2, 3. Elävä heikennetty Sabin kanta.

J Clin Virol. 2015 Jan;62:80-3. doi: 10.1016/j.jcv.2014.11.027. Epub 2014 Nov 29.

Circulating vaccine-derived polioviruses in the Extreme North region of Cameroon.

Endegue-Zanga MC¹, Sadeuh-Mba SA¹, Iber J², Burns C², Nimpa-Mengouo M³, Demanou M¹, Vernet G¹, Etoa FX⁴, Njouom R⁵.

TAUSTA,  BACKGROUND: 
WHO:lla on  polioviruksen juurtmisohjelma ja siihen kuuluu polioviruksesta johtuvan  akuutin velttohalvauksen ilmenemisen tarkka valvonta  ja massarokotukset rutiinisti  suun kauta annettavalla poliorokotteella (OPV).
Sellaisissa väestöissä, joissa rokotuksen kattavuus on matala, saattaa elävä heikennetty Sabin kanta , OPV tyypit 1, 2 ja 3, kehkeyttää virulentteja  rokotteesta  peräisin olevia   polioviruksia  (VDPV) ja niitä voi kierrellä  yhteiskunnissa. 
Toistaiseksi ei ole Kamerunin puolella esiintynyt  kiertäviä  VDPV (cVDPV)  kantoja vaikka niiden purkauksia on Kamerunin lähivaltioissa esiintynyt

The World Health Organization (WHO) poliovirus eradication program includes careful surveillance of acute-flaccid paralysis (AFP) and mass and routine immunization with oral polio vaccine (OPV). In populations with low vaccine coverage, the live-attenuated Sabin strains, OPV types 1, 2 and 3, can evolve into virulent vaccine-derived polioviruses (VDPVs) and circulate in the community. Until recently, circulating VDPVs (cVDPVs) had not been reported in Cameroon despite the fact that VDPV2 outbreaks have occurred in nearby countries.

OBJECTIVES:

This study aimed to characterize virus isolates from four AFP patients infected with cVDPV2 in the Extreme North region of Cameroon in 2013.

STUDY DESIGN:

The complete VP1 region of the four VDPV strains was sequenced and the relationships with cVDPVs from neighboring countries were investigated.

RESULTS:

All four patients were infected by cVDPV2 strains showing 1.2-2.0% nucleotide difference compared to the reference Sabin 2 VP1 sequence. Phylogenetic analysis indicated that the VDPV strains were genetically linked to cVDPV2 lineages of the recent Chad cVDPV2 outbreak.

CONCLUSIONS:

The circulation of pathogenic VDPVs suggests that there are localized immunization gaps in some districts like Makary, Mada and Kolofata in Cameroon. To avoid poliomyelitis outbreaks in Cameroon, especially in the districts close to neighboring countries with ongoing cVDPV outbreaks, high polio vaccine coverage is essential. Copyright © 2014 Elsevier B.V. All rights reserved.

KEYWORDS:

Acute-flaccid paralysis; Cameroon; Poliomyelitis; Vaccine-derived poliovirus