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Polio Highlight

Aide Memoire – Types of Vaccine-derived Poliovirus (VDPV)


T
ypes of Vaccine-derived Poliovirus

 

There are three types of vaccine-derived poliovirus [2,3]:

1. Circulating vaccine-derived poliovirus (cVDPV)

On very rare occasions, if a population is seriously under-immunized, and other risks factors are present (crowding, poor hygiene and tropical climate) the probability that the Sabin viruses can mutate or recombine and change to VDPV exists, if there are enough susceptible children for the excreted vaccine-derived polioviruses to begin circulating in the community. These viruses are called circulating vaccine-derived polioviruses (cVDPV).

As with naturally occurring poliovirus, the only protection against cVDPV is full vaccination. Circulating VDPVs in the past have been rapidly stopped with 2–3 rounds of high-quality immunization campaigns. The solution is the same for all polio outbreaks: immunize every child several times with the oral vaccine to stop polio transmission, regardless of the origin of the virus.

2. Immunodeficiency-related vaccine-derived poliovirus (iVDPV)

Prolonged replication of vaccine-derived viruses has been observed in a small number of people with rare immune deficiency disorders (ej: B cell immunodeciencies). Because they are not able to mount an immune response, these people are not able to clear the intestinal vaccine virus infection, which is usually cleared within six to eight weeks. They therefore excrete immunodeficiency-related vaccine-derived polioviruses (iVDPVs) for prolonged periods.

The occurrence of iVDPVs is very rare. Only 42 cases have been documented worldwide. Of these, most stopped excretion within six months or died. Three people excreted the virus for more than 5 years.

3. Ambiguous vaccine-derived poliovirus (aVDPV)

Ambiguous vaccine-derived polioviruses (aVDPVs) are vaccine-derived polioviruses that are either isolated from people with no known immunodeficiency, or isolated from sewage whose ultimate source is unknown. Very little is known about them but to go into this classification, there has to be no more AFP cases related to VDPV in the community.

 
Last Updated on Thursday, 26 July 2012 06:30

Officially reported wild polio virus cases as of 03 Jul 2012

Total global cases in 2012: 88 (compared with 252 for the same period in 2011)
Total in endemic countries in 2012: 84 (compared with 226 for the same period in 2011)
Total in non-endemic countries in 2012: 4 (compared with 26 for the same period in 2011)

• Nigeria: 52 cases in 2012 (compared with 17 for the same period in 2011), onset of paralysis of most recent case: 06-Jun-12
• Pakistan: 22 cases in 2012 (compared with 58 for the same period in 2011), onset of paralysis of most recent case: 22-May-12
• Afghanistan: 10 cases in 2012 (compared with 8 for the same period in 2011), onset of paralysis of most recent case: 29-May-12
• Chad: 4 cases in 2012 (compared with 85 for the same period in 2011), onset of paralysis of most recent case: 11-May-12
• Niger: 0 case in 2012 (compared with 1 for the same period in 2011), onset of paralysis of most recent case: 22-Dec-11
• DRC: 0 case in 2012 (compared with 60 for the same period in 2011), onset of paralysis of most recent case: 20-Dec-11
• CAR: 0 case in 2012 (compared with 0 for the same period in 2011), onset of paralysis of most recent case: 08-Dec-11
• China: 0 case in 2012 (compared with 0 for the same period in 2011), onset of paralysis of most recent case: 09-Oct-11
• Guinea: 0 case in 2012 (compared with 1 for the same period in 2011), onset of paralysis of most recent case: 03-Aug-11
• Kenya: 0 case in 2012 (compared with 0 for the same period in 2011), onset of paralysis of most recent case: 30-Jul-11
• Côte d'Ivoire: 0 case in 2012 (compared with 11 for the same period in 2011), onset of paralysis of most recent case: 24-Jul-11
• Angola: 0 case in 2012 (compared with 4 for the same period in 2011), onset of paralysis of most recent case: 07-Jul-11
• Mali: 0 case in 2012 (compared with 4 for the same period in 2011), onset of paralysis of most recent case: 23-Jun-11
• Congo: 0 case in 2012 (compared with 1 for the same period in 2011), onset of paralysis of most recent case: 22-Jan-11
• Gabon: 0 case in 2012 (compared with 1 for the same period in 2011), onset of paralysis of most recent case: 15-Jan-11
• India: 0 case in 2012 (compared with 1 for the same period in 2011), onset of paralysis of most recent case: 13-Jan-11

By changing yourself, you can change the world!

During the polio management training in Afghanistan, participants agreed on a slogan and theme that expresses their spirit and sense of optimism for polio eradication in the country: “By changing yourself, you can change the world!”

Source: Wild Poliovirus Weekly Update 06-Jun-2012, World Health Organization

Last Updated on Friday, 08 June 2012 05:28

Programmatic Emergency:

The World Health Assembly (WHA) declared the completion of polio eradication a programmatic emergency for global public health. In total, 35 member states spoke to offer their strong support to the resolution, many highlighting the feasibility and opportunity of eradication in the near-term, but expressing concern at the ongoing funding gap that is threatening success.

Global Polio Emergency Action Plan launched

The Global Polio Eradication Initiative officially launched
a Global Emergency Action Plan 2012-2013 in the margins of the World Health Assembly this week.  The Plan aims to better support the remaining endemic countries to boost vaccination coverage to levels needed to stop polio transmission.  The Plan is launched as polio eradication is at a tipping
point.  Although the number of polio cases is lower this year than in any
previous 4-month period over the last ten years, it is estimated that failure
to achieve success could lead within a decade to as many as 200,000 paralyzed children a year worldwide. 

The full Plan is available at www.polioeradication.org



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