Published Date: 2018-06-09 17:20:58
Subject: PRO/EDR> Poliomyelitis update (19): Venezuela, vaccine virus found, VAPP susp
Archive Number: 20180609.5848416
POLIOMYELITIS UPDATE (19): VENEZUELA, VACCINE VIRUS FOUND, VACCINE-ASSOCIATED PARALYTIC POLIO SUSPECTED
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In this update:
[1] PAHO Epidemiological update
[2] Comment
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[1] PAHO Epidemiological update
Date: Fri 8 Jun 2018
Source: Pan American Health Organization (PAHO) Epidemiological Update Poliomyelitis [edited] [link to PDF]
https://www.paho.org/hq/index.php?option=com_topics&view=article&id=257&Itemid=40900&lang=en
Detection of Sabin type 3 vaccine poliovirus in a case of acute flaccid paralysis
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Situation summary
On [7 Jun 2018], the World Health Organization (WHO) International Health Regulations (IHR) Regional Contact Point received an unofficial report on the detection of Sabin type 3 vaccine poliovirus in a sample of a Venezuelan patient with acute flaccid paralysis (AFP). The same day [7 Jun 2018], a request for verification was sent to the Venezuela IHR National Focal Point (NFP).
On [8 Jun 2018], PAHO/WHO received updated information. The case is child aged 2 years and 10 months, with no history of vaccination, resident of an under-immunized indigenous community in Delta Amacuro, Venezuela; with paralysis onset on [29 Apr 2018]. As of [31 May 2018], the flaccid paralysis persisted in a lower limb. A Sabin type 3 vaccine poliovirus was isolated and typified by the national reference laboratory, the National Institute of Hygiene "Rafael Rangel" (INHRR), in the sample of this patient obtained on [30 Apr 2018]. The sample will be sent to a regional reference laboratory for confirmatory testing. Other children from the same community were vaccinated in April 2018 with oral bivalent polio vaccine.
The ongoing field investigation identified an 8 year old girl, resident of the same community with a vaccine history of at least 1 dose of tOPV, who presented flaccidity in a lower limb. No additional AFP cases have been identified to date through active search for AFP cases carried out in the community.
Advice to national authorities
PAHO/WHO reiterates to member states the importance of reaching and maintaining polio vaccination coverage of more than 95 per cent in each district or municipality, maintaining high quality of epidemiological surveillance, and updating the national poliovirus outbreak response plans.
References
1. PAHO/WHO. Final report of the 3rd Ad-Hoc Meeting of the TAG. Ad-hoc Virtual Meeting, 19 March 2018. Available at:
https://bit.ly/2Jt8lrH
2. PAHO/WHO. Polio Weekly Bulletin, 2018. Available at:
https://bit.ly/2JmhVR2
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[2] Comment
Date: Thu 7 Jun 2018
From: T Jacob John, <tjacobjohn@yahoo.co.in>
The polio could be VAPP following infection with Sabin 3 in OPV. This is to supplement your comment that it could be WPV3 or cVDPV-3.
Sabin 3 is the commonest cause of VAPP in OPV-given children. It is usually sporadic, since PV-3 is a very inefficient spreader. Hope we will have a clear picture very soon.
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T Jacob John
Retired Prof and Head of Department of Clinical Virology
Christian Medical College, Vellore
India
<tjacobjohn@yahoo.co.in>
[The above information provides more detailed technical description on the reported case of acute flaccid paralysis in Venezuela. From the information provided it appears as though this child's illness would be classified as a case of VAPP -- vaccine-associated paralytic poliomyelitis -- in a contact of a recently vaccinated individual. VAPPs can occur in recipients of the OPV (oral poliovirus vaccine) or in close contacts of recently vaccinated individuals. The incidence of VAPP cited by WHO is approximately 1 per 2.7 million doses. Cases of VAPP are distinctly different from those associated with cVDPV where the virus has undergone significant changes in neurovirulence and have not been reported to cause outbreaks.
When I was involved with polio surveillance as an Epidemic Intelligence Service [EIS] officer at the Centers for Disease Control and Prevention (many moons ago), in the era when the USA was using OPV as the primary vaccine for polio prevention, the overwhelming majority of polio cases confirmed in the USA were cases of VAPP in both recipients as well as contacts (usually parents of recently vaccinated children). As always, Professor T Jacob John was right on target with his excellent reminder comment in response to my original post. Unfortunately in my haste to post on the media report, I got as far as the VDPV discussion but neglected to mention the possibility of this being a VAPP, which Prof T Jacob John rightfully reminded me and to whom I am very grateful.
The disconcerting information in the above report (and in the media report we posted on 7 Jun 2018) is the mention of a possible 2nd case of AFP in this community. The other disconcerting information from the original media report was the noticeable absence of mention of a vaccination campaign in the affected community preceding the onset of illness, but rather a comment that there had been no vaccination in the community since 2016. An apparent manipulation of the facts.
We await further information on confirmatory testing by the reference laboratory as well as additional information on this 2nd AFP case.
