Re: India: 2011 Polio cases
http://www.promedmail.org/pls/apex/..._BACK_PAGE,F2400_P1001_PUB_MAIL_ID:1000,89698
India - VDPV (vaccine derived poliovirus)
Date: Sun 7 Aug 2011
Source: The Times of India (TOI), Times News Network (TNN) [edited]
<http://timesofindia.indiatimes.com/india/Kids-getting-polio-through-vaccine/articleshow/9511191.cms>
5 children contract polio from vaccine
--------------------------------------
From being labelled the world's lone polio exporter in 2006 to
reporting just one positive case till the 8th month of this year
[2011], the polio scenario has never looked better for India. But
celebrations are not in offing as the country is now faced with the
challenge of fighting the vaccine derived poliovirus [VDPV] rather
than the wild virus itself.
Simply put, the small quantity of the weakened poliovirus present in
the oral polio vaccine [OPV] (to activate immune response) is the one
seemingly causing polio in children now. At least, 5 children from
Chhattisgarh, Punjab, Rajasthan, [Uttar Pradesh, and Madhya Pradesh]
have been struck by the vaccine derived polio, whereas only one child
from West Bengal has tested positive for the wild poliovirus. The
child from Chhattisgarh, who had a congenital anomaly and was highly
immunodeficient, recently died. There were 21 cases of vaccine derived
polio in 2009 that came down to 6 in 2010.
But, experts are of the view that even though cases of vaccine derived
polio are a cause of worry, it is not as scary as the wild poliovirus
that India has been fighting for decades. A senior official from the
ministry of health and family welfare, New Delhi, told TOI, "We are
aware of the vaccine derived poliovirus cases. But, all the 5 cases
are isolated and they do not seem to be circulating the virus in the
community," the official said. He, however, admitted the virus in the
vaccine can "mutate" and cause paralysis. "But, it is much easier to
bring vaccine derived polio under control," the official said.
Yet, some experts say the government should have been better prepared
for such a scenario as it was alerted at least a decade back that
there will be a stage when vaccine derived virus will be a bigger
danger. Former chairman of the India Expert Advisory Group Dr T Jacob
John said vaccine derived polio has a tendency to "become wild-like",
and experts had informed the policy-makers about it long ago. He,
however, added that India not reporting any wild poliovirus from
environment sampling in the last 8 months is a very positive sign.
According to sources in the health ministry, deliberations are on as
to how to tackle this. Since all the 5 cases of vaccine derived polio
are of type II [2] strain, there were discussions of stopping the
trivalent immunizations (dosage for all 3 polio strains) for a while
so that the type II virus is not fed in the community. But, the idea
was soon aborted thinking it could lead to an outbreak in the
low-immune population. "The situation is more like a double-edged
sword now," said Dr John, adding that benefits of OPV still outweigh
cases of vaccine derived poliovirus.
[byline: Sumitra Deb Roy]
--
communicated by:
HealthMap Alerts via ProMED-mail
<promed@promedmail.org>
[
The newswire above refers to the 5 additional paralytic cases
reported in 2011 as being due to infection with vaccine derived
polioviruses (VDPV). The newswire also mentions that these cases are
sporadic, and not associated with "circulating vaccine derived
poliovirus (VDPV)". More detailed information on each of the cases was
not provided so that it was not clear to this moderator if these cases
were classified as VAPP (vaccine associated paralytic polio) cases,
where the individuals were those who developed paralysis after
directly receiving a dose of the oral polio vaccine (OPV), versus
those individuals who did not have a history of recent receipt of a
dose of OPV, but had paralytic disease where a vaccine derived
poliovirus was obtained from stool specimens. In the latter instance,
the cases would be classified as associated with circulating VDPV
(cVDPV).
According to Andrus and colleagues, the rate of VAPP in Latin America
during the period 1989-1991 was found to be one case per 1.5-2.2
million doses of vaccine administered, compared with 1 case per 2.5
million doses distributed in the USA during the period 1980-1989, and
1.4 doses of vaccine administered in England and Wales during the
period 1985-1991 (Andrus JK, Strebel PM, deCuadros CA, Olive JM. Risk
of vaccine-associated paralytic poliomyelitis in Latin America,
1989-91. Bull World Health Organ. 1995; 73(1): 33-40;
<http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2486585>).
The Technical Consultative Group to the WHO on the eradication of
polio gives an estimated rate of VAPP as 1 case per 1 million live
births (see Technical Consultative Group to the World Health
Organization on the Global Eradication of Poliomyelitis. "Endgame"
issues for the global polio eradication initiative. Clin Inf Dis.
2002; 34(1): 72-7;
<http://cid.oxfordjournals.org/content/34/1/72.long>.) (For an
interesting discussion on these estimates in India, see Jacob John's
letter to the editor Vaccine associated paralytic polio in India, Bull
World Health Organ. 2002, 80(11): 917;
<http://www.who.int/bulletin/archives/80%2811%29917.pdf>).
With respect to cVDPV, according to data available on the Global Polio
Eradication Initiative website, during the period 2000-2011, 77 cases
due to cVDPV-1 have been reported (cases reported from Mozambique,
Myanmar, Indonesia, China, Philippines and DOR/Haiti), 442 cases due
to cVDPV-2 (cases reported from Nigeria, Somalia, Afghanistan, Chad,
DR Congo, Niger, India, Ethiopia, and Madagascar), and 9 cases due to
cVDPV-3 (cases reported from Ethiopia and Cambodia). (Of note,
according to the data available on the Polio Eradication Initiative
website, the most recent cVDPV-2 virus isolated in India was on 18 Jan
2010 -- the 5 cases mentioned above have not been included in the
database (see
<http://www.polioeradication.org/Dataandmonitoring/Poliothisweek/Circulatingvaccinederivedpoliovirus.aspx>
for tables with number of cases by country, year, and VDPV virus
type.) In addition, only 2 cases of VDPV were reported from India in
2010.
On further investigation, this moderator found that according to the
data available on the Indian National Polio Surveillance Project
(NPSP) website, there have been 5 cases of VDPV associated paralytic
disease in 2011 -- one each in Chhattisgarh, Madhya Pradesh, Punjab,
Rajasthan, and Uttar Pradesh as mentioned in the newswire above.
(<http://www.npspindia.org/bulletin.pdf>). With respect to VAPP cases,
according to the NPSP data, there have been 573 type 1, 397 type 2,
612 type 3, and 480 mixed vaccine virus types isolated in 2011 as of
the week ending 30 Jul 2011, in association with acute flaccid
paralysis cases. Hence, the "apparent" discrepancy is most likely
related to the definition of cVDPV as a VDPV associated with at least
2 cases, whereas the VDPV cases in India in 2011 are single,
non-related cases.
Of note, there have been no cases of paralytic polio due to infection
with WPV-2 (wild poliovirus type 2) since October 1999. Looking at a
risk benefit assessment, it appears as though the risk of paralytic
polio due to infection with WPV-2 worldwide is presently zero (and has
been since the last isolate in October 1999), whereas there have been
442 cases of paralytic polio due to infection with a VDPV-2. Perhaps
the time has come to re-evaluate the use of a trivalent OPV, and
consider using a bivalent OPV with vaccine virus types 1 and 3 -- the
2 WPV types presently in circulation and responsible for all paralytic
polio cases due to WPV infections.
For a map of India with states, see
<http://www.theindiatravelguide.com/test/indiamap1.JPG>. For the
HealthMap/ProMED map of India, see <http://healthmap.org/r/008o>. -
Mod.MPP]
