viernes, 30 de junio de 2017



ProMED logo    ISID logo

« prev

ProMED logo    ISID logo

Published Date: 2017-06-29 23:02:16
Subject: PRO/EDR> Poliomyelitis update (14): Syria (DY), new cases, cVDPV, global
Archive Number: 20170629.5139997
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases

In this update:
[1] Global update, Syria, new cases - GPEI/WHO
[2] VDPV impact - media report
[3] AFP private sector reporting challenges - Kuwait, media report

[1] Global update, Syria, new cases - GPEI
Date: Thu 29 Jun 2017
Source: Global Polio Eradication Initiative

Poliovirus Weekly Update 28-Jun-2017

New wild poliovirus cases reported this week: 0
Total number of wild poliovirus cases in 2017: 6
Total number of wild poliovirus cases in 2016: 37

New cVDPV cases reported this week: 5
Total number of cVDPV cases in 2017: 26
Total number of cVDPV cases in 2016: 5

- WHO Director-General Dr Margaret Chan retirement : GPEI offers sincere thanks for her ten-year leadership, which brought the world to the threshold of being polio-free.
- Containment update: progress towards containment of poliovirus type 2 published .
- "Coffee with Polio Experts": a short video-chat with Dr Ousmane Diop, Coordinator of the Global Polio Laboratory Network, on the increasingly important role of environmental surveillance to help track down every last poliovirus strain.
- Summary of newly-reported viruses this week: Syria - 5 new circulating vaccine-derived poliovirus type 2 (cVDPV2) isolated from acute flaccid paralysis (AFP) cases. Pakistan - 1 new wild poliovirus type 1 (WPV1) positive environmental sample.

- No new wild poliovirus type 1 (WPV1) cases were reported in the past week. The total number of WPV1 cases for 2017 remains four. The most recent WPV1 case had onset of paralysis on [16 Apr 2017] from Nawzad district, Hilmand province.
- With most of Afghanistan polio-free, efforts are focused on continuing to strengthen operations, in close coordination with Pakistan, to address remaining low-level transmission in the common reservoir area of the Quetta-Kandahar corridor.
- Afghanistan is carrying out a programme review focusing on the implementation of the National Emergency Action Plan and making necessary adjustments for the second half of 2017.
- Polio eradication teams from East and South East Afghanistan and neighbouring FATA and Khyber Pakhtunkhwa in Pakistan met in Kabul on 24-25 May [2017] to review the current coordination mechanisms and agree on additional measures to further improve implementation in the WPV common reservoirs. Core teams from the National Emergency Operation Centres Afghanistan and Pakistan also met to discuss next steps on further improving the vaccination strategies for high risk mobile populations.

- No new wild poliovirus type 1 (WPV1) cases were reported in the past week. The total number of WPV1 cases for 2017 remains two. The most recent case had onset of paralysis on [13 Feb 2017], from Diamir district, Gilgit Baltistan.
- One new WPV1 positive environmental sample was reported in the past week, from Karachi Gadap, Sindh, collected on [5 Jun 2017].
- The year 2016 saw the lowest ever annual number of polio cases in the country but poliovirus continues to be isolated through environmental surveillance over a significant geographical range. Efforts are ongoing through implementation of the national emergency action plan to address remaining gaps in coverage and surveillance, in close coordination with neighbouring Afghanistan.
- The National Polio Management Team met on [8-9 Jun 2017] to review implementation of the National Emergency Action Plan during the low transmission season, and to agree on essential adjustments to the plan for the second half of 2017.

- No new cases of wild poliovirus type 1 (WPV1) were reported in the past week. The total number of WPV1 cases for 2016 remains 4 and no cases have been reported in 2017. The most recent case had onset of paralysis on [21 Aug 2016] in Monguno Local Government Area (LGA), Borno.
- Nigeria continues to implement emergency response to the detected WPV1 strain and circulating vaccine-derived poliovirus type 2 (cVDPV2) strains affecting the country.
- The response is part of a broader regional outbreak response, coordinated with neighbouring countries, in particular the Lake Chad sub-region, including northern Cameroon, parts of Central African Republic, Chad and southern Niger.
- Detection of the polio cases in Nigeria underscores the risk posed by low-level undetected transmission and the urgent need to strengthen subnational surveillance.

Lake Chad Basin
- The detection of wild poliovirus type 1 (WPV1) and circulating vaccine-derived poliovirus type 2 (cVDPV2) in Nigeria poses a risk to the neighbouring countries of the Lake Chad basin and hence an outbreak response plan is being implemented as part of the response to the Nigeria outbreak.
- Emergency outbreak response efforts continue across the Lake Chad basin, together with activities to fill subnational surveillance gaps across the region.

Central Africa
- No new cases were reported in the past week. The Democratic Republic of the Congo (DR Congo) is affected by 2 separate outbreaks of circulating vaccine derived poliovirus type 2 (cVDPV2), in Haut Lomami province (2 cases, with onset of paralysis on [8 Mar 2017 and 20 Feb 2017]); and in Maniema province (2 cases with onset of paralysis on [26 Mar 2017 and 18 Apr 2017], with an additional isolate detected in a healthy individual with sample collection on 2 May [2017]).
- Outbreak response plans are currently being finalised, with supplementary immunization activities using monovalent oral polio vaccine type 2 (mOPV2) in line with internationally-agreed outbreak response protocols.
- The 1st mOPV2 campaign is being implemented this week ([27-29 Jun 2017]) targeting more than 750 000 children under the age of 5 years in the 2 affected provinces.
- Surveillance and immunization activities are being strengthened in neighbouring countries.
- DR Congo is also affected by an Ebola outbreak, in Bas Uele province in the north of the country. Coordination among both outbreak response teams will be necessary and teams are already working on this.

Syrian Arab Republic
- In Syria, 5 new cases of circulating vaccine-derived poliovirus type 2 (cVDPV2) were reported in the past week, bringing the total of cVDPV2 cases to 22. All cases had onset of paralysis between [3 Mar 2017 and 25 May 2017]. 21 of the cases are from Mayadeen district, Deir-Al-Zour governorate, and 1 case is from Raqua district, Raqua governorate.
- Confirmation of these latest cases is not unexpected at this time and does not change the operational situation, as outbreak response plans are being finalized, in line with internationally-agreed outbreak response protocols. Although access to Deir-Al-Zour is compromised due to insecurity, the Governorate has been partially reached by several vaccination campaigns against polio and other vaccine-preventable diseases since the beginning of 2016. Most recently, 2 campaigns have been conducted in March and April 2017 using the bivalent oral polio vaccine ([bOPV]). However, only limited coverage was possible through these campaigns.

Officially reported wild poliovirus cases as of 20 Jun 2017
Total global cases in 2017: 6 (compared with 18 for the same period in 2016)
Total in endemic countries in 2017: 6 (compared with 18 for the same period in 2016)
Total in non-endemic countries in 2017: 0 (compared with 0 for the same period in 2016)
- Afghanistan: 4 cases in 2017 (compared with 6 for the same period in 2016), onset of paralysis of most recent case: 16-Apr-17
- Pakistan: 2 cases in 2017 (compared with 12 for the same period in 2016), onset of paralysis of most recent case: 13-Feb-17
- Nigeria: 0 case in 2017 (compared with 0 for the same period in 2016), onset of paralysis of most recent case: 21-Aug-16
- Total global cases in 2016: 37
· Total in endemic countries: 37
· Total in non-endemic countries: 0

Officially reported cVDPV cases as of 20 Jun 2017
Total global cases in 2017: 26 (compared with 3 for the same period in 2016)
- Syrian Arab Republic: 22 cases in 2017 (compared with 0 for the same period in 2016), onset of paralysis of most recent case: 25-May-17
- Democratic Republic of the Congo: 4 cases in 2017 (compared with 0 for the same period in 2016), onset of paralysis of most recent case: 18-Apr-17
- Pakistan: 0 case in 2017 (compared with 0 for the same period in 2016), onset of paralysis of most recent case: 17-Dec-16
- Nigeria: 0 case in 2017 (compared with 0 f or the same period in 2016), onset of paralysis of most recent case: 28-Oct-16
- Lao People's Democratic Republic: 0 case in 2017 (compared with 3 for the same period in 2016), onset of paralysis of most recent case: 11-Jan-16

- Total global cases in 2016: 5
- Total in endemic countries: 2
- Total in non-endemic countries: 3

Communicated by:

[With the addition of these 5 newly confirmed cases of cVDPV associated polio in Syria, the tally is now up to 26 total cVDPV cases during 2017 -- 22 in Syria and 4 in the Democratic Republic of the Congo. All 5 of the newly confirmed cases were from Deir Al Zour suggesting transmission is still somewhat localized in the province. As a reminder, in the previous update (see Poliomyelitis update (13): Syria (DY, RA), global 20170622.5124548) there was mention of a total of 65 acute flaccid paralysis (SFP) cases that had been detected in Deir al Zour since the beginning of 2017. Of those 65, 22 had tested negative, 5 were pending final laboratory results (?the 5 newly confirmed cases), 22 were en route to a laboratory for analysis. Presumably those latter 22 are still undergoing testing, and we should expect additional cases to be confirmed in the coming period. Unfortunately, the affected area in Syria is an area with civil unrest, with difficult access to provide both outbreak focused as well as routine focused immunization activities.

The identification of WPV1 in an environmental sample in Karachi (Sindh province) Pakistan is also cause for concern. Of note is that this sample was taken from the same location as the previous week's environmental sample that was also positive for WPV1, suggesting there is ongoing circulation of the WPV1 in the country, and in Sindh province specifically.

A map showing the locations of both WPV1 and cVDPV2 cases worldwide can be found at:

For a map of Syria showing provinces, see Deir Al Zour is referred to as Dayr az Zawr in this map.

The HealthMap/ProMED map of Syria can be found at - Mod.MPP]

[2] VDPV impact - media report
Date: Wed 28 Jun 2017
Source: NPR [Naational Public Radio]

Mutant Strains Of Polio Vaccine Now Cause More Paralysis Than Wild Polio
For the 1st time, the number of children paralyzed by mutant strains of the polio vaccine are greater than the number of children paralyzed by polio itself.

So far in 2017, there have been only 6 cases of "wild" polio reported anywhere in the world. By "wild," public health officials mean the disease caused by polio virus found naturally in the environment.

By contrast, there have been 21 cases of vaccine-derived polio this year [note in the above GPEI update, the tally is now up to 26 with the addition of the 5 newly confirmed cases in Syria. - Mod.MPP]. These cases look remarkably similar to regular polio. But laboratory tests show they're caused by remnants of the oral polio vaccine that have gotten loose in the environment, mutated and regained their ability to paralyze unvaccinated children

"It's actually an interesting conundrum. The very tool you are using for [polio] eradication is causing the problem," says Raul Andino, a professor of microbiology at the University of California at San Francisco.

The oral polio vaccine used throughout most of the developing world contains a form of the virus that has been weakened in the laboratory. But it's still a live virus. (This is a different vaccine than the injectable one used in the U.S. and most developed countries. The injectable vaccine is far more expensive and does not contain live forms of the virus.)

Andino studies how viruses mutate. In a study published in March [2017], he and his colleagues found that the laboratory-weakened virus used in the oral polio vaccine can very rapidly regain its strength if it starts spreading on its own. After a child is vaccinated with live polio virus, the virus replicates inside the child's intestine and eventually is excreted. In places with poor sanitation, fecal matter can enter the drinking water supply and the virus is able to start spreading from person to person.

"We discovered there's only a few [mutations] that have to happen and they happen rather quickly in the 1st month or 2 post-vaccination," Andino says. "As the virus starts circulating in the community, it acquires further mutations that make it basically indistinguishable from the wild-type virus. It's polio in terms of virulence and in terms of how the virus spreads."

In June [2017], the World Health Organization reported 15 cases of children paralyzed in Syria by vaccine-derived forms of polio. These cases come on top of 2 other vaccine-derived polio cases earlier this year in Syria and 4 in the Democratic Republic of the Congo.

"In Syria, there may be more cases coming up," says Michel Zaffran, the director of polio eradication at the World Health Organization. He says lab work is still being done on about a dozen more cases of paralysis to confirm whether they're polio or something else.

The cases in Syria are all in the east of the country near the border with Iraq.

It has become fairly common each year for there to be 1 or 2 small outbreaks of vaccine-derived polio. These outbreaks tend to happen in conflict zones where health care systems have collapsed.

"These outbreaks are occurring only in very rare cases and only in places where children are not immunized," says Zaffran. The regular polio vaccine protects children from vaccine-derived strains of the virus just as it protects them from regular polio. Vaccine-derived outbreaks, he says, "occur where there are large pockets of unimmunized children, pockets sufficiently large to allow for the circulation of the virus."

WHO is staging a massive response to the Syrian outbreak. WHO plans to work with local health officials and aid groups to vaccinate a quarter of a million children in early July [2017]. The goal is to reach every child younger than 5 in the area with 2 doses of 2 different types of polio vaccine, spaced 1 to 2 weeks apart. This would be a logistical challenge in most parts of the world, never mind in war-torn Syria.

"The access in these areas is a bit limited because of the presence of ISIS," Zaffran says in what seems like an understatement. Eastern Syria is home right now to Syrians who've fled from Raqqa (the ISIS capital in Syria), other parts of the country and even Iraq. "Also there's a risk that the fighting might actually move to this area."

Zaffran is confident that the rogue vaccine-derived virus circulating in eastern Syria right now can be wiped out with a massive blast of more vaccine.

"We knew that we were going to have such outbreaks. We've had them in the past. We continue to have them now. We know how to find them, and we know how to interrupt them. We have the tools to do that," Zaffran says. "So it's hiccup ... a very regrettable hiccup for the poor children that have been paralyzed, of course. But with regards to the whole initiative, you know it's not something that is unexpected."

WHO is attempting to phase out the use of live oral polio vaccine to eliminate the risk that the active virus in the vaccine could mutate into a form that can harm unvaccinated children.

But for now, the live vaccine continues to be the workhorse of the global polio eradication campaign for a couple of reasons. 1st it's cheap, costing only about 10 cents a dose versus USD $3 a dose for the injectable, killed vaccine. 2nd, it can be given as drops into a child's mouth, which makes it far easier to administer than the inactivated or "killed" vaccine, which has to be injected. 3rd, there simply isn't enough killed vaccine on the market to vaccinate every child on the planet, and vaccine manufacturers don't have the capacity to produce the quantities that would be needed if such a switch happened immediately.

And finally, the live vaccine stops transmission of the polio virus entirely in a community if sufficient numbers of people are vaccinated. The killed vaccine doesn't fully block the virus from spreading because a person who is immunized can still carry and spread the polio virus. And this is an important difference between these 2 types of vaccines when the goal is to exterminate the polio virus.

"The fact is this [the live oral polio vaccine] is the only tool that we have that can eradicate the disease," says Zaffran.

That eradication effort has been incredibly successful. In 1988, when the campaign began, there were 350 000 cases of polio around the world each year compared with the 6 so far this year [2017].

Zaffran credits the oral polio vaccine with getting the world incredibly close to wiping out a terrible disease.

"Four regions of the world have totally eradicated the disease with the use of the oral polio vaccine," he notes. "Of course we need to recognize that there have been a few cases of children paralyzed because of the vaccine virus, which is regrettable. But, you know, from a public health perspective, the benefits far outweigh the risk."

[Byline: Jason Beaubien]

Communicated by:

[In formulating vaccination policies, a risk benefit analysis is a key process. In the case of polio vaccination, a critical question a country faces is "what is the risk of disease from the wild poliovirus" vs "what is the risk of disease from the vaccine virus". In the case of the WPV, the risk of paralysis among unvaccinated individuals averages 1 case per every 200 infected individuals. In the case of the vaccine virus, the risk of paralysis among those receiving the vaccine is approximately 1 case per every 2.7 million doses of vaccine administered. In the case of cVDPV there have been a total of 865 cases reported to WHO since 2000 with more than 10 billion doses administered during the period 2005 to 2015 - hence a very very low risk. Wherever there is persistent circulation of the WPV (wild poliovirus), the risk of infection with the WPV is high, especially if there are pockets of susceptibles for the virus to circulate through. In contrast, in countries where there has not been circulation of the WPV in years, when there is the appearance of vaccine associated disease as the only form of polio identified in the country, that balance of risk and benefit has shifted. That being said, with the 2016 identification of WPV associated disease in Nigeria, in an area that had suboptimal vaccination coverages due to civil unrest, served as a reminder that the WPV could be circulating "under the radarscope" of the public health infrastructure, only to surface when there is access to the area or population at risk. Hence, the risk benefit analysis doesn't necessarily have a clearly definable risk identification.

In response to the observation above that "It's actually an interesting conundrum. The very tool you are using for [polio] eradication is causing the problem," countries that have been polio-free were migrating to the use of the inactivated poliovirus vaccine (IPV) through the years, and the end game strategy for polio eradication includes the complete shift to IPV worldwide. As type 2 VDPV is the most labile virus, with 723 out of 865 (83.6 percent) cVDPV polio cases associated with type 2 cVDPV, as of April 2016, the trivalent oral poliovirus vaccine was replaced with a bivalent poliovirus vaccine, omitting the type 2 vaccine virus, with the intent being to eliminate OPV2 virus from the environment. Unfortunately the virus was already circulating in Syria pre-dating this vaccine switch. (see for tables showing the cVDPV isolates since 2000 and for a description of the endgame strategy.

The advantages of the OPV include the ease in administration (drops are administered into the mouth), thereby permitting less technical training than needed to administer an injection, the observation that a recently vaccinated individual excretes the vaccine virus into the environment and thereby "vaccinates" others in the process (the conundrum), and produces local immunity in the intestines blocking continuation of circulation of WPV if the individual is exposed to it. This latter advantage was seen in Israel in 2013. Israel had been using exclusively IPV since 2005. In 2013, there were multiple isolates of WPV1 from environmental samples tested moving chronologically from the south of the country to the north. While the WPV was identified from weekly samples, during a 5-6 month period in 2013, there were no cases of paralytic poliomyelitis identified in the country in general and in the geographic areas surrounding were the positive environmental samples were taken from. Hence, while the vaccine protected the vaccinated individuals (Israel had reported a 94 percent vaccination coverage at that time), it did not completely interrupt transmission of the WPV. (see prior ProMED-mail posts listed below).

We are not far away from the switch in use of the trivalent OPV (containing vaccine viruses type 1, 2 and 3), to the elimination of the type 2 vaccine virus from the vaccine administered in the majority of countries around the world... the switchover date was in April 2016, a bit more than a year ago. As there are other geographic areas with suboptimal vaccination coverages, it would not be too much of a surprise to identify other (hopefully small) foci with cVDPV associated polio cases in the coming period. - Mod.MPP]

[3] AFP private sector reporting challenges - Kuwait
Date: Wed 28 Jun 2017
Source: Arab Times - Kuwait

Ministry blames private health sector of failure to report detection of cases - 'Acute flaccid paralysis'
Ministry of Health has blamed private health sector for failure to report detection of cases of acute flaccid paralysis to the Department of Public Health on time, reports Al-Jarida daily quoting a health source.

According to the report released by the Department of Public Health at the Ministry of Health, the situation coincides with a warning from the World Health Organization against resurface of polio in Syria and newly detected cases of polio in Der Al-Zour, Syria through the same stock of oral vaccine. It blames private health sector for defying the ministerial decision that ordered prompt report of acute flaccid paralysis detected. It indicated failure to report the cases has negative implication on integrity and position of Kuwait by continuing to declare to the World Health Organization that the country is free from polio.

It recommended the ministry should contact the private health sector to urge them give precise information about cases detected to enable the ministry record it appropriately. This is one of the standard conditions and procedures required to declare the country polio free, it stated.

Communicated by:

[This last article was included as a reminder of both concerns of countries near to Syria as well as a reminder of the challenges the public health infrastructure in receiving timely reports from the private sector. An unfortunate but common situation experienced by many countries. - Mod.MPP


See Also

Poliomyelitis update (13): Syria (DY, RA), global 20170622.5124548
Poliomyelitis update (12): Syria (DY, RA), susp. cases 20170621.5122019
Poliomyelitis update (11): Afghanistan, WPV, global update 20170615.5108445
Poliomyelitis update (10): Syria (DY), Congo DR, cVDPV, WHO 20170613.5103235
Poliomyelitis update (09): Syria (DY), conf. cVDPV 20170608.5093275
Poliomyelitis update (08): global (Congo DR cVDPV) 20170526.5064449
Poliomyelitis update (07): Mozambique, Congo DR, VDPV, RFI 20170525.5060299
Poliomyelitis update (06): Syria (DY), cVDPV susp 20170512.5032401
Poliomyelitis update (05): Syria (DY) susp, RFI 20170506.5015784
Poliomyelitis update (04): fractional IPV 20170430.5003843
Poliomyelitis update (03): Pakistan (GB, IS, PB), environmental samples, global 20170316.4905775
Poliomyelitis update (02): Pakistan (GB) WPV1 20170314.4901037
Poliomyelitis (01): Pakistan (GB), global, RFI 20170314.4898724
Poliomyelitis update (21): IPV shortage, global 20161231.4733243
Poliomyelitis update (01): India, VDPV, wild type-free 20160115.3939297
Poliomyelitis - update (03): Lebanon ex Syria, susp, global, RFI 20140312.2328674
Poliomyelitis update (28): Syria, global, WHO 20131128.2078961
Poliomyelitis update (26): Syria, WHO 20131115.2050618
Poliomyelitis update (25): Syria (DZ) conf, WHO 20131030.2027954
Poliomyelitis update (24): Syria susp, Cameroon, global 20131024.2019404
Poliomyelitis update (23): Syria susp., global, RFI 20131020.2010654
Poliomyelitis update (19): Somalia, Israel, global 20130817.1884992
Poliomyelitis update (18): Israel 20130807.1869032
Poliomyelitis update (16): Israel, Somalia, Global 20130801.1854632
Poliomyelitis update (14): Israel, environmental samples, global 20130715.1826123
Poliomyelitis update (12): Kenya, Somalia, RFI, Israel environ. samples 20130614.1772461
Poliomyelitis update (10): Israel, positive environmental samples, MOH 20130605.1756289
Poliomyelitis update (09): Israel, positive environmental samples, RFI 20130604.1754766
Poliomyelitis update (08): Israel, environmental isolates, WHO, RFI 20130603.1753099

No hay comentarios: