Tag: AFP

Is Polio Returning to Venezuela?

Breaking News – further tests have found that the person with suspected polio did not have either wild polio or vaccine-derived poliovirus (VDPV). Could it still be polio? (see below).

Polio is on the verge of being eradicated.

In 2017, there have only been 118 cases of polio in the whole world, including 22 cases of wild poliovirus in Afghanistan and Pakistan and 96 cases of vaccine-derived poliovirus (VDPV) in the Democratic Republic of Congo and Syria.

So far this year, there have only been 15 cases of polio in the whole world, including 10 cases of wild poliovirus in Afghanistan and Pakistan and five cases of vaccine-derived poliovirus (VDPV) in the Democratic Republic of Congo and Nigeria.

Is Polio Returning to Venezuela?

Most of us are aware that vaccine-preventable diseases are just a plane ride away.

We see it, or at least read about it, all of the time, as we continue to see outbreaks of measles affecting our communities.

But polio?

Could polio return?

Venezuela has been polio free for nearly 30 years. The last case of a wild poliovirus infection was in March 1989. And yet ,there are now thought to be at least four cases of poliovirus, type 3 in the Delta Amacuro state of north east Venezuela, where they are also seeing cases of diphtheria and measles.

Report of polio in Venezuela

Among the polio cases is a 2-year-old boy who was unvaccinated, an unvaccinated child who lived next to him, and a partially vaccinated child 8-year-old who lived next door.

“It has been reported unofficially that it is polio vaccine virus.”

Venezuelan Society of Public Health Report

But what is the source of the polio vaccine virus?

We supposedly stopped using oral polio vaccines that can shed in January 2016, right?

Actually, we began the switch from trivalent OPV (tOPV) to bivalent OPV (bOPV) in 2016, removing the the type 2 polio virus that is most likely to cause VAPP. Making sure kids get a dose of IPV first also lowers the risk of VAPP. At least it does when kids get vaccinated according to plan.

“Other children from the same community were vaccinated in April 2018 with oral bivalent polio vaccine.”

PAHO on Epidemiological Update Detection of Sabin type 3 vaccine poliovirus in a case of Acute Flaccid Paralysis 

When did the first case appear? Although we are just hearing about it now, his symptoms began in April, right around the time another child received a bivalent oral polio vaccine.

“No additional AFP cases have been identified to date through active search for AFP cases carried out in the community.”

PAHO on Epidemiological Update Detection of Sabin type 3 vaccine poliovirus in a case of Acute Flaccid Paralysis 

Fortunately, in the past month, no further cases have been identified.

Children in Venezuela are supposed to get at least one dose of IPV (inactivated polio vaccine), followed by four doses of bOPV (bivalent oral polio vaccine).
Children in Venezuela are supposed to get at least one dose of IPV (inactivated polio vaccine), followed by four doses of bOPV (bivalent oral polio vaccine).

So what does this all mean?

For one thing, wild polio isn’t returning to Venezuela. And it doesn’t look like we will see a large outbreak of cVDPV, as there are no further cases of AFP in the area.

But it does illustrate that we can easily see a return of vaccine-preventable disease if we don’t keep vaccinating until they are eradicated. Remember, low vaccination coverage is associated with outbreaks of cVDPV. If everyone is vaccinated and protected, then they won’t get polio, whether it is wild type or shed from someone who was vaccinated.

Latest Updates on AFP in Venezuela

While a Sabin type 3 polio virus had been initially isolated from the stool samples of the unvaccinated 34-month-old boy with polio symptoms, further tests have now been completed.

“Tests carried out by the specialized global laboratory for genetic sequencing have ruled out the presence of both wild poliovirus and vaccine-derived poliovirus (VDPV). The latter- VDPV- is a Sabin virus with genetic mutations that give it the ability to produce the disease. There is no risk of spread to the community or outbreaks of polio from this case.”

PAHO

So what does he have?

The possibilities are non-polio AFP, as many viruses and other diseases can cause polio-like symptoms.

So why did he have the Sabin type 3 polio virus in his stool?

It is well known that the oral polio vaccines shed. Even though he was  unvaccinated, he was likely exposed to others in the community who were recently vaccinated, as it is possible to shed the vaccine virus in your stool. The attenuated (weakened) vaccine virus is unlikely to cause symptoms though, unless it develops the mutations found in VDPV strains, which this one didn’t.

“The child is being further evaluated clinically to determine alternative causes of paralysis. The final classification of the case of acute flaccid paralysis [to define whether or not it is associated with the vaccine] will be based on clinical and virological criteria assessed at 60 days after the onset of paralysis.”

PAHO

So despite what folks are reporting, they didn’t say that this case couldn’t be associated with the polio vaccine. We just know that it is isn’t wild polio and the virus doesn’t have the mutations associated with cVDPV strains, which can not only cause polio symptoms, but can also spread from one person to another, causing outbreaks.

Remember, although the attenuated vaccine virus in the oral polio vaccine is unlikely to cause polio symptoms, it sometimes can, in about 1 in 2.7 million doses.

“VAPP at this time can’t be ruled out, of course, as it’s one of the possibilities.”

Communications Officer
Global Polio Eradication Initiative

Could this child have VAPP?

“A VAPP case was most often defined as a case of acute flaccid paralysis (AFP) with residual paralysis (compatible with paralytic poliomyelitis) lasting at least 60 days, and occurring in an OPV recipient between 4 and 40 days after the dose of OPV was administered, or in a person who has had known contact with a vaccine recipient between 7 and 60–75 days after the dose of OPV was administered.”

Platt et al on Vaccine-Associated Paralytic Poliomyelitis: A Review of the Epidemiology and Estimation of the Global Burden

I guess we will find out in a few weeks, as his symptoms started at the end of April.

Still, remember that VAPP is not contagious.

What to Know About Polio Returning to Venezuela

Several cases of a vaccine strain of polio virus have been found in Venezuela, which is linked to low vaccinated levels.

More on Polio Returning to Venezuela

Updated June 17, 2018

Myths About Polio and Acute Flaccid Paralysis

Polio is one of the most well known causes of acute flaccid paralysis.

Although most people with polio infections have no symptoms at all, or just have a very mild illness, with a sore throat and a low grade fever, a small percentage can develop:

  • a loss of superficial reflexes
  • severe muscle aches and spasms in their limbs or back
  • an asymmetrical flaccid paralysis with diminished deep tendon reflexes

This acute flaccid paralysis only affects the child’s strength in the affected muscle groups – there is no loss of sensation. The severity of the symptoms and the disease depends on which muscles are affected the most. If it is just your legs, then you will have trouble walking. On the other hand, if it affects your chest, then you might not be able to breath, unless you are put on a ventilator (iron lung).

Acute Flaccid Paralysis

Thinking about it in the context of polio, it becomes easy to understand acute flaccid paralysis or AFP.

It is the sudden onset (acute) of a flaccid (floppy or poor muscle tone) paralysis (weakness or inability to move) of one or more muscles.

But what many people don’t understand, is that in addition to polio, there are many more non-polio causes of AFP.

Non-Polio AFP

Many of us got a crash course in non-polio acute flaccid paralysis (NP-AFP) a few years ago when we started hearing reports of kids developing polio-like paralysis in 2014. Now thought to be caused by enterovirus D68 infections (EV-D68), the paralysis followed respiratory tract infections in many of the affected children. All together, at least 120 children in 34 states developed acute flaccid paralysis that year.

Interestingly, EV-D68 is one of more than 100 non-polio enteroviruses. The virus that causes hand, foot, and mouth disease, coxsackievirus A16, is another. Others cause pinkeye, meningitis, or encephalitis.

Keep in mind that many other viruses and conditions can cause non-polio AFP too, including:

  • Guillian-Barré syndrome
  • toxins (botulism)
  • tumors
  • transverse myelitis
  • traumatic neuritis
  • other infections, including novel enterovirus C105, a non-polio enterovirus, and even tick-borne (Lyme disease) and mosquito-borne (Japanese encephalitis) infections

How do you determine the cause and how do you know it isn’t polio?

These kids with AFP typically have extensive testing to determine what is causing their AFP, including an MRI, antibody tests, and testing of their cerebrospinal fluid, etc. Although it isn’t always possible to identify a cause, you can at least rule out many potential suspects, like trauma, polio, and other infections.

Myths About Polio and Acute Flaccid Paralysis

Some folks don’t believe in non-polio AFP.

They believe that polio never really disappeared because vaccines don’t really work and that polio was simply renamed to, you guessed it, acute flaccid paralysis.

“Unbeknownst to most doctors, the polio-vaccine history involves a massive public health service makeover during an era when a live, deadly strain of poliovirus infected the Salk polio vaccines, and paralyzed hundreds of children and their contacts. These were the vaccines that were supposedly responsible for the decline in polio from 1955 to 1961! But there is a more sinister reason for the “decline” in polio during those years; in 1955, a very creative re-definition of poliovirus infections was invented, to “cover” the fact that many cases of ”polio” paralysis had no poliovirus in their systems at all. While this protected the reputation of the Salk vaccine, it muddied the waters of history in a big way.”

Suzanne Humphries, MD on Smoke, Mirrors, and the “Disappearance” Of Polio

What’s their evidence?

A rise in cases of non-polio AFP in India since 1997.

How do we know that there has been a rise in non-polio AFP cases in India since 1997?

It’s very simple and explains why there isn’t any data on before that 1997. 

As part of the strategy to eliminate polio in that country, starting in 1997, all cases of AFP started getting tested for polio. It was a way to track the effectiveness of the immunization program. If you were seeing too many cases of AFP caused by polio, then not enough people were getting vaccinated. On the other hand, if you weren’t seeing any cases of AFP in an area, then the testing and surveillance probably wasn’t getting none, since there will always be some cases of non-polio AFP.

Unfortunately, they found many cases to track. And the cases kept increasing, although more and more, they weren’t being caused by polio. At least not by live polio virus.

Were they caused by the polio vaccine?

In some cases, yes. It is well known that the live polio vaccine can rarely cause VAPP and cVDPV.

By 2015, after India was declared free of polio (the last case was in 2011), none of those cases of AFP were found to be caused by wild polio though. And India hasn’t had a case of cVDPV since 2010.

Why the increase in cases of non-polio AFP? It certainly isn’t because of Suzanne Humphries’ polio virus renaming conspiracy or any other anti-vaccine conspiracy involving the polio vaccine itself.

The 'data' that Susanne Humphries uses to try and make her case about AFP neglects to mention that in the pre-vaccine era, polio paralyzed 500 to 1,000 children in India each day! Those 180,000 to 365,000 cases of paralysis wouldn't fit on her chart though...
The ‘data’ that Susanne Humphries uses to try and make her case about AFP neglects to mention that in the pre-vaccine era, polio paralyzed 500 to 1,000 children in India each day! Those 180,000 to 365,000 cases of paralysis wouldn’t fit on her chart though…
If we simply renamed polio to non-polio AFP, why did the numbers drop for so long and then slowly start to increase? Shouldn’t it have been a rapid crossover?

More importantly,  why are the case of paralysis from non-polio AFP so much lower than the pre-vaccine era cases of AFP from polio?

And how come we rarely see large outbreaks of AFP like we did in the pre-vaccine era?

Sure, 120 kids in the EV-D68 non-polio AFP outbreak of 2014 is way more than any of us would like to see, but it is tremendously less than what we used to see in the pre-vaccine era from polio.

“Poliomyelitis is one of the important emergent viral diseases of the twentieth century… At its height, from 1950–1954, poliomyelitis resulted in the paralysis of some 22,000 U.S. citizens each year… Many thousands were left permanently disabled by the disease, while many others suffocated as a consequence of respiratory paralysis.”

Barry Trevelyan on the The Spatial Dynamics of Poliomyelitis in the US

While anti-vaccine conspiracy theories about AFP are as easy to dismiss as all of the rest they bring up,  what is behind the rise in AFP in some areas of the world?

Although one study that was published in Pediatrics, “Trends in Nonpolio Acute Flaccid Paralysis Incidence in India 2000 to 2013,” did find a correlation between the use of the OPV vaccine and the incidence of non-polio AFP, many experts think the rise is a result of better screening. Also, once polio gets under control, other more neglected diseases start getting more attention, like enteroviral infections. Not surprisingly, other parts of the world have had the same experience.

There is also the fact that in 2005, the Global Poliomyelitis Eradication Initiative began “to cast a wider net for poliovirus detection and to maximize sensitivity so that every poliomyelitis case is detected.” Why? If even a single case was missed, it could lead to continued outbreaks and would get in the way of polio elimination in the country.

“This large increase in NP-AFP cases, which represent AFP cases caused by agents other than poliovirus, probably reflects the excellent implementation of the expanded definition of AFP and highly sensitive surveillance and detection methods used by NPSP in India from 2005 onwards…”

C. Durga Rao on Nonpolio Acute Flaccid Paralysis in India

So did the polio vaccine recently cause 53,000 paralysis victims in India?

No. 

The polio vaccine has worked to get us on the brink of eradicating polio though.

What To Know About Acute Flaccid Paralysis

Acute flaccid paralysis can be caused by the polio virus, but non-polio acute flaccid paralysis becomes a more important cause once polio is eliminated in a region.

More About Acute Flaccid Paralysis