Tag: diphtheria

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

What Are Hypotonic-Hyporesponsive Episodes?

Just about any side effect after a vaccine can be scary for parents.

What if your child suddenly became limp, wasn’t responsive, and was pale?

That would be scary for any parent.

What Are Hypotonic-Hyporesponsive Episodes?

But that’s just what can happen when a child has a hypotonic–hyporesponsive episode (HHE).

“A hypotonic-hyporesponsive episode (HHE) is the sudden onset of hypotonia, hyporesponsiveness, and pallor or cyanosis that occurs within 48 hours after childhood immunizations.”

DuVernoy et al on Hypotonic-hyporesponsive episodes reported to the Vaccine Adverse Event Reporting System (VAERS), 1996-1998

These types of episodes were once thought to happen once for every 1,750 DTP vaccines given.

HHE is much more rare since we switched to a new pertussis vaccine.
HHE is much rarer since we switched to a new pertussis vaccine.

Fortunately, although they certainly do sound scary, the episodes stop on their own and  don’t cause any permanent harm.

Hypotonic-hyporesponsive episodes were even removed as table injuries after DTP back in 1995. It is not that HHE can’t occur after DTP, DTaP, or other vaccines, but rather that HHE doesn’t then cause any permanent neurological damage to the child.

And it is rare for kids to have a second episode, so they can continue to get vaccinated. HHE is not a good reason to skip or delay all of your child’s vaccines. While not a contraindication to getting vaccinated, having an episode of HHE “within 48 hours after receiving a previous dose of DTP/DTaP,” is listed as a precaution to getting another dose of DTaP or Tdap though.

“In general, vaccinations should be deferred when a precaution is present. However, a vaccination might be indicated in the presence of a precaution if the benefit of protection from the vaccine outweighs the risk for an adverse reaction.”

CDC on Vaccine Contraindications and Precautions

Also, HHE has become even more rare since we switched to using DTaP, instead of the older DTP vaccine. So being worried about HHE is definitely not a good reason to skip or delay any vaccines.

What to Know About Hypotonic-Hyporesponsive Episodes

Hypotonic-hyporesponsive episodes were more common after the older DTP vaccines, but still didn’t cause any long term problems and aren’t a good reason to skip or delay your child’s vaccines.

More About Hypotonic-Hyporesponsive Episodes

Diphtheria in Canada

Breaking News – there is a new case of diphtheria in Canada (June 2018).

A lot of people were surprised by the news of a case of diphtheria in Canada last year.

Some folks were quick to blame the anti-vaccine movement, assuming it was in an unvaccinated child.

News soon came that the child was vaccinated!

“I’ve always been on top of that, I’m a firm believer in immunizations.”

Mother of 10-year-old with diphtheria

What happened next?

Anti-vaccine folks began using the fact that he was vaccinated, but still developed diphtheria, as some kind of proof that vaccines don’t work.

The Case of Diphtheria in Canada

They are wrong.

The diphtheria vaccines have worked very well to control and eliminate diphtheria from Canada, just like it has in the United States.

Diphtheria has become rare since the pre-vaccine era.
Diphtheria has become rare since the pre-vaccine era.

So how did a vaccinated child in Canada get diphtheria?

It’s simple.

He has cutaneous diphtheria, not respiratory diphtheria.

What’s the difference?

“Extensive membrane production and organ damage are caused by local and systemic actions of a potent exotoxin produced by toxigenic strains of C. diphtheriae. A cutaneous form of diphtheria commonly occurs in warmer climates or tropical countries.”

Vaccines Seventh Edition

Cutaneous diphtheria occurs on your skin. It is usually caused by non-toxigenic strains of Corynebacterium diphtheriae.

On the other hand, respiratory diphtheria is usually caused by toxigenic strains of Corynebacterium diphtheriae.

Diphtheria strikes unprotected children.The diphtheria vaccine (the ‘D’ in DTaP and Tdap), a toxoid vaccine, covers toxigenic strains. More specifically, it covers the toxin that is produced by toxigenic strains of Corynebacterium diphtheriae. It is this toxin that produces the pseudomembrane that is characteristic of diphtheria.

It was the formation of this pseudomembrane in a child’s airway that gave diphtheria the nickname of the “strangling angel.”

So why the fuss over this case in Canada? They likely don’t yet know if it is a toxigenic strain. If it is, then it could be a source of respiratory diphtheria.

But remember, even if these kids developed an infection with the toxigenic strain of Corynebacterium diphtheriae, those that are fully vaccinated likely wouldn’t develop respiratory diphtheria. Again, it is the toxin that the bacteria produces that cause the symptoms of diphtheria. The vaccine protects against that toxin.

For example, when an intentionally unvaccinated 6-year-old in Spain was hospitalized with severe diphtheria symptoms a few years ago, although many of his friends also got infected, non of them actually developed symptoms because they were all vaccinated.

Diphtheria Is Still Around

Diphtheria is DeadlyTragically though, especially since diphtheria is still endemic in many countries, we are starting to see more and more lethal cases of diphtheria, including cases in many more countries where it was previously under control:

  • at least 142 diphtheria deaths in Venezuela since 2016, among about 1,602 cases
  • at least 85 deaths in Yemen, among about 1,584 cases since 2017
  • at least six deaths among Rohingya refugees in Bangladesh
  • at least two cases of diphtheria in Ukraine
  • a family that became infected in South Africa in which at least one child died (August 2017)
  • an unvaccinated 3-year-old who died in Belgium (2016)
  • a 22-year-old unvaccinated women who died in Australia (2011)

It is even more tragic that diphtheria is not under control in so many more countries.

In 2016, the WHO reported that there were just over 7,000 cases of diphtheria worldwide. While that is down from the 30,000 cases and 3,000 deaths in 2000, thanks to improved vaccination rates, there is still work to be done.

And as this recent case in Canada shows, diphtheria is still around in many more places than we would like to imagine.

Get educated. Vaccines are necessary.

What to Know About Diphtheria in Canada

The case of cutaneous diphtheria in Canada is a good reminder that vaccines are still necessary.

More on Diphtheria in Canada

Updated on June 24, 2018