Tag: polio outbreaks

Why Do We Still Vaccinate If Polio Has Been Eliminated?

It’s true, polio has been eliminated in the United States.

Are these folks serious with this anti-vaccine nonsense?
Are these folks serious with this anti-vaccine nonsense?

But that doesn’t mean that we can stop vaccinating kids against polio yet.

Why Do We Still Vaccinate If Polio Has Been Eliminated?

For one thing, the last polio case in the United States was a lot more recent than 40 years ago.

What happened 40 years ago?

That was when we had the last endemic case of polio in the United States, in 1979. After that, in addition to cases of VAPP, there were at least 6 cases of imported paralytic poliomyelitis. In fact, the last case of wild polio in the United States was in 1993, just 26 years ago.

And just ten years ago, in 2009, was the very last case of VAPP, a patient with a long-standing combined immunodeficiency who was probably infected in the late 1990s, even though she didn’t develop paralysis until years later.

But still, why couldn’t we stop vaccinating against polio in the United States, even though polio isn’t eradicated yet? After all, we stopped using the smallpox vaccine in 1972, before smallpox was declared eradicated (1980).

While that is true, smallpox isn’t as contagious as polio and there hadn’t been a case of smallpox in the United States for over 30 years when we stopped using the vaccine.

Until wild polio is eradicated and the oral polio vaccine isn’t used anymore (OPV switch), we must continue to vaccinate against polio to prevent new outbreaks.

That is the polio eradication and endgame strategic plan.

Over the next few years, the world will hopefully switch to using just the injectable form of the polio vaccines, which eliminates the risk of VAPP.

But if we are so close, why not just stop vaccinating in those parts of the world that don’t have polio?

Because we are so close to eradicating polio.

Why take the risk of polio spreading from one of the remaining endemic countries, paralyzing kids, and putting eradication efforts further behind?

Should we stop vaccinating kids because anti-vaccine folks are pushing misinformation about DDT, renamed diseases, or vaccine induced diseases?

Of course not!

Vaccines are safe, effective, and necessary.

Let’s continue the work and eradicate polio, once and for all!

And for the record – we don’t pump “kids full of polio” when we give them a polio vaccine. The polio shot is an inactivated vaccine, so doesn’t contain live polio virus.

More on Why Do We Still Vaccinate If Polio Has Been Eliminated?

Vaccine-Preventable Diseases – Year in Review 2018

Does it seem like we are moving in the wrong direction?

The eradication of smallpox shows just what vaccines can do!
The eradication of smallpox shows just what vaccines can do!

No, smallpox isn’t coming back, but many other vaccine-preventable diseases are.

Vaccine-Preventable Diseases – Year in Review 2018

With the availability of new vaccines and the expanded use of other vaccines, many of us were hopeful of the progress that was being made against vaccine-preventable diseases so far this decade.

Remember, it was just four years ago that the WHO certified India as a polio free country. And after years of declining numbers of wild polio cases, 2018 will be the first year with a higher number of cases than the previous year.

This hasn’t been a good year for measles either. The WHO Region of the Americas has lost its status as having eliminated measles!

In Bolivarian Republic of Venezuela, endemic transmission of measles has been re-established, with spread to neighbouring countries. As a result, the Region has lost its status as having eliminated measles. The Regional Technical Advisory Group, which met in July 2018, emphasized the importance of Regional action and an urgent public health response to ensure re-verification of measles elimination in Bolivarian Republic of Venezuela.

Meeting of the Strategic Advisory Group of Experts on Immunization, October 2018 – Conclusions and recommendations

After years of declining rates, global measles cases and deaths began to jump in 2017, a trend that continued in 2018.

“Outbreaks in North America and in Europe emphasize that measles can easily spread even in countries with mature health systems. Due to ongoing outbreaks, measles is again considered endemic in Germany and Russia.”

2018 Assessment Report of the Global Vaccine Action Plan

And no, this isn’t just a problem in other parts of the world.

Vaccine preventable diseases are just a plane ride away.
Vaccine preventable diseases are just a plane ride away.

More cases in other parts of the world mean more cases in the United States because unvaccinated folks travel out of the country and bring these diseases home with them, getting others sick.

But it wasn’t just measles outbreaks, including the second largest number of cases in 22 years, that we were seeing in 2018:

  • chicken pox – although the 41 cases involving a North Carolina Waldorf school got the most attention, there were at least 6,892 cases of chicken pox last year, which continues to trend down from recent highs of over 15,000 in 2010
  • hepatitis A – clusters of outbreaks in 15 states with at least 11,166 cases, many deaths, with exposures at popular restaurants
  • mumps – from recent highs of over 6,000 cases the last few years, we were “back down” to just over 2,000 mumps cases in 2018
  • pertussis – cases were also down in 2018, with a preliminary count of about 13,439 cases last year
  • meningococcal disease – isolated outbreaks continued last year, with cases at Smith College, Colgate University, and San Diego State University

And of course, we had one of the worst flu seasons in some time last year, with 185 pediatric flu deaths.

Fortunately, there were no cases of diphtheria, neonatal tetanus, polio, or congenital rubella syndrome. At least not in the United States.

Why are some disease counts down when so many folks say the anti-vaccine movement is more active than ever?

Remember, the great majority of people vaccinate and protect their kids!

And vaccines work!

It is best to think of the anti-vaccine movement, which has always been around, as a very vocal minority that is just pushing propaganda to scare parents away from vaccinating and protecting their kids.

As more people are vaccinated and diseases disappear, they forget how bad those diseases are, skip or delay getting their vaccines, and trigger outbreaks.
As more people are vaccinated and diseases disappear, they forget how bad these diseases are, allow themselves to be influenced by anti-vaccine propaganda, skip or delay getting their vaccines, and trigger outbreaks. Photo by WHO

Also remember that many of these diseases occurred in multi-year cycles in the pre-vaccine era. When an up year hits a cluster of unvaccinated kids, we get bigger outbreaks. And then more folks get vaccinated, starting the cycle all over again. At least until we finally get the disease under better control or finally eradicated.

Want to avoid getting a vaccine-preventable disease this year?

Get vaccinated and protected and encourage everyone else to get vaccinated too.

More on Vaccine-Preventable Diseases – Year in Review 2018

Milestones Towards the Eradication of Polio

There is a lot more interest in polio these days, but not because we are close to eradicating this deadly disease, but rather because of the emergence of cases of acute flaccid myelitis (AFM).

Although the cases have a different cause, the symptoms of AFM are the same that we used to see during the outbreaks of polio that used to hit each summer in the pre-vaccine era.

Polio

Surprisingly, in most people, the poliovirus doesn’t actually cause any symptoms. They simply have an asymptomatic infection.

In some others, the poliovirus causes flu-like symptoms, including a fever, sore throat, nausea, and a headache – symptoms that last about 3 to 5 days.

Much more rarely, the poliovirus causes meningitis or paralysis.

It is these cases of paralytic polio that most people are aware of and that panicked parents during summers in the 1940s and 50s.

In addition to respiratory problems (think iron lungs), polio causes muscle atrophy.
In addition to respiratory problems (think iron lungs), polio causes muscle atrophy. (CC BY-NC 4.0)

After having flu-like symptoms, those kids who would develop paralytic polio can develop pain and then flaccid paralysis.

“The most severe form, paralytic poliomyelitis, which is seen in less than 1% of patients, presents as excruciating episodes of pain in back and lower limbs. In children, the disease may present in biphasic form—a period of prodrome followed by a brief symptom-free period of 7 to 10 days and then appearance of asymmetrical paralysis of limbs. Flaccid paralysis is the hallmark with loss of deep tendon reflexes eventually.”

Mehndirattta et al on Poliomyelitis Historical Facts, Epidemiology, and Current Challenges in Eradication

Of course, polio wasn’t always called polio.

Other names have included infantile spinal paralysis, infantile paralysis, Heine-Medin disease, poliomyelitis anterior acuta, and acute anterior poliomyelitis.

The first use of the name “polio” came from Adolph Kussmaul, with his use of the term poliomyelitis anterior acuta, which was derived from the Greek polios “grey” and myelos “marrow” and itis “inflammation.” It was because he knew that it was caused by inflammation of the spinal cord gray matter, even if he didn’t know why.

Polio History

Polio didn’t just suddenly appear in the middle of the 20th century though, it was likely around for ages.

That this Ancient Egyptian priest's leg is smaller than the other and he uses a staff to walk suggests that he could have had polio.
That one of this Ancient Egyptian priest’s legs is smaller than the other and he uses a staff to walk could suggest that he had polio.

In addition to an Egyptian funeral stele (a stone slab used as a monument) portraying Roma the Doorkeeper from 1500 BCE that suggests he had paralytic polio, archeologists have found evidence of polio in skeletons as far back as the Neolithic period.

A medical book from 1789 likely describes people with polio.
A medical book from 1789 likely describes people with polio.

Still, we don’t really know how long polio has been around and we don’t know why we began to see more cases in the mid-20th Century, although there are theories, including, ironically, about hygiene. While we often credit improved sanitation and hygiene for helping to reduce mortality from many diseases, some think that this actually set us up for polio outbreaks, as we were no longer exposed as infants, when we still had some maternal immunity.

The one thing that we do know is that we are on the verge of eradicating polio, as there are very cases now, in just a few countries.

Polio Timeline and Milestones

In addition to the more ancient discoveries about polio, there is a lot to learn about vaccines and vaccine-preventable diseases if we look at the major milestones of this important disease.

Although in the end it is a success story, the road to figuring out what caused polio symptoms and how polio could be prevented was very long.

  • Michael Underwood describes what is thought to be paralytic polio in his book A Treatise on the Diseases of Children, with General Directions for the Management of Infants from Birth  in a section on “Debility of the Lower Extremities” (1789)
  • first reported outbreak of polio in Worksop, England (1835)
  • Jacob von Heine, head of an orthopedic hospital in Germany, publishes a monograph that describes 29 cases of paralytic polio, and actually attributes the condition to inflammation of the anterior horns of the spinal cord, although the cause was still not known (1840)
  • first use of the term poliomyelitis by Adolph Kussmaul (1874)
  • Nils August Bergenholtz reports on an outbreak of paralytic polio in Sweden (1881)
  • Karl-Oskar Medin, a pediatrician who reported on a polio epidemic in Sweden (1887), later presents his findings at the Tenth International Conference in Berlin (1890)
  • the first major outbreak in the United States is documented in Rutland County, Vermont and causes 132 cases of paralysis and 18 deaths (1894)
  • Ivar Wickman tracks cases of polio during an epidemic in Sweden in 1905 and was the first to suggest that polio was contagious and that you could get it from “those afflicted with the abortive type” (1907)
  • although they don’t actually identify the poliovirus, Dr. Karl Landsteiner and Dr. Erwin Popper  identify that a virus causes polio when they inject material from the spinal cord of a child who had recently died with polio into the peritoneum of two monkeys, both of which soon developed paralytic polio (1908)
  • Simon Flexner, first discovers polio antibodies (1911), but unlike other researchers at the time, pushes the theory that polio was spread by the olfactory route, instead of the fecal-oral route, which was why we saw the development of nose sprays, etc., to try and prevent polio, none of which worked of course
  • a large polio epidemic in the United States causes at least 27,000 cases and 6,000 deaths (1916)
  • Philip Drinker and Louis Agassiz Shaw invent the first iron lung, the Drinker respirator (1929)
  • Frank M. Burnet and Jean Macnamara proposed that there were antigenically different strains of poliovirus (1931)
  • John R. Paul and James D. Trask help figure out how polio was spread by identifying the polio virus in human waste and sewage samples (1932)
  • Maurice Brodie and John Kolmer have unsuccessful field trials of early polio vaccines, including allergic reactions and vaccine induced polio because of poor attenuation (1935)
  • Sister Elizabeth Kenny establishes a clinic in Australia to treat polio survivors (1932) and later publishes her treatment recommendations, Infantile Paralysis and Cerebral Diplegia (1937)
  • the National Foundation for Infantile Paralysis is founded by FDR to stop polio (1937)
  • the first March of Dimes fundraisers to stop polio (1938)
  • Carl Kling found traces of the poliovirus in the Stockholm sewage system (1942)
  • the Sister Kenny Institute is built in Minneapolis, as her treatment methods become widely accepted after years of controversy (1942)
  • the U.S. Army Neurotropic Virus Commission, including Albert Sabin, gets a grant from the NFIP to study polio in North Africa (1943)
  • Isabel Morgan actually developed the first inactivated polio vaccine, but only tested it on monkeys (1949)
  • John Enders, with T. H. Weller and F. C. Robbins, received the Nobel Prize in 1954 for their work on the cultivation of the poliomyelitis viruses (1949)
  • David Bodian creates the monkey model using field isolates of poliovirus and with Jonas Salk, identifies the three poliovirus serotyes (1950s)
  • Hilary Koprowki develops the first oral, live polio vaccine, (1950) although Sabin’s vaccine eventually gets licensed because it is thought to be less neurovirulent in monkeys and undergoes more testing
  • there are 58,000 cases of paralytic polio in the United States (1952)
  • Renato Dulbecco, with Marguerite Vogt, successfully grows and purifies polio virus (1952)
  • the Polio Pioneers vaccine field trial, led by Thomas Francis Jr.,  that proves that Jonas Salk’s polio vaccine is safe and effective begins (1954)
  • Jonas Salk gets approval for his polio vaccine (1955)
  • improperly inactivated polio vaccine from Cutter Laboratories (Cutter Incident) causes 40,000 cases of polio, 200 cases of paralysis, and kills ten people (1955)
  • Albert Sabin develops the first live, oral polio vaccine, which replaced Jonas Salk’s inactivated polio vaccine (1961)
  • that polio survivors can develop new, late complications or post-polio syndrome begins to get reported (1969)
  • last endemic case of polio in the United States (1979)
  • the National Foundation for Infantile Paralysis officially changes its name to the March of Dimes Birth Defects Foundation (1979)
  • the World Health Assembly adopts a resolution for the worldwide eradication of polio by 2000 and the the Global Polio Eradication Initiative is launched (1988)
  • last imported case of polio in the United States (1993)
  • the WHO Region of the Americas is declared polio free (1994)
  • “last” case of VAPP that was acquired in the United States (1999)
  • last case of wild poliovirus type 2 (1999)
  • the WHO Western Pacific Region is declared polio free (2000)
  • the United States switches back to using the an inactivated polio vaccine because of concerns over VAPP (2000)
  • the WHO European Region is declared polio free (2002)
  • outbreak of vaccine derived polio among a group of unvaccinated Amish in Minnesota (2005)
  • last case of VAPP that was acquired outside the United States, an unvaccinated 22-year-old U.S. college student who became infected with polio vaccine virus while traveling in Costa Rica in a university-sponsored study-abroad program (2005)
  • last case of VAPP in the United States, a patient with a long-standing combined immunodeficiency who was probably infected in the late 1990s (2009)
  • last case of type 3 poliovirus (2012)
  • seasonal reports of acute flaccid myelitis in the late summer and early fall, which might be caused by a non-polio enterovirus, are reminiscent of polio epidemics in the early part of the 20th century (2014)
  • type 2 poliovirus eradicated (2015)
  • Bob Sears says that it is okay to delay the polio vaccine on his alternative vaccine schedule because “we don’t have polio in the United States” (2015)
  • a global switch from trivalent OPV to bivalent OPV in routine immunization programs (2016)
  • polio remains endemic in just two countries, Afghanistan and Pakistan (2018)

So it should be clear, that despite what some folks think, polio wasn’t conquered overnight. And Salk and Sabin obviously had a lot of help, although those are the names we most commonly hear connected with polio eradication.

“Until poliovirus transmission is interrupted in these countries, all countries remain at risk of importation of polio, especially vulnerable countries with weak public health and immunization services and travel or trade links to endemic countries.”

Global Polio Eradication Initiative on Endemic Countries

And to be clear, polio hasn’t yet been conquered.

There is still some work to do unless we want to see cases of polio and paralytic polio return.

That’s why it is important that you don’t skip your child’s vaccines, even for diseases that we don’t have in the United States anymore.

More on the History of Polio

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