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Commentary by James J. Tuite, III
Will The Poliovirus Eradication
Program Rid the World of
Childhood Paralysis?
With So Little Poliovirus Detected Around the World,
What Is Causing Today’s Outbreaks of Acute Flaccid Paralysis?
By Neenyah Ostrom
April 20, 2001
Every child of the early ’50s surely remembers the polio
panics that swept the nation, invariably during the hottest
days of summer, closing public pools and resulting in
doctor visits at the first sign of a stiff neck or leg prone to falling
asleep. My memory of the terror induced by the whispered
word “polio” resides in a spot in the pit of my stomach just
distal to the one recalling the Cold War era duck-and-cover
drills we practiced in grammar school.
In retrospect, it seems darkly hilarious that we ever
believed plywood desks and plump little arms would
protect school children from a nuclear attack. Our not-
quite-rational fear of the poliovirus, however, endures
despite World Health Organization eradication programs
[www.polioeradication.org] in the corners of the develop-
ing world where poliovirus is thought to lurk. One reason for
this lingering concern is the continuing prevalence of acute
flaccid paralysis, polio’s most crippling symptom that can leave
its victims unable to control entire muscle groups, even those
that allow us to breathe.
Worldwide polio-related public health alarms sounded on the
first day of 2001 when a new epidemic was reported to have broken
out on the island of Hispaniola, on which Haiti and the Dominican
Republic are located. David Brown reported in the Washington Post
that a “mutant” poliovirus, derived from strains present in the oral
polio vaccine, appeared to have run amok on this Caribbean island
during the latter half of 2000.3
When the US Centers for Disease Control and Prevention (CDC)
examined these cases, another mystery was revealed: Only about one-third of
the paralysis cases were
associated with poliovirus. The CDC identified 19 individuals in the Dominican
Republic who developed
acute flaccid paralysis (AFP, the hallmark symptom of poliovirus infection as
well as a syndrome unto itself)
between July 12 and November 18, 2000. However, poliovirus was detected in only
six of those individuals.
missing picture - A man demonstrates one of the US
government's protocols for surviving a
nuclear attack: "duck-and-cover" in the
doorway of a building, c.1955.
© 2000 Hulton Getty Picture Collection
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The cause of the other cases of paralysis remains unknown.25
The mystery deepens when we examine World Health
Organization (WHO) statistics on AFP and poliovirus infection
in the Dominican Republic for the last several years. [http://www-
nt.who.int/vaccines/polio/case.asp] Although the number of
cases of AFP in the Dominican Republic from 1996 to 1999 range
from 4 to 24, not a single case of poliovirus was detected.
If we further examine other WHO statistics on poliovirus-
associated AFP and those in which the virus is not detected, a
striking fact becomes clear: Most acute flaccid paralysis diagnosed
around the world today is NOT associated with poliovirus.
This fact raises new, disturbing questions, including wheth-
er there ever was an epidemic of poliovirus infection in the United
States and Canada. There was a greatly increased prevalence of
AFP, to be sure, during which many children (and some adults)
tragically were paralyzed or died. Since many of those cases
showed all the hallmarks of a typical poliovirus infection—fever,
stiff neck and back, severe headache, muscle pain, sore throat and,
in severe cases, paralysis—and occurred in clusters, they were
assumed to be caused by the easily-transmitted poliovirus.
But were they? If not, what is the cause of so much misery
today in areas of the world least-equipped to be able to deal
with it? Is it correct to assume that poliovirus causes most cases
of paralysis?
The Search for the
Transmissible Agent of
Poliomyelitis
Poliomyelitis became an important public health concern
when it first spread along the eastern seaboard of the United States,
as well as in industrialized areas of Europe, in the early 1900s. Its
inexplicable outbreaks were frightening to the public and medical
personnel alike, as Simon Flexner and Paul A. Lewis (both of
the Rockefeller Institute for Medical Research in New York)
demonstrated when they wrote in the Journal of the American
Medical Association in 1909, “The cause and mode of dissemina-
tion of the disease [poliomyelitis] are unknown; and hence there
exists no intelligent means of prevention. While the severity and
fatality of the disease fluctuate widely, its effects are always
so disastrous as to make it of the highest medical and social
importance.”14
Just a year earlier, Austrian researchers Karl Landsteiner
and Erwin Popper had made a historic breakthrough in the study of
poliomyelitis. Landsteiner had a nine-year-old poliomyelitis patient
What Is Poliomyelitis?
The word “poliomyelitis” comes
from two Greek words: “polio,” which
means gray, and “myelitis,” inflamma-
tion of the spinal cord. Poliomyelitis
can cripple and kill vulnerable individu-
als, especially children, within days. It
often affects the very young, which is
why it is also called “infantile paraly-
sis.” Some individuals develop only
flu-like symptoms without paralysis;
“aseptic meningitis” (swelling of the
membranes surrounding the brain) can
result. This “minor illness” of poliomy-
elitis (as it is called) is characterized
by slight fever, malaise, headache,
sore throat, and vomiting; patients
usually recover completely in 24-72
hours. Non-paralytic poliomyelitis can-
not be differentiated clinically from
aseptic meningitis caused by other
transmissible agents. Surprisingly,
fewer than one in 100 cases (and
possibly as few as one in 1,000 cases)
of infection with poliovirus produces
any obvious disease, even during out-
breaks.23,24
The “major illness” of poliomyelitis
usually develops suddenly, with fever,
stiff neck and back, severe headache,
and muscle pain. Major illness can
progress to loss of tendon reflexes and
asymmetrical weakness or paralysis.
Poliomyelitis is generally diagnosed
clinically by the concurrent presence
of high fever and acute, asymmetrical
flaccid paralysis, which develops in
2-4 days following the fever and
muscle aches. Approximately 50% of
people stricken with paralytic polio-
myelitis remain disabled throughout
their lives.24
The paralysis produced by polio-
myelitis results from inflammation and
destruction of motor neurons in the
gray matter of the spinal cord and
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who died on November 18, 1908, after just four days of illness.
With his colleague Popper, Landsteiner created a suspension from
the child’s spinal cord and injected it into two monkeys, as well
as a number of rabbits, guinea pigs, and mice. While the other
animals were unaffected by the injections of spinal cord material,
the two monkeys developed lesions in their spinal cords and
brains that appeared indistinguishable from those found in humans
suffering from poliomyelitis. One of the monkeys developed acute
flaccid paralysis in both legs. Although Landsteiner and Popper
attempted to transmit paralysis to other monkeys using the sick
monkeys’ nervous system tissues—which is called “passaging”
of
the transmissible agent—they were unsuccessful.10,20
The following year, Flexner and Lewis succeeded where
Landsteiner and Popper had not: Flexner and Lewis reported
in the Journal of the American Medical Association that they
had successfully passaged poliomyelitis through several monkeys
(i.e., from monkey to monkey). They began, like Landsteiner
and Popper, by injecting diseased human spinal cord tissue into
the brains of monkeys. After a monkey fell ill, a suspension of
its diseased spinal cord tissue was injected into other monkeys.
Flexner and Lewis’s 1909 work was considered a breakthrough
because the second monkey (and the third, and fourth, through
at least six by the time of publication) developed poliomyelitis.
Flexner and Lewis had successfully passaged the disease’s trans-
missible component from animal to animal.14
But what was the passaged agent? “We failed utterly
to discover bacteria, either in film preparations or in cultures,
that could account for the disease,” Flexner and Lewis reported.
Therefore, they concluded, “…the infecting agent of epidemic
poliomyelitis belongs to the class of the minute and filterable
viruses that have not thus far been demonstrated with certainty
under the microscope.”14
Did Flexner and Lewis succeed in isolating poliovirus
in 1909? Hindsight being 20/20, it is possible to see that early
experiments attempting to create purified poliovirus preparations
might well have contained other agents.
The debate over the nature of the causative agent of
poliomyelitis continued. One research team speculated in 1919
that a type of bacteria, cautiously named “poliococcus,” was
either the culprit or a co-factor.
7
In early experiments, all kinds
of biological materials—spinal cord, brain, fecal matter, even
flies—were ground up and injected into monkeys to induce paraly-
sis.4,7,15,21,22,33
These early “virus preparations” were known
to contain bacteria. The amount of bacteria was determined by
seeding a tissue culture plate with some of the spinal cord (or
fecal matter) emulsion to measure how long it took for bacterial
colonies to appear. As F.B. Gordon and colleagues pointed out
in a paper published in the Journal of Infectious Diseases,
brain. The type or degree of paralysis
induced depends upon the location
and extent of motor neuron destruc-
tion, and can range from minor to
severe limb paralysis, to paralysis of
the muscles that allow us to breathe.
The iron lung was used in the 1940s
and ’50s to assist children who could
not breathe on their own. As frighten-
ing as iron lungs look in the old photos,
many children recovered completely.
However, paralytic poliomyelitis is fatal
in 2-10% of cases.24
With the exception of patients who
go into respiratory failure, poliomy-
elitis treatment is symptomatic: non-
narcotic pain killers, application of hot
packs, and physical therapy.
\
What Is Poliovirus?
Despite the damage it causes to
nerve tissue, the poliovirus has been
placed in the enterovirus family of
viruses that live in the gastrointestinal
system. It is formed of a single strand
of RNA enclosed in a protein coat
that protects it from environmental
attack (inactivation). Poliovirus is quite
small by viral standards (22-32 nano-
meters). Humans are thought to be
poliovirus’s only host, which is why
the WHO launched an eradication pro-
gram. According to the CDC, the only
confirmed cases of poliovirus-associ-
ated paralysis in the US since 1979
have been associated with the oral,
live-virus vaccine.24,31
In fact, the CDC now concludes that “Both laboratory
surveillance for enteroviruses and sur-
veillance for polio cases suggest that
endemic circulation of indigenous wild
polioviruses ceased in the United
States in the 1960s.”24
Other investigators question the CDC’s conclusion
that wild poliovirus circulation truly
“ceased” in the United States four
decades ago.
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Page 4
“If there was no [bacterial] growth after approximately 22 hours incubation
at 37 C., the specimen was
considered suitable for inoculation into monkeys. This was not an actual sterility
test, since growth would
usually occur on longer incubation; it was rather an indication of the amount
of bacterial contamination
in the specimen.”15
Early poliovirus researchers, then, knew that the “virus” they were
injecting into monkeys also contained
an undetermined amount of bacteria. They had no way of determining what else
might be present.
While Flexner and Lewis may have been incorrect in assuming they had transmitted
a purified form of
“filterable virus” into their monkeys, they certainly transferred
a disease-causing agent or agents from animal
to animal. Although they could not actually visualize this agent, they described
it in the greatest detail that they
could. In doing so, which they undoubtedly meant to be a service to other researchers,
they may have voiced
their conclusions in ways that would haunt poliomyelitis research for decades.
At the beginning of the 20th century, as scientists began trying to understand
and characterize viruses
and viral diseases, many of them—including poliomyelitis researchers like
Flexner and Lewis—overstated
their findings.
Early poliomyelitis researchers were true scientific pioneers: Flexner, Lewis,
Dalldorf, Landsteiner,
Popper, Dulbecco, Sabin, Salk, and many others worked with unknown agents. They
didn’t understand the
properties of the contaminated tissues they handled, and they didn’t know
how to protect themselves from the
diseases those tissues might contain. Their bravery in undertaking these risks
should never be underestimated,
especially in our era when latex gloves, biosafety cabinets, and many other
methods of protecting scientists
from dangerous transmissible agents are readily available.
Nevertheless, these early 20th century researchers should not get a free pass
for their lack of precision
in describing experiments and their results.For example, in 1948, Gilbert Dalldorf
and Grace M. Sickles from the New York State Department
of Health published a research report that illustrates some problems in virology
that persist even today.
Dalldorf and Sickles described an “unidentified, filterable agent”
that they had “isolated” from the feces
of paralyzed children.6
The problems become clear when Dalldorf and Sickles described how they "isolated"
this agent:
“Twenty per cent fecal suspensions, prepared by ether treatment and
centrifugation, were inoculated intracerebrally into albino mice of the laboratory
strain. Suckling mice, 3-7 days of age, became paralyzed, while mice 10-12 gm
in
weight did not. The isolations were repeated several times.…”6
Dalldorf and Sickles used the word “isolation” to describe their creation
of a suspension of fecal
matter—which was a vast overstatement, to put it mildly.
Dalldorf and Sickles then attempted to identify the agent. In 1948, antibodies,
like viruses, could not
be characterized as they now can. “Neutralizing serum”—the non-cellular
portion of the blood, taken from a
person or animal presumed to be infected with the agent—was used to differentiate
between viral strains. This
neutralizing serum probably contained antibodies against the agent.
According to Dalldorf and Sickles, neutralizing serum from paralyzed children
inhibited paralysis in
mice when they were injected simultaneously with it and the unidentified agent.
This absence of evidence—that
the mice did not develop paralysis—was interpreted to mean that the agent
injected into the mouse had
been successfully stopped by the neutralizing serum (i.e., the immune response
generated by the sick child).
There was no proof, as Dalldorf and Sickles asserted, that the neutralizing
serum was reacting with and
inhibiting one specific agent.
Dalldorf and Sickles believed they’d “isolated” a novel agent
that could infect people, although they did
not argue that it was responsible for producing the paralysis seen in their
patients. “The patients we studied
may possibly have been coincidentally infected with the new agent and classical
poliomyelitis virus, although
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Page 5
isolations were not successful in [causing disease in] the rhesus monkey,”
they write.6
Again, they write of “isolation” when they are referring to taking
a partially processed specimen (spinal tissue or feces) from
a paralyzed person and injecting it into an animal to see if the diluted specimen
produced paralysis. True
isolation did not take place.
Has Poliovirus Ever Really Been Isolated?
It is an article of faith in modern medicine that poliovirus has been isolated,
characterized, is fully
understood and on its way to extinction, thanks to aggressive vaccination/eradication
programs. As the recent
outbreak in the Dominican Republic illustrates, however, we may be further from
eradicating poliomyelitis
than we are generally led to believe.
Furthermore, while the agent identified as poliovirus was certainly cultured
in the late 1940s, do we
know for sure that it was truly isolated, i.e., grown in a pure form containing
no contaminants? We now know that
adventitious (“passenger”) viruses like SV40 are common in the monkey
tissues that early poliovirus researchers
used for cell cultures. While these agents apparently cause no harm to the monkeys,
their long-term effects on
humans remain to be determined. [http://www.chronicillnet.org/online/bensweet.html#anchor714274]
Some 90 years after Landsteiner and Popper’s report of successful transfer
of poliomyelitis to monkeys,
Dr. Wolfgang K. Joklik reviewed the great leaps forward during the 20th century
by its defining discipline,
virology.19
The occasion was the concurrent 100th anniversaries of the American Society
for Microbiology and
the field of virology itself. Having served as editor-in-chief of Virology and
an editor of Journal of Virology
over his long career as a professor of microbiology, Joklik was uniquely placed
(as he noted) to evaluate what
had been learned since early experiments in virology.
Before the founding of Virology and Journal of Virology in the 1950s and ’60s,
respectively, Joklik
noted, a number of “epoch-making discoveries in virology” appeared
in journals not devoted to the field.
Among the seven discoveries he singled out were two related to paralysis research.
The first was “the discovery
by Enders et al. in 1949 that poliomyelitis virus could be grown in human embryonic
tissue cells cultured
in vitro, which formed the basis of the technique of tissue culture (single
cell culture)”; the second, “…the
demonstration by Dulbecco, also in 1952, that an animal virus … was capable
of forming plaques in monolayers
of cloned cultured cells, which opened up the field of molecular animal virology.”19
While Dulbecco's 1952 study did not involve poliovirus, it led directly to
his 1954 paper in which he extended the new methodology
to the study of poliovirus.8,9
In 1949, as Joklik recounted, Harvard Medical School researcher John F. Enders,
along with his
colleagues Thomas H. Weller (a Fellow of the U.S. Public Health Service) and
Frederick C. Robbins (a Senior
Fellow in Virus Diseases of the National Research Council) showed not only that
poliovirus could grow in
cultured cells, but also that it could replicate in non-nervous system tissues,
a stunning discovery at the time.13
It was already suspected that poliovirus was often present in the intestines
of affected individuals. However, no
one had been able to propagate the virus in gut tissue, primarily because of
the bacteria that naturally live there.
Enders and colleagues were successful in part because they added antibiotic
(penicillin and/or streptomycin)
to their cell cultures to kill the bacteria—a technique that had not, of
course, been available to researchers
working in the pre-World War II era.
While Enders and colleagues’ 1949 paper is widely acknowledged to be a
turning point in poliomyelitis
research—many, including World Health Organization poliovirus eradication
researchers, credit this piece of
science with paving the way for the development of both the Salk and Sabin polio
vaccines—poliovirus was not
actually isolated by these investigators, either. They successfully grew “filterable
agents,” which they assumed
to be poliovirus, in human embryonic tissues. Like Landsteiner and Popper 40
years earlier—and like just
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Page 6
The Dulbecco “Isolation” Experiment
In 1954, Dulbecco and his colleague Margaret Vogt published a classic
research paper that is credited with having set the standard for purifying
poliovirus for decades.9
In it, they introduced a technical innovation to the
process of “purifying” viruses from tissue culture. This new technique
was
called “plaque purification”; a single plaque (a circular area of
cells that
stained differently from the surrounding culture) was considered to represent
a
pure virus population. Plaque purification utilized trypsinization, which involves
treating the cells—in this case, monkey kidney cells—with the enzyme
trypsin,
breaking up any clumps of cells that might have formed and resulting in a
single-cell suspension.
In the early days of poliovirus research, tissue culture was usually
conducted using monkey kidneys (or, sometimes, monkey testes). Dulbecco
and Vogt explained where the “virus” they grew came from:
“The virus was supplied as a 20 per cent
suspension of spinal cord of rhesus monkey in distilled
water. Type 1 virus obtained from passage through
the monolayer kidney cultures was used. Type 2,
Yale-SK strain, and Type 3, Leon strain, were kindly
supplied by Dr. J.L. Melnick in form of tissue culture
supernatants.”9
That passage clearly demonstrates that Dulbecco and Vogt did not
isolate pure poliovirus in any of the experiments described in this 1954 report.
While they write of seeding their cultures with “virus,” they actually
used
unpurified suspensions, not pure viral isolates.
Once the monkey kidneys were ground up into “single cells, cell
clusters, and cell debris,” they were seeded with the monkey spinal cord
emulsion. The appearance of the plaques was evidence that the virus was
growing, according to the model Dulbecco had developed in 1952.
8
The control for these experiments was to treat the cultures with
monkey antiserum (derived from monkeys infected with Type 1, 2, or 3
poliovirus); if Type 1 antiserum inhibited plaque formation but Type 2 or 3
(or
normal monkey) antiserum didn’t, then Type 1 poliovirus was assumed to
be
exclusively present in the culture. In other words, it was assumed that no other
organism or disease-associated agent was growing in the culture.
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Page 7
Once again, what Dulbecco and Vogt describe as “isolation” of the
poliovirus is not isolation in the way we would understand it in modern
microbiology. To perform their “plaque purifications,” they simply
pipetted some
liquid (“plaque stock”) from one culture plate and replated it onto
other culture
plates. When the second-generation cell cultures showed evidence of viral
growth (i.e., plaques), monkeys were inoculated with the plaque stock. The
inoculated monkeys developed paralysis and, subsequently, most died. Since
the plaque purified viral stock both grew new plaques in second-generation
cell culture and caused monkeys to develop flaccid paralysis, Dulbecco and
Vogt concluded they had “isolated” poliovirus.
Like poliovirus researchers before them, it is clear that Dulbecco and
Vogt were propagating disease-associated substances in their tissue cultures,
and that they later transferred these substances to monkeys in whom acute
flaccid paralysis developed. These were impressive accomplishments.
Dulbecco and Vogt’s claims, however, went further than they had
evidence to support. They asserted not only that they had isolated poliovirus,
but that, “Since each plaque stock originated from a
single virus particle (as proved in the Discussion), these
stocks constitute the purest lines of virus presently
available.”
How could they possibly know that a “single virus
particle,” something they had never seen or measured,
was causing the growth of exactly one plaque in their
cultures? The evidence Dulbecco and Vogt supplied
to “prove” that a single virus particle produced each
plaque is contained in a mathematical equation: They
extrapolated the cell culture’s assumed “virus concentra-
tion” from the number of times the original fluid (for
example, monkey spinal cord suspension) was diluted.
The fewer times the fluid was diluted, the more plaques grew in laboratory
cultures; the more times it was diluted, the fewer plaques grew. Dulbecco
and Vogt’s mathematical model assumed this linear relationship between
dilution of virus stocks and number of plaques formed and, when they reached
the greatest possible dilution that still caused a single plaque to grow, they
assumed that only one “virus particle” was present therein. And how
did
they prove that assumption, as promised? They provided their mathematical
model. This is a perfectly tautological proof. Its most apparent flaw is that
the
mathematical model did not—could not—distinguish between a “single
virus
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Page 8
about everyone else in the field during its first 60 years or so—Enders
and co-workers called this disease-
transmitting suspension of tissue “virus.”
Despite this overstatement, Enders, Weller, and Robbins were the first to prove
that a transmissible
agent associated with poliomyelitis could be propagated in cells in the laboratory,
and that cell cultures could
be substituted for live animals in studying such transmissible agents. In 1954,
their ground-breaking work
was rewarded with a Nobel Prize.
Renato Dulbecco’s 1952 paper lauded by Joklik is considered to have made
a significant contribution
to viral research in general and, by extrapolation, to poliovirus research.
Working at the California Institute
of Technology (in Pasadena), Dulbecco developed a method of growing plates of
cells so that “virus plaques"
could be visualized. He grew Western Equine Encephalomyelitis virus plaques
on a substrate of chicken embryo
cells and, when he published his paper, he pointed out that it was still unknown
whether all viruses could be
cultured in this manner. These were truly the very earliest days of modern virological
research, and Dulbecco
expressed hope that investigators would some day be able to distinguish between
various viruses grown in cell
culture by using his methodology and examining the resulting plaques under the
microscope.8
In 1954, Dulbecco and his colleague Margaret Vogt published a classic research
paper [see sidebar, “The
Dulbecco Isolation Experiment,” above] that set the standard for purifying
poliovirus cultures for decades.9
Dulbecco and Vogt, like their colleagues, used monkey kidney cells to culture
tissues thought to contain
particle” and a biological complex that may have contained a single virus.
This is made clear in Dulbecco and Vogt’s description of the plaque-forming
“single virus particle” they claim to have isolated:
“Having arrived at this point, it is now possible to
define properly the characteristics of the virus particle
detected by a plaque. Owing to its all-or-none effect, it
has the character of a particle. It corresponds to a unit
of the virus which is not further subdivisible at high
dilution. From the property by which it is recognized,
we call it a plaque-forming particle. We do not know
its morphological or genetic properties. It might be a
single elementary body, or a clump of them, provided
that the clump persists indefinitely at high dilution....”9
It is puzzling, in retrospect, that Dulbecco and Vogt raised the possibility
that they were detecting a “clump” of material, but thereafter ignored
it. What
if another type of virus was also included in these particles? Or, what if host
genetic material attached itself to the particle to form a “clump”?
Although electron microscopy—which would have allowed them to
visualize a single viral particle—existed in 1954, Dulbecco and Vogt did
not
use it. Instead, they employed the time-honored technology in which viruses
were assumed to be present in cultures if certain chemicals stained them, or
if
fluids thought to contain them produced characteristic patterns of growth, like
the poliovirus-related plaques described here. Dulbecco and Vogt could not
possibly determine that they were viewing single viruses in their cultures and,
therefore, their assumption that they had isolated a “single virus particle”
was a
vast overstatement. Dulbecco and Vogt did not isolate poliovirus.
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Page 9
poliovirus. Dulbecco and Vogt explained where the “virus” they grew
came from:
“The virus was supplied as a 20 per cent suspension of spinal cord of
rhesus monkey in distilled water. Type 1 virus obtained from passage through
the monolayer kidney cultures was used. Type 2, Yale-SK strain, and Type 3,
Leon strain, were kindly supplied by Dr. J.L. Melnick in form of tissue culture
supernatants.”9
In other words: Dulbecco and Vogt did not isolate pure poliovirus in any of
the experiments described
in this 1954 report. While they write of seeding their cultures with “virus,”
they actually used unpurified
suspensions, not pure viral isolates.
It is clear from this historical review of early poliovirus research papers
that none of these poliomyelitis
researchers truly isolated poliovirus. Additionally, they were injecting monkeys
with experimental fluids that
were probably contaminated with other disease-associated agents.
Further confusing the picture (but not reviewed here) is the fact that enteroviruses
other than poliovirus
are associated with AFP. For example, as recently as February 2001, it was shown
that Coxsackie A24 is
associated with nonpolio AFP.5
How Much Flaccid Paralysis Is NOT Caused by the Poliovirus?
There is an astonishing number of cases of paralysis around the world not associated
with poliovirus. If
you visit the World Health Organization website that tracks acute flaccid paralysis
(AFP), polio and non-polio
[http://www-nt.who.int/vaccines/polio/case.asp], you will see that the world
is not rid of the scourge
of AFP. For example, India reported 9,580 cases of AFP in 1999; 2802 of them,
fewer than one-third, were
associated with poliovirus. China reported 5,064 cases of AFP to WHO in 1999;
only one of those cases was
associated with poliovirus. Poliovirus eradication and vaccination programs
have not eliminated paralysis.
WHO recently declared Egypt on the threshold of eradicating poliovirus. "We
are now at the end of a
polio era," a UN Children’s Fund Project Officer told Reuter’s
news service in late February 2001. Egypt had
"not a single case of the crippling virus reported so far this year"
or in 2000, according to Reuters.17
According to the WHO AFP/polio surveillance web site, however, there were 54
cases of acute flaccid
paralysis in Egypt in 2000 (the most recent year for which statistics are available).
In 1999, although there
were 9 AFP cases classified as due to poliovirus, 276 were classified as nonpolio.
During 1998, Egypt had 295
cases of AFP, 35 of which were classified as poliovirus-related; in 1997, Egypt
reported 217 cases of non-polio
paralysis compared to 14 cases in which poliovirus infection was confirmed;
and in 1996, the earliest year for
which statistics are available, Egypt reported 309 cases of acute flaccid paralysis.
One hundred of those were
classified as poliovirus-related, leaving 209 cases—two-thirds of the total—probably
due to a cause other than
poliovirus (with the caveat that epidemiological statistics are not perfectly
accurate in every country of the
world). [http://www-nt.who.int/vaccines/polio/case.asp]
Afghanistan is another country in which there is an increasing prevalence of
AFP compared to a
decreasing incidence of poliovirus. As the U.S. Centers for Disease Control
and Prevention’s Morbidity and
Mortality Weekly Report (MMWR) notes on March 2, 2001, "During 1999-2000,
the number of AFP cases
[in Afghanistan] increased from 230 to 253, and the number of wild polioviruses
isolated from AFP cases
decreased from 63 to 28."
28
How does the CDC explain the increase in AFP cases in Afghanistan, in the face
of a vigorous poliovirus
eradication campaign? Well, it doesn’t. In fact, the MMWR report almost
makes the increase in nonpolio AFP
sound like a triumph of public health: "During 1999-2000, the nonpolio
AFP rate almost doubled and the
number of districts reached by NIDs [National Immunization Days] increased steadily.
Careful planning and
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Page 10
supervision of house-to-house vaccination and support from an increasing number
of local partners resulted
in the largest number of children ever being reached. Monitoring by nongovernment
organizations, United
Nations’ agencies, and local authorities has increased the quality of NIDs…."28
In other words, the more National Immunization Days there were, the more cases
of paralysis appeared. Does this mean immunizations
were causing paralysis? No, but neither was increased immunization preventing
children from becoming paralyzed.
The Western Hemisphere has also been impacted by an increased case load of
AFP. As mentioned earlier,
the island of Hispaniola (the Dominican Republic and Haiti) experienced what
the CDC called an "outbreak
of poliomyelitis" that began in July 2000. There were 54 cases in the Dominican
Republic, 12 of which were
"laboratory-confirmed poliomyelitis cases attributed to vaccine-derived
poliovirus type 1," according to the
CDC. Although the oral polio vaccine is known to cause polio in about 1 of every
750,000 infants who
receive it or their mothers—unlike the inactivated Salk vaccine "shot,"
the Sabin oral vaccine contains live
viruses—the 45 cases reported in January 2001 in the Washington Post are,
if confirmed, clearly outside
the realm of this statistic.3
As of the end of February 2001, the cause(s) of 33 AFP cases in the Dominican
Republic and three in
Haiti remained undetermined.27
All of these cases might be due to the oral polio vaccine, in which case the
mystery would be solved—leaving unanswered, however, the question of what
factors contributed to such a
large vaccine-associated outbreak of paralysis.
If these 36 AFP cases are not related to the polio vaccine, however, then what
is causing them? What is
causing other nonpolio outbreaks of AFP identified by WHO all over the world?
And in cases in which poliovirus is fingered as the culprit in an outbreak,
how sensitive are the current
methodologies that virologists use to isolate and identify it?
Polio Vaccination
Recommendations
U.S. Centers for Disease Control and Prevention
Recommendations for children in the United States include
a 4-dose vaccination series with inactivated poliovirus vaccine
(IPV) at ages 2, 4, 6–18 months, and 4–6 years. Unvaccinated
adults should receive three doses of IPV, the first two doses at
intervals of 4–8 weeks and the third dose 6–12 months after
the second. If three doses cannot be administered within the
recommended intervals before protection is needed, alternative
schedules are proposed. For incompletely vaccinated persons,
additional IPV doses are recommended to complete a series.
Booster doses of IPV may be considered for persons who
previously have completed a primary series of polio vaccination
and who may be traveling to areas where polio is endemic.
Morbidity and Mortality Weekly Report, March 2, 2001, Vol. 50, No. 8, p. 147
------------------------------------------------------------------------
Page 11
How Is Poliovirus Detected Today?
It is nearly unimaginable how sensitive and sophisticated laboratory technology
has become over the last
30 years. As we examine the entire sequence of the human genome in early 2001,
it’s difficult to imagine that it
was only in the 1970s that scientists first developed the technology that allowed
the rapid sequencing of genes,
including genetic sequences from transmissible agents like bacteria and viruses.
This new sequencing methodology was immediately applied to poliovirus research.
During the
1970s, the CDC began routinely performing genotypic testing ("molecular
sequencing" or "oligo-nucleotide
fingerprinting") on stool samples collected in suspected poliovirus outbreaks
to determine whether the virus
was present. Using findings from the new technology to extrapolate to the prior
decade, CDC documents now
state that, "Both laboratory surveillance for enteroviruses and surveillance
for polio cases suggest that endemic
circulation of indigenous wild polioviruses ceased in the United States in the
1960s."24
To detect poliovirus today, according to CDC and WHO guidelines, two stool samples
should be
collected from each patient, 24-48 hours apart within 14 days of the onset of
paralysis, and they must arrive at
the laboratory in "good condition." While WHO’s target is to
obtain two good samples in at least 80% of all
AFP cases, some areas of the world fall short of this, approaching only 50%.28
The CDC provides the following guidelines on how to detect poliovirus:
"The following tests should be performed on appropriate specimens collected
from
persons who have suspected cases of polio: a) isolation of poliovirus in tissue
culture; b)
serotyping of a poliovirus isolate as serotype 1, 2, or 3; and c) intratypic
differentiation using
DNA/RNA probe hybridization or polymerase chain reaction to determine whether
a poliovirus
isolate is associated with a vaccine or wild virus.
"Acute-phase and convalescent-phase serum specimens should be tested for
neutralizing
antibody to each of the three poliovirus serotypes. A fourfold rise in antibody
titer between
appropriately timed acute-phase and convalescent-phase serum specimen is diagnostic
for
poliovirus infection. The recently revised standard protocol for poliovirus
serology should be
used. Commercial laboratories usually perform complement fixation and other
tests. However,
assays other than neutralization are difficult to interpret because of inadequate
standardization
and relative insensitivity."24
While this procedure is a time-honored method of detecting the poliovirus and
the body’s response to
it, it does not "isolate" the poliovirus—it simply detects poliovirus.
The samples tested by the CDC and WHO
should be described as "poliovirus reactive material," not as samples
that contain isolated, pure poliovirus.
Once again, we have no proof that poliovirus has been isolated.
If Not Poliovirus, Then What Is Causing Today’s Cases of
Flaccid Paralysis?
“The history of the etiology of poliomyelitis is a history of errors.”
J.F. Eggers, Medicine, 1954
If the majority of the U.S. population has been immunized since the 1950s, why
did it take until 1979
to “eradicate” poliovirus within the United States?24,31
And what is causing the nonpolio cases of paralysis that continue to occur all
over the world?
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Page 12
It is becoming clear that one culprit capable of causing not only paralysis
but also other neurological
conditions is organophosphate pesticides. Recent research has tied chronic organophosphate
pesticide exposure
to development of Parkinson’s disease signs and symptoms in an animal model.2
And researchers in Paraguay
have good evidence that an outbreak of AFP among children in 1990-1991 was associated
with organophosphate
pesticide exposure.
The 50 Paraguayan children identified in this study—given that it was conducted
in a rural, isolated
area meant that quite a number of affected children might have been excluded
from the study, as investigators
noted—developed a type of AFP named Guillain-Barré Syndrome, or
GBS. As is the case in other forms
of AFP, the myelin sheath that surrounds and protects nerves is damaged in GBS.
The disease's causes are
unknown, but it's generally believed to be an autoimmune condition provoked
by infections, toxins, or a
combination of both.
16
The children became ill during the Paraguayan summer (January to April), with
weakness, upper
respiratory tract infection, fever, and gastrointestinal symptoms. Three children
developed difficulty breathing,
and two of them required mechanical help to breathe (intubation). "Weakness
progressed in an ascending
pattern in 95% of the children, and simultaneously in all limbs in 5%; the average
time to reach the nadir was
7 days (range, 2-12 days)," the investigators reported. Of the 35 children
observed while they were in the acute
stage of AFP, 18 were unable to walk, 10 walked with assistance, four walked
independently, and three were
too young to walk. The children exhibited full or partial paralysis of facial
muscles and their bladders; they also
experienced autonomic nervous system changes that created fluctuations in blood
pressure, erratic heartbeat,
flushing of skin, and intestinal motility. One child died.16
The study was conducted as part of the Pan American Health Organization’s
effort to eradicate
poliomyelitis. David E. Hart of the U.S. National Institute of Neurological
Disorders and Stroke at the
National Institutes of Health was the lead investigator working alongside researchers
from the Paraguayan
Ministry of Health.16
The majority of cases, they point out, were clustered in a rural, farming province
named Concepcion.
"The clustering of patients in Concepcion could be related to the use of
organophosphate pesticides
in the cotton fields," Hart and colleagues suggest. "Farmers use great
amounts of these pesticides, often in
concentrated form, and empty containers serve as toys. Also, the maximum usage
of organophosphates occurs
during the summer (December-March)," when these children became ill.
16
Although they note that retrospective measurement of organophosphate exposure
is very difficult,
Hart and co-workers cite a report that the cotton industry officially spent
approximately US$ 6.7 million on
organophosphate pesticides in 1991. However, more than half of the pesticides
used in Paraguay are obtained
"unofficially," according to this report.
"Four children were excluded from this study because of definite exposure
to this product and
presentation with concurrent acute cholinergic syndrome," the severe disease
produced by organophosphate
pesticide exposure. Hart and colleagues added, "Their clinical course,
however, was similar to that of the
children included" in the study.
16
By examining the possibility that the AFP observed in these Paraguayan children
might be associated
with organophosphate pesticides, Hart and colleagues took that extra step that
is so often omitted. Clusters of
illnesses in communities can arise from any number of causes; they are not exclusively
due to transmissible
agents. Toxins in the environment are significant factors in many illnesses.
Since the time of Koch, bacteriologists have used the gold standard he described
for the assignment of
the disease process to single organisms. Bacteria and fungi can be truly isolated
and grown independently on
artificial media; they don’t require the presence of human or other cells.
One problem that researchers have
faced in describing non-bacteriologic related diseases has been the assumption
that a single entity can cause
them, without interaction from the cells in which they are grown, the human
genome, or the environment.
We live in a important time: We are about to redefine much of what we know about
medical
science. In early 2001, two stunning reports on the Human Genome Project, published
simultaneously in
------------------------------------------------------------------------
Page 13
February issues of Science [http://www.sciencemag.org/feature/data/genomes/landmark.shl]
and Nature
[http://www.nature.com/genomics/], turned much of what we thought we knew about
the human genome on
its head. Instead of possessing 100,000 genes, for example, we learned that
the human genome is made up of
only about 30,000 genes—fewer than the number possessed by rice.1
Our new understanding of the human genome was produced, in part, by new technologies
that we can
now apply to revisiting many of the assumptions of modern medicine. One of the
most important lessons learned
from the challenge of decoding the human genome is that scientists need to describe
laboratory experiments
and results accurately. Technologically advanced tools can provide detailed
and precise information, but the
researchers using them must describe those results with equal precision. When
a sample is laboratory reactive,
it should not be assumed to be infectious. Likewise, suspensions of diseased
brain tissue should not be called
"virus" and dilutions of brain tissue material should not be called
"isolations."
As the human genome comes more precisely into focus, our understanding of how
our genes interact
with one another, the environment, and other organisms will also become more
precise.
Precision should also be applied to research objectives. Clearly, it is incorrect
to state that poliomyelitis
has been eradicated from many countries. The surprisingly large number of cases
of nonpolio acute flaccid
paralysis around the world warrants continued pursuit of the original objective
of the March of Dimes: the
elimination of infantile paralysis. On its website, the March of Dimes takes
some well-deserved credit for
helping to limit the amount of paralysis in the world today. “Historians
have called the conquest of polio one
of the great achievements of this century,” a fact sheet on the website
states. “Thanks to the March of Dimes,
and the millions of people who supported it, we no longer have the devastating
epidemics that terrorized
generations.” [http://www.modimes.org/HealthLibrary2/factsheets/Polio.htm]
Clearly, the original objective of the March of Dimes has not yet been met,
or there would not be so
much acute flaccid paralysis around the world today. Examining the last 50 years
of poliomyelitis research
shows that the objective of eliminating infantile paralysis has been replaced
with the objective of eliminating
poliovirus. As governments, international health organizations, and charitable
foundations pour hundreds of
millions of dollars into poliovirus eradication efforts, shouldn’t we also
invest in basic research that will
prevent all cases of childhood paralysis?
Acknowledgement: The author wishes to thank Dr. Howard Urnovitz, Science Director
of the Chronic
Illness Research Foundation, for bringing this story to her attention and approving
the scientific content
of this article.
Literature Cited
1.
Abate, Tom. February 11, 2001. Genome discovery shocks scientists. San Francisco
Chronicle.
2.
Betarbet, R., T.B. Sherer, G. MacKenzie, M. Garcia-Osuna, A.V. Panov, and J.T.
Greenamyre. December 2000. Chronic
systemic pesticide exposure reproduces features of Parkinson's disease. Nature
Neuroscience 3(12):1301.
3.
Brown, David. January 1, 2001. Ready to let go of polio? Mutant virus in Caribbean
outbreak alarms health experts.
Washington Post, p. A7.
4.
Burnet, F.M. and J. MacNamara. 1931. Immunological differences between strains
of poliomyelitic virus. The British
Journal of Experimental Pathology 12(2):5.
5.
Chaves, S.S., S. Lobo, M. Kennett, and J. Black. February 24, 2001. Coxsackie
virus A24 infection presenting as acute flac-
cid paralysis. The Lancet 357:605.
6.
Dalldorf, G. and G.M. Sickles. 1948. An unidentified, filtrable agent isolated
from the feces of children with paralysis.
Science 108:61.
7.
Davis, W.M. 1919. The demonstration of immune opsonins for the pleomorphic streptococcus
in the experimental
poliomyelitis in monkeys. Journal of Infectious Diseases 24:176.
8.
Dulbecco, R. 1952. Production of plaques in monolayer tissue cultures by single
particles of an animal virus. Proceedings
of the National Academy of Sciences USA 38:747.
9.
Dulbecco, R. and M. Vogt. 1954. Plaque formation and isolation of pure lines
with poliomyelitis viruses. J. Exp. Med.
99:167-182.
------------------------------------------------------------------------
Page 14
10.
Eggers, H.J. 1999. Milestones in early poliomyelitis research (1840-1949). Journal
of Virology 73(3):4533.
11.
Enders, J.F. 1954. Some recent advances in the study of poliomyelitis. Talk
given on the occasion of receiving the Passano
Award, June 3, 1953. Published in Medicine 33:87, May 1954.
12.
Enders, J.F. 1972. Early observations on cytopathogenicity of poliovirus. American
Journal of Clinical Pathology
57(6):846.
13.
Enders, J.F., T.H. Weller, and F.C. Robbins. 1949. Cultivation of the Lansing
strain of poliomyelitis virus in cultures of vari-
ous human embryonic tissues. Science 109:85.
14.
Flexner, S. and P.A. Lewis. 1909. The transmission of acute poliomyelitis to
monkeys. Journal of the American Medical
Association 53:1639.
15.
Gordon, F.B., F.M. Schabel, Jr., A.E. Casey, and W.I. Fishbein. 1948. Laboratory
study of the epidemiology of
poliomyelitis. Journal of Infectious Diseases 82:294.
16.
Hart, D.E. et al. 1994. Childhood Guilliain-Barré Syndrome in Paraguay,
1990 to 1991. Annals of Neurology 36(6):859.
17.
Hassan, Abdalla. February 22, 2001. Egypt appears close to wiping out polio
scourge. Reuters News Service.
18.
International Human Genome Sequencing Consortium. February 15, 2001. Initial
sequencing and analysis of the human
genome. Nature 409:860.
19.
Joklik, W.K. When two is better than one: Thoughts on three decades of interaction
between Virology and the Journal of
Virology. 1999. Journal of Virology 73(5):3520.
20.
Landsteiner, K. and E. Popper. 1909. Uebertragung der poliomyelitis acuta auf
affen. Z. Immunitatsforsch 2:377.
21.
Melnick, J.L. and R. Ward. 1945. Susceptibility of vervet monkeys to poliomyelitis
virus in flies collected at epidemics.
Journal of Infectious Diseases 77:251.
22.
Melnick, J.I. and N. Ledinko. 1952. Vaccination as a provoking factor in poliomyelitis:
An experimental approach. Journal
of Infectious Diseases 90:279.
23.
Merck Manual, Fifteenth Edition. 1987. Merck & Co., Inc., Rahway, NJ, USA.
24.
Morbidity and Mortality Weekly Report. May 19, 2000. Poliomyelitis prevention
in the United States: Updated
Recommendations of the Advisory Committee on Immunization Practices (ACIP).
U.S. Department of Health & Human
Services, Centers for Disease Control and Prevention, Atlanta, GA 30333.
25.
Morbidity and Mortality Weekly Report. December 8, 2000. Outbreak of poliomyelitis—Dominican
Republic and Haiti,
2000. U.S. Department of Health & Human Services, Centers for Disease Control
and Prevention, Atlanta, GA 30333.
26.
Morbidity and Mortality Weekly Report. January 26, 2001. Circulation of a Type
2 vaccine-derived poliovirus—Egypt,
1982-1993. U.S. Department of Health & Human Services, Centers for Disease
Control and Prevention, Atlanta, GA
30333.
27.
Morbidity and Mortality Weekly Report. March 2, 2001. Outbreak of poliomyelitis—Dominican
Republic and Haiti, 2000-
2001. U.S. Department of Health & Human Services, Centers for Disease Control
and Prevention, Atlanta, GA 30333.
28.
Morbidity and Mortality Weekly Report. March 2, 2001. Progress toward poliomyelitis
eradication—Afghanistan, 1999-
2000. U.S. Department of Health & Human Services, Centers for Disease Control
and Prevention, Atlanta, GA 30333.
29.
Morales, E.G. 1930. Acute anterior poliomyelitis at Vega Baja, Porto Rico. Journal
of Infectious Diseases 46:32.
30.
Schabel, F.M., Jr., H.T. Smith, W.I. Fishbein, and A.E. Casey. 1950. Stool virus
recovery in subclinical poliomyelitis during
incubation, febrile, and convalescent periods. Journal of Infectious Diseases
82:294.
31.
Strebel, P.M., R.W. Sutter, S.L. Cochi, et al. 1992. Epidemiology of poliomyelitis
in the United States one decade after the
last reported case of indigenous wild virus-associated disease. Clin. Infect.
Dis. 14:568.
32.
Venter, J.C., et al. February 16, 2001. The sequence of the human genome. Science
291:1304.
33.
Wenner, H.A., R.W. Menges, and G.S. Harshfield. 1954. Sporadic bovine encephalomyelitis:
3. Reproduction of the
disease, with particular reference to the role of poliomyelitis viruses in experimental
infection in calves. Journal of
Infectious Diseases 94:284.
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