MEpedia - User contributions [en]

Epidemic myalgic encephalomyelitis

2018-07-07T21:09:17Z

Owasow:/* History */

There have been [[List of myalgic encephalomyelitis and chronic fatigue syndrome outbreaks|at least 75 documented outbreaks]] of [[ME]] and [[CFS]] since the 1930s. The true number of clusters and outbreaks is likely much higher. Many of these outbreaks occurred in institutions like hospitals and schools, and frequently coincided with outbreaks of [[poliomyelitis]].

The first recorded outbreak of epidemic was in [[1934 Los Angeles atypical polio outbreak|1934 in Los Angeles]] and the most recent was a putative outbreak was in Arizona in 1996.
==History==
{{Main article|List_of_myalgic_encephalomyelitis_and_chronic_fatigue_syndrome_outbreaks}}

The first recorded outbreak of epidemic myalgic encephalomyelitis was in [[1934 Los Angeles atypical polio outbreak|1934 in Los Angeles]] and was thought to be an outbreak of atypical polio. After the outbreak in [[Akureyri]], Iceland in 1946, the disease came to be called "Akureyri Disease" or [[Icelandic disease]] through much of the 1940s and 1950s. It was named [[Myalgic Encephalomyelitis|myalgic encephalomyelitis]] after London's [[Royal Free Hospital outbreak]] in 1955. Other names included benign myalgic encephalomyelitis and epidemic neuromyasthenia.

After the [[1984 Incline Village chronic fatigue syndrome outbreak|Incline Village]] outbreak in Nevada in 1984, the disease came to be called and redefined as [[Chronic Fatigue Syndrome]]. The most recent was a putative outbreak was in Arizona in 1996.

== Onset ==
The incubation period was generally estimated at 5 to 8 days<ref name=":4" /><ref name=":0" />, with a prodromal period of flu-like symptoms followed by a symptom complex involving muscle weakness, muscle fatiguability and central nervous system involvement in a significant proportion of cases.<ref name=":0" /><ref name="Shelokov, 1957" />

== Symptoms ==
Reported symptoms could vary considerably from outbreak to outbreak. Common symptoms included:

* low-grade [[fever]]
* [[post-exertional malaise]] ("fatigue on walking short distances and on the least exertion was prominent"<ref name=":0" />)
* [[muscle fatigability|muscle fatiguability]]
* muscle weakness (10-80%<ref name="Acheson, 1959" /> of cases)
* ataxia
* [[myalgia]] and [[neuralgia]]
* stiffness of the neck and spine
* tender lymph nodes, spleen and/or liver
* cognitive symptoms including impaired memory and concentration
* sleep disturbances
* sensory symptoms including sensitivity to [[Photophobia|light]] and sound, [[Paresthesia|paraesthesiae]], [[hyperaesthesiae]]
* autonomic symptoms such as tachychardia, coldness of the extremities, sweating

== Findings ==

Findings varied considerably based on the technology of the time and what tests physicians attending to these outbreaks chose or were able to run:

* Abnormal [[electromyogram]] showing generalized, mild, lower motor neuron changes indicative of a [[radiculopathy]]
* Muscle weakness measured via quantitative muscular-testing<ref name="Shelokov, 1957">{{Citation
| last1 = Shelokov | first1 = Alexis | authorlink1 =
| last2 = Habel | first2 = Karl | authorlink2 =
| last3 = Verder | first3 = Elizabeth | authorlink3 =
| last4 = Welsh | first4 = William | authorlink4 =
| title = Epidemic Neuromyasthenia — An Outbreak of Poliomyelitis-like Illness in Student Nurses
| journal = New England Journal of Medicine | volume = 1957 | issue = 257 | page = 345-355
| date = August 1957
| doi = 10.1056/NEJM195708222570801
}}</ref>
* Normal or minimal [[cerebrospinal fluid]] findings<ref name="Shelokov, 1957" />
* [[Autonomic nervous system]] dysfunction, [[Hypothalamus|hypothalamic]] dysfunction
* [[Postural orthostatic tachycardia syndrome|Orthostatic tachycardia]]
* Ulnar neuritis or lesion<ref name=":2">{{Cite journal|last=White|first=D|last2=Burtch|first2=Robert|date=July 1, 1954|title=Iceland Disease: A New Infection Simulating Acute Anterior Poliomyelitis|url=http://n.neurology.org/content/4/7/506.short|journal=Neurology|volume=4|pages=|via=}}</ref> (Iceland, north of England)
* Microscopic infiltration of nerve roots with [[lymphocytes]] and [[Mononuclear cell|mononuclear cells]]; patchy damage to the myelin sheaths and axon swellings (in monkeys infected with unidentified virus from the [[1949-53 Adelaide outbreak|Adelaide]] outbreak)
* Raised urinary [[creatine]] excretion<ref name=":2" /><ref name=":1">{{Cite journal|last=Albrecht|first=Robert|date=March 21, 1964|title=Epidemic Neuromyasthenia Outbreak in a Convent in New York State|url=https://www.ncbi.nlm.nih.gov/pubmed/14100144|journal=Journal of the American Medical Association|volume=187|pages=904-907|via=}}</ref>

In the majority of epidemics, no viral or bacterial infectious agent was successfully cultured. However, in many cases patients were only examined well after the onset of acute illness. In a small number of epidemics [[Coxsackie B]]<ref name="Fegan1983">{{Citation
| last1 = Fegan | first1 = KG | authorlink1 = KG Fegan
| last2 = Behan | first2 = PO | authorlink2 = Peter Behan
| last3 = Bell | first3 = EJ | authorlink3 = Eleanor Bell
| title = Myalgic encephalomyelitis — report of an epidemic
| journal = J R Coll Gen Pract | volume = 33| issue = 251| pages = 335–337
| date = 1 Jun 1983
| pmid = 6310104
| url = http://bjgp.org/content/33/251/335
}}</ref><ref name="Calder1984">{{Citation
| last1 = Calder | first1 = BD | authorlink1 = BD Calder
| last2 = Warnock | first2 = PJ | authorlink2 = PJ Warnock
| title = Coxsackie B infection in a Scottish general practice
| journal = Jrnl Royal Coll Gen Pract | volume = 34| issue = 258| pages = 15–19
| date = Jan 1984
| pmid = 6319691
| url = http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1959663/
}}</ref> and [[Bethesda-Ballerup paracolon organism]]<ref name="Shelokov, 1957" /> were found. In others, infection of animal models with samples from patients results in identifiable nervous system damage on autopsy, in spite of being unable to identify the agent.<ref name=":0" />

==Epidemiology==
Many of these outbreaks occurred at institutions for example, hospitals<ref name="Shelokov, 1957" /><ref name="Gilliam, 1936-38" />, schools, army bases or convents. The pattern of spread suggested a highly infectious agent that spread person to person, rather than through contaminated food or drink or exposure to a single toxic agent.<ref name=":0">{{Cite journal|last=Parish|first=JG|date=1978|title=Early outbreaks of 'epidemic neuromyasthenia'|url=https://www.ncbi.nlm.nih.gov/pubmed/370810|journal=Postgraduate Medical Journal|volume=54|pages=711-7|via=}}</ref><ref name="Gilliam, 1936-38">{{Citation
| last1 = Gilliam | first1 = A.G. | authorlink1 =
| title = Epidemiological Study Of An Epidemic, Diagnosed As Poliomyelitis, Occurring Among The Personnel Of The Los Angeles County General Hospital During The Summer Of 1934
| journal = Public health bulletin, 1936-1938 | volume = no.231-240 | issue = | page =
| date = 1938
| pmid =
| url = http://babel.hathitrust.org/cgi/pt?id=mdp.39015022082260;view=1up;seq=617
}}</ref><ref name="Poskanzer, 19572" />

Outbreaks tended to begin in the summer months, with most initial cases reported from April to September.<ref name="Acheson, 1959" />

In outbreaks involving both medical personnel and the general community, medical personnel had a higher attack rate and/or greater central nervous system involvement.<ref name="Poskanzer, 19572" /> A similar pattern was seen in hospital outbreaks, where those in roles that involved more frequent or intimate contact with patients or those working in an infectious disease ward were more affected than other hospital staff.<ref name=":0" /><ref name="Gilliam, 1936-38" /> A large proportion of recorded outbreaks have taken place in hospital settings.<ref name="Acheson, 1959" />

In many outbreaks including [[1934 Los Angeles atypical polio outbreak|Los Angeles]], [[Akureyri]], [[1953 Maryland outbreak|Rockville, MD]], [[1955 Royal Free Hospital outbreak|Royal Free Hospital]], and [[1956 Punta Gorda outbreak|Punta Gorda, Florida]], women were disproportionately affected.<ref name=":0" /><ref name="Shelokov, 1957" /><ref name="Gilliam, 1936-38" /><ref name="Acheson, 1959">{{Citation
| last1 = Acheson | first1 = E.D. | authorlink1 =
| title = The Clinical Syndrome Variously Called Benign Myalgic Encephalomyelitis, Iceland Disease and Epidemic Neuromyasthenia
| journal = American Journal of Medicine | volume = 26 | issue = 4 | page = 569–595
| date = 1959
| pmid =
| url = http://www.name-us.org/defintionspages/DefinitionsArticles/Acheson1959.pdf
}}</ref><ref name="Poskanzer, 1957">{{Citation
| last1 = Poskanzer | first1 = David C. | authorlink1 =
| last2 = Henderson | first2 = Donald A. | authorlink2 =
| last3 = Kunkle | first3 = E. Charles | authorlink3 =
| last4 = Kalter | first4 = Seymour S. | authorlink4 =
| last5 = Clement | first5 = Walter B. | authorlink5 =
| last6 = Bond | first6 = James O. | authorlink6 =
| title = Epidemic Neuromyasthenia — An Outbreak in Punta Gorda, Florida
| journal = New England Journal of Medicine | volume = 1957 | issue = 257 | page = 356-364
| date = 1957
| pmid = 13464939
| doi = 10.1056/NEJM195708222570802
| url = http://www.nejm.org/doi/full/10.1056/NEJM195708222570802
}}</ref><ref name=":3" /><ref>{{Cite journal|url=https://www.ncbi.nlm.nih.gov/pubmed/14771044|title=A disease epidemic in Iceland simulating poliomyelitis|last=Sigurdsson|first=B|date=September 1950|journal=American Journal of Hygiene|volume=52|pages=222-38|via=}}</ref> In other outbreaks, including the 1949-1953 [[1949-53 Adelaide outbreak|Adelaide]] outbreak and an outbreak in [[1955 North of England outbreak|northern England in 1955]], a 1:1 gender ratio was reported.<ref name=":0" /> In hospital epidemics, young female nurses were disproportionately affected, but this may have been due to risk factors like higher repeated exposure to the same infection during an epidemic<ref name=":0" /> and in some outbreaks, gender-segregated living quarters.<ref name=":3">[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1962472/ An Outbreak of Encephalomyelitis in the Royal Free Hospital Group, London, in 1955 - The Medical Staff Of The Royal Free Hospital]</ref> However, the higher ratio of women were also reported in outbreaks in the general population.<ref name="Acheson, 1959" /> In Akureyri, while the incidence among adults was significantly higher for females, there was no significant difference in incidence between sexes among those under twenty.<ref name=":4">{{Cite journal|url=https://www.ncbi.nlm.nih.gov/pubmed/14771044|title=A disease epidemic in Iceland simulating poliomyelitis|last=Sigurdsson|first=B|date=September 1950|journal=American Journal of Hygiene|volume=52|pages=222-38|via=}}</ref> This comports with studies of age and sex distribution in sporadic cases.{{Citation needed}}

Those most affected tended to be adults in their twenties,<ref name=":0" /><ref name="Gilliam, 1936-38" /><ref name=":1" /> although cases of young children and adults as old as 80 have been recorded in outbreaks.<ref name="Acheson, 1959" />

== Prognosis ==

Although many patients improved over time, in follow-up studies, a large percentage were still ill months to years later. Many case studies note long periods of convalescence with relapses following exertion<ref name="Shelokov, 1957" /><ref name=":1" /><ref name="Poskanzer, 19572">{{Citation
| last1 = Poskanzer | first1 = David C. | authorlink1 =
| last2 = Henderson | first2 = Donald A. | authorlink2 =
| last3 = Kunkle | first3 = E. Charles | authorlink3 =
| last4 = Kalter | first4 = Seymour S. | authorlink4 =
| last5 = Clement | first5 = Walter B. | authorlink5 =
| last6 = Bond | first6 = James O. | authorlink6 =
| title = Epidemic Neuromyasthenia — An Outbreak in Punta Gorda, Florida
| journal = New England Journal of Medicine | volume = 1957 | issue = 257 | page = 356-364
| date = 1957
| pmid = 13464939
| doi = 10.1056/NEJM195708222570802
| url = http://www.nejm.org/doi/full/10.1056/NEJM195708222570802
}}</ref> or before or during [[Menstrual cycle|menstrual periods]].<ref name="Shelokov, 1957" /><ref name=":1" /><ref name="Poskanzer, 19572" />

==Relationship to polio==
Prior to the poliovirus vaccine, several [[outbreaks]] of what later came to be called [[myalgic encephalomyelitis]] coincided with confirmed outbreaks of [[poliomyelitis]] including the [[1934 Los Angeles atypical polio outbreak|1934 Los Angeles outbreak]], the [[1948-49 Akureyri outbreak|1948 Akureyri, Iceland outbreak]], and 1949 outbreak in [[1949-53 Adelaide outbreak|Adelaide, Australia]]. Many outbreaks were initially misinterpreted as clusters of [[poliomyelitis]] or [[abortive poliomyelitis]], hence one of [[ME]]'s earliest names, [[atypical polio]]. It is not known whether there is a direct relationship between polio outbreaks and ME or if outbreaks of ME were more likely to be reported when public health authorities were already mobilized for an earlier crisis.

No serological evidence of polio was ever found in these outbreaks and the ultimate pattern of the outbreaks differed in significant ways, chief among them the higher attack rate, the tendency to affect adults rather than children, and the higher [[morbidity]] than poliomyelitis but no [[mortality]].<ref name=":0" /><ref name="Acheson, 1959" /> Findings in several outbreaks seemed to suggest that symptoms were caused by an [[enterovirus]] distinct from but related to polio including findings of mild, diffuse peripheral nervous system damage in monkeys infected with the virus; a stronger response to polio vaccination in children who had been in epidemic areas; and seasonal patterns of infection resembling polio, i.e., the rises in cases during summer months.<ref name=":0" /><ref name="Acheson, 1959" />

After the Akureyri outbreak, children in areas that had been affected responded to poliomyelitis vaccination with higher antibody titres, as if these children had already been exposed to an agent immunologically similar to poliomyelitis virus.<ref name=":0" />

== Controversy ==
In 1970, a paper by Colin P. McEvedy and AW Beard claimed that the [[1955 Royal Free Hospital outbreak]] was actually [[mass hysteria]].<ref>[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1700894/ Royal Free epidemic of 1955: a reconsideration. 1970 PubMed.gov]</ref><ref>[https://www.telegraph.co.uk/news/health/12033810/Its-time-for-doctors-to-apologise-to-their-ME-patients.html It’s time for doctors to apologise to their ME patients by Dr. Charles Shepherd - The Telegraph]</ref>

== See also ==

* [[List of myalgic encephalomyelitis and chronic fatigue syndrome outbreaks]]

== Learn more==

*"[https://www.newyorker.com/magazine/1965/11/27/in-the-bughouse In the Bughouse]," ''The New Yorker'' by Berton Roueché.
*[https://www.amazon.com/Oslers-Web-Labyrinth-Syndrome-Epidemic/dp/0595348742 ''Osler's Web''] by Hillary Johnson

== References ==
<references />
[[Category:Outbreaks]]

Epidemic myalgic encephalomyelitis

2018-07-07T21:04:34Z

Owasow:switched vastly higher to much higher to avoid overstating claim. Corrected a typo.

There have been [[List of myalgic encephalomyelitis and chronic fatigue syndrome outbreaks|at least 75 documented outbreaks]] of [[ME]] and [[CFS]] since the 1930s. The true number of clusters and outbreaks is likely much higher. Many of these outbreaks occurred in institutions like hospitals and schools, and frequently coincided with outbreaks of [[poliomyelitis]].

The first recorded outbreak of epidemic was in [[1934 Los Angeles atypical polio outbreak|1934 in Los Angeles]] and the most recent was a putative outbreak was in Arizona in 1996.
==History==
{{Main article|List_of_myalgic_encephalomyelitis_and_chronic_fatigue_syndrome_outbreaks}}

The first recorded outbreak of epidemic myalgic encephalomyelitis was in [[1934 Los Angeles atypical polio outbreak|1934 in Los Angeles]] and was thought to be an outbreak of atypical polio. After the outbreak in [[Akureyri]], Iceland in 1946, the disease came to be called "Akureyri Disease" or [[Icelandic disease]] through much of the 1940s and 1950s. It was named [[Myalgic Encephalomyelitis|myalgic encephalomyelitis]] after London's [[Royal Free Hospital outbreak]] in 1955. Other names included benign myalgic encephalomyelitis and epidemic neuromyasthenia.

After the [[1984 Incline Village chronic fatigue syndrome outbreak|Incline Village]] outbreak in Nevada in 1984, the disease came to be called and redefined as [[Chronic Fatigue Syndrome]]. The most recent was putative outbreak was in Arizona in 1996.

== Onset ==
The incubation period was generally estimated at 5 to 8 days<ref name=":4" /><ref name=":0" />, with a prodromal period of flu-like symptoms followed by a symptom complex involving muscle weakness, muscle fatiguability and central nervous system involvement in a significant proportion of cases.<ref name=":0" /><ref name="Shelokov, 1957" />

== Symptoms ==
Reported symptoms could vary considerably from outbreak to outbreak. Common symptoms included:

* low-grade [[fever]]
* [[post-exertional malaise]] ("fatigue on walking short distances and on the least exertion was prominent"<ref name=":0" />)
* [[muscle fatigability|muscle fatiguability]]
* muscle weakness (10-80%<ref name="Acheson, 1959" /> of cases)
* ataxia
* [[myalgia]] and [[neuralgia]]
* stiffness of the neck and spine
* tender lymph nodes, spleen and/or liver
* cognitive symptoms including impaired memory and concentration
* sleep disturbances
* sensory symptoms including sensitivity to [[Photophobia|light]] and sound, [[Paresthesia|paraesthesiae]], [[hyperaesthesiae]]
* autonomic symptoms such as tachychardia, coldness of the extremities, sweating

== Findings ==

Findings varied considerably based on the technology of the time and what tests physicians attending to these outbreaks chose or were able to run:

* Abnormal [[electromyogram]] showing generalized, mild, lower motor neuron changes indicative of a [[radiculopathy]]
* Muscle weakness measured via quantitative muscular-testing<ref name="Shelokov, 1957">{{Citation
| last1 = Shelokov | first1 = Alexis | authorlink1 =
| last2 = Habel | first2 = Karl | authorlink2 =
| last3 = Verder | first3 = Elizabeth | authorlink3 =
| last4 = Welsh | first4 = William | authorlink4 =
| title = Epidemic Neuromyasthenia — An Outbreak of Poliomyelitis-like Illness in Student Nurses
| journal = New England Journal of Medicine | volume = 1957 | issue = 257 | page = 345-355
| date = August 1957
| doi = 10.1056/NEJM195708222570801
}}</ref>
* Normal or minimal [[cerebrospinal fluid]] findings<ref name="Shelokov, 1957" />
* [[Autonomic nervous system]] dysfunction, [[Hypothalamus|hypothalamic]] dysfunction
* [[Postural orthostatic tachycardia syndrome|Orthostatic tachycardia]]
* Ulnar neuritis or lesion<ref name=":2">{{Cite journal|last=White|first=D|last2=Burtch|first2=Robert|date=July 1, 1954|title=Iceland Disease: A New Infection Simulating Acute Anterior Poliomyelitis|url=http://n.neurology.org/content/4/7/506.short|journal=Neurology|volume=4|pages=|via=}}</ref> (Iceland, north of England)
* Microscopic infiltration of nerve roots with [[lymphocytes]] and [[Mononuclear cell|mononuclear cells]]; patchy damage to the myelin sheaths and axon swellings (in monkeys infected with unidentified virus from the [[1949-53 Adelaide outbreak|Adelaide]] outbreak)
* Raised urinary [[creatine]] excretion<ref name=":2" /><ref name=":1">{{Cite journal|last=Albrecht|first=Robert|date=March 21, 1964|title=Epidemic Neuromyasthenia Outbreak in a Convent in New York State|url=https://www.ncbi.nlm.nih.gov/pubmed/14100144|journal=Journal of the American Medical Association|volume=187|pages=904-907|via=}}</ref>

In the majority of epidemics, no viral or bacterial infectious agent was successfully cultured. However, in many cases patients were only examined well after the onset of acute illness. In a small number of epidemics [[Coxsackie B]]<ref name="Fegan1983">{{Citation
| last1 = Fegan | first1 = KG | authorlink1 = KG Fegan
| last2 = Behan | first2 = PO | authorlink2 = Peter Behan
| last3 = Bell | first3 = EJ | authorlink3 = Eleanor Bell
| title = Myalgic encephalomyelitis — report of an epidemic
| journal = J R Coll Gen Pract | volume = 33| issue = 251| pages = 335–337
| date = 1 Jun 1983
| pmid = 6310104
| url = http://bjgp.org/content/33/251/335
}}</ref><ref name="Calder1984">{{Citation
| last1 = Calder | first1 = BD | authorlink1 = BD Calder
| last2 = Warnock | first2 = PJ | authorlink2 = PJ Warnock
| title = Coxsackie B infection in a Scottish general practice
| journal = Jrnl Royal Coll Gen Pract | volume = 34| issue = 258| pages = 15–19
| date = Jan 1984
| pmid = 6319691
| url = http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1959663/
}}</ref> and [[Bethesda-Ballerup paracolon organism]]<ref name="Shelokov, 1957" /> were found. In others, infection of animal models with samples from patients results in identifiable nervous system damage on autopsy, in spite of being unable to identify the agent.<ref name=":0" />

==Epidemiology==
Many of these outbreaks occurred at institutions for example, hospitals<ref name="Shelokov, 1957" /><ref name="Gilliam, 1936-38" />, schools, army bases or convents. The pattern of spread suggested a highly infectious agent that spread person to person, rather than through contaminated food or drink or exposure to a single toxic agent.<ref name=":0">{{Cite journal|last=Parish|first=JG|date=1978|title=Early outbreaks of 'epidemic neuromyasthenia'|url=https://www.ncbi.nlm.nih.gov/pubmed/370810|journal=Postgraduate Medical Journal|volume=54|pages=711-7|via=}}</ref><ref name="Gilliam, 1936-38">{{Citation
| last1 = Gilliam | first1 = A.G. | authorlink1 =
| title = Epidemiological Study Of An Epidemic, Diagnosed As Poliomyelitis, Occurring Among The Personnel Of The Los Angeles County General Hospital During The Summer Of 1934
| journal = Public health bulletin, 1936-1938 | volume = no.231-240 | issue = | page =
| date = 1938
| pmid =
| url = http://babel.hathitrust.org/cgi/pt?id=mdp.39015022082260;view=1up;seq=617
}}</ref><ref name="Poskanzer, 19572" />

Outbreaks tended to begin in the summer months, with most initial cases reported from April to September.<ref name="Acheson, 1959" />

In outbreaks involving both medical personnel and the general community, medical personnel had a higher attack rate and/or greater central nervous system involvement.<ref name="Poskanzer, 19572" /> A similar pattern was seen in hospital outbreaks, where those in roles that involved more frequent or intimate contact with patients or those working in an infectious disease ward were more affected than other hospital staff.<ref name=":0" /><ref name="Gilliam, 1936-38" /> A large proportion of recorded outbreaks have taken place in hospital settings.<ref name="Acheson, 1959" />

In many outbreaks including [[1934 Los Angeles atypical polio outbreak|Los Angeles]], [[Akureyri]], [[1953 Maryland outbreak|Rockville, MD]], [[1955 Royal Free Hospital outbreak|Royal Free Hospital]], and [[1956 Punta Gorda outbreak|Punta Gorda, Florida]], women were disproportionately affected.<ref name=":0" /><ref name="Shelokov, 1957" /><ref name="Gilliam, 1936-38" /><ref name="Acheson, 1959">{{Citation
| last1 = Acheson | first1 = E.D. | authorlink1 =
| title = The Clinical Syndrome Variously Called Benign Myalgic Encephalomyelitis, Iceland Disease and Epidemic Neuromyasthenia
| journal = American Journal of Medicine | volume = 26 | issue = 4 | page = 569–595
| date = 1959
| pmid =
| url = http://www.name-us.org/defintionspages/DefinitionsArticles/Acheson1959.pdf
}}</ref><ref name="Poskanzer, 1957">{{Citation
| last1 = Poskanzer | first1 = David C. | authorlink1 =
| last2 = Henderson | first2 = Donald A. | authorlink2 =
| last3 = Kunkle | first3 = E. Charles | authorlink3 =
| last4 = Kalter | first4 = Seymour S. | authorlink4 =
| last5 = Clement | first5 = Walter B. | authorlink5 =
| last6 = Bond | first6 = James O. | authorlink6 =
| title = Epidemic Neuromyasthenia — An Outbreak in Punta Gorda, Florida
| journal = New England Journal of Medicine | volume = 1957 | issue = 257 | page = 356-364
| date = 1957
| pmid = 13464939
| doi = 10.1056/NEJM195708222570802
| url = http://www.nejm.org/doi/full/10.1056/NEJM195708222570802
}}</ref><ref name=":3" /><ref>{{Cite journal|url=https://www.ncbi.nlm.nih.gov/pubmed/14771044|title=A disease epidemic in Iceland simulating poliomyelitis|last=Sigurdsson|first=B|date=September 1950|journal=American Journal of Hygiene|volume=52|pages=222-38|via=}}</ref> In other outbreaks, including the 1949-1953 [[1949-53 Adelaide outbreak|Adelaide]] outbreak and an outbreak in [[1955 North of England outbreak|northern England in 1955]], a 1:1 gender ratio was reported.<ref name=":0" /> In hospital epidemics, young female nurses were disproportionately affected, but this may have been due to risk factors like higher repeated exposure to the same infection during an epidemic<ref name=":0" /> and in some outbreaks, gender-segregated living quarters.<ref name=":3">[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1962472/ An Outbreak of Encephalomyelitis in the Royal Free Hospital Group, London, in 1955 - The Medical Staff Of The Royal Free Hospital]</ref> However, the higher ratio of women were also reported in outbreaks in the general population.<ref name="Acheson, 1959" /> In Akureyri, while the incidence among adults was significantly higher for females, there was no significant difference in incidence between sexes among those under twenty.<ref name=":4">{{Cite journal|url=https://www.ncbi.nlm.nih.gov/pubmed/14771044|title=A disease epidemic in Iceland simulating poliomyelitis|last=Sigurdsson|first=B|date=September 1950|journal=American Journal of Hygiene|volume=52|pages=222-38|via=}}</ref> This comports with studies of age and sex distribution in sporadic cases.{{Citation needed}}

Those most affected tended to be adults in their twenties,<ref name=":0" /><ref name="Gilliam, 1936-38" /><ref name=":1" /> although cases of young children and adults as old as 80 have been recorded in outbreaks.<ref name="Acheson, 1959" />

== Prognosis ==

Although many patients improved over time, in follow-up studies, a large percentage were still ill months to years later. Many case studies note long periods of convalescence with relapses following exertion<ref name="Shelokov, 1957" /><ref name=":1" /><ref name="Poskanzer, 19572">{{Citation
| last1 = Poskanzer | first1 = David C. | authorlink1 =
| last2 = Henderson | first2 = Donald A. | authorlink2 =
| last3 = Kunkle | first3 = E. Charles | authorlink3 =
| last4 = Kalter | first4 = Seymour S. | authorlink4 =
| last5 = Clement | first5 = Walter B. | authorlink5 =
| last6 = Bond | first6 = James O. | authorlink6 =
| title = Epidemic Neuromyasthenia — An Outbreak in Punta Gorda, Florida
| journal = New England Journal of Medicine | volume = 1957 | issue = 257 | page = 356-364
| date = 1957
| pmid = 13464939
| doi = 10.1056/NEJM195708222570802
| url = http://www.nejm.org/doi/full/10.1056/NEJM195708222570802
}}</ref> or before or during [[Menstrual cycle|menstrual periods]].<ref name="Shelokov, 1957" /><ref name=":1" /><ref name="Poskanzer, 19572" />

==Relationship to polio==
Prior to the poliovirus vaccine, several [[outbreaks]] of what later came to be called [[myalgic encephalomyelitis]] coincided with confirmed outbreaks of [[poliomyelitis]] including the [[1934 Los Angeles atypical polio outbreak|1934 Los Angeles outbreak]], the [[1948-49 Akureyri outbreak|1948 Akureyri, Iceland outbreak]], and 1949 outbreak in [[1949-53 Adelaide outbreak|Adelaide, Australia]]. Many outbreaks were initially misinterpreted as clusters of [[poliomyelitis]] or [[abortive poliomyelitis]], hence one of [[ME]]'s earliest names, [[atypical polio]]. It is not known whether there is a direct relationship between polio outbreaks and ME or if outbreaks of ME were more likely to be reported when public health authorities were already mobilized for an earlier crisis.

No serological evidence of polio was ever found in these outbreaks and the ultimate pattern of the outbreaks differed in significant ways, chief among them the higher attack rate, the tendency to affect adults rather than children, and the higher [[morbidity]] than poliomyelitis but no [[mortality]].<ref name=":0" /><ref name="Acheson, 1959" /> Findings in several outbreaks seemed to suggest that symptoms were caused by an [[enterovirus]] distinct from but related to polio including findings of mild, diffuse peripheral nervous system damage in monkeys infected with the virus; a stronger response to polio vaccination in children who had been in epidemic areas; and seasonal patterns of infection resembling polio, i.e., the rises in cases during summer months.<ref name=":0" /><ref name="Acheson, 1959" />

After the Akureyri outbreak, children in areas that had been affected responded to poliomyelitis vaccination with higher antibody titres, as if these children had already been exposed to an agent immunologically similar to poliomyelitis virus.<ref name=":0" />

== Controversy ==
In 1970, a paper by Colin P. McEvedy and AW Beard claimed that the [[1955 Royal Free Hospital outbreak]] was actually [[mass hysteria]].<ref>[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1700894/ Royal Free epidemic of 1955: a reconsideration. 1970 PubMed.gov]</ref><ref>[https://www.telegraph.co.uk/news/health/12033810/Its-time-for-doctors-to-apologise-to-their-ME-patients.html It’s time for doctors to apologise to their ME patients by Dr. Charles Shepherd - The Telegraph]</ref>

== See also ==

* [[List of myalgic encephalomyelitis and chronic fatigue syndrome outbreaks]]

== Learn more==

*"[https://www.newyorker.com/magazine/1965/11/27/in-the-bughouse In the Bughouse]," ''The New Yorker'' by Berton Roueché.
*[https://www.amazon.com/Oslers-Web-Labyrinth-Syndrome-Epidemic/dp/0595348742 ''Osler's Web''] by Hillary Johnson

== References ==
<references />
[[Category:Outbreaks]]