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Old 01-12-2016, 04:14 AM   #1
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Default 1918 deaths-by-agegroup mystery

other than previous influenza epidemics, the deadly 1918-1920 pandemic
killed the younger people, mostly those aged 20-35.
The reason for this is still unclear.

The most favoured theory is, that a similar virus was circulating
before the 1889-1893 pandemic to which people born before 1889
had been exposed and had acquired some immunity.
This is supported by similar observations from the 1957-1958
and 1968-1970 pandemics.
However, one problem with this theory is, that that supposed
seasonal (H1-) strain before 1890 was hardly observed.
Especially in England, where we had good surveillance, there
just were almost no reports about (seasonal) influenza in 1870-1888.

Another theory is, that the 1889-1893 virus had negative consequences
to the immunity for those who contacted it at young age,
consequences that lasted until 1918 and maybe lifelong.
But there is not much evidence for such things from other influenza
outbreaks and especially it looks strange why this affected only
children in 1889-1893 (IMO)

There was one Canadian author, Alain Gagnon, [also Shanks,Bundage]
who favoured this 2nd theory, attributing it to original antigenic sin,
and now one of his students had published her 326-page-thesis where -
for Ontario - they gathered not only age-by-year of the deceased
in 1918 but also age-by-month.

I had been waiting for this and I think it should had been done
long before, and I think the genealogy organisations do have the
data. The month of birth is important to examine the effects
of seasonal influenza waves on immunity.

It seems to me that their database is non-public so I estimated
the 156 datapoints from Figure 5.12 and plotted the
1918 age-distribution by month of birth :

And -to me- that doesn't seem to support either of the 2 above
theories. For the first theory the month should matter if born
before 1890 but not after. Vice versa for the 2nd theory.

Birth in January,March were bad for survival in 1918, birth in
May,June,July,Nov were good, the August-peak is unexplained.

At that time many young children died in August (Jul.-Sep.) from
summer diarrhoe diseases.

Western, McMaster, Montreal Influenza Pandemic (WMMIP) Database

Those who were in utero at the time of potential maternal exposure [1890?]
died in greater numbers [in 1918?]

these data most closely support that of antigenic imprinting,
[I don't see this]
[I do see some signs of bias, (e.g. she doesn't compare with the timing of the seasonal waves)
she finds support for their previously established theory, (somehow unusual,absurd, IMO) ]

There is cautious support for the fetal growth
[see the 1890 peaks for Mar. - May. in my chart above]
restrictions hypothesis, but these data do not support the scarring mechanism.
[childhood conditions influencing adult mortality]
no support for the tuberculosis hypothesis
These data are amply available in the WMMIP database.
There were proportionally more French Canadians among
the decedents, more catholic individuals, and more people from Eastern Ontario.

they examined 1883-1895 only, but interesting would be
especially 1875 and 1900-1901 with widespread flu,
some authors even called those "pandemics"

a chart says more than 1000 words

Last edited by gsgs; 01-13-2016 at 07:44 AM.
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Old 01-12-2016, 09:49 AM   #2
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I read here somewhere - several years ago that younger people had a stronger immune response which was itself more deadly. In other words, a younger persons immune system was more volatile or dangerous to the person. I think there was some mention of a "cytokine storm" (Or something like that). CS is up on that.

(potentially fatal immune reaction consisting of a positive feedback loop between cytokines and white blood cells)
Backing off on the tranqs..... petting puppies instead!
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Old 01-12-2016, 10:57 AM   #3
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yes, cytokene storm. But that was only part of the problem.
Most people still died from pneumonia.
1918 influenza virus increased host susceptibility to less-invasive pneumococci.2

2: http://www.sciencedirect.com/science...64410X09008500
The majority of the mortality associated with the influenza pandemic of 1918
was attributable to bacterial infections, especially the pneumococcus

deaths in 1918 were ~50-50 attributed to pneumonia or influenza
the military reports often spoke about bronchopneumonia in soldiers,
similar to those following measles, but the civil death statistics have
little bronchopneumonia, mostly lobar pneumonia


And why the peak at 28 years = born in 1890 ?
a chart says more than 1000 words

Last edited by gsgs; 08-21-2016 at 05:29 AM.
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Old 08-21-2016, 05:26 AM   #4
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the severe Influenza epidemic 1915/16 in USA was a potential precursor of the 1918 pandemic
with a presumably somehow reassorted virus, people had little immunity, so there
was an early seasonal outbreak, flu was widespread with big peak but short duration.

It was first officially reported in Jackson MS 2015/12/20,
Southern US-States got it earlier.
(this was before the US-Mexican military expedition)

from Public Health Reports, 01/1916

Reported Widely Prevalent in the United States.
Officers of the Public Health Service have reported on the unusual
prevalence of what is said to be influenza in various parts of the
United States during the last week in December and the first week
in January, as shown by the following reports.
The disease is undoubtedly epidemic in many places from which no reports
have been received, as a large number of cases of a malady can exist in
a community without their presence being known or the existence of
an epidemic suspected unless the local health department makes it
its business to keep currently informed in regard to such matters.
Collaborating Epidemiologist Garrison reported January 3, 1916:
Influenza prevalent in Little Rock and all over State.
#California-Los Angeles.
Senior Surg. Brooks reported December 31, 1915: Extensive
epidemic influenza of moderate severity began about two monthls ago;
not much diminished.
#California-San Diego.
Surg. Carrington reported December 31, 1915:
Influenza not epidemic in this locality. A few cases have been imported recently,
but not being notifiable the exact number is unknown.
#California-San Francisco.
Surg. Williams reported December 31,1915: Secretary State
Medical Society, Lane Hospital, and University Hospital, report
influenza widespread and severe. Bacillus isolated.
Dr. J. Henry Barbat says most severe epidemic since 1891.
Some severe cases at Exposition Hospital, and many mild
ones in Marine Hospital recently.
Several other hospitals have no information.
Local board of health can give no information until Monday.
Passed Asst. Surg. Ridlon reporte(I December 31, 1915: Pulmnonary
infectionis prevalent.
Two deaths influeniza, 22 deaths pneumonia,
December 1 to 30.
Senior Surg.Gassaway reported January 1, 1916: Influenza present,
probably 500 cases.
Surg. Cobb reported December 31, 1915: Influenza not a reportable
This week so far reported 57 deaths from influenza, last
week 30 deaths.
Fourteen hundred and forty cases pneumonia
reported this month, 666 deaths, 201 deaths within the last four
Collaborating Epidemiologist Crumbine reported January 3, 1916:
Influenza epidemic, widely prevalent over Kansas, especially'severe
in Topeka, 700 Santa Fe shopmen unable to work last week.
Passed Asst. Surg. Herring reported January 4, 1916: Board of
Health estimates 2,400 cases influenza Louisville.
Slight increase
pneumonia morbidity to date.
#Louisiana-New Orleans.
Surg. von Ezdorf reported December 31, 1915: City healtlh officer
reports 66 deaths from influenza this month, 11 deaths reported
Collaborating Epidemiologist Fulton reported January 3, 1916:
Influenza probably epidemic in Baltimore and other parts of Maryland.
Surg. Brown reported December 31, 1915: Board of Health Boston
reports pneumonia cases doubled, influenza epidemic.
Not considered serious.
Senior Surg. Austin reported December 31, 1915: Influenza not
City health officer reports 25 deaths December.
Epidemic, general estimate, 100,000 cases; hospitals crowded, includinig
Collaborating Epidemiologist Bracken reported January 4, 1916:
Influenza epidemic in Minnesota.
Asst. Surg. Waring reported January 4, 1916: Influenza opidemic
in Jackson is reported to be decreasing.
Collaborating Epidemiologist Stingily reported January 3, 1916:
Influenza is present throughout the State, but general prevalence of
the disease seems to be on the decrease.
#New Mexico-Fort Stanton.
Surg. Smith reported December 31, 1915: Influenza very preva-
lent, both along railroad and in mountains; only average severity.
#New York-Stapleton.
Senior Surg. Stoner reported December 31, 1915: Health de-
partment reports widely spread epidemic grippe-like infection simu-
lating influenza, not yet proven bacteriologically, marked increase
pneumonia mortality, also mortality of persons over 65, several
patients and two attendants of this hospital down with similar
Health department sending out warning.
Surg. Wille reported December 31, 1915: Influenza, mild type, first
reported Cleveland and vicinity December 19.
Wi4espread since December 20.
Newspaper estimate number of cases, 100,000.
Collaborating Epidemiologist McCampbeU reported January 4,1916:
Large number cases severe coryza, Columbus and other parts
of Ohio.Considerable number cases true influenza.
Mlortality very lowv.
Surg. Magruder reported December 31, 1915: Influenza not epi-
demic, a few severe cases having clinical symptoms of influenza have
occurred; bacillus not yet found.
Senior Surg. Irwin reported December 31, 1915: Influenza epi-
demic here, total deaths five weeks ended to-day 141, 72 deatths
last week, number of cases not reported, total cases of pneumnonia
in December 881, total deaths pnuemonia last week 284.
Dr. Irvin further reported January 3, 1916: It is very difficult to
estimate the numiiber of cases of influenza in Philadelphia, because
of the fact that it is not a reportable disease.
However, a great
many of the various services of the city have been badly crippled
by the number of cases of illness, while the incidence of pneumonia
shows a ratlher serious con(lition.
As an indication, it may bc stated that at one hotel, which has
now about a hundred guests, 16 are confined to bed with influenza,
while others have it in a milder form.
Perhaps one-quarter of
the total number of the people in the house have the disease,
and this seems to be the case to a greater or less degree in the
various hotels of the city.
There were reported 408 new cases of
pneumonia during the week ended December 31.
#Rhode Island-Providence.
Passed Asst. Surg. Marshall reported January 1, 1916: Influenza
is prevalent in vicinity; deaths, 2.
#South Carolina-Columbia.
Collaborating Epidemiologist Hayne reported January 4, 1916:
Influenza is prevalent in South Carolina, but is of a mild form and not
Senior Surg. White reported December 31, 1915: Commnissioner
of health says he e'timates seven to eight thousand cases of inifluenza,
but miorbidity reports not made.
Outbreak declining rapidly.
Surg. Young reported December 31, 1915: Influenza is prevalent
-in iNoirolk and vicinity.
Collaborating Epidemiologist Brumfield reported January 3, 1916:
No epidemicof influenza has been officially reported as yet,
There is,however, an unusual number of deaths from pneumonia.
#Washington-Port Townsend.
Passed Asst. Surg. Earle reported December 31, 1915: Influenza is
present here in mild form; no deaths, no serious cases.
Surg. Lloyd reported December 31, 1915: Influenza reported epi-
demic throughout State, including Seattle; moderately severe type;
schools partially depopulated many places.
Deaths from all causes in Seattle durinig month of December 15%
greater than during similar period last year.
Influenza undoubtedly a factor, together with its complications,
of which pneumonia is particularly important.
Assist. Surg. Waring reported by telegraph, December 20, 1915,
that an epidemic of influenza existed at Jackson, Miss., the estimated
number of cases of the disease being 500.

CA:Los Angeles. Extensive epidemic influenza began about two monthls ago;
MS:in Jackson is reported to be decreasing.
NY:also mortality of persons over 65
OR:Portland.not epidemic,
OH:Cleveland and vicinity December 19
TN:Memphis.8000 cases, Outbreak declining rapidly.
VA:Richmond.No epidemic, unusual number of deaths from pneumonia.
WA:epidemic throughout State,
Deaths from all causes in Seattle durinig month of December 15%
greater than during similar period last year.

pneumonia peak in Chicago 1916/01/05
pneumonia peak in Philadelhia 1915/12/28
pneumonia peak in Los Angeles ~1915/12/15
pneumonia peak in Kansas City ~1915/12/10
a chart says more than 1000 words
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1918, deathsbyagegroup, mystery

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