Natural Immunity





They’ve had


P O X!




M.B. O’Hare



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© M. B. O’ Hare. 2018. May be used for educational purposes without written permission but with a citation and copyright notice linked to this source.


Can We Now Count Our Children?
 How was the War on Bugs Won?
Whatever happened the Bubonic Plague and what has Chickenpox got to
do with it
The Many ‘Typhoid Marys’
From Typhus to Typhoid
Dysentery & Cholera: A Tale of Two Pathogens
Scarlet Fever Returns: but it is a lot less deadly
 More died from TB annually in Ireland than from any other disease that
we have stats for
 What Happened to the ‘Spanish Flu’ & will we ever see its likes again
 Don’t Count Your Children Before They Get The Pox
 Would we survive Smallpox if it escaped from a Lab today?
 From the Plague to the Pox

Can We Now Count Our Children?

 Can we now count our children with increasing confidence because they have survived these real diseases via natural exposure over generations?

For instance, whatever happened to the Great Plague of the middle ages, a disease we never had any medical or hygiene interventions to try and counteract or even eradicate (as we had no vaccines or antibiotics back then, and no amount of cleaning up rat-infested cesspits would have limited the devastating spread as it turns out that black rats and their fleas may be innocent after all)?

Imagine, though, what would happen if the old Plague in its true original colours (the same genes as the original Plague) returned to our modern communities today? Would we begin to die in our millions, or a third of Ireland’s population and the same proportion in Europe be wiped out as before?

How would one know what the impact would be before it would be too late? What about bioterrorism and it being unleashed out into the public? Do we have a vaccine for the Plague?  As it happens, we don’t need to panic as the actual same Plague that once killed millions has already escaped out into the public at large on a number of occasions not that long ago, and demonstrates surprisingly little impact.  And curiously, having Chickenpox may actually have a lot to do with why we aren’t currently dying in our millions from the Plague if it does happen to escape out into the public.

Similarly, we could ask: What if Smallpox returned in its old colours? We don’t even have a vaccine any more to protect us! As it turns out, some of the most virulent strains escaped quite by accident into the public arena from several labs not long ago, and again, the impact was surprisingly minor. You see, Nature works in much more sophisticated and mysteriously molecular ways than we have hitherto appreciated. For instance, our history books describe in terrifying detail what can happen when an isolated indigenous community was initially devastated when they had first encountered some foreign and unfamiliar pathogens. Interestingly, these isolated populations were some of the healthiest and fittest individuals and naturally pristine natives.

However, this phenomenon has been studied in more recent times and we can now see that the relatively rapid recovery – over a few generations from such an event – cannot be explained via our current genetic inheritance evolutionary model as this kind of rapid adaptation simply could not have occurred by Darwinian means. Instead, it seems that these communities recovered and became ancestrally resistant to these same pathogens and our more recent molecular insights help explain just how this rapid robust resilience occurs.

Many, particularly older diseases, are viewed as having become somehow naturally extinct; living on only in our folk memory, or gotten consigned to the old dusty medical journals as curiosities of the past. However, unbeknownst to ourselves, it seems that Nature has an incredibly long-term memory for such pathogen/host battles of the past. She apparently has left an imprint of the best strategy to take when dealing with such clever pathogens – leaving us with something of immense value to pass on silently to our children – even if we had long ago forgotten these devastations – thankfully, our immune cells haven’t.

The successive onslaught throughout the generations, due to natural exposure – even without symptoms, a pathogen’s impact is proven to be less and less, and our innate resistance, more and more. It is this pattern of near-simultaneous rises in highly infectious diseases, and dramatically declining death rates – an almost universal phenomenon – that is clearly seen throughout our developed nations over a similar timeframe for the same diseases and is indelibly imprinted  in the charts presented throughout this study –  illustrating our in real time our ancestral battle with the bugs. charting the rise and fall of some of the deadliest contagions known to humankind.

Thankfully, therefore, we can now count our children because our ancestors have had the Plague, the Pox and just about everything else that has ever circulated in the past. Otherwise, the earth would be colonised by bacteria and viruses and not much else.

Read on to explore natural immunity within its historical context and the newly emerging molecular science behind it...


How was the War on Bugs Won?

Fig. 1Fig. 1: Comparative scaled charts for all annual number of deaths recorded for all the major epidemic diseases in Ireland since first officially recorded. Charts generated using annual statistics reports since records began – “Annual Reports on Marriages, Births and Deaths in Ireland, from 1864 to 2000” courtesy of An Phríomh-Oifig Staidrimh, Central Statics Office CSO, link. © Copyright
Fig. 1a: Comparative charts showing the annual number of deaths recorded for many major epidemic diseases – bacterial and viral in Ireland since first officially recorded. Note the significant decline post mid-20th Century. Charts generated using annual statistics reports since records began – “Annual Reports on Marriages, Births and Deaths in Ireland, from 1864 to 2000” courtesy of An Phríomh-Oifig Staidrimh, Central Statics Office CSO, link. © Copyright


It is difficult to grasp just how many deaths occurred in Ireland from infectious disease over the course of 19th and earlier 20th Century. Each chart above represents those individual deaths recorded each year since records began in 1864.

As you can see from the above charts in Figure 1 (showing the relative scale of mortality), some diseases were significantly deadlier than others. Compare, for instance, the annual death toll at its peak from TB to Smallpox which is discussed in greater detail in their relevant topics within this series. 1a shows a range of once that these, irrespective of whether they are viral or bacterial become significantly less deadly, particularly by the mid-20th Century.

Some diseases such as Tetanus, Chickenpox, Mumps and Rubella would not even register on such charts, as the deaths from the diseases were so rare throughout the hundred years of data in Ireland.

The essential pattern from the above charts is that all infectious diseases became significantly less deadly over the course of the 20th Century to the point where they no longer register on the graphs above. This dramatic decline in deaths is not of course peculiar to Ireland, as irrespective of which disease we are talking about, or in which region we are viewing in the developing world of the later 19th and throughout the 20th Century, this great mountain of historical devastation would look essentially similar and just as insurmountable as our fledgling nations grew to maturity.


The almost Universal Decline in Infectious Diseases Beyond Ireland

It seems that all our developing nations have one thing in common, in that, these same diseases became dramatically less deadly to the point where the annual number of deaths registered go from thousands, and some regions, hundreds of thousands to a point where they hardly register on the graphs.


Twentieth Century Mortality Trends in England and Wales, 2003

“Infectious diseases have declined to low levels, with the epidemics of the early part of the century no longer occurring”.

Clare Griffiths and Anita Brock, Office for National Statistics 1


For comparative graphs to those from Ireland, see Thomas McKeown’s publication for England and Wales: The Role of Medicine: Dream, Mirage, or Nemesis? 2

Again, these same type diseases are seen to become significantly less deadly across the board in the U.S. as well.

Annual summary of vital statistics: trends in the health of Americans during the 20th century.

At the beginning of the 20th century, the leading causes of child mortality were infectious diseases, including diarrheal diseases, diphtheria, measles, pneumonia and influenza, scarlet fever, tuberculosis, typhoid and paratyphoid fevers, and whooping cough. Between 1900 and 1998, the percentage of child deaths attributable to infectious diseases declined from 61.6% to 2%.

Guyer B1Freedman MAStrobino DMSondik EJ.Pediatrics. 2000 Dec;106(6):1307-17. 3

For comparative graphs of the dramatic decline of deaths throughout the earlier part of the 20th Century in the U.S. See:, January 6, 1999, Trends in Infectious Disease Mortality in the United States During the 20th Century, Gregory L. Armstrong, MD; Laura A. Conn, MPH; Robert W. Pinner, MD, JAMA. 1999; 281(1): 61-66. doi:10.1001/jama.281.1.61 for graphs. See also graphs of the decline of infectious diseases, again relating to the U.S. dated to February 1996, Infectious Diseases and Human Population History, Andrew P. Dobson and E. Robin Carper.

Certainly, judging by the above graphs and historical records in general, by the earlier part of the 20th Century, our developing nations were becoming significantly safer for infants in particular that they were some decades before. This and a very similar decline in highly infectious diseases for essentially the same diseases are also noted as far north as Iceland corresponding to a comparable timeframe.

The Development of Infant Mortality in Iceland, 1800–1920

The great epidemic infant and child killers of the nineteenth century, such as measles and whooping cough, had lost much of their virulence. Occasionally, they were even successfully coped with in individual places with quarantine measures. By 1920 Iceland had become relatively safe for infants and young children in comparison with the dreadful situation prevailing around the mid-nineteenth century.

Loftur Guttormsson and Ólöf Garðarsdóttir 4


What is perhaps more remarkable, is the fact that this common pattern of deaths from once deadlier diseases behaved similarly within nations on the other side of the world such as Australia as indicated in the two excerpts that follow: one references the earlier era and the other brings this data up to our present day. And surprisingly, the drop rate in deaths in terms of percentages is equally dramatic for the earlier part of the 20th Century as seen elsewhere:


Death registration and mortality trends in Australia 1856–1906

The age-standardised rate of all-cause mortality peaked at around 2,000 per 100,000 population in 1860—a year of fearsome epidemics. An important turning point occurred in 1885, after which mortality declined steadily and with less annual variation. The death rate fell from 1,600 in 1885 to under 1,000 in 1906, a fall of one-third over two decades.

Michael Willem de Looper, Abstract, p. iv 5


Epidemiologic Transition in Australia: The last hundred years

Long-term changes in major causes of death Australia experienced substantial changes in cause-specific mortality over the period 1907 to 2012 … mortality from infectious diseases decreased substantially during the first half of the twentieth century: in 1907, infectious diseases accounted for 16 per cent of the total standardised mortality rate for males and 23 per cent for females, but by 1946 accounted for less than 6 per cent for both sexes, and decreased to insignificant levels by 1960.

Heather Booth, Leonie Tickle,  Jiaying Zhao 6


Closely matched troughs and peaks a case of three major killers – particularly of infants of the past, in three very different populations


Fig. 2: Dramatic decline in deaths from some of the greatest killer infectious diseases (mainly effecting children) in the pre-vaccine era.- Ireland (chart generated by A. Parent using annual statistics reports since records began – “Annual Reports on Marriages, Births and Deaths in Ireland, from 1864 to 2000” courtesy of: An Phríomh-Oifig Staidrimh, Central Statics Office CSO, link. © Copyright Fig, 1a: U.S. comparable data. Source: Tavia Gordon, Public Health Reports, (1896-1970), Vol. 68, No. 4 (Apr., 1953), figure. 3.  Link to PDF The charts above compare the actual deaths recorded officially for Ireland since records began with deaths per 100, 000 from the United States. Below are comparable charts relating to the same dramatic decline in these same diseases as recorded from England and Wales for infants and children.


Take for example Figure 2, comparing a few of such major diseases where deaths from these diseases declined throughout the 20th Century in as far-flung nations as Ireland and the U.S. Deaths from the Measles virus or the bacterial pathogens known as: Pertussis (whooping cough) and Scarlet Fever – the other great killers of the 19th and earlier 20th Century – particularly amongst children, similarly plummeted according to a near identical pattern irrespective of the diversity or geographical location of our developing nations.

When we compare the decline in deaths from Scarlet Fever, Whooping Cough (Pertussis) and Measles seen within the charts (Fig. 2) from such diverse regions as Ireland and the U.S. with charts generated from England and Wales, we find once again, a very similar pattern of decline as seen in Figure 3. The only real difference between them all is that of number or rate of deaths annually which of course scales according to population sizes between these respective regions. For instance, if we removed the number individual deaths (as all the Irish charts employ), or the rate of deaths (used by most other more populous nations – per 100,000 or sometimes per million if their population is very large), apart from scale, these graphs would be difficult to tell apart.


Fig. 3: Adapted graphs based upon figures: 4.15 (Scarlet Fever), 4.24 (Whooping Cough/Pertussis) and 4.18 (Measles) showing rates of annual death rates per 100,000 of the population in England and Wales from 1901 – 2000. The shaded area represents post-WWII, after, Clare Griffiths and Anita Brock, Office for National Statistics Link


Regarding the commentary about the above charts adapted for the purposes of this study (Fig. 3), the following statistics corresponds in percentage terms (not actual numbers of deaths as England and Wales would have a much larger overall population size compared to Ireland for the same period) very closely to what we observe in the Irish charts for the same diseases over the same timeframe.

A total of 67, 791 deaths from scarlet fever were recorded in England and Wales during the twentieth century, with the overwhelming majority (over 99 percent) occurring in the period 1901-45…


A total of 274,347 deaths from measles were recorded in England and Wales during the twentieth century, with over 98 percent occurring in the period 1901-45…


A total of 233,698 deaths from whooping cough were recorded in England and Wales during the twentieth century, with 97 percent occurring in the period 1901-45…

Clare Griffiths and Anita Brock, Office for National Statistics [7]


Causes of Death: A Study of a Century of Change in England & Wales

It is interesting that 3%, 2% and 4% of the reduction in mortality rate between 1901 and 1971 was due to whooping cough, measles and scarlet fever, respectively, but none of the decline in the mortality rate after this period. This is because by 1971 the mortality rate from these diseases already was extremely low.

Baillie, 2012, p.6. [8]



This is just an example of the commonality of the decline in deaths over the same period and by similar percentages of certain diseases: Measles, Pertussis and Scarlet Fever across far-flung nations.


Not by our interventions?

Thomas McKeown’s study dating to the late 1970s, highlighted earlier in relation to comparative graphs to those from Ireland and elsewhere, The Role of Medicine: Dream, Mirage, or Nemesis? [9] in this, he proposes, based upon the statistics of declining deaths within the context of our historical record of medical practice, that our medical intervention cannot, for the most part, be the direct cause of this decline – as these interventions came either too late or were not available at all to account for the almost universal decline in deaths from almost all of these once deadlier contagions of the past.

For instance, almost all of the previously more deadly diseases declined most significantly throughout the first half of the 20th Century, where there was a near 99 percent reduction in deaths in many regions as discussed above from the beginning of the 1900s if not earlier in some cases, to almost zero per by 1945 or the end of the Second World War (WWII), a time when antibiotics were only becoming more widely available which could begin combating the deadlier effects of many diseases and some antibiotics came later still depending upon specific infections.

Antibiotics are also only useful in fighting a disease that is bacterial and therefore, even taking into account their relatively late availability, cannot explain in any way for the decline in deaths from viral diseases that are discussed throughout this study. Nor can many of our vaccine or inoculation interventions be correlated directly with either the most significant decline in deaths, or the final demise of all the diseases discussed here as they either came too late – after the fact – or were not implemented at all.

A few particular diseases that may not at first be considered within this overall pattern are the classic textbook examples of the decline of deaths from Smallpox and its ultimate eradication as one example, as it is often portrayed as being directly a result of our health measures and timely interventions. However,  when we examine the long-term historical data, even this once deadly diseases appears to have naturally resolved itself well before our efforts to resolve the issue via artificial means. See Fig. 4:

smallpox compared London Ireland

Fig. 4: Reproduced from Fig. 5.4. Deaths from smallpox per 1000 deaths from all causes in London, from 1629 to 1900. (Data from Guy (1882) and the Registrar General’s Statistical Review of England and Wales.) in F. Fenner, D. A. Henderson, I. Arita, Z. Jezek, I. D. Ladnyi (1988) – Smallpox and its Eradication. World Health Organization (WHO) 1988. Online here at the WHO website with Irish original data superimposed.   F. Fenner, D. A. Henderson, I. Arita, Z. Jezek, I. D. Ladnyi (1988) – Smallpox and its Eradication. World Health Organization (WHO) 1988. Online here at the WHO website. Irish graph superimposed number of annual deaths since records began in 1864, one year after compulsory vaccination – significantly scaled down to make a comparison with London data. Data derived from “Annual Reports on Marriages, Births and Deaths in Ireland, from 1864 to 2000” courtesy of An Phríomh-Oifig Staidrimh, Central Statics Office CSO, link.

Similarly, in Ireland and elsewhere, the worst impact of a comparatively much less deadly and much shorter lived disease such as Polio, for example, had also begun resolving itself prior to our medical interventions. (See comparison in Fig. 5 of deaths from Scarlet Fever which never had a vaccine, compared to deaths from Polio in Ireland).

polio compared to scarlet fever

For instance, most other diseases in Ireland killed thousands annually, and this is demonstrably not due to any of our particular interventions, whereas Polio, like Smallpox, is frequently assumed to have been eradicated and brought under control by vaccination. However,  in Ireland, even at its peak, deaths from this disease were recorded as less than 60 deaths in its worst years during epidemics of the late 1930s/early 1940s and by the 1950s these epidemics were already fading out as almost everyone had become immune and indeed, Ireland was rather late in getting the vaccine which was introduced in 1957 when the vaccine trials to combat the disease. Interestingly, for various reasons, England and Wales and indeed, the rest of the UK was also rather late in introducing the vaccine against Polio, by which time the disease had surely begun to run its natural course and had become significantly less deadly and debilitating (See Fig. 6).


Polio Eng and Wales paralysis and deaths

Incidence Rates of Poliomyelitis in England

Incidence Rates of Poliomyelitis in Other Countries     In the US

PHI thanks The British Polio Fellowship for obtaining the following records.

Acute Poliomyelitis became notifiable in 1912.

*Deaths include late effects.

Source: Annual Reports of the Registrar General. Communicable Disease Surveillance Centre, London,

“Only after delays and struggles did the British IPV vaccination programme reach the necessary percentage of the population, morbidity rates declining from 1959 onwards”.

Med Hist. 2006 Oct 1; 50(4): 425–446. PMCID: PMC1592614 Vaccine Innovation and Adoption: Polio Vaccines in the UK, the Netherlands and West Germany, 1955–1965



U.S. data

Sophie Ochmann and Max Roser (2018) – “Polio”. Published online at from: ‘’ [Online Resource]

Post-Polio Health International (PHI)

Including International Ventilator Users Network

Post-Polio Health International (PHI)

Including International Ventilator Users Network


We even have diseases that irrespective of region and the timing of our medical interventions, if at all, closely pattern match following troughs and peaks to ultimate resolution – i.e they are no longer major killers. Note the very close pattern of rise and fall in death rates declining over the same timeframe from diphtheria from regions as diverse as Scotland, Northern Ireland, England and Wales and coming to a natural end by the time mass vaccination becomes available for all infants within these diverse nations (See Fig. 7).diphtheria ENG Wales, NI and Scotland

Fig.7: Comparative charts for all annual rates per 100,000 of respective populations of deaths from Diphtheria between England/Wales, Scotland and Northern Ireland from 1901 to 1950 – mass vaccination becomes widely available coincidently with the ultimate decline in deaths from this once deadlier disease. Chart generated using tabulated statistics from various “Annual Reports on Marriages, Births and Deaths in Ireland: An Phríomh-Oifig Staidrimh, Central Statics Office CSO, link.

This, of course, begs the question as to what is the cause of such an almost universal phenomenon in terms of the dramatic decline in deaths from some of the most deadly diseases? Scholars such as Thomas McKeown, suggest that other factors such as economics, improved living standards, better nutrition and a cleaner environments (the hygiene hypothesis as it is sometimes referred to) have commonly been offered as possible driving factors in the overall decline in infectious disease, as it now looks very like our medical interventions played a, perhaps surprisingly, small part in the historical and most major decline of deaths throughout the 20th Century – which is essentially the finding of this present study.

However, although this present study broadly supports McKeown’s conclusions regarding the fact that our medical interventions did not directly cause the decline in deaths from infectious diseases throughout the past few hundred years, the evidence that emerged from this present investigation does not support the alternative proposal offered by McKeown and others to account for the significant and often dramatic decline in deadly contagions throughout so many diverse nations for approximately the same timeframe. Their proposal simply doesn’t fit the data, or the historical record when we dig deeper into the context, rise and fall pattern over the course of time for each of the major diseases under discussion throughout this Natural Immunity Series.

This study will offer instead, a natural biological explanation as it relates to generational immunity over the course of time that can explain the almost universal pattern of decline in deaths from some of our most deadly contagions clearly evidenced throughout our nations as they developed into the modern era.

These more recent insights into the dynamic and sophisticated interplay between pathogens and us as their hosts are well supported by the historical record and matches the overall pattern of death statistics in general than either the medical intervention or the hygiene/population dynamics offered by others as an alternative. This present study revisited historical accounts of each of these plagues of humanity in the light of the findings produced from several lines of molecular investigations and found that this matched the data much better than other proposals offered thus far.

1. Griffiths C and Brock A (2003) Twentieth Century Mortality Trends in England and Wales. Health Statistics Quarterly, Issue 18, pp. 5–17. [Available online as PDF]–18–summer-2003/twentieth-century-mortality-trends-in-england-and-wales.pdf
2 Mc Keown, T (1979) The Role of Medicine: Dream, Mirage, or Nemesis? Basil Blackwell, Oxford [Available online as PDF]
3 Guyer B, Freedman MA, Strobino DM, Sondik EJ. (2000) Annual summary of vital statistics: trends in the health of Americans during the 20th century, Pediatrics. Vol. 106, [6]: pp. 1307-17.
4. Gregory L. Armstrong, G.L, Conn L.A, Pinner, RW (1999) Trends in Infectious Disease Mortality in the United States During the 20th Century, JAMA. Vol. 281 [1]: pp.61-66. DOI: 10.1001/jama.281.1.61
5. Dobson, AP. and Carper, ER (1996) Infectious Diseases and Human Population History: Throughout history the establishment of disease has been a side effect of the growth of civilization, BioScience, 46, Issue [2,] pp. 115–126, DOI: 10.2307/1312814 [Available online as PDF]
6 Guttormsson, L and Garðarsdóttir, Ó (2002) The Development of Infant Mortality in Iceland, 1800–1920, Hygiea Internationalis, An Interdisciplinary Journal for the History of Public Health, Vol. 3 [1] pp. 151 – 176, PDF · [Available online as PDF] DOI: 10.3384/hygiea.1403-8668.0231151
7 De Looper, MW (2014) Death registration and mortality trends in Australia 1856–1906, Abstract, p. iv. PhD Thesis: The Australian National University [Available online as PDF]…/De%20Looper%20Thesis%202015.pdf
8 Booth, H, Tickle, L, Zhao, J (2016) Epidemiologic Transition in Australia: The last hundred years, Canadian Studies in Population Vol. 43, [1–2]: pp. 23–47.
9 Baillie, L. and Hawe, E. (2012) Causes of Death: A Study of a Century of Change in England & Wales, OHE (Office of Health & Economics) p.6.
10 Smallman-Raynor, M, Cliff, A (2012), Atlas of Epidemic Britain: A Twentieth Century Picture, Oxford University Press, Oxford. p.50, figure 4:18 (Measles); p. 52, figure 4:24 (Whooping Cough); p.49, figure 4:15 (Scarlet Fever).,+with+97+percent+occurring+in+the+period+1901-45&source=bl&ots=5HQRkPk9dI&sig=HP2ZzfmADcwV3l7XJzL9gzL-B58&hl=en&sa=X&ved=0ahUKEwiJpfPNhvnbAhWICsAKHZ1SDEAQ6AEIKTAA#v=onepage&q=England%20and%20Wales%20during%20the%20twentieth%20century%2C%20with%2097%20percent%20occurring%20in%20the%20period%201901-45&f=true



Whatever happened the Bubonic Plague and what has Chickenpox got to do with it?

BBC History


‘there were hardly enough living to care for the sick and bury the dead‘

…scarcely a tenth of mankind was left alive.

Tom James, ‘Black Death: The lasting impact’ 17th Feb, 2011 [10]


A plague tsunami swept across Europe in the year 1348 wiping out more than a third of its population. By the late summer, the Black Death descended upon Irish shores with a particularly harsh impact in the urban centres which took its greatest toll in the dead of winter. Spreading out in a second wave reaching its tentacles beyond to the most desolate hills in search of fresh victims, this plague knew no social boundaries as Nobles, Clergy, Merchants and Peasants either survived the disease – gaining immunity, or succumbed and died.

‘1348: A Medieval Apocalypse – The Black Death in Ireland’

To anyone back in the middle ages, surely they would have believed that a pestilence had descended upon them sent from the Almighty himself. What punishment was this as they watched in horror that left no one merchant, pauper and lords alike asunder. ..


1348 was one of the darkest years in European history. The most deadly of all diseases – the Black Death – swept across the continent reaching Ireland in the late summer. Within twelve months over one-third of the population had died. Towns and villages were abandoned.

Finbar Dwyer,. 2016. Book Synopsis [11]


Rats and their fleas may not be guilty after all



Now looking at the archaeological evidence, it seems strange that something could spread so rapidly, having its worst impact initially in Ireland, when the fleas who stand accused of hitching a ride on black rats and spreading the Bubonic form of the plague were not even in season. Where urban centres such as London, have been excavated, it turns out that there are no expected heaps of dead black rats either. This is supported by recent evidence excerpted below:

…Archaeologists and forensic scientists … have examined 25 skeletons … Analysis of the bodies and of wills registered in London at the time has cast serious doubt on “facts” that every schoolchild has learned for decades: that the epidemic was caused by a highly contagious strain spread by the fleas on rats…


Mortality continued to rise throughout the bitterly cold winter, when fleas could not have survived, and there is no evidence of enough rats… In sites beside the Thames, where most of the city’s rubbish was dumped and rats should have swarmed, and where the sodden ground preserves organic remains excellently, few black rats have been found.

Vanessa Thorpe ‘Black Death? Rats and fleas finally in the clear’ 30th March 2014, 10


And we know from the historical record that in Ireland and indeed elsewhere in north-western Europe, that the plague was spectacularly lethal during the winter months also. In other words, the fleas that are supposed to be the culprits in spreading it via black rats would not have survived in this season.


‘Unheard of mortality’ The Black Death in Ireland

The plague raged in Dublin between August and December, setting a pattern for the terror it would spread through other parts of the country.



A clue to the true cause of such a devastatingly rapid and severe spread of disease might lie in the following. If anyone is old enough to remember actually singing this little rhyme below having no idea whatsoever what we were singing about, then you might be interested to know what it was all about.

Ring a’ ring a rosies,

A pocket full of posies,

A Tishoo,a tishoo,

We all fall down.

Bugl, ‘History of Epidemics and Plagues’ 2008, p.8.



Apparently, according to Bugl in the History of Epidemics and Plagues’, the common interpretation of the Rosies refers to rosary beads (the religious item used for prayer – presumably in the hope that this would provide protection from the plague and imminent death) and the part of the rhyme when the children hold hands forming a ring and moving in a circle indicates the ring.

Presumably, the pocket full of posies (wild flowers or I would suggest herbs for medicinal use) helped mask the odour from these plague victims. But, perhaps the most interesting part of the rhyme from the perspective of this study, is that last line (the fun part for children as they all collapse unto the ground in a giggle at the end), relates to children doing a mock sneezing “A Tishoo, atishoo,” – strongly suggests that they are referencing the pneumonic form of transmitting the plague rather than the bubonic means of transmission, as they all fall down after being sneezed on.

In this last part of the rhyme lies a very strong clue to the fact that the main form of the plague that led to its swift and deadly spread, may have started/triggered by a few smaller and isolated eruptions as the bubonic black rat transmitted version (Black Death due to the large pustules of black and purple swelling in victims), but, soon became transmitted in the pneumonic (lung infected).

As the pneumonic and bubonic plague are essentially the same disease; and simply manifested in different ways within the body, it would be interesting to see if the bubonic form could ever become a pneumonic form. And indeed, there is evidence of this very process, albeit indirect, which provides supporting evidence for this form of transmission in the article excerpt below which, although it stresses how difficult it is to spread the plague in its Bubonic form, the fact that the sneezing form (pneumonic) can originate from bubonic plague by making its way into the lungs via the bloodstream (hematogenous – meaning to spread by the blood) (see   ), gives us a very large clue to the possibility that the plague could have become much more deadly simply because it had found a much more efficient way of spreading itself directly from person-to-person that would not require exposure directly to infected rats.

hematogenous. (n.d.). The American Heritage® Science Dictionary. Retrieved May 9, 2018 from website [7]


Risk of Person-to-Person Transmission of Pneumonic Plague

Bubonic plague never spreads directly from one person to another. The bacteria may reach the lungs of people through hematogenous spread… Pneumonic plague is the only form of plague that can be transmitted from human to human. [8]

by Jacob L. Kool Robert A. Weinstein


In other words, people could have initially died of the bubonic plague (possibly from infected rats) and this is good news for us in our modern era, as thankfully most of us are no longer plagued by infested flea-ridden black rats, and besides, black rats have become fairly rare: at least in Ireland. However, this didn’t help the people back in the Middle Ages, as it seems they were probably dealing with the sneezing transmitted version, which is a whole lot more lethal – because it can be passed directly person-to-person and this is most likely the main cause of why so many all fell down once they were sneezed on. But, thankfully, this lethal contagion disappeared, at least in Ireland, as quickly as it first erupted as you will see below:


What ever happened to the Plague?


     Today we have the benefit of hindsight. We know, as fourteenth-century people suspected, that the mortality caused by the bubonic plague of the Black Death was the worst demographic disaster in the history of the world. We also know that the mortality came to an end in the first outbreak soon after 1350; contemporaries could not have known this would happen – so far as they were concerned everyone might well die…

Maria Kelly, ‘Unheard-of Mortality’…

The Black Death in Ireland, Issue 4 (Winter 2001), Medieval History (pre-1500), Volume 9 [2]

As the plague was virtually unheard of after the 1350s in Ireland and most other parts of Europe and only intermittently, with gaps of great centuries plagued the urban centres such as London, leaving most others alone as indicated in the excerpts above and below, how could it have become so rapidly less lethal in such a short space of time – particularly in a small country like Ireland? Why didn’t we all die?

BBC History

…We also know that the plague returned regularly, an increasingly urban disease, right through until the Great Plague of 1665 in London. But by around 1670 it disappeared from England for over two centuries until a number of outbreaks occurred either side of 1900.

Professor Tom James, ‘Black Death: The lasting impact’ 17th Feb, 2011. [8]


A clue lies in the return in our more modern era; some 550 years plus later. It was around1900 that it began to reemerge in Great Britain and was poised to invade Irish ports via the great traffic between here and Scotland. You can imagine what people were thinking at the time. Where they going to be struck down again. The Irish ports were now on high alert as their close connection with the Glasgow port in Scotland seen the deaths from the Plague rise to thirteen and preparations were made as outlined by Findwyer ‘1900: Ireland’s last bubonic plague scare’ 5TH Jan, 2016, Irish History Podcast [9]

1900: Ireland’s last bubonic plague scare

While bubonic plague evokes images of the Middle Ages, Ireland has had more than one brush with the dreaded disease. As recently as the year 1900, ports across Ireland prepared for an imminent outbreak of the Black Death…

…The last great plague scare in Ireland began after the illness broke out in Glasgow in August 1900. Ireland with its constant and frequent traffic with the Scottish port was immediately at risk of infection… As the death toll in Glasgow reached 13 by September 8th 1900, petty politics in Ireland hamstrung preparations to prevent an outbreak… Nevertheless in spite of such attitudes all vessels arriving in Ireland from Glasgow continued to be subjected to rigorous checks. Meanwhile the Glaswegian authorities, not only isolated those who contracted the disease but also those who lived in close proximity to them. This drastically reduced contagion and by the end of September there was a dwindling number of new cases.

Findwyer ‘1900: Ireland’s last bubonic plague scare’ 5TH Jan, 2016, Irish History Podcast [9]


Fortunately, the new cases began to quickly dwindle as pointed out by Finbarr Dwyer, but, surely, if this had been anything like the original plague no amount of containment could have halted its path of destruction. Something had changed? Was it, in fact, the actual bubonic plague form of transmission and the fact that some flea-ridden rats were taking up residence around these ports? It doesn’t sound like it was very contagious.

One could reasonably argue that this indeed answers the quandary of how the plague of the bubonic form was self-limiting and at the same time see how the rats and their plague spreading fleas could be vindicated in the cause of the much deadlier means of spreading the plague via the pneumonia-type plague. However, we don’t know if these unfortunate individuals who did succumb to the plague had the bubonic type (did they erupt in black boils?), or did they appear to have pneumonia?

Furthermore, judging by the discussion below, it looks like even the pneumonic form of the plague when it escapes unintentionally within our modern day communities – which believe it or not, it still does from time to time, it doesn’t appear to be anywhere as near deadly and virulent as it was back in middle ages and when it erupted intermittently within a metropolis such as London in the 17th Century, where the death-tolls certainly pale into insignificance judging by the minuscule outbreaks reported in Great Britain at the turn of 20th Century. The Great Plague had ceased in Ireland almost as quickly as it erupted in the 14th Century as noted above. But what if someone came up with a deadly bio-weapon using it as bio-terrorism – would we all die in our millions again?

Fortunately, the outlook is more positive than you might think as seen in the incidences and discussion about such an attack, where it seems that modern-day incidences and more recent historical experiences with outbreaks of the plague suggest:

‘… that pneumonic plague is not as contagious as it is commonly believed to be’.

Risk of Person-to-Person Transmission of Pneumonic Plague

Jacob L. Kool Robert A. Weinstein 

Clinical Infectious Diseases, Volume 40, Issue 8, 15 April 2005, Pages 1166–1172,


Plague has received much attention because it may be used as a weapon by terrorists. Intentionally released aerosols of Yersinia pestis would cause pneumonic plague. In order to prepare for such an event, it is important, particularly for medical personnel and first responders, to form a realistic idea of the risk of person-to-person spread of infection… The disease resulting from direct infection of the airways is usually called primary pneumonic plague. This form would also occur after an intentional release of aerosolized Yersinia pestis…

Since 1925, person-to-person transmission of pneumonic plague has not been documented in the United States. From 1925 to 2003, there were 447 cases of plague reported to the CDC, and 48 developed into secondary pneumonic plague. Thirteen cases of primary pneumonic plague were reported in the same period; 5 of these were caused by cats with plague pneumonia, 1 was associated with caring for a sick dog, and 3 cases were laboratory-acquired. In 4 cases, the origin of the infection remained unknown (CDC; unpublished data) [16–20]. None of the contacts of these 61 patients with pneumonic plague seem to have developed the disease.

One of these type cases is worth reviewing, just to demonstrate how tame the plague appears to have become compared to that of the middle ages. For instance, although its only victim did unfortunately die, it was only discovered that she had the Plague sometime later after having gone about her everyday business, which included her day job working with small children in the day-care centre as described in the excerpted article below:

Discover Magazine

‘Will the Black Death Return?’

On October 2, 1980, a 47-year-old woman from south lake Tahoe, California, lost her 9-month-old pet cat to an acute infection. Three days later, the woman’s own temperature shot up, but she still went to her job at a day-care center. The fever worsened; she developed chest pains and shortness of breath. Two days later she drove herself to the hospital. The diagnosis was pneumonia, and she was treated with tetracycline. Shortly afterward the woman died.

Not until four days later did anyone realize that the woman had died of plague…


….Fearing that treatment might arrive too late, doctors rushed prophylactic antibiotics to the children and staff at the day-care center.. Luckily, no one exposed to the woman fell ill.

Wendy Orent 1st Nov, 2001 [10].

All the other contacts from the cases outlined above sometimes could have been hundreds of people, who judging by middle ages account, should have in turn died and rapidly spread it to hundreds more, leading to thousands and millions. However, in more recent times, not only are the original plague victims surviving for the most part, but when they were unwittingly going about their daily lives – no one suspecting plague as it is so rare these days and certainly not showing any obvious signs such as great black boils for the most part in an obvious way that would send off alarm bells and everyone running a mile, their contacts were uninfected.

Of course, this then raises the obvious question: well, the plague must have changed somehow as we know those clever bacteria can adapt very rapidly, unlike our relatively fixed genetic code. Perhaps this wasn’t the once deadly plague? Maybe it had become tamer over the centuries? This very question has recently been answered by extracting DNA from the original once deadly Plague:

Black Death? Rats and fleas finally in the clear’ Discovery Magazine

By extracting the DNA of the disease bacterium, Yersinia pestis,.. [T]o their surprise, the 14th-century strain, the cause of the most lethal catastrophe in recorded history, was no more virulent than today’s disease. The DNA codes were an almost perfect match…

Vanessa Thorpe, 30 th March 2014, [11]


Scientific America

How Black Death Kept Its Genes but Lost Its Killing Power

The newly sequenced genome of the plague-causing bacterium Yersinia pestis suggests human adaptations are what have kept this disease in check… The global population has likely built up some immunity from centuries of exposure to the pathogen.

Katherine Harmon ‘How Black Death Kept Its Genes but Lost Its Killing Power’ [Video], 12th Oct. 2011 [12]


Just think about that for a moment. This is the same once lethal plague that killed millions some few hundred years previously and now, even if some mad terrorists release it into the public, we might not even notice. Of course, this is really good news for most of us – I am sure we wouldn’t all escape, but we simply shouldn’t worry too much about such an event in our day and age. However, it still doesn’t explain how we became so resistant to such previously deadly contagions like the plague. The answer to this quandary came from a very unlikely source: another friendlier pathogen in the form of some familiar viral characters that most of us have had some experience with.

For instance, if mice can combat the deadly form of the PLAGUE with common viruses most of us are already infected with, could we do the same – do we already do the same as suggested in the science excerpt below?

     The herpes family of viruses can have a surprising upside–it can protect against the bubonic plague and other bacterial contagions, at least in mice. …Nearly all humans become infected with multiple herpes virus family members during childhood. These germs not only include the herpes simplex viruses, which lead to cold sores and possibly genital herpes, but also the diseases responsible for chickenpox and “mono,” as well as several less well-known ailments. Herpes infections have bedeviled animals for more than 100 million years…

….The scientists discovered latent infections with these viruses could protect mice from bacterial infections, including Yersinia pestis, which causes bubonic plague… findings detailed in the May 17 issue of the journal Nature. The herpes viruses spur the immune system to boost levels of a protein hormone called interferon gamma “that in effect puts some immune system soldiers on yellow alert, causing them to patrol for invaders with their eyes wide open and defense weapons ready,” Virgin said. As a result, the bacteria grew more slowly and were less likely to kill the mice.

Charles Q. Choi ‘The Good Thing About Herpes’ Live Science , 16th May 2007 [15]


Essentially it looks like the host (that’s us) learns to defend itself making it impossible for critters to continue their destruction. Some other germs such as viruses can slow the attack (E.g. Herpes family viruses which most of us have already living inside us) and give the immune system time to respond. The more the immune system does this: the more efficient it becomes. Boosting immunity via exposure. They have to adapt or suffer the consequences of our mighty defence. They usually learn to behave themselves and become less invasive and quite tame.

It is just as well that Nature has found a way as we may have all died! Although, back in the day, protection was adopted by visiting doctors who attended the sick – the mask with the beak of a bird was filled with various herb potions and if the afflicted didn’t die from the plague, surely they would have died of fright at the sight of such a vision on one’s sick bed.


Unintended consequences of trying to eliminate our foes in the war against the plague

As Chickenpox is part of this family that seems to be implemented in the reason why we no longer are dying in our millions from the plague, it may be important to keep it around. However, more recently, we have begun trying to eradicate this natural disease via vaccination and it seems that it is probably better to let it circulate naturally for the reasons outlined above and for other reasons as discussed below.

As we never had routine vaccines here in Ireland against Chickenpox – at least to date, and as no deaths have occurred since the late 1980s, and so very few – thankfully before this date, it looks like deaths from Chickenpox has essentially always been a relatively benign childhood disease that most children get naturally without complications. It also comes with rather interesting benefits as more that only came to light when Ireland and the UK were considering bringing in routine vaccinations as part of the existing schedule.

Seemingly getting chickenpox later in life becomes riskier. So it is probably important to have the disease at the usual time during childhood. Indeed, in more recent times the UK and other regions of Europe are beginning to consider implementing the vaccine within their schedules (Ireland doesn’t currently offer this as part of the infant and childhood vaccine schedule), they are looking to the US who have had it within theirs for some time, to assess its usefulness. See article excerpt below which may make us reconsider this option, particularly in the light of knowing what this family of viruses may be doing in the background to keep itself and the old plague in check.

Chickenpox, chickenpox vaccination, and shingles


Chickenpox in the United Kingdom, where vaccination is not undertaken, has had a stable epidemiology for decades and is a routine childhood illness. Because of vaccination, chickenpox is now a rarity in the USA. In the UK vaccination is not done because introduction of a routine childhood vaccination might drive up the age at which those who are non‐immune get the illness (chickenpox tends to be more severe the older you are), and the incidence of shingles may increase. The United Kingdom is waiting to see what happens in countries where vaccination is routine.


…We know that exposure to chickenpox can significantly prevent or delay shingles (by … boosting of immunity).6 Increased annual chickenpox rates in children under 5 are associated with reduced shingles in the 15–44 age group. Having a child in the household reduced the risk of shingles for about 20 years, the more contact with children the better, and general practitioners and paediatricians have a statistically significant lowering of risk,7 possibly because of their contact with sick children (teachers did not have a significantly reduced rate).8,9


If there is less chickenpox in children then there will be no boosting of immunity by exposure to chickenpox for middle and older aged people and thus there will be more shingles, at least until all the elderly have been vaccinated as children but this assumes that immunity conferred by vaccination is lifelong… The greater the chickenpox vaccination rates the higher the initial incidence of shingles would be until everyone was vaccinated (in other words until those of us my age who harbour varicella zoster virus in our nervous ganglia die off). It may be that a less than 100% cover by vaccination might reduce the combined chickenpox and shingles morbidity by allowing the virus to circulate in the population with only minor increases in the age of chickenpox while boosting immunity to shingles…

… The extent of decline in vaccination induced immunity to chickenpox over future years is not, of course, known and neither is the proportion of those vaccinated in the USA from 1995 that will become susceptible to “geriatric chickenpox.”

P D Welsby

Postgrad Med J. 2006 May; 82(967): 351–352.


As the excerpt of the study on chickenpox strongly suggests: there may be other benefits to keeping something as relatively benign around to keep topping up our defences as we get older, allowing children to get the disease at the right age so that they do get it when older and have it much harder.

Loss of Passively Acquired Maternal Antibodies in Highly Vaccinated Populations: An Emerging Need to Define the Ontogeny of Infant Immune Responses

Hayley A. Gans Yvonne A. Maldonado

The Journal of Infectious Diseases, Volume 208, Issue 1, 1 July 2013, Pages 1–3,

Varicella is infrequently seen in neonates, and while the severity of disease is higher than in older age groups, mortality is not [22]. This latter phenomenon may change as vaccine immunity replaces naturally induced immunity for varicella in pregnant woman and will require future monitoring.

All in all, it would seem that no amount of capturing rats and cleaning up the sewage system would have helped much, as the evidence is vindicating them and their companion fleas and we never had a vaccine to try and eradicate the disease or antibiotics back then. And I don’t think the plague doctors going around with prodding sticks and bird mask with beak filled with herbs and poisons did anything other than protecting them against getting the disease itself – if it protected them at all – we don’t know. Seemingly, the plague resolved itself naturally as there are still cases in parts of the U.S. annually that typically don’t end in death and their contacts are not falling down after going: “A Tishoo…atishoo…”

It looks like Nature has tamed this once deadly beast via viral infections and it did it in a very strange way indeed by allowing members of the Herpes Family of viruses to take up residence if they behaved themselves within the host. And for the most part, they do. This seems a reasonable trade-off between pathogens, something as benign (for the most-part) as cold sores (just don’t go kissing any new-born infants), or childhood chickenpox, which as the study above proposes, seems to keep itself in check by giving it to children in a particular age group and adults exposure to it to keep them from getting chickenpox too severely when older and ending up with other non-deadly, but, otherwise painful shingles in later life and these in turn inhibit the worst effects of something historically a whole lot deadlier. So if a live plague does escape from the lab, find some children having a pox party and see if they’ll let you in.


From the Plague to Polio in Ireland and BeyondEpisode One the plague

Click on PDF Booklet above and download. Or, follow the slides below for episode one of this series

Next weekly episode: What Ever Happened Smallpox?

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