By Ida Milne
Sometimes, in the tedium of trawling through dry-as-dust official reports, we historians have a discovery that initially seems little more than an amusing distraction, but later casts a bright light on our topic. In 2016, while reading the 1911 annual reports of Dublin’s long-serving Medical Officer of Health Sir Charles Cameron in the National Library, I had such a find.
Cameron reported that in the heatwave in the late summer of 1911, infant mortality from diarrhoea rose, as it usually did in heatwaves in this re-pasteurisation and pre-refridgeration era. Infant mortality rates increased significantly in Dublin, but also, as newspapers reported, in a swathe following the heatwave across Britain, Europe and north America.
The numbers dying in Dublin were exacerbated by the appalling condition of the tenements; some 23,000 families lived in one room with no running water, cooking on an open fire, usually one bed shared with all the family, and sharing an outside privy with the other families living in the house. As a 21st century middle class mother, I look with horror at the challenge of nursing a sick child using cloth nappies, without a washing machine, or even running water.
Some 2166 infants under two years of age died from the disease in 1911 in Ireland, an increase 927 on the colder summer of 1910. Urban livers were worst hit. More than half of the deaths took place in Dublin and Belfast; 111 were registered in the Cork Union, 37 in Limerick Union, 46 in Derry and 60 in Waterford.
What caught my eye was that Cameron revealed that he had offered a bounty for collecting paper bags of flies. Cameron, a frequent and empathic visitor to the homes of Dublin’s poor as he worked diligently to find ways to ameliorate their conditions, had noticed that in ‘those most badly affected by the epidemic, flies abounded’, and came to the conclusion that removing the flies might lower the incidence of infant diarrhoea.
He persuaded the Public Health Committee to issue 100 brown paper bags and offer 3d for returning them to the disinfecting depot he had installed at Marrowbone Lane, in the hope that ‘boys who were not at work’ might be encouraged to trap the flies and therefore remove a source of contagion from their home. Twenty one bags were returned with about 6,000 flies in each, or 126,000 in all. Cameron, clearly taking his task very seriously, found that the average weight of each fly was 0.7 grams.
Later, he considered that he had made two mistakes: not starting the scheme earlier in the year, and making the bags too large, as killing 6,000 flies was an onerous task. He had found several partly filled bags lying around the tenements, and so advised reducing the size in 1912 to something that would hold 3,000 flies, also for 3d. However, 1912 proved to be a cooler summer with fewer flies – and a much diminished incidence of infant mortality from diarrhoeal diseases – and no bags were turned.
This amusing little story – trade unionist James Larkin slagged him off in the Irish Worker by suggesting he pin the bags to clotheslines and train the flies to jump in – got me exploring contemporary thinking about the impact of the fly on health, not all of which I will inflict on you here! In the 1911 report, Cameron said that it was firmly established that insects played an essential factor in humans acquiring infective disease, as they introduced the microganisms that caused the disease into the human system.
He wrote: ‘The house fly is a frequent visitor to manure heaps and filthy places generally, where it gets infected. Finding its way subsequently into houses it infects food. The dirtier the dwellings are, and especially those with remnants of repasts scattered around the floor, the more likely are they to swarm with flies. There are few to be found in churches.’ In 1911, many homes were not tied into piped sewage systems, meaning human excrement and urine was collected in chamber pots and buckets and dumped in an outside privet or on local manure heaps or cesspits.
I started following a line of inquiry on contemporary thinking on flies and contagion; it was like a little lightbulb moment. Cameron’s novel idea clearly emerged from new scientific understanding of how such diseases came to be. Ideas about the connection between filth and disease were coming from the emerging science of bacteriology, which had progressed rapidly in the late nineteenth century with the research of Koch, Pasteur and others. I found that sanitarian interest in preventing the accumulation of flies in homes was a surprisingly new phenomenon, and one that had come increasingly associated with the ‘summer disease’ or infant diarrhoea in hotter weather. In medical textbooks, it seems to be mentioned as a factor from about 1909.
Ann Hardy points out that anxieties about contaminated flies transmitting disease arose once germ theory of disease causation had gained acceptance. Flies began to be associated with the transmission of typhoid and infant diarrhoea around 1900, at a time when the environmental conditions which generated the fly problem fell within the remit of local authority public health departments.
Sanitarians in Britain in this period explored the links between flies, food, diarrhoeal patients and cesspits used to dispose of human waste.  Similar work was going on across Europe and north America, as the medical professions began to recognize that infant summer diarrhoea was a problem that was not insurmountable, that it COULD be tackled, through scientific research and through educating mothers about better hygiene and feeding practices. Such education schemes for mothers were taking place in Ireland, but it’s the association of flies with infant diarrhoea as part of new scientific knowledge that interests me here.
How does such public health knowledge transfer? Cameron’s diaries show that he kept in close contact with fellow scientists and sanitarians across Britain and in continental Europe, and this contact had probably informed his opinion.But how was his move regarded by those in the tenements? Again, my 21st century mother perspective kicks in: can you imagine coping with Junior leaping about to swat flies in a crowded tenement, as you struggle to nurse your diarrhoea-stricken infant? As a tenement mother, I would probably have been rather annoyed with Cameron.
 Anne Hardy, Salmonella Infections, Networks of Knowledge and Public Health in Britain 1880-p 1975 Oxford: Oxford University Press, 2015, p 64.
 Weirich A, Hoffmann GF ‘Ernst Moro (1874-1951)–a great pediatric career started at the rise of university-based pediatric research but was curtailed in the shadows of Nazi laws.’ Eur J Pediatr. 2005 Oct;164(10):599-606. Epub 2005 Jun 2.
 Lydia Carroll, In the fever King’s Preserves: Sir Charles Cameron and the Dublin Slums, Dublin, Four Courts Press, 2012.