In the early twentieth century, urban centres in Britain and Ireland experienced increased incidence of diphtheria. Dublin failed to evade this ominous trend. In 1911, Dublin's long-standing Chief Medical Officer, Sir Charles Cameron, conceded that ‘diphtheria had been more than usually prevalent in the city’. Cameron issued ‘a serious warning’ about the dangers of the disease through local newspapers, and appealed to the education commissioners for a temporary closure of primary schools in the city. The editor of the Irish Times commented: ‘The terms of Sir Charles Cameron's letter are carefully framed in order to obviate any kind of panic, but it is clear that the authorities regard this matter with some concern’. In early February, the Dublin public health committee reported an average increase of six new diphtheria cases per day, and by mid-February, Cameron conceded that the disease had become ‘epidemic in the city’.

Prior to the introduction of the Infectious Disease (Ireland) Act, 1906, Dublin's public health officials insisted that diphtheria had been ‘a rare disease’ in the city, and diphtheria is largely absent from the statistical record relating to this period. After 1906, diphtheria gained prominence in Dublin. It regularly appeared in epidemic form and became endemic throughout the city in a relatively short period. It appears that Dublin public health authorities, under Cameron, wilfully neglected to report outbreaks of diphtheria or to implement any intervention to combat the disease. This grave disease, ‘childhood's deadliest scourge’ according to some, levied a heavy toll on infant and child life during the nineteenth century. While it is highly unlikely that Dublin children were exempt from the ravages of diphtheria, it is equally likely that their plight went unacknowledged by the city's public health authorities.

Lydia Carroll maintained that Cameron worked tirelessly to confront the commercial interests of Dublin property owners in a bid to protect the welfare of the powerless working poor. However, when it came to outbreaks of infectious disease, Cameron regularly blamed the poor themselves for their ills. Positioning less well-off citizens as vectors, rather than victims of disease, Cameron regularly diverted blame for endemic diphtheria in the city from the sanitary authorities under his control, to the ‘poorer classes’ and the ‘the filthy condition of the tenement houses which they occupied’.