In November 1928, a scheme for ‘the eradication of diphtheria’ launched in the Urban District of Dundalk and the adjacent rural area of County Louth under the supervision of newly appointed county medical officer, Dr John Musgrave. Musgrave estimated that 3,500 children aged six months to six years would require immunization treatment to guarantee a successful scheme. Although Musgrave, alluded to ‘loose talk calculated to undermine public confidence in the effectiveness of the work’, by the end of 1928, 1,500 children received the full course of treatment with no ill effects. Louth traditionally supplied the second largest contingent of urban diphtheria cases after Cork city; by 1929 Musgrave's intervention radically altered Dundalk's unenviable position on that league table. During 1928, Louth's urban centres, Drogheda and Dundalk, registered five, and 43 diphtheria cases respectively. During 1929, Drogheda recorded an increase of over 800 per cent with 41 notified cases, while Dundalk recorded a decrease of over 50 per cent with just 20 notifications.

Satisfied with the results of Musgrave's work, in April 1929, the DLG&PH introduced the Public Health (Infectious Diseases) Regulations. This legislation empowered sanitary authorities and county medical officers to ‘organise arrangements for testing susceptibility to diphtheria infection and for the administration of protective agents’. During 1929, immunization schemes sprang into operation in selected areas where diphtheria was prevalent, and in health districts under the supervision of a full-time medical officer. Diphtheria scourged Kildare, Wexford, and Tipperary that year, yet health boards in these counties remained embroiled in protracted disputes with central health over the cost of employing full-time medical officers. As a result, children residing there continued to suffer the ill effects, and often-fatal consequences associated with diphtheria.

Reporting on the prevalence of diphtheria in his district, departmental health inspector, Robert McDonnell, observed ‘a very marked increase on former years’. During 1929, 322 cases occurred, a 360 per cent increase on the 70 cases recorded the previous year. McDonnell opined that the substantial increase in diphtheria notifications was more apparent than real and blamed the improved system of notification, which ‘the advent of the Medical Officers of Health have brought about’. He acknowledged that diphtheria had been endemic in the Dundalk district for some years, and that Musgrave's intervention influenced a marked decrease in incidence there.