In this paper I will analyse the relation between animals and ‘the influenza-question’ in the Netherlands, from the ‘Spanish’ influenza pandemic (1918-1919) until the ‘Asiatic’ influenza pandemic (1957). Like anywhere in the aftermath of the virulent pandemic of 1918, Dutch medical researchers asked questions on the cause of influenza, on the differences in virulence between seasonal epidemics and occasional virulent pandemics, and on the control of the disease. In this research, animal models were of large importance. Animals also suffered ‘spontaneously’ from influenza, and were observed to do so. My questions concern this zoonotic character of influenza in a sociocultural context: how was it addressed in the framing of influenza? How did different parties encountering people and animals suffering from influenza react to the disease and deal with it? How did these parties relate to one another? I will discuss the conceptual shift in medicine from animal influenza as a curious side-effect of human influenza epidemics in the 1920s, towards the view that animals (especially pigs and horses) were the ‘primary influenza virus reservoirs’ in the 1950s. During the same period, farmers were struggling with an unknown, often deadly infectious respiratory disease among their piglets, which they called ‘piglet disease’, ‘sniff disease’ or ‘pig flu’. Vets were reluctant to call this disease swine influenza, like for instance the American animal pathologists R.E. Shope did – Shope was a central figure in international research on the influenza virus. Rather, Dutch vets framed respiratory diseases of piglets as a problem of changing practices in agricultural pig production, which had negative effects on the pigs’ resistance against a variety of usually harmless germs. As a consequence, the influenza-question received little attention in veterinary circles, despite calls to the contrary.

This paper is part of a broader PhD project on the history of dealings with zoonoses in the Netherlands during the twentieth century. This project aims to put present concerns on zoonoses in a historical context. The questions I ask are partly based on current scientific knowledge on the zoonotic character of influenza and other zoonoses. Therefore, I will devote some time to the methodological problem of using current scientific knowledge to investigate the past. I will argue that such knowledge on the influenza virus provides a useful source on the past, when carefully used.