Last week’s conference on One Health for the Real World was an enriching experience. All the participants agreed that One Health means linking together our understandings of, and responses to, human, livestock and ecosystem health. See for example, this blog by Ian Scoones. There was also widespread agreement that doing so was important, although in practice achieving those linkages, and also coupling knowledge with practice, are rather difficult.

While many of my own beliefs were reinforced and supplemented with the insights of others, I have been struggling with a puzzle, which the formal presentations failed to illuminate or resolve.  The puzzle concerns how the concept of ‘One Health’ should be interpreted in practice. The puzzle emerged for me in the context of a STEPS study of the implications for veterinary and public health and policy from the intensification of pig production in South West China.

The Chinese government has adopted the goal of substantially increasing domestic pig production, and intends to achieve that objective by replacing small-scale backyard production with larger-scale intensive production units. That shift is being encouraged, for example, by preferential access to loans and insurance cover.

The project is complicated, however, because increasing intensification risks greatly increased vulnerability of the pigs to infectious diseases, especially gastro-intestinal infections that cause severe diarrhoea. Pig producers in the industrialised world have found that intensive pig production requires very high standards of hygiene and bio-security, but similar standards are not being achieved in the majority of Chinese pig units.

The Chinese farmers who we have been carrying out research with explained that they respond to outbreaks of such infections by administering antibiotics, but most frequently they are unable to identify the particular pathogen, nor do they know which types of antibiotics are most appropriate to particular disease outbreaks.

The consequent risks are aggravated by the fact that all commercial pig feeds available to the farmers contain antibiotics, but no information is available to the farmers to tell them which antibiotics are in which feeds, let alone the levels at which they are present. Antibiotics are included in the feeds, not only because they might provide some prophylactic protection against bacterial infections, but also because they are growth promoters, which enhance weight gain for a given amount of feed – at least in healthy pigs. Moreover, the farmers choose amongst competing pig feed brands for foods which provide the most rapid rate of weight gain.

When their pigs get sick, farmers give them large doses of whatever antibiotic mixtures they can buy, rather than administering carefully calibrated doses of specifically selected antibiotics. They can buy antibiotics not just from agricultural suppliers and veterinarians, but also from physicians and pharmacies. Issues about the identity and purity of commercially available products also remain problematic and unresolved.

Consequently, antibiotics are being administered to pigs in ways that almost inevitably contribute to the emergence of antibiotic resistant strains of bacteria. In February 2016 The Lancet published a paper by Liu et al, which reported the ‘Emergence of plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China’. In other words, antibiotic resistant strains of bacteria have already emerged in both pigs and people in China.

One health or two health?  

So here is my puzzle: should we interpret ‘One Health’ to mean that we should treat severe bacterial infections in both livestock and people with exactly the same portfolio of antibiotics, or should antibiotics be carefully and deliberately separated into two groups: one to be used to treat infections in people and the other for the treatment of diseases in livestock? Currently antibiotics are not generally separated into two such groups in industrialised countries, in China or in underdeveloped countries.

I discussed this puzzle with a colleague at the conference and we agreed that it makes most sense to interpret ‘One Health’ as implying the separation of antibiotics for people from those for livestock; perhaps it could be called ‘Two Health’ rather than ‘One’.

I would be very grateful for comments from members of the One Health community for any thoughts they have on how this puzzle should be resolved.

Find out more about One Health for the Real World.

Read about our research on responding to zoonotic and related diseases in intensifying livestock systems and the Myanmar Pig Partnership project.

Image credit: Woodleywonderworks. CC by 2.