Belief, or perhaps suspicion, of a link between animal and human disease is nothing new. During the fourteenth century Black Death epidemic doctors would don a bird-like mask in the hope it would protect them from the bubonic plague that was spread to humans (we now know) by fleas on rats. It was seven hundred years before genome sequencing characterised the bacteria underlying the plague, and confirmed that strains very similar to the ancient parasite still exist today.
As with so much in the genomic arena, momentum is gathering, and understanding of the links between animal and human disease is rapidly advancing. Today, instances of cross-species (i.e. animal to human) infection are common, including in some of the most virulent and deadly diseases. Examples where genomics has suggested an animal origin of a human disease outbreak include:
- Pigs - Influenza virus (swine flu)
- Fruit bats - Ebola coronavirus
- Camels - MERS coronavirus
- Armadillos – Leprosy mycobacterium
- Livestock - MRSA bacterium
One health and antibiotic resistance
The number of bugs developing resistance to antibiotics is of increasing concern in the UK and globally. In July 2015, the government published its UK One Health Report, which details the importance of considering animal and human health concordantly, specifically to combat antibiotic resistance. The report provides important recommendations for public health organisations.
Four reasons for a one health approach
There are at least four reasons why a one health (cross-species) approach to disease surveillance is important:
1) As highlighted above, many globally important infectious diseases have been passed from animals to humans
2) Complete eradication of a human infectious disease is likely impossible if the causative pathogen still resides in animal populations
3) Millions of kilograms of antibiotics are given to livestock every year and this can facilitate the development of antibiotic resistance
4) Pathogens are pervasive within the food industry
For example, one study found that 70% of chickens tested from large super market chains contained the Campylobacter pathogen, a common cause of food poisoning diarrhoea from undercooked meat, and which is estimated to cause more than one hundred deaths per year in the UK and cost the economy around £900 million.
Using pathogen genomics for animal and human surveillance
Pathogen genomics can offer an appropriate methodology for conducting surveillance of animal and human infections for:
• Accurate and rapid diagnosis of infections
• Tracing disease outbreaks at high resolution
• Testing for antimicrobial resistance
However, there are at least two important challenges for the widespread implementation of one health genomics. The first is a reluctance to invest in initial overheads to set up integrated one health pathogen genomic services, which requires bioinformatics expertise, new infrastructure and specific standards, particularly for non-human surveillance. Some of these costs may be mitigated through increased collaboration.
The second challenge is in driving the development of fully integrated, cost-effective and accredited genomic methods. Researchers, who are generally the experts in cutting-edge applications of genomic technologies, often lack the incentives and resources to develop their methods from research tools into optimised health service tools. The emphasis for a researcher is often on rapid novel software development software, while the priorities in a health service setting can be quite different, for instance being more focussed on cost, reproducibility, and ease of use.
A single scenario
The result is a classic ‘chicken and egg’ scenario - there is a reluctance to invest heavily in one health genomics until the approach is ‘proven’ to be highly effective and efficient, but such evidence is unlikely to be gathered without considerable up-front investment.
In our new briefing note One health genomics: why animal diseases matter for human health we argue for the considered implementation of one health genomics services, and set out some important aspects to be addressed in order to achieve this goal. These include appropriate investment in pathogen genomics, evaluation and accreditation of methods, and further coordination between human and animal health agencies.
A more in-depth review of the field of pathogen genomics, including current and potential future applications, can be found in our 2015 report Pathogen Genomics Into Practice .