Challenges for One Health surveillance¶
Foodborne diseases (FBDs) represent an epidemiological scenario in which pathogens and humans contact through contaminated food or water. FBDs affect 600 million people every year, representing an important burden for human health (WHO). Proper management of FBDs requires a good understanding of the disease, a fast detection and a proper response (WHO 2018). Therefore, good surveillance systems able to track the circulation of pathogens and monitor their medically relevant features, such as the resistome or the virulome, are essential for disease control. Such systems could, for example, allow the early detection of multidrug-resistant pathogenic populations and lead to the implementation of specific control strategies reducing future human or even animal illness. Moreover, information regarding virulence potential or drug resistance may be crucial for public health decision-making on the allocation of resources during outbreaks.
WGS and One Health surveillance¶
As described in this handbook, WGS technologies represent the most discriminatory pathogen typing method (thus far), thus providing the highest surveillance resolution. For example, the application of WGS for listeriosis surveillance has increased the number of detected outbreaks, but decreased the number of cases per outbreak, thus contributing to a reduction of human illness (PulseNet). A major factor leading to these results is WGS highest ability to identify the sources of infection. For this reason, an integrated system where the clinical and the food and water sectors not only surveil for the presence of pathogens and their characteristics, but also interchange their data is a key to the proper FBDs management. In this regard, WGS represents an important advance as WGS data can be easily shared and compared between laboratories at national and international levels. Nevertheless, WGS implementation is challenging and many things need to be taken into consideration. In this section we do a brief overview of the challenges associated to WGS implementation in the surveillance of foodborne diseases which were raised by the WHO in 2018.
Organizational perspective¶
The existence of an integrated system for FBDs surveillance requires the implementation of different strategies which may be hampered at different stages. For instance, as reported by WHO (2018), from an organizational perspective, public authorities need to work on the implementation of adequate legislation and regulation that encourages the clinical and the food and water sectors to perform continuous FBDs surveillance and to report their results. However, to demand such a protocol, investment in proper surveilling infrastructures needs to be made. For example, the implementation of WGS-based surveillance requires a technological transition which is not affordable in many countries. Also, resources and funding opportunities are unequal between different sectors (Human health, Animal Health, Environmental Health and Food Safety).
Scientific and technical perspective¶
From a scientific perspective, WGS-based surveillance systems require multi-tasked teams with different scientific backgrounds for proper data analysis, including specialized microbiologists and bioinformaticians (WHO 2018). Hence, investment (not only financial but also of time) in training highly skilled technicians to integrate the different teams is crucial for proper data analysis and interpretation of the results. Furthermore, there is a need to guarantee inter-laboratory data integration and comparability of results. For example, efforts should be made in the harmonization of genetic nomenclatures, because, as mentioned before in this handbook, different platforms use different allele nomenclatures hampering the comparison of their data. Such efforts in training human resources, standardizing protocols and in the harmonization of the results would definitely contribute to ease the comparison between different labs, sectors and even countries. In this regard, some technical aspects may also influence the implementation of such systems, such as the need for high computing power to handle the data, or servers where data can be stored and shared between partners. Good political strategies for investment have the power to overcome these issues. Noteworthy, data protection should always be guaranteed, and robust anonymization strategies implemented.
Cultural barriers¶
Ultimately, even if all the above-mentioned barriers for the implementation of a proper WGS-based surveillance system are overcome, cultural barriers may also be an issue (WHO 2018). Besides the language barrier in international cooperation, and the usual resistance to change, cross-sectoral collaboration may be difficult to implement. As stressed by several international entities during the last years, actions promoting the concept of One Health, and showing the relevance of this integrated perspective where human, animal and environmental health are connected, may contribute to raise the awareness of politicians, scientists, health practitioners, and ultimately all the citizens and surpass some of the above-mentioned obstacles (ECDC 2017).
Future perspectives¶
WGS is gradually being integrated in the surveillance system of developed countries. The possibility of connecting WGS data with data obtained from previous technologies allows a gradual transition, where data from the past is not lost because data from different technologies are still comparable with WGS. An agreement has been made that Listeria would be the first bacterial pathogen where such a system would be implemented, and this has been progressing fast. Meanwhile, WGS is gradually expanding to other FBDs causative agents, such as Salmonella, Escherichia or Campylobacter, but there is still a long way to go. This gradual technological transition is important for a proper allocation of resources and management of the different obstacles. In the end, it is expected that in a few years WGS-based surveillance systems are fully operational for several FBDs monitorization from a One Health perspective.