A unified health approach for emerging and re-emerging infectious diseases

A recent editorial published in The lanceolate microbe highlighted the One Health policy for surveillance of emerging infectious diseases.

Study: Avian influenza: the need to apply experience. Image credit: AnaLysiSStudio/Shutterstock


Eighty-one human cases of highly pathogenic avian influenza (HPAI) subtype H5N6 have been detected since the first human case in 2014. Most (68%) of these cases occurred in 2021-22, mainly in China. In contrast, millions of birds died this year due to bird flu; for example, more than 40 million birds have been killed in the United States (US) since January 2022.

Incidence of bird flu is also increasing across Europe. The European Center for Disease Prevention and Control (ECDC) reported over 1,100 detections of HPAI H5 in birds from March to June 2022. This is an increase of 38% compared to last year during the same period. The increased incidence of HPAI infections, especially H5N6 in humans, is worrisome.

The resurgence of H5N6 amid an ongoing pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is fitting because the political appetite and funding for disease surveillance has never been greater. The influenza sentinel surveillance program has been prevalent for decades, even before the coronavirus disease 2019 (COVID-19) pandemic, as shown by the Global Influenza Surveillance and Response System (GISRS) of the World Health Organization (WHO).

The development of the Pandemic Influenza Preparedness Framework is credited to GISRS, advocating for the sharing of influenza data leading to timely interventions such as rapid development or access to vaccines. His role in the publication of SARS-CoV-2 sequence data was pivotal, contributing to the rapid and impressive spread of vaccines against COVID-19. Although HPAI viruses can be a significant threat to public health, it is a known threat and therefore can be monitored.

Role of genomic surveillance

As of October 2021, all HPAI H5 viruses detected in Europe were of the class associated with outbreaks in Asia in the past few years. This clade is widespread and appears to be evolving; a recent study from China revealed a new reassortment of H5N6 viruses with other H5 viruses, resulting in newer strains. Antigenically, these strains differ from the vaccine used in poultry.

Genomic surveillance programs are essential to reduce reassortment, inform vaccination policies, and prevent spread to humans. Additionally, sequencing also revealed the importation of a new rearrangement of H5 genotypes into the US and Europe, possibly due to bird migration. Therefore, metagenomic sequencing of HPAI infections in humans may not be sufficient to contain avian influenza in humans.

One approach to health

The need for a One Health approach to surveillance of emerging infectious diseases is well established. The Wildlife Conservation Society published the Manhattan Principles in 2004, calling on world leaders to recognize the link between public health and environmental health. The spread of SARS-CoV-2 has renewed interest in One Health, but integrating different disciplines into surveillance is complex.

For example, in medicine, clinical diagnostics attract public and private funding, but this is not the case for animal diagnostics. Cost-effective innovations are therefore needed to bridge this disparity between animal and human health. In the context of innovation, a recent modeling study identified 47 new bat reservoirs for beta-coronaviruses using machine learning, with the prospect that it may be applicable to the surveillance of other zoonotic viruses.

Monitoring and preparedness

The emergence of a new strain of influenza is a pandemic-level threat. Nevertheless, surveillance and preparedness can be done by learning from past epidemics and with a multidisciplinary approach and innovation. All recent cases of H5 infections have been in individuals in direct contact with birds; the important thing is that no human transmission has been detected. This threat can be seen coming and the One Health concept is essential to prevent a flu pandemic.

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