A healthcare approach for emerging and resurgent infectious diseases

A recent editorial published in The Microbe Lancet stressed the “One Health” policy for the surveillance of emerging infectious diseases.

Study: Bird flu: the need to apply experience. Image Credit: AnaLysiSStudiO / Shutterstock

Background

To date, 81 cases of highly pathogenic avian influenza (HPAI) A subtype H5N6 in humans have been detected from the first human case in 2014. Most (68%) of these cases occurred in the period 2021-22, mainly in China. Conversely, millions of birds have died this year from bird flu; for example, more than 40 million birds have been killed in the United States (USA) since January 2022.

The incidence of avian flu is also increasing across Europe. The European Center for Disease Prevention and Control (ECDC) reported over 1100 HPAI H5 detections in birds from March to June 2022. This is a 38% increase over last year over the same period. The increased incidence of HPAI infections, particularly H5N6 in humans, is of concern.

The resurgence of H5N6, amid an ongoing pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is timely as political appetite and funding for disease surveillance have never been more significant . A sentinel surveillance program for influenza prevailed for decades, even before the 2019 coronavirus (COVID-19) pandemic, as demonstrated by the World Health Organization’s (WHO) Global Influenza Surveillance and Response System (GISRS).

GISRS is credited with developing a “pandemic influenza preparedness framework”, which supports the sharing of influenza data, leading to timely interventions such as rapid development or access to vaccines. Its role in publishing the SARS-CoV-2 sequence data was critical, contributing to the rapid and impressive launch of COVID-19 vaccines. Although HPAI viruses can be a significant threat to public health, it is a known threat and therefore could be monitored.

Role of genomic surveillance

As of October 2021, all HPAI H5 viruses detected in Europe belonged to the 2.3.4.4b clade associated with outbreaks in Asia in recent 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 new strains. Antigenic, these strains were distinct from the vaccine used in the poultry industry.

Genomic surveillance programs are essential to reduce restocking, inform vaccination policies and prevent spillover to humans. Additionally, sequencing also revealed the importation of a new reassortment of H5 genotypes to the United States and Europe, possibly due to bird migration. Therefore, metagenomic sequencing of HPAI infections in humans may not be sufficient to curb avian flu in humans.

An approach to health

The need for a ‘One Health’ approach to emerging infectious disease surveillance has been well established. The Wildlife Conservation Society published the Manhattan Principles in 2004, urging world leaders to recognize the link between public and environmental health. The SARS-CoV-2 spillover has rekindled interest in One Health, but integrating multiple disciplines into surveillance is complex.

For example, in medicine, clinical diagnostics attract public and private funding, but the same is not true for animal diagnostics. Therefore, cost-effective innovation is needed to address 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 could be applicable for monitoring other zoonotic viruses.

Surveillance and preparation

The emergence of a new flu strain has been a pandemic-wide threat. However, surveillance and preparations could be made by learning from past epidemics and with a multidisciplinary approach and innovation. All recent cases of H5 infections have occurred in individuals in direct contact with birds; Importantly, transmission between humans was not detected. This threat can be seen coming and the “One Health” concept is essential to avoiding a flu pandemic.

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