Chinese infectologists say another pandemic could be coming

Two Chinese scientists, George Fu Gao and Weifeng Shi, underlined in these hours of the journal Science that after the COVID another pandemic can happen. And investigators point to a suspect: the H5N8 avian influenza virus.

The pathogen is an old acquaintance. It has been circulating in Europe since 2014, causing outbreaks that have affected millions of wild birds and poultry, according to the European agency dedicated to the control of infectious diseases, ECDC. February 20, 2021, Russia warned virus jumped to humans for the first time. Seven workers were infected in a gigantic farm of 900,000 laying hens in the Astrakhan region, in the south of the country. None of the seven had symptoms.

“The global spread of H5N8 avian influenza viruses is a public health problem”Chinese researchers warn in the journal Science. George Fu Gao is the Director General of the China Center for Disease Control and Prevention and Weifeng Shi is the Director of the Reference Laboratory for Emerging Infectious Diseases at Shandong Universities. Both participated in the identification of the new coronavirus in December 2019. Avian influenza viruses can cause “disastrous pandemics” in humans, he said.

At least 46 countries in Europe, Asia and Africa have reported fatal outbreaks of H5N8 in birds. Chinese researchers point out that the Russian Seven Workers’ virus belonged to subgroup 2.3.4.4b, with “disturbing” mutations that appear to increase its affinity for human cells. This same variant of the virus has caused the slaughter of more than 20 million poultry in South Korea and Japan, warn Fu Gao and Shi. “It is imperative that the global spread and potential risk of H5N8 avian influenza viruses not be ignored. for poultry, wild birds and for global public health, ”they warn according to the newspaper El País.

The two Chinese experts believe that replacing small family farms with large industrial ones, theoretically with strict biosecurity measures, will help reduce the risk of the virus spreading from birds to humans.

Viruses and animals

In March, the WHO had already judged as “probable” that an animal served as an intermediary in the transmission of SARS-CoV-2, which confirms the role of the latter as reservoirs of viruses capable of infecting the man. Which species transmit viruses? Where could the next pandemics come from?

According to the World Organization for Animal Health (OIE), 60% of human infectious diseases are zoonotic, that is, they are found first in another animal.

This percentage even rises to 75% for new infectious diseases, according to a British study published in 2001, considered as a benchmark in the field. Among the pathogens responsible for these diseases, one in six is ​​a virus, a third a bacterium and another third a parasite. 10% are microscopic fungi, this study indicates.

Bats act as a reservoir for a large number of viruses that affect humans. They accommodate them without falling ill themselves.

Some have been known for a long time, such as the rabies virus, but many have appeared in recent years, such as Ebola, the SARS coronavirus, SARS-CoV-2 and the Nipah virus, which appeared in Asia in 1998.

Bats “have always been good reservoirs for many viruses, but before we had very little contact” with these species, Eric Fèvre, professor of veterinary infectious diseases at the University of Liverpool, told AFP ( United Kingdom) and International Livestock Research. Kenya).

The reduction in tropical forests due to the advancement of cities and cultivated areas, combined with the effects of climate change, are bringing these animals closer to inhabited areas and causing them to “interact more and more with human populations,” he says.

The study published in March by experts from the WHO and China also did not clarify a point. “Among the viruses which come from these two mammals (bat and pangolin, editor’s note) identified to date, none resembles SARS-CoV-2 sufficiently to be considered as its direct ancestor”, according to the experts.

“Ecological hypotheses are also necessary, which explain to us how a pangolin could have come into contact with a bat: it was certainly not on a market”, he specifies.

The measles virus, now fully human, was born from the adaptation of a virus in the Middle Ages that affected cattle.

The Spanish flu of 1918-1919, the “Asian” flu in 1957, the “Hong Kong” flu eleven years later, the H1N1 flu in 2009: all the viruses responsible for the major flu pandemics were directly or indirectly of origin. avian.

Two other strains of avian influenza, H5N1 between 2003 and 2011, then H7N9 from 2013, have led to direct infections in Asia from infected birds, or in very rare cases of human-to-human transmission.

Then, the mutations can promote their passage to humans, as in the case of the H5N8 virus, present in many European farms for a few months, and which was detected in Russia in seven workers of a poultry processing plant.

But above all because the expansion of human activities and increasing interactions with wildlife increase the risk that viruses capable of infecting humans find a host.

AFP and El País newspaper