Home » Health » Worst bird flu outbreak in history shows no signs of abating

Worst bird flu outbreak in history shows no signs of abating

A particularly deadly and contagious strain of bird flu killed millions of farmed poultry and wild birds in 2022. This new epidemic of H5N1, the worst recorded since the appearance of the disease, does not seem to want to slow down. Scientists, lawmakers and animal advocates are worried and looking for solutions to try to contain the bleeding.

After a dark year, the avian flu epidemic continues to wreak havoc across the planet. A viral disease that rages among birds, avian flu is exceptionally contagious and deadly this season. In question, a highly pathogenic strain of H5N1 which causes a real slaughter in the breeding of chickens, turkeys, geese or even ducks, where the detection of a single case on a farm causes the slaughter of all the animals.

All over the planet, health authorities are recording record numbers of infected animals. Japan, which had to euthanize a record 10 million poultry during the winter season, recorded a peak in contamination last week leading to hundreds of thousands of new slaughters in half of the country’s prefectures. In the United States, 58 million poultry have been affected by the disease. For its part, Europe is experiencing the most devastating epidemic ever observed with 2,500 outbreaks of infection detected across 37 countries between October 2021 and September 2022 and around 50 million animals euthanized during this period.

Since the return of the virus at the end of 2021, the rate of new infections has remained at a very high level and shows no signs of slowing down. On the contrary, it seems to be accelerating. The epidemic was more virulent in the fall than last year at the same time, with a 35% higher number of infected farms, according to European health authorities.

“If you take into account the number of birds, farms and countries affected as well as the duration of the epidemic and the number of poultry culled, the current outbreak of avian flu is the largest we have ever seen.” , notes professor of virology Ian Brown, expert in avian flu with the World Health Organization (WHO). In 2022, “the virus has managed to persist throughout the summer, particularly in northern European countries. This is the first time that this has happened. Avian flu has become a disease present throughout of the year”, adds the scientist.

“Dead Birds Everywhere”

First detected in a domestic goose in southern China in 1996, the H5N1 virus appeared periodically before dying out naturally or being contained by preventive culling campaigns. Traditionally, it spreads during the winter migration phases of wild birds carrying the disease. The reproduction rate is particularly high: a single individual being likely to contaminate up to 100 by saliva or other bodily fluids.

But this season is distinguished by the strong spread of the disease during the summer, a period which normally is the least at risk. Example in Scotland, whose coast offers an ideal refuge for migratory birds and a large number of endangered species. The great skua or great skua, a gull-like seabird, has a population of 16,000 individuals, more than half of which is concentrated in the northwest of the country. When Great Skua’s colonies in Scotland began to be decimated this summer, authorities first thought it was an anomaly.

Then, in the fall, barnacle geese in the Norwegian archipelago of Svalbard in the Arctic Ocean began to die. “First by tens, then by hundreds and finally we counted 16,000 deaths”, explains Claire Smith of the Royal Society for the Protection of Birds (RSPB). In the spring of 2021, the organization estimates that a third of the barnacle geese had been decimated. Losses continued throughout the summer among great skuas, gannets, seagulls, geese and even eagles with an impact on migratory bird populations and sedentary species.

In July, the Scottish government decided to close access to certain islands used as habitats for seabirds. “There were dead birds everywhere,” says Claire Smith. And the mortality rate observed this winter does not invite optimism for the year 2023. On the island of Islay, the head of the RSPB assures that “the number of dead birds is already higher than the last year, when we are not even at the end of winter yet”.

Although not all birds are susceptible to the virus, many species have been hard hit around the world, such as penguin populations in South Africa, Dalmatian pelicans in the Balkans and cranes in Israel. As environmental threats grow ever more pressing, some may never recover. “It’s no exaggeration to say that endangered species of birds could go extinct,” says Ian Brown.

“Viruses can mutate over time”

Dramatic for wildlife, the current epidemic is a nightmare for the poultry industry. With more than 140 million poultry slaughtered, bird flu represents a loss of income for breeders and bad news for the consumer, who sees the prices of poultry and eggs, two sources of cheap protein, skyrocket.

Some farms are looking to put in place biosecurity measures and reinforce farm hygiene to prevent the outbreak of the virus. “But even with good hygiene, the virus can get in,” notes Ian Brown. “As wild birds carry H5N1, a single individual can easily fly from farm to farm and spread the virus.”

In the United Kingdom, cases of species, which, a priori are not susceptible to avian flu, have been identified as the barn owl and the kestrel. “Large poultry farms harbor rodents and they are thought to carry the virus on their fur and pass it on to owls and kestrels when they hunt these rodents,” says Ian Brown.

Another particularity this season: the cases of mammalian infections have been more numerous even if no contamination between mammals has ever been listed. In humans, cases remain rare and are most often mild. “At the moment, the virus does not have a great capacity to spread in humans, but viruses can mutate over time”, nuance Ian Brown.

What solutions to control the epidemic?

In the coming weeks, the epidemic should not weaken, while the winter period, a favorable season for the spread of the virus, is far from over. For the first time, bird flu has been detected in South America with outbreaks recorded in Colombia, Peru, Venezuela, Chile and Ecuador. A real challenge for the poultry industry and a threat to fragile species like those that have taken up residence on the Galapagos island.

To prevent the spread of the virus among wildlife, the solutions seem far from obvious. Killing these wild animals would be totally unethical but preventative measures like isolating infected birds can be put in place without disturbing wildlife.

In the UK, the RSPB is also calling for restrictions on hunting and the release of farmed game birds to reduce the risk of contamination.

Among wild birds, experts wonder about the development of resistance to the virus. “There are barnacle geese that have returned to Scotland this year and have not been infected, raising questions about antibody production,” says Claire Smith. “Many species of birds seem immune”, like crows even if they ingest the flesh of infected birds.

For farmed poultry, vaccination appears to be the best solution to reduce the risk of contamination and the need for slaughter. However, it is unlikely that all farms will be able to vaccinate their animals and a vaccine will not be available until the summer of 2023. “There is intense work to carry out clinical trials and the European Commission is developing a framework to distribute vaccines next summer”, explains Ian Brown. According to the WHO expert, vaccination of poultry will be inevitable. As humanity has entered the “age of pandemics” with Covid-19, the same observation can be made for birds. “We need to understand how to intervene and control the disease to fix the problem. In this context, vaccination will clearly have a key role to play.”

Article adapted from English by Grégoire Sauvage. The original can be found here.

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