Photography: Ken Jack/Getty Images
Lockdowns are a horrible experience, but thankfully that’s over now. Unless you are a domestic bird in Britain. Since November 7, a British directive has ordered all farmers to keep their birds indoors as part of a strict measure aimed at stopping the spread of the bird flu, or H5N1 virus. This measure aims to prevent the infection of domestic birds by wild birds and will lead to the introduction of tens of millions of chickens, ducks, geese and turkeys in the foreseeable future. We also saw island birds affected, resulting in the shutdown of human visitors to the Isle of May in Scotland for five weeks, among other measures.
Avian flu is known as one of the most infectious diseases: the R number, which has often been mentioned for the spread of Covid-19, can reach 100 for avian flu, which means that a bird can infect it up to 100 others. And the past few months have seen an exponential spread of the virus, with Britain and Europe particularly hard hit. A Surrey lab testing samples says it has seen a 600 per cent rise in cases over the past three months.
Why does this epidemic not only worry scientists, but also poultry farmers and government officials? Currently, outbreaks of bird flu have been limited in humans because the virus does not spread easily between us. But it’s a ticking time bomb. A mutation allowing this virus to circulate more easily between humans is possible. This would be a game changer and greatly increase the risk to humans. And the more likely the virus is to jump into a human and mutate, the more likely a dangerous strain will emerge that could trigger the next pandemic.
Although humans have been infected by birds, they are usually workers on poultry farms and people in close contact with infected birds, and even these cases have been rare. For example, on November 3, two farm workers in Spain tested positive; this was the second known human infection in Europe since 2003. Infection usually occurs through handling sick or dead birds.
Infected birds have the flu virus in their saliva, blood, mucus and feces, and humans can become infected if they catch this virus in their eyes, nose or mouth, or inhale nearby droplets (you cannot get bird flu from eating fully cooked poultry or eggs). And this virus is not benign. The mortality rate is thought to be high in humans: the World Health Organization estimate is around 60% for H5N1. We currently have no vaccine for use in humans; the seasonal flu vaccine also does not work against bird flu.
But while the risk of human transmission is a future concern, right now the virus is affecting people’s livelihoods and farms, and putting hundreds of millions of domestic and wild birds at risk. Disease outbreaks in chickens can kill the entire local population; in other birds, such as ducks and geese, the disease is often mild or even asymptomatic. Ducks have even been called the “Trojan horses” of the virus, given their ability to carry it and infect others while remaining unharmed themselves.
Avian flu is highly contagious and poses a high risk to chickens and turkeys. As a result, if a farm tests positive for bird flu, the entire flock is culled. This can result in hundreds of thousands to millions of pounds of lost revenue and put enormous pressure on poultry farms. It also has implications for the price and availability of turkeys and chickens ahead of Thanksgiving and Christmas. And, of course, it’s a huge loss of birds.
The crux of the matter is how we raise and treat animals, and their interactions with humans. Poultry are often raised in harsh conditions where they are crowded and diseases pass through them easily. Some experts believe this more infectious strain developed in an industrial factory environment, where animals are kept cramped and viruses have room to circulate and mutate.
And it’s not just a bird flu problem, but also other infectious diseases. In places like China and India, antibiotics are given to animals for free in order to prevent infection (especially in factory farming) and to make them as fat as possible. A survey of chicken farmers in China found that they all used antibiotics. The rationale here is cheap, fast meat to meet growing demand in emerging economies.
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But that creates its own problems. Administration of antibiotics to animals can result in the emergence of resistant bacterial strains and then humans such as farmers infected with antibiotic resistant infections. These then circulate in humans and reduce the effectiveness of one of the most powerful drugs in modern medicine. Chemotherapy, infections and surgeries of all kinds have become safer thanks to antibiotics. If the drugs don’t work, these procedures become high-risk and life-threatening, just as they were in the pre-antibiotic era. And as we’ve learned, all it takes is one person to fly with a new infectious disease and it will soon become a problem everywhere else in the world.
The main infectious disease threats in humans tend to come from animals: think Sars-CoV-2, Sars, Mers, Ebola… the list goes on. There are over a million viruses circulating in the animal kingdom, and it would be a mad rush to try and stop that circulation. But we can limit the chances of them spreading through the human population and limit their circulation in domestic animals. This requires taking the animal-human interface seriously, and knowing that although it is a major problem for the economy, animal welfare and agriculture, the situation is getting worse is just one mutation away.