Coronavirus: Conservationists sound alarm over use of horseshoe crab blood in race to find vaccine

Over half a million of the ‘living fossils’ are rounded up by US pharmaceutical companies each year, but numbers are going down

Harry Cockburn
Wednesday 08 July 2020 10:11 BST
Scientist points to the place where horseshoe crabs are 'milked' for their blood
Scientist points to the place where horseshoe crabs are 'milked' for their blood (Getty)

The horseshoe crab is a strange creature. It is not actually a crab, lacking pincers, and is considered a living fossil due to its origin 450 million years ago. What’s more, this unlikely animal has now become highly prized by the pharmaceutical industry due to the peculiar properties of its blood.

Horseshoe crab blood is used to test the sterility of vaccines. This is because components of the animals’ blood react particularly strongly if they come into contact with any endotoxins – the materials from pathogenic bacteria. The result is a clot. If scientists add horseshoe crab blood to their vaccines and see a clot, it means the vaccine is not safe to be tested.

In Europe, a new synthetic alternative to horseshoe crab blood was recognised as being safe in 2016, but in America, it is yet to gain approval from the Federal Drug Administration (FDA).

As a result, US pharmaceutical firms – some of the biggest in the world – remain dependent on horseshoe crabs.

Every year around half a million horseshoe crabs are rounded up during the spring when they come ashore to lay their eggs.

The crabs are taken to labs where they are “milked” – a process in which around a third of their blood is removed, before they are then returned to the water.

This time-consuming procedure makes the crabs’ blood expensive – worth around £48,000 per gallon (£180,000 a litre).

Environmentalists say the impact of the bleeding of crabs has not been well-researched enough to know the exact impact.

However, the numbers of horseshoe crabs are falling in some of their key habitats.

According to the National Geographic, in 1990, biologists estimated 1.2 million crabs spawned in Delaware Bay, which is both a prime egg-laying spot and one of the main collection points for the drug companies.

By 2002, that number had dropped to 333,500.

And it is not only the drug companies which are dependent on the crabs.

Seabirds such as the red knot and the semipalmated plover both rely on the crabs’ eggs to provide sustenance for their migratory flights to the Arctic where they breed.

As a result, environmentalists are calling for the synthetic alternative to horseshoe crabs’ blood to be made available to US drug companies.

Due to the rush to create vaccines to fight the coronavirus pandemic, the calls for action have become increasingly urgent.

Dr Barbara Brummer, state director for nature conservancy in New Jersey told BBC Radio 4: “When they’re put back [in the sea] they’re alive, but nobody really knows the impact that withdrawal of blood has on the life of that crab.

“There are at least 30 companies working on a vaccine and every one of them has to go through a lot of sterility testing – so my concern is about the population of the horseshoe crabs, because they’re such a key part of the ecosystem.”

She said environmentalists are now pushing to have the synthetic alternative to horseshoe crab blood to be recognised “so we can move away from relying on this natural source of endotoxin test.”

“It’d be good news for crabs, good news for birds. The nature conservancy that I’m a part of believes in protecting the lands and waters which we all depend on.”

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