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Stratford warden on standby in case of more swan deaths




Cyril Bennis counting swans on the River Avon, Stratford.
Cyril Bennis counting swans on the River Avon, Stratford.

MYSTERY surrounds the death of two swans recently pulled out of the River Avon with experts at Defra now investigating the possibility the birds were killed by the deadly West Nile Virus.

The virus is carried by mosquitoes and is being investigated because at this stage avian flu doesn’t appear to be the cause of death.

In 2021 and 2022 bird flu ravaged the swan population of Stratford with dozens killed in an agonisingly painful end sometimes lasting days.

Last year there were few if any outbreaks but the spectre of bird flu striking again can never be ruled out.

The Herald has seen an interim report into the swan deaths by a Veterinary Investigation Officer and it concludes: Avian influenza has not been detected in this bird but worryingly adds, work in progress - West Nile Virus RNA.

“An interim report suggests it isn’t avian flu this time,” said Cyril Bennis, Stratford swan warden. “It could however be the West Nile Virus which is carried by mosquitos. The two dead swans were removed from the river and taken away to the Defra laboratory for testing but we won’t know the results of those tests for three months which is too long a time. Birds with West Nile virus often show neurological signs including loss of coordination, head tilt, tremors, weakness, apparent blindness, and lethargy.”

According to the World Health Organisation West Nile Virus (WNV) can cause a fatal neurological disease in humans but 80 per cent of people who are infected will not show any symptoms. It’s transmitted to humans through the bites of infected mosquitoes which become infected when they feed on infected birds. During later blood meals (when mosquitoes bite), the virus may be injected into humans and animals, where it can multiply and possibly cause illness. Symptoms can include fever, headache, sore throat, muscle aches, nausea and vomiting.

Defra this week told the Herald: There are currently no confirmed cases of West Nile virus in the UK and the current risk level is low. We are aware it is present in Europe.

We test birds with unusual mortality (that is, certain species like passerines, and particularly where there has been a mass mortality event) for West Nile virus in addition to avian influenza. Testing for West Nile virus is standard and expected practice for unusual or mass mortality events.

Some birds affected by West Nile virus may show severe neurological signs and may die. Others birds affected by West Nile virus do not show any clinical signs. Most bird species could be infected with this virus if they are bitten by an infected mosquito.

Passerines are usually considered the most common species of bird that are affected by the virus without showing any clinical signs.

We have a cross government plan in the event that cases of West Nile virus are found. Public Health England provide guidance for humans to avoid being infected.



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