FARMERS across the north of Scotland have been warned of the increasing danger of blood sucking parasites from the Southern Hemisphere threatening their sheep due to climate change.
The barber’s pole worm, Haemonchus contortus, is a vampire parasite that has devastated flocks of sheep in Australia and across South America.
Dr Hilary Burgess, the veterinary adviser to the Shetland Islands council, said that the parasite, although sounding “pretty nasty”, was always comfortably far away from Scottish livestock.
However, due to climate change, the parasite has made its way into southern England, with outbreaks now spreading as far as the northeast in Scotland.
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The outbreaks have prompted wildlife protection staff to introduce quarantine measures in Shetland to help prevent the parasites from spreading to the islands, according to The Shetland Times.
“It is thought the parasite has been able to spread north because of sheep movements and warmer temperatures and changing rainfall patterns, with a change from hot and dry weather to warm and wet, triggering outbreaks,” Dr Burgess said.
She added: “Back in the day, when I was studying parasitology at Kings Buildings in Edinburgh, Haemonchus contortus was a blood sucking parasite found in southern England and Australia which sounded pretty nasty, but comfortably far away.
“As a vet in Scotland, I wouldn’t have to worry about it. After all parasitology was hard enough, what with having to identify all those flies by their wing vein patterns, tape worm segments etc.
“Now, however, with climate change, these long-established patterns are changing, and parasites that have not been a problem before in the north of Scotland are increasingly being identified.”
The barber’s pole worm has been identified in several flocks in Aberdeenshire over the past several years, but has yet to be identified in Shetland.
However, due to a large proportion of Shetland’s breeding rams being sourced from Aberdeenshire, the Shetland Animal Health has had to step up its security measures at ferry ports.
“Haemonchus is different from the other worms that farmers and crofters are accustomed to managing in their flocks,” Dr Burgess explained.
“It doesn’t cause scour, and age immunity does not develop - so it can affect adult sheep as well as lambs.
“Because the worms are sucking blood from the sheep, very heavy infections can cause sudden deaths which tend to occur after gathering or moving. In these cases death can be so sudden that sheep remain in good condition.”
Barber’s pole worms can produce between 5000 and 15,000 eggs every day, meaning infections can build up quickly in sheep and goats.
Sheep that come to Shetland receive a quarantine drench as each animal is treated with dewormer upon arrival at the port and then sent to graze in a confined area to help dilute the impact of any parasites that may have survived the treatment.
However, Burgess has warned that treatment is “likely to become increasingly difficult” as, in a small number of cases, worms have been identified as resistant to all three groups of the dewormers.
The Moredun Research Institute, based in Penicuik, Midlothian, has developed a vaccine, but it is licensed for use in Australia and can only be obtained by “special arrangements” in the UK.
“Climate change is already having a large impact on livestock diseases,” Burgess told The Shetland Times.
She added: “Our work here in Shetland over this summer has found that the vets are removing increasing number of ticks from pets and several of these have been identified as Ixodes ricinus or the common sheep tick which can spread disease in both animals and people.
“Different patterns of infectious disease influenced by climate change can be worrying and bewildering - but I believe that by keeping an eye on the scientific evidence and acting accordingly we can best protect our livestock and industry from whatever comes next.”
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