Publication
Bluetongue Virus
From Department of Agriculture, Food and the Marine
Published on
Last updated on
• Bluetongue is a notifiable exotic viral disease caused by Bluetongue virus (BTV) which can cause severe clinical signs in ruminant species and camelids. Any suspect case of Bluetongue must be reported to the Department of Agriculture, Food and the Marine (DAFM) without delay. Farmers, veterinary practitioners and other relevant stakeholders should remain vigilant for Bluetongue.
• Ireland is currently free from Bluetongue, however remains at risk of disease introduction, as Bluetongue is present across Europe. An outbreak of Bluetongue in Ireland would have serious implications for the Irish agri-industry Bluetongue can result in very severe on-farm impacts (serious illness and death), resulting in animal welfare concerns and economic impacts on the livestock sector.
There are no public health risks associated with Bluetongue, as Bluetongue poses no risks to human or food safety.
Bluetongue virus can infect and cause severe clinical signs in ruminant species (including sheep, cattle, goats and deer) and camelids (such as llama and alpaca).
Bluetongue virus is spread by infected biting midges (Culicoides species) many of which are found throughout the island of Ireland. Bluetongue transmission primarily occurs when biting midges feed off the blood of an infected animal and subsequently spread the virus to animals they bite.
Midge activity levels are dependant on average temperatures. The high-risk period for Bluetongue spread is when midges are most active. Traditionally this would be between April and November, however rising global temperatures and mild weather conditions during winter may see midge activity persisting for longer, extending the periods of potential disease transmission. Wind speed and direction can also affect how far midges can travel and could potentially facilitate the spread of disease.
Infected pregnant animals can also pass the virus to their unborn offspring in the womb, who can be a source of infection when they are born.
There is evidence to show that the virus can be spread through biological products such as blood, and germinal products such as semen and embryos.
Ireland is currently free from Bluetongue, but the disease is present in many parts of the Europe that susceptible animals can be imported from.
Although the threat of Bluetongue disease to the Irish livestock sector has been of significant ongoing concern for many years, recent spread of a new Bluetongue serotype, ‘serotype 3’ across Northern Europe between September-December 2023 has increased the risk of spread to Ireland. During this period, Bluetongue was detected in the Netherlands, Belgium, Germany and Great Britain. Previously Bluetongue (serotypes 1,4,8) were more commonly detected in Southern Europe due to warmer climates.
Information detailing Bluetongue cases globally and in Europe can be found here
Sheep are more likely to show obvious clinical signs of Bluetongue than cattle if they become infected, and mortality rates can be as high as 70%. Some animals may not show any clinical signs however, and these animals can pose a risk for spreading the disease to new areas or countries. If infections resolve, recovery can take months.
There is a wide range of clinical signs of Bluetongue to look out for including:
• Fever
• Inappetance (loss or lack of appetite)
• Drop in milk yield
• Apathy, lethargy
• Lesions, sores, reddening and/or ulcerations
o Mucous membranes (nose, mouth (gums, dental pads), eyes)
o Teats/udder (cattle)
• Swelling of the face, lips and tongue (i.e. “Bluetongue”)
• Breathing difficulties if the tongue swells
• Increased salivation and drooling from the mouth
• Discharge from the eyes and/or nose
• Lameness (due to periarthritis, hoof sloughing, swollen legs)
• Abortion, stillbirths or deformities in offspring
• Possible death in severe cases
If you have any concern that one of your animals has Bluetongue, do not delay in taking action. Isolate the suspect animal(s) indoors immediately and report the case to the Department of Agriculture Food and the Marine. Farmers, veterinary practitioners, and other relevant stakeholders should remain vigilant for Bluetongue transmission.
To report a suspect case, please contact your local Regional Veterinary Office (RVO) (9am-5pm). Outside of office hours, you can ring the National Disease Emergency Hotline on 01-492-8026 (which is operational 365 days of the year).
In the event of an outbreak of Bluetongue occurring in Ireland control measures would have to be introduced to try and eradicate the disease. Restriction zones would be established which would extend for a minimum of 150km in size, and movement controls for susceptible animals would be introduced. Other control measures, including mandatory vaccination (if available) or housing periods could also be implemented.
There are 3 main ways that Bluetongue could enter the country:
• Import of infected animals
• Import of infected biological material (e.g. blood) or germinal products (e.g. semen or embryos)
• Weather conditions (wind dispersal, speed and direction) allowing for infected midges to be carried on the wind to Ireland from countries where Bluetongue is circulating
Infected pregnant animals can also pass Bluetongue virus onto their unborn offspring in the womb.
A short video on ‘How to keep Bluetongue out of Ireland’ by clicking here
The greatest threat to Bluetongue entering the country comes from the import of an infected animal from a country in which Bluetongue is circulating. Reducing the numbers of introduced cattle and sheep from areas where Bluetongue is present will reduce the risk of introducing this disease into Ireland.
Although testing and animal health legislative requirements are in place for animals entering Ireland; Bluetongue could still enter Ireland in as yet undetected animals who do not display clinical signs of disease. These animals could then infect midges in Ireland leading to a disease outbreak.
Therefore, anyone intending to import an animal from mainland Europe should ask themselves the following questions before doing so:
It is possible that the breed changes or genetic gain that you are seeking for your animals can be obtained locally. Avoid importing animals that could compromise the health of your own and the national herds/flocks, as a matter of priority.
Every effort should be made to only import susceptible animals from December-March inclusive, which is outside of the higher activity midge season. The Department of Agriculture, Food and the Marine has published specific biosecurity advice for livestock farmers who are planning to import animals (see below).
Pregnant susceptible animals can pose a higher risk of bringing Bluetongue into Ireland as they can pass the virus to the unborn offspring in the womb. Once born, this animal could then be a source of spread of Bluetongue virus. If the import is necessary, then the risk can be reduced by importing a non-pregnant female and then breeding the animal in Ireland.
Always consult with your Private Veterinary Practitioner before purchasing animals from another country for advice on pre-import tests and health status requirements to ensure that they do not bring disease into your herd, flock or the country. Always purchase animals from reputable sources and obtain proof of vaccination and pre-export test results for any relevant diseases such as Bluetongue before you import.
Contact your local Regional Veterinary Office (RVO) for information on import requirements such as Intra-EU Health Certificates, and ensure that have you have adequate facilities for isolating the animals indoors away from the rest of the herd or flock.
The Biosecurity for Livestock Farmers Importing Animals leaflet contains detailed advice (see below), of which the following are some first steps:
a) Check that the correct documents accompanied the animals e.g. identification cards, Intra-EU Health Certificates etc.
b) Check that animals appear healthy and have access to clean dry bedding, clean water and food. If any animals appear unwell contact your Private Veterinary Practitioner without delay.
c) Inform your local Regional Veterinary Office (RVO) as soon as the animals arrive onto your premises to arrange a post-import visit. Keep animals isolated and housed on your farm until the RVO is satisfied that they do not present a risk of spreading Bluetongue.
d) All Bluetongue susceptible animals that enter Ireland should be treated with an appropriate insecticide (synthetic pyrethroid pour-on for use on sheep and/or cattle against biting flies and lice) and be confined indoors away from other animals until blood results from both post-entry blood samples are confirmed as favourable.
Biosecurity advice for farmers importing livestock can be found here
The Department performs post-entry testing on all ruminants arriving into Ireland. ALL recently purchased ruminant and camelid animals originating from mainland Europe must be sampled for Bluetongue. This is irrespective of whether they come from, or transit through a Bluetongue-infected country on their way to Ireland.
Although pre-purchase Bluetongue testing can be valuable, it is not an absolute guarantee that disease is absent, as animals may become infected on their journey to Ireland. Any animals tested prior to movement (i.e. in the country of origin) will still require post-entry testing following arrival in Ireland.
If an animal that enters Ireland gives birth in the period between arrival and sampling, the offspring must also be sampled. If a calf is born to an antibody positive animal within 10 months of that dam’s arrival into Ireland, both the dam and calf must be tested for Bluetongue.
Herd and flock owners should notify and submit any aborted or stillborn foetuses from pregnant animals that entered Ireland to their RVO.
Two blood sampling are performed on each animal arriving in Ireland, as part of post-entry testing requirements by the RVO.
The 1st blood sample is taken within 5 days of arrival to Ireland, and the 2nd sample is taken 10 days after the 1st sample.
All Bluetongue susceptible animals that enter Ireland should be isolated and confined indoors away from other animals until blood results from both samples are confirmed as favourable.
Any positive results will require immediate action to be taken with appropriate guidance provided by the National Disease Control Centre (NDCC).
Please consult the Bluetongue disease updates (attached below) for the most recent updates from DAFM on Bluetongue and the risks that present to Ireland.
A short video on ‘How to keep Bluetongue out of Ireland’ by clicking here
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