Since 2022, western Europe experienced major insect-borne viral diseases outbreaks in cattle and sheep, such as bluetongue and epizootic haemorrhagic disease, leading to significant socio-economic consequences and posing major issues in terms of animal welfare and pain management.

With the observed rise in temperature in the last few weeks, new outbreaks are currently ongoing.

How could the veterinary and farming community get better prepared to fight these viral illnesses once again, whilst ensuring animal welfare remains the utmost priority?

With no licensed treatment currently available on the market and vaccines approved for emergency use only seeming to have a mild effect on clinical signs of bluetongue and epizootic haemorrhagic disease, a more pragmatic approach centred on animal welfare and effective pain management based on published scientific evidence could be the way forwards.

Worrying emergence of bluetongue and epizootic haemorrhagic disease in western Europe since 2022

Global warming, as well as other environmental factors, are therefore conceivably likely to influence factors related to the incubation period of the virus, the distribution of Culicoides and its ability to transmit both EHDV and BTV, partially explaining the significant epidemiological changes for both EHD and BT in the last decade.

Respectively initially located in North America, Asia, Africa and Oceania in the case of EHD, and in Africa, Middle East and Asia for BT, these diseases have now expanded to western European countries, posing a serious threat to animals and farming communities.

In the last 18 months, western Europe witnessed major outbreaks of EHD in cattle and BT in sheep and cattle. Whilst not posing any threat to human health, both diseases are listed as significant diseases by the World Organisation for Animal Health (WOAH), and, in most countries, it is mandatory to promptly report cases to the authorities, to ensure national surveillance.

Since November 2022, EHD is worryingly spreading in Europe (EHDV-8 serotype).^5,6 

• It first started in Italy and then Spain with respectively three and two outbreaks of EHD reported in November 2022.
• Portugal and south of France respectively had their first EHD outbreaks in July 2023 and in September 2023.^5,6
• France is the most affected country, with a spike in new cases since June 2024 (518 new outbreaks between June 1st and September 5th 2024).^6,6bis

New outbreaks are also still ongoing in Spain (20 new outbreaks in August 2024) and Portugal (last outbreak reported on August 13th 2024) with new declared cases of EHD since June 2024.⁶

Meanwhile, an outbreak of BT in sheep ignited in Netherlands^₇ in September 2023 (BTV-3 serotype), followed by other outbreaks in Germany⁸ (BTV-3 serotype) from October 2023, in the United Kingdom (BTV-3 serotype), as well as a major outbreak in France since September 2023 with a new strain of the BTV-8 serotype. Italy also recorded a significant number of BT outbreaks from multiple strains since September 2023 (over 270 outbreaks as of September 2023). ^9,10

In the last few weeks, alongside a rise in temperatures, the epidemiological situation dramatically changed especially in the Netherlands, France, Germany and Italy.

Since June 2024, the Netherlands have experienced a rise in new cases, with outbreaks still ongoing and reaching a total number of 5 872 confirmed cases through RT-PCR (BTV-3 serotype) for 2024 as of September 12th 2024⁷, despite vaccination efforts.

At the end of July, a worrying increase in new BTV-3 serotype cases also re-ignited in the north of France. As of September 5th, France reported 712 outbreaks of BTV-3 serotype cases since early June.⁶ Since early August, France has rolled out a free vaccination plan (BTV-3 serotype) and set up a monitored regulated zone in the north and the east of France. Since then, new cases of BT (BTV-3 serotype) have emerged in Belgium, close to the French border, with a total of 2 316 outbreaks since June 2024.⁶ Since July 2024⁸, Germany has also experienced a significant spike in new cases (mainly BTV-3 serotype): there were 7 841 outbreaks declared on the national surveillance platform as of September 5th 2024⁶, with at least 3 500 confirmed outbreaks of the BTV-3 serotype, despite vaccination efforts. Italy has also seen a rise in cases since June 2024 (595 confirmed outbreaks), mainly due to the BTV-8 serotype.

Other European countries reported a few outbreaks over the summer, including Spain (BTV-8 serotype), the UK (BTV-3 serotype), Switzerland (BTV-3 serotype) and Denmark (BTV-3 serotype). BT is now also spreading to other countries: Norway and the Czech Republic have declared their first cases (serotypes currently in the process of being identified) respectively at the end of August and early September 2024.⁶

Treatment

In terms of treatment, there is currently no licensed drug to treat both conditions, as there is no medicine available against both viruses responsible for EHD and BT.

However, it is often possible to influence the consequences of these viral infections: treatment of both EHD and BT is often aimed at pain relief and inflammation inhibition, as well as preventing secondary bacterial infections.

Therefore, the current approach for both diseases consists of implementing a supportive and symptomatic treatment, often involving the use of antimicrobials, to prevent the risk of wound secondary infection, and of non-steroidal anti-inflammatory drugs (NSAIDs) for their pain relief and anti-inflammatory properties.

Local pain relief can be provided for oral lesions, in order to facilitate food intake. For instance, some sheep farmers reportedly use white willow bark as a natural local pain relief for oral lesions, as it contains salicin, a chemical component similar to acetylsalicylic acid known for its anti-inflammatory and pain relief properties.

Corticosteroids can also be used to manage acute inflammation and oedema of nose and mouth if needed. Fluid administration, whether by drenching the affected animals or via infusion, is recommended to prevent dehydration if the animals are not drinking. Other possible concurring diseases, if any, need to be adequately treated as well to improve chances of recovery.

Prevention and control measures

Prevention and control measures include active surveillance programs of both insect vectors activity and potentially affected animals. Quarantine and/or movement restrictions are often applied too, to reduce the opportunity for vector transmission. If a case is confirmed and the spread restricted locally, animals may be culled to prevent the disease from spreading. In Europe, the management of BT is regulated and is subject to optional eradication programmes.

As we are now facing multiple new outbreaks of EHD and BT cases in Europe, due to a sharp increase in Culicoides activity and virus spread, and despite vaccination efforts, vets and farmers should carry on fighting these diseases once again, to mitigate the risks associated with them, while making pain management a priority. 

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