Évora, Portugal, Oct. 30, 2024 (Lusa) - Animal diseases transmitted by insect bites, such as bluetongue, which is widespread in Alentejo, are becoming increasingly frequent in Portugal due to climate change, a professor at the University of Évora (UÉ) said on Wednesday.

Speaking to the Lusa news agency, Ricardo Romão, a lecturer in the Department of Zootechnics and also a veterinary doctor, said that "vector-borne diseases [only transmitted through an insect bite] are appearing with much greater incidence".

"We know it's because of climate change" and because “the viruses that normally circulate in North Africa have been moving northwards and accompanying the rise in temperatures, particularly at the end of summer and in autumn," he said.

Ricardo Romão was talking about the new bluetongue serotype 3, first detected in the Évora district mid-September and has since spread throughout Alentejo.

Pointing out that the current temperatures are "conducive to the transmission of viruses," the lecturer stressed that at least three viruses are circulating in livestock species, specifically bluetongue, epizootic haemorrhagic disease, and the Nilevirus.

"They are all diseases transmitted by vectors, insects, mosquitoes, which know no borders and are very difficult to control just by moving animals because it doesn't stop the mosquitoes from progressing," he emphasised.

The veterinarian also said that he expects "the [bluetongue] virus to disappear with the cold", which will increase as winter approaches. The insect that transmits it cannot withstand low temperatures, but he predicted that it will continue to circulate due to the current mild conditions.

According to the UÉ professor, bluetongue first appeared in Portugal in 2004, so the disease "is nothing new" and what is new is serotype 3, which had already appeared this year in Belgium and France.

"It's a disease that affects animals in a more degraded immune situation or in a more complicated metabolic phase, such as pre-lambing or thinner and older ewes and lambs already a few months old," he emphasised.

As for the symptoms, Ricardo Romão described the animals with the disease as having "lesions on the mucous membranes, particularly in the mouth, the typical inflammation of the head and they stop eating, which also makes them weaker," and less active.

"The disease appears almost unnoticed," as the animals “get a fever and then end up developing the disease after two or three days, and often the condition starts to worsen from there,” he said.

According to reports from breeders and what he has seen on farms, the lecturer said that when bluetongue hits a herd, many of the animals become infected, acknowledged around 70%, with between 10% and 20% dying.

"We can only control this through vaccination and the disinsection measures that have been recommended for many years," he said, pointing out that one of the problems is the lack of knowledge about whether a herd to be vaccinated already has the disease.

According to the veterinarian, the vaccine against the virus "is preventative and not curative" and should only be applied to uninfected animals because it will not be effective in animals that already have the disease.

Bluetongue, which is not transmissible to humans, must be declared, and farms where the disease is confirmed are prevented from moving animals for 60 days.

Gaining ground in the Alentejo, the bluetongue disease is decimating herds and has already killed thousands of animals, causing losses for farmers, who complain of a lack of support.

The Confederation of Portuguese Farmers (CAP) has already called for urgent government intervention. In contrast, the National Confederation of Agriculture (CNA) has called for a free animal vaccination campaign and extraordinary support for producers.

SM/ADB // ADB.

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