infections

ANP Sheep infected with the bluetongue virus

NOS Nieuws•vandaag, 18:26

Suddenly it reared its head: the bluetongue virus. Ruminants such as sheep and cattle can become very ill and some of the animals die after infection. Three months after the start of the outbreak, bluetongue has largely disappeared due to the cold, but there is great fear of its return.

On September 6, the Ministry of Agriculture, Nature and Food Quality (LNV) announced that the virus had been found again in the Netherlands after fourteen years. It appeared at four sheep farms in North Holland and Utrecht. Since then it has spread rapidly and has been identified in more than 5,500 locations.

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Swelling joints, limping and drooling are symptoms of an infestation. Some of the animals recover, but some animals also die. There are no exact mortality figures yet, but in mid-November outgoing minister Adema wrote that more than 5 percent of the sheep population had died.

The organization that collects the carcasses is not told what the animals died from, but says that during the period in which bluetongue was around, 40,000 more sheep were collected than expected. After a peak at the end of October, the organization now sees the number of dead sheep decreasing towards the normal number.

The midge, a type of small mosquito, spreads the bluetongue virus. The insect becomes less active when temperatures drop and therefore there have been fewer infections recently. This is reflected in the number of bluetongue tests that turn out positive in the laboratory, although it cannot be ruled out that testing is now less consistent than earlier in this outbreak.

This graph shows the number of positive PCR tests per week:

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“It is too cold for the midge,” says Melle Holwerda, researcher at Wageningen Bioveterinary Research. “When it is around eight degrees, the virus spreads less quickly. That is why infections decrease.”

That does not mean that we have gotten rid of the bluetongue virus for good. “It is possible that the midges dive into the stables. In this way, the virus can get through the winter and return in the spring.”

Farmer Gert Vendrig had fifty sheep and half of them are dead. Cows also had to suffer. “It was terrible how quickly it went. At one point we had six dead sheep on the road that were being picked up.”

In addition to the emotional damage, it is also a financial blow. “Every animal costs money. In addition, we can no longer sell milk from the cows and we will have no lambs next year. Nothing will be reimbursed by insurance or by a compensation fund.”

If all goes well, we can use a well-functioning vaccine in animals on livestock farms by the middle of next year.

Melle Holwerda, researcher at Wageningen Bioveterinary Research

“We are happy that it is now quiet again,” Vendrig continues. “But there is a good fear that it will come back. We therefore fervently hope for a vaccine.”

There is not yet a vaccine against the current bluetongue variant that the ministry considers suitable. It is therefore in discussions with seven pharmaceutical companies about developing a new vaccine.

In the meantime, at the request of LNV, Wageningen Bioveterinary Research is setting up a place where possible vaccines can be tested in the laboratory on sheep.

“A lot of work still needs to be done to vaccinate all ruminants in the Netherlands,” says researcher Holwerda. “If all goes well, we can use a well-functioning vaccine at livestock farms by the middle of next year.”

To get a grip on bluetongue, we are not only looking for a vaccine. Supervisory authority the Dutch Food and Consumer Product Safety Authority is investigating which midge species carry the virus and whether they hibernate in stables. Research is also underway into the mortality rates and recovery of ruminants after infection.

2023-12-03 17:26:54
#infections #bluetongue #due #cold #danger #passed