An update from Wageningen Bioveterinary Research (WBVR) in September 2023 shared that the European reference laboratory in Madrid has confirmed the characterisation performed by WBVR of the bluetongue virus found on Dutch sheep farms. This means that the characterisation is confirmed as serotype 3. Serotype 3 is the most recently reported serotype across Europe and is presumed to have entered the continent through Italy from Tunisia.
Bluetongue virus
WOAH states that bluetongue virus is an “infectious, non-contagious, vector-borne viral disease”. It affects wild and domestic ruminants, particularly sheep, for whom infection can cause “fatal disease”. The virus has more than 30 different identified serotypes, which the WBVR suggests cause “little or no cross-protection”. Serotype 3 reportedly forms a “kinship cluster” with serotypes 13 and 16. However, pinning down the origin of a specific serotype is difficult.
Bluetongue is transmitted by midges, which are not easily observed by humans as they are a few millimetres in size. Despite this, they come in multitudes and host the virus before releasing it to ruminants through the midges’ salivary glands. Clinical symptoms include lesions on the tongue, point bleeding, nasal discharge, and edema.
Whole Genome Sequencing
The characterisation of the serotype at WBVR was performed using Whole Genome Sequencing. Professor Piet van Rijn, senior researcher at WBVR, commented that this “new technique” enables the identification of a serotype “much earlier” than in previous outbreaks. However, he warned that more infections can be expected.
What about a vaccine?
Professor van Rijn suggests that in a previous outbreak of bluetongue serotype 8, an effective vaccine was developed. However, a similar candidate has not yet been approved for serotype 3, he says.
“For sure not a vaccine based on dead virus like we use in Northwest Europe.”
He urges pharmaceutical companies to pursue this challenge. Although we are about to head into winter, the chances of the virus dying out are “slim”.
“The sooner we have access to a working vaccine, the faster we can stop the disease.”
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