Iceland beats infectious bursal disease outbreak

Following a single outbreak of infectious bursal disease (IBD) at a broiler farm last year, veterinary authorities in Iceland have declared the disease situation “resolved.”

(ankreative | Bigstock)
(ankreative | Bigstock)

In the past week, the Icelandic Food and Veterinary Authority (MAST) reported to the World Organisation for Animal Health (OIE) that the infectious bursal disease (IBD) situation in the country has been resolved. As a result, all restrictions have been lifted.

In mid-July of 2019, daily mortality reached 0.5% in 23-day-old broilers at a farm in the Rangarvalla region in the south of Iceland. Subsequently, younger flocks in the other poultry houses were affected. Veterinarians diagnosed inclusion body hepatitis (IBH) and IBD (which is also known as Gumboro disease).

Out of the flock of 47,850 birds, 11,830 showed symptoms, and almost 10,300 died, according to the official report to the OIE. Of the rest of the flock, 1,538 were humanely killed and disposed of, and 36,020 broilers were slaughtered.

According to MAST, IBD had not been reported in Iceland since 1998, and so vaccination was not routinely practiced by the poultry industry.

Successful IBD control

The infected premises were thoroughly cleaned and disinfected, and then left empty for 16 weeks with the aim to eradicate the disease. For 3-7 days, the interior temperature of each of the houses was heated to 48degC (118degF).

At the start of 2020, broiler rearing at the premises resumed, with day-old chicks obtained from a parent flock that had been vaccinated against IBD. The chicks were also vaccinated — with a live recombinant vaccine against IBD and Marek’s disease. Tests on the birds showed that they did not acquire a field infection during rearing.

Subsequent PCR testing of samples taken during the original infection confirmed the presence of the IBD virus. Partial sequencing of the virus genetic material suggests that it was related to very virulent IBD virus strains circulating elsewhere in Europe.

No signs of the disease have been observed at any other Icelandic poultry farms.

Total poultry meat production in Iceland was just under 9,800 metric tons in 2017, according to Statistics Iceland in its most recent publication on the country’s agriculture.

More on IBD

IBD is endemic in many parts of the world, according to the Pirbright Institute of the United Kingdom (U.K.).

Infecting both domestic and wild birds, the IBD virus targets the immune system tissues. This leads to immunosuppression, and infected chickens are susceptible to other infections. Clinical symptoms include depression and ruffling of feathers; lack of appetite; huddling; unsteady gait; reluctance to rise, and diarrhea.

Virus is spread via direct contact, or by contaminated feed, water and feces. A hardy virus, it can persist in poultry houses for several months after infected birds are removed.

Genome of the IBD virus is split into two segments, which have a tendency to reassort — a characteristic that makes it more difficult to track and control the disease. Very virulent strains have mutations that facilitate faster replication, and more severe symptoms, according to Pirbright.

In 2019, the Pirbright Institute entered into an agreement with an animal health company to develop a novel vaccine to protect poultry against multiple economically important diseases, including IBD. The worldwide exclusive partnership with ECO Animal Health Ltd. was based on innovative technology developed at Pirbright.

Previously, research in Spain indicated that Asia is the origin of the very virulent IBD virus. This conclusion was reached following studies on the characterization of the genome, and molecular epidemiology.

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