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Number of bluetongue virus outbreaks in France increased to 297

Staff Writer |
France has reported eight new outbreaks of bluetongue virus since the last update on July 21 in the départements of Allier, Ariege, Haute-Loire, Puy de Dome and Saone et Loire regions.

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This makes a total of 297 outbreaks. All of the cases were detected as part of active surveillance, and all were in cattle where just one or two animals tested positive out of a sample size of 60 per farm.

The animals were tested using PCR, which detects viral RNA rather than antibodies and suggest virus continues to circulate. The extent of the restriction zones have not changed as a result of these cases and have been the same since April 2016.

Information available on the website of French Ministry of Agriculture suggests that there is passive surveillance taking place in the restriction zone and active surveillance in sentinel herds in the free areas.

bluetongue virus is primarily a disease of sheep but other species such as goats, cattle, buffaloes, camels, antelopes and deer can be infected. Humans are not affected.

The virus is present in most countries of Africa, the Middle East, India, China, the United States, and Mexico. Bluetongue virus infection, without associated clinical disease, is present in Southeast Asia, Papua New Guinea, northern South America and northern Australia.

A strain of bluetongue virus was first identified in Australia in 1975 from trapped insects but despite its long-term presence, it has not caused any clinical disease.

The disease is characterised by fever, widespread haemorrhages of the oral and nasal tissue, excessive salivation, and nasal discharge. In acute cases the lips and tongue become swollen and this swelling may extend below the lower jaw.

Lameness, due to swelling of the cuticle above the hoofs and emaciation, due to reduced feed consumption because of painful inflamed mouths, may also be symptoms of this disease. The blue tongue that gives the disease its name occurs only in small number of cases.

Convalescence of surviving sheep is slow. The high fever in sheep results in wool breaks, which adds to production losses.

The virus cannot be transmitted between susceptible animals without the presence of the insect carriers.

The incidence and geographical distribution of bluetongue depends on seasonal conditions, the presence of insect vectors, and the availability of the susceptible species of animals.

The insect carriers, biting midges, prefer warm, moist conditions and are in their greatest numbers and most active after rains.

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