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Ticks kill sheep

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Posted November 13, 2013
Ticks kill sheep
Predator attacks are not the only explanation for the high lamb mortality in Norway, particularly in coastal areas. Ticks are high on the list of suspects as far as scientists from Bioforsk are concerned, in their attempt to find the reasons for the losses at hand. Credit: Anette Tjomsland
In some lamb herds, a mortality rate of 30 percent has been recorded, albeit, no predators have been involved in these losses. The situation is so serious that the sheep industry could be under threat. It is therefore crucial to identify the causes and implement preventative measures. The answer may be found somewhere within the genetics of the sheep and the course of the disease, assessment and control of tick populations and biological control of ticks.

Weakens the immune system

Tick-bites in sheep may result in the disease tick-borne fever (TBF), induced by the bacterium Anaplasma phagocytophilum (A.ph). TBF causes high fever and weakens the immune system.

“It is estimated that approximately 300,000 lambs are exposed to this bacteria each year. However, they do not necessarily die from the infection”, says tick researcher Lise Grøva at Bioforsk Organic at Tingvoll in Norway.

The disease itself is not fatal, but makes sheep more susceptible to secondary infections.

“Arthritis is the most common disease that can arise. Illness normally occurs 10-14 days after grazing starts. Blood tests show that almost all the lambs are infected during the season in tick infested areas.”

The direct cause of death due to TBF is often an acute pasteurella infection – a bacterial disease which can cause acute blood poisoning with inflammation of the heart sac, heart, lungs or digestive organs. It is therefore recommended to vaccinate sheep against pastuerella in areas where tick-borne fever is prevalent.

Read more at: Phys.org

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