Lamb mortality in Norway is on the rise with a mortality
rate of 30% threating the lamb industry. However predation is not a factor in
the death of lambs. Researchers from Bioforsk suspect tick-bites are the cause
of lamb mortality infecting 300,000 lambs a year. Tick-bites in lambs result in
tick-borne fever (TBF) and is a result of the bacterium Anaplasma phaagocytophilum (A.ph). This bacterium causes fever and
weakens the immune system. In humans, the bacteria can cause flu like symptoms
and decrease the immune system resulting in pneumonia in many cases. The disease
is not fatal in either humans or lambs, but arthritis is common after lambs
have been infected. Lambs are more susceptible to secondary infections after
being infected with A.ph and the majority of deaths are a result of acute
pasteurella infections. The bacterial infection causes blood poisoning and
inflammation of the heart, heart sac, lungs and digestive organs. Vaccinations
are available for acute pasteurella infections and are recommended for lambs
that are in areas of high tick-borne fever.
Research is
currently underway to develop measures that help sheep tolerate tick-bites
better. Although, researchers know lambs respond to infections differently. It
has been discovered some lambs experience shorter fever or a shorter period
with a decreased immune system. Research is also being conducted on the number
of ticks lambs have and how this correlates to the growth of lambs. There is
also on-going research on long-term acaricides used to kill mites and ticks;
lambs are still being infected despite the use of acaricides. More research
needs to be conducted that focuses on prevention of tick bites and how to
control tick populations to decrease the occurrence of tick bites in lambs.
Bioforsk-Norwegian Institute for Agricultural and
Environmental Research (2013, November 12). Ticks kill sheep. Sciencedaily. Retrieved November 14,
2013, from http://www.sciencedaily.com-/releases/2013/11/131112091015.htm