Evaluation of novel vaccines for Enzootic Abortion of Ewes (EAE) - 6340

Teagasc Project Team: Dr. Orla Keane (PI), Lauren O’Neill Project dates: Sept 2013 – Aug 2017

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Chlamydia abortus, the causative agent of enzootic abortion of ewes (EAE), is the second most common diagnosable form of infectious ovine abortion in Ireland. It is also a serious risk to pregnant women. EAE results in necrotizing placentitis leading to abortion in late pregnancy, premature lambing or birth of weak lambs. The disease can spread easily, especially at lambing time when a large number of bacteria can be excreted with the placenta and in vaginal discharge. In Ireland EAE has been estimated to cost upwards of €5 million per annum. The rate of abortion in infected flocks is typically 2-3% per flock per year but the introduction of infection into a naïve flock can result in abortion storms. After abortion infected ewes develop immunity and rarely abort again but these ewes can continue to shed bacteria at subsequent births resulting in transmission of the infection to other ewes in the flock. There is one commercial vaccine available in Ireland for EAE, which is a live attenuated vaccine. This vaccine reduces, but does not stop, the shedding of infective bacteria. This vaccine has also recently been found to be a cause of abortion in some flocks, indicating the need for safer vaccines.