The pathogen
Chlamydia abortus is one of the main causes of abortion in small ruminants. The clinical signs of enzootic abortion are: abortions towards the end of pregnancy, neonatal mortality, premature births or the birth of weak lambs.
“Chlamydia abortus, is one of the main causes of abortions in small ruminants globally, causing great economic losses”
The disease is easily spread during lambing, maintaining the risk of infection in the flock.
Why was this study necessary?
The safety of live attenuated vaccines has recently been questioned by the scientific community; inactivated vaccines had been shown to induce immunity in ewes, but their efficacy has been questioned and they did not succeed in reducing shedding.
“The vaccines marketed against Enzootic Abortion had certain problems regarding safety and efficacy”
This is why this study was carried out, which evaluated both the efficacy and the safety of this inactivated vaccine, INMEVA.
What were the results?
In order to evaluate the efficacy of this vaccine, the results of two groups of pregnant ewes, infected experimentally with C. abortus, were compared: a vaccinated group and a control (unvaccinated) group. Data on clinical signs, behaviour, temperature and weight of the lambs were compared.
The results showed a 75% reduction in clinical signs and a 55% reduction in shedding in the vaccinated group compared to the unvaccinated group. Moreover, a positive effect was observed on the weight gain of the lambs.
“The results confirm that INMEVA reduces clinical signs and shedding”
In terms of safety, no significant adverse effects were recorded in the vaccinated group.
Conclusions
The commercial inactivated vaccine INMEVA is safe and has been successfully demonstrated to confer a protective level of immunity against OEA caused by Chlamydia abortus.
The following effects of the vaccine were observed in the study:
● Reduction of reproductive clinical signs.
● Reduction of chlamydial shedding.
● Minimisation of weight loss by lambs.
● No adverse effects.
