Ovine enzootic abortion (OEA), caused by Chlamydia abortus, an obligate intracellular Gram-negative bacterium belonging to the Chlamydiaceae family, is an economically important disease in many countries. In fact, OEA is one of the major causes of small ruminant abortion and is found throughout the world (including North America, Europe and Africa), but not in Oceania (Australia and New Zealand). In addition, it has been described that C. abortus can cause miscarriages in women and atypical pneumonia in humans as a zoonotic agent. The infection results in a purulent placentitis, leading to reproductive failures such as late-term abortion, premature lambing with neonatal death or the birth of weak lambs.
The disease spreads easily in infected flocks, particularly at lambing time when ewes shed large amounts of C. abortus via vaginal discharges at abortion or parturition (placenta and fetuses). On the other hand, this infection will provide an effective immune response in OEA-affected ewes, protecting from future C. abortus-induced abortions. They could, however, shed the bacteria in subsequent estrus or parturition, maintaining the risk of infection in the flock ). The ingestion of contaminated material or inhaling aerosols can infect susceptible animal. After an infection of a naïve ewe it is believed that C. abortus may remains in a latent state in lymphoid tissue, controlled by cytokines like IFN-γ , and may not show clinical signs until the last weeks of the next gestation, leading to potential reproductive failure. The reproductive failure rate in an endemically infected flock is around 10%, whereas in a newly infected naïve flock it is around 30%, up to 60% in goat herds
Sheep become infected with C. abortus via the oronasal route by contact with pasture contaminated with abortive placental membranes and fluids, aborted and pre-term foetuses or infected lambs that survive . Primary infection of non-pregnant sheep can result in an asymptomatic, latent infection that leads to colonisation of placental trophoblast cells in the subsequent pregnancy, destruction of the chorionic epithelium and abortions that manifest in the last 2–3 weeks of gestation . These events appear to be synchronised with the later stages of pregnancy as placental lesions have only been reliably observed from day 90 gestation onwards
Features of Chlamydia Vaccine Sheep
The lower lambing and weaning percentages associated with this disease obviously impacts negatively on the farmer’s profitability. Intervet markets Ovilis Enzovax – a quality vaccine for the control of Chlamydiosis in sheep and goats. The use of Ovilis Enzovax vaccine has shown improvements in lambing percentages and reduction in abortion rates in flocks having problems with Chlamydiosis. One of the major benefits of this vaccine is that the immunity lasts for 2 years. This means less handling of animals and also a saving on costs as compared to vaccines that have to be administered every year.
Dosage & Administration
Dose: 2 ml by intramuscular or subcutaneous injection.
Ewe lambs, where it is intended to breed from them, may be vaccinated from 5 months of age.
Shearlings and older ewes should be vaccinated during the 4 month period prior to mating.
Prices of Chlamydia Vaccine Sheep
$25.60 – $34.42