LIVACOX Vaccines and their Mode of Action

The vaccines work on the principle of infecting the chickens with live sporulated coccidian oocysts from the genus Eimeria. The coccidia replicate in the cells of the host intestines and at the end of the coccidian life-cycle unsporulated oocysts are excreted in the faeces. The oocysts sporulate outside of the host. The ingestion of these sporulated oocysts in turn infects the host again and the whole reproduction cycle is repeated again.

Lines of Eimeria that are present in LIVACOX® vaccines are attenuated, which means that compared to virulent field type coccidia the attenuated lines have a lowered pathogenicity and are thus not able to cause clinical coccidiosis.

Two methods of attenuation are used, namely: selection for precociousness (artificial abbreviation of life cycle) in chickens, and long-term passaging in chicken embryos. Pathological changes observed in the intestinal wall, from the safety tests carried out with LIVACOX® in a 10 times overdose challenge, were mild to none.

LIVACOX® vaccines include live sporulated oocysts of the economically important coccidian species, which during their 2nd to 3rd postvaccinal life cycles induce cell-mediated immunity. Owing to the limited infection the host is able - in good time - to develop an immune response to the parasite without the risk of clinical coccidiosis outbreak. This immunity is then maintained through continuous ‘revaccination’ (boosting) with oocysts present in the litter. It is important to note that the chickens must have continuous contact with oocysts from their faeces to maintain and boost their immune response to the parasite.

After a single administration of the vaccine life-long protective immunity against coccidiosis is induced within 14 days after vaccination. Usually clinical coccidiosis occurs in chickens at the age of 21 – 28 days. Therefore vaccination of chickens as young as possible is strongly recommended.