Tick fever vaccination

About the vaccine

The trivalent tick fever vaccine is a live, whole organism, blood-based vaccine containing attenuated strains of B. bovis and B. bigemina as well as Anaplasma centrale. The attenuated vaccine strains of Babesia spp are derived from Australian field isolates. A centrale is a related organism imported from South Africa in the 1930s and provides reasonable cross protection against the Australian isolates of Anaplasma marginale.

The vaccine is mostly sold in a chilled ready-to-use form with just a short 4-day shelf life. A frozen vaccine (Combavac 3in1; stored in liquid nitrogen) is available for remote areas where it can be difficult to deliver overnight, or for larger holdings where it is convenient to have vaccine stocks on hand for use as required. Combavac 3in1 is also available for export.

Clinical disease associated with use of the live vaccine is possible, but most animals show no visible reactions.

Vaccination program

Vaccination is the only reliable method for long-term protection of susceptible cattle against all three causes of tick fever.

Cattle of any age can be vaccinated, but it is best to vaccinate animals between 3-9 months of age when the age-related resistance is present and there is little risk of reactions to the vaccine. Many producers find it convenient to vaccinate around weaning time. It takes about 3-4 weeks after vaccination for immunity to develop to babesiosis and up to two months for immunity to develop to anaplasmosis.

When introducing cattle from outside the tick areas which have never previously been exposed to tick fever organisms, keep in mind this time taken for immunity to develop after vaccination. Ideally, vaccination occurs well before introduction to allow time for immunity to develop to all components of the vaccine.

One dose of vaccine is sufficient in most cases for lifetime immunity; but there will always be a small percentage of vaccinated animals which do not become immune to all three organisms in the vaccine after a single dose. An argument can therefore be made for a second dose for introduced cattle and especially for valuable animals such as bulls.
 

Figure 1. Tick fever vaccine. Image courtesy of the Tick Fever Centre
Figure 1. Tick fever vaccine. Image courtesy of the Tick Fever Centre