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Vector-transmitted diseases in cattle
The main vector-transmitted diseases in cattle are three-day sickness (bovine ephemeral fever) and akabane disease.
Increased mosquito and midge populations after high rainfall can result in outbreaks of three-day sickness. Consider vaccinating before the wet season as you may not be able to muster stock in wet weather. Even if this were possible, the disease peak may be well past before any significant immunity could develop. (Stock would have to be vaccinated twice, 2 weeks apart, and it would take about 4 weeks for full immunity to develop.)
The three-day sickness epidemic may cause:
- ongoing neuromuscular impairment (staggering or incoordination) in some animals
- some reduced or delayed fertility in females due to abortion or fevers
- temporary or permanent infertility in bulls.
Neuromuscular disease requires owners to monitor and treat animals for welfare and management reasons.
Fertility issues in females may require some management intervention such as:
- diagnosing pregnancy and culling empties, and replacing with more heifers
- reducing culling for non-fertility reasons (age)
- extending mating periods
- accepting reduced calvings and making up numbers in the next season.
In multiple sire herds, bull fertility may be less of an issue but we highly recommend some bull assessments or introducing new known fertile bulls. In single-sire herds it is especially critical to do bull assessments to determine the effects of disease and post-flood stress on bull fertility.
Learn more about bovine ephemeral fever.
Akabane disease is spread by biting insects, but disease rarely shows until calving time when a range of presentations from abortions, limb malformations and dumb calves can occur. There is no preventative treatment, but owners need to be aware of the possibility in naive cattle.
Find out more about Akabane disease.