Investigation of the Prevalence of Neospora caninum in Queensland Beef Cattle

Summary

Neospora caninum was a recognised parasite that has been shown to be a major cause of bovine abortion worldwide. In addition to the impact on reproduction, overseas studies have reported decreased weight gain in infected cattle and lower milk production in dairy heifers. Globally, considerable resources have been committed into the understanding this parasite. Neospora was identified in the MLA funded North Australia Program 1998 Review of Reproduction and Genetics Projects (pp. 76&80) as a pathogen which warranted investigation in Queensland beef herds, but this was not done at that time due to lack of funds and also lack of trade significance.

Since that time, there have been indications from countries importing our cattle that neosporosis may be an issue. The Department of Primary Industries, Queensland (QDPI) fielded questions about our Neospora status from the Philippines, Thailand and Indonesia. The serologist from the main government veterinary laboratory in Tasmania has also reported to QDPI that a Victorian cattle exporter was looking into testing cattle for Neospora prior to export to Mexico.

An increasing number of breeding cattle were being exported from Australia, therefore this parasite had the potential to impact our live cattle trade. We needed to be pro-active in defining the Neospora status of our beef cattle, not only for the domestic advantages, but also for the risk assessments that may have been required by our international trading partners. Queensland has about 40% of the national beef herd and spans a range of climatic zones and this makes it an ideal state to start such an investigation.

Our preliminary Neospora seroprevalence study looked at sera from 45 animals on 32 properties. This study revealed a seroprevalence if 15% in 1400 cattle tested, with only one property not showing infection. This seroprevalence of fifteen percent was much higher than initially anticipated, being much higher than that found in many overseas surveys, for example, New Zealand beef cattle only had a 2.8% seroprevalence.

This project tested 5785 Queensland beef cattle from 154 properties, and found 14.8% of these cattle and 90% of properties were infected with the parasite. The mapping of these results showed distinct areas of infection, the parasite being most abundant along the coastal and northern areas of the state. The inland southern region had the lowest level of infection, which also coincided with a low rainfall level and lower numbers of wild dogs. This project has provided the first step in defining the Neospora situation in the Queensland beef Industry, and will serve as a model for the rest of Australia to structure its research priorities.