Testing of pooled milk samples could provide an efficient tool for foot and mouth disease (FMD) screening, and for facilitating movement of milk supplies during an FMD outbreak. Researchers at The Pirbright Institute, in collaboration with USDA/APHIS scientists at the Foreign Animal Disease Diagnostic Laboratory on Plum Island, New York, have shown that such testing is feasible and sensitive enough to detect the presence of one infected cow in a milking herd of up to 1,000 head.
The researchers compared two high-throughput real-time reverse transcription polymerase chain reaction (rRT-PCR) protocols with different RT-PCR chemistries, and in both cases detected the FMD virus in in milk one to two days before the presentation of characteristic foot lesions. They also found:
- The rRT-PCR detection from milk was extended, up to 28 days post contact (dpc), compared to detection 14 dpc for virus isolation.
- Detection of FMDV in milk by rRT-PCR was possible for 18 days longer than detection by the same method in serum samples.
- Dilution studies using milk from the field and experimentally-infected animals showed the test could detect FMDV at 10-7, meaning the test could detect one acutely-infected milking cow in a typical-sized dairy herd of 100 to 1,000 individuals.
The research report, titled “Detection of foot-and-mouth disease virus in milk samples by real-time reverse transcription polymerase chain reaction: optimisation and evaluation of a high-throughput screening method with potential for disease surveillance,” is published in the journal Veterinary Microbiology, and is available online.