|MO, JONGSEO - Orise Fellow|
Submitted to: Transboundary and Emerging Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2020
Publication Date: 7/22/2020
Citation: Mo, J., Spackman, E., Stephens, C.B. 2020. Identification of optimal sample collection devices and sampling locations for the detection environmental viral contamination in wire poultry cages. Transboundary and Emerging Diseases. 00:1-7. https://doi.org/10.1111/tbed.13721.
Interpretive Summary: After a disease outbreak on a farm it is critical to ensure that the farm has been completely sanitized and that no virus remains in the environment. Numerous poultry operations, including layer farms, wet markets, and transport, use wire cages. Cages can be difficult to sample because they damage the sample collection devices and have limited surface area. To determine the best way to collect samples from wire cages, three devices that have been utilized for virus sample collection in other environments were compared. Which locations around the cage we also tested to determine where testing should be focused. It was found that 4" X 4" cotton gauze premoistened with a sample stabilization solution was the most sensitive detection device, compared to dry 4" x 4" cotton gauze and a foam swab. All locations around the cage were similarly good for detecting virus, but the most was found on the cage floor and when all locations were sampled with one single device.
Technical Abstract: Environmental testing of poultry premises after an outbreak of an infectious disease like avian influenza (AI) or Newcastle disease is essential to promptly verify virus-free status and subsequently return to normal operations. In an attempt to establish an optimized sampling protocol, a laboratory study simulating an AI virus-contaminated poultry house with wire layer cages was conducted. Three sample collection devices, pre-moistened cotton gauze, dry cotton gauze and a foam swab, were evaluated with each of four sample locations within a cage and when sampling all four locations with one device. Virus was detected with quantitative real-time RT-PCR utilizing a standard curve of a quantified homologous isolate of AI virus to determine titre equivalents of virus. The pre-moistened gauze detected the most virus RNA (100% positive, geometric mean titre [GMT): 3.2 log10 50% embryo infectious doses [EID50] equivalents per 25 cm2) in all four sample locations compared to dry gauze (93% positive, GMT: 2.6 EID50 equivalents per 25 cm2) and foam swabs (95% positive, GMT: 2.8 log10 EID50 equivalents per 25 cm2). The highest viral RNA loads were observed from the cage floor, and when the four locations were sampled with the same device. Overall, the pre-moistened gauze performed the best, and sampling multiple locations within a cage with the same device would likely optimize detection of residual virus.