|Weaver, Todd - Animal And Plant Health Inspection Service (APHIS)|
|Malladi, Saidhar - University Of Minnesota|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2014
Publication Date: N/A
Technical Abstract: Rapid detection of highly pathogenic avian influenza virus (HPAIV) in the field is critical for effective disease control and to differentiate it from other diseases, such as Newcastle disease. Lateral flow devices (LFD) are commercially available and provide a fast, highly specific, on-site test for type A influenza. Because LFD lack sensitivity at low virus concentrations, sampling has always targeted sick and dead birds. In order to quantify how clinical condition correlates to the detection of HPAIV with LFDs and whether delayed testing of dead chickens affects detection we exposed 50 chickens to a low dose of an H5 HPAIV and 50 chickens to a low dose of H7 HPAIV. Low doses were used in an attempt to increase mean death times. Oro-pharyngeal swabs were collected from all birds at 12, 24, 36, 48, 60, 72, 84, 96 and 108hrs post exposure. During sample collection each chicken was scored as healthy, sick or dead. Half of the dead birds were placed in an empty isolator and samples were not collected until the next sample time, so swab collection was delayed 12hr. All swab samples were tested at the time of collection with a commercially available U.S. licensed LFD for avian influenza virus and were subsequently tested with quantitative real-time RT-PCR to quantify the virus in each swab sample. With the combined data of both experiments 9.1% of healthy chickens, 82.4% of the sick chickens, 90.3% of the dead birds tested immediately, and 91.3% of the dead birds with 12hr delayed sampling were positive with the LFD. There was a direct correlation between the titer in the sample and whether the LFD was positive; the lowest titer the LFD could detect was 40,000 50% egg infectious doses per ml (EID50/ml) and at the titer of 400,000 EID50/ml and above 100% of samples were positive. Delaying testing of dead birds by 12hrs did not affect results and titers from swabs collected after a 12hr delay were significantly higher than those collected from freshly dead birds.