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Monitoring of Avian Flu Outbreaks Compared

by 5m Editor
30 June 2010, at 9:28am

ITALY - Active surveillance seems to be most effective in detecting infection, especially when a vaccination programme is in place, according to researchers who had monitored four bird flu outbreaks in turkeys in Italy between 2000 and 2005.

A. Comin of Istituto Zooprofilattico Sperimentale delle Venezie in Legnaro, Italy, and co-authors have published a paper in the journal Zoonoses and Public Health about an intensive monitoring programme for avian influenza in meat-type turkey flocks during four epidemics in northern Italy.

Surveillance programmes for low pathogenicity (LPAI) and high pathogenicity avian influenza (HPAI) infections in poultry are compulsory for EU Member States, they explain, yet these programmes have rarely been evaluated.

In Italy, following a 1999 HPAI epidemic, control measures, including vaccination and monitoring, were implemented in the densely populated poultry area (DPPA) where all epidemics in Italy have been concentrated. The authors of the paper evaluated the monitoring system for its capacity to detect outbreaks rapidly in meat-type turkey flocks. The evaluation was performed in vaccination areas and high-risk areas in the DPPA, in 2000–2005, during which four epidemics occurred.

Serum samples and cloacal swabs were taken from vaccinated birds and unvaccinated (sentinel) birds. The researchers compared the detection rate of active, passive and targeted surveillance, by vaccination status, using multinomial logistic regression.

A total of 13,275 samplings for serological testing and 4,889 samplings for virological testing were performed; 6,315 production cycles of different bird species were tested.

The outbreaks detection rate in meat-type turkeys was 61 per cent for active surveillance (n=222/363 outbreaks), 32 per cent for passive surveillance and seven per cent for targeted surveillance.

The maximum likelihood predicted values for the detection rates differed by vaccination status: in unvaccinated flocks, it was 50 per cent for active surveillance, 40 per cent for passive surveillance and 10 per cent for targeted surveillance, compared to respectively 79 per cent, 17 per cent and four per cent for vaccinated flocks.

Active surveillance seems to be most effective in detecting infection, especially when a vaccination programme is in place, concluded Comin and co-authors. This is the first evaluation of the effectiveness of different types of surveillance in monitoring LPAI infections in vaccinated poultry using field data.

Reference

Comin A., J.A. Stegeman, D. Klinkenberg, L. Busani and S. Marangon. 2010. Design and results of an intensive monitoring programme for avian influenza in meat-type turkey flocks during four epidemics in northern Italy. Zoonoses and Public Health. (online ahead of publication). doi 10.1111/j.1863-2378.2010.01343.x

Further Reading

- You can view the full report (fee payable) by clicking here.


Further Reading

- You can visit the Avian Flu page by clicking here.