Article

Transmission of the highly pathogenic avian influenza virus H5N1 within flocks during the 2004 epidemic in Thailand.

Department of Livestock Development, Ministry of Agriculture and Cooperatives, Bangkok, Thailand.
The Journal of Infectious Diseases (impact factor: 6.41). 01/2008; 196(11):1679-84. DOI:10.1086/522007
Source: PubMed

ABSTRACT This present study is the first to quantify the transmission of avian influenza virus H5N1 within flocks during the 2004 epidemic in Thailand. It uses the flock-level mortality data to estimate the transmission-rate parameter ( beta ) and the basic reproduction number (R(0)). The point estimates of beta varied from 2.26/day (95% confidence interval [CI], 2.01-2.55) for a 1-day infectious period to 0.66/day (95% CI, 0.50-0.87) for a 4-day infectious period, whereas the accompanying R(0) varied from 2.26 (95% CI, 2.01-2.55) to 2.64 (95% CI, 2.02-3.47). Although the point estimates of beta of backyard chickens and fighting cocks raised together were lower than those of laying hens and broiler chickens, this difference was not statistically significant. These results will enable us to assess the control measures in simulation studies. They also indicate that, for the elimination of the virus, a critical proportion of the susceptible poultry population in a flock (i.e., 80% of the population) needs to be vaccinated.

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Keywords

95% confidence interval [CI]
 
accompanying R(0)
 
avian influenza virus H5N1
 
backyard chickens
 
basic reproduction number
 
broiler chickens
 
control measures
 
critical proportion
 
elimination
 
flock-level mortality data
 
flocks
 
hens
 
point estimates
 
transmission-rate parameter
 

Thanawat Tiensin