Epidemiology and Infection

Comparison of the transmission characteristics of low and high pathogenicity avian influenza A virus (H5N2)

J. A. VAN DER GOOT a1, M. C. M. DE JONG a2, G. KOCH a1 and M. VAN BOVEN a2c1
a1 Central Institute for Animal Disease Control, PO Box 2004, 8203 AAE Lelystad, The Netherlands
a2 Animal Sciences Group, Wageningen University and Research Centre, PO Box 65, 8200 AB Lelystad, The Netherlands

Article author query
van der goot j   [PubMed][Google Scholar] 
de jong m   [PubMed][Google Scholar] 
koch g   [PubMed][Google Scholar] 
van boven m   [PubMed][Google Scholar] 


Low pathogenicity avian influenza A strains (LPAI) of the H5 and H7 type are noted for their ability to transform into highly pathogenic counterparts (HPAI). Here we compare the transmission characteristics in poultry of LPAI H5N2 (A/Chicken/Pennsylvania/83) and corresponding HPAI virus by means of transmission experiments. In the experiments, five inoculated animals are placed in a cage with five contact animals, and the infection chain is monitored by taking blood samples, and samples from the trachea and cloaca. The data are analysed by final size methods and a generalized linear model. The results show that HPAI virus is more infectious and induces a longer infectious period than LPAI. In fact, fully susceptible animals are invariably infected when confronted with HPAI virus and die within six days after infection. Animals previously infected with LPAI virus, on the other hand, survive an infection with HPAI virus or escape infection all together. This implies that a previous infection with LPAI virus effectively reduces susceptibility of the host to infection and decreases transmission of HPAI virus. We discuss the implications of these conclusions for the control and evolution of avian influenza viruses.

(Accepted May 19 2003)

c1 Author for correspondence.