Assessment of national strategies for control of high-pathogenicity avian influenza and lowpathogenicity notifiable avian influenza in poultry, with emphasis on vaccines and vaccination

Abstract

Twenty-nine distinct epizootics of high-pathogenicity avian influenza (HPAI) have occurred since 1959. The H5N1 HPAI panzootic affecting Asia, Africa and Eastern Europe has been the largest among these, affecting poultry and/or wild birds in 63 countries. A stamping-out programme achieved eradication in 24 of these epizootics (and is close to achieving eradication in the current H5N2 epizootic in South African ostriches), but vaccination was added to the control programmes in four epizootics when stamping out alone was not effective. During the 2002 to 2010 period, more than 113 billion doses of avian influenza (AI) vaccine were used in at-risk national poultry populations of over 131 billion birds. At two to three doses per bird for the 15 vaccinating countries, the average national vaccination coverage rate was 41.9% and the global AI vaccine coverage rate was 10.9% for all poultry. The highest national coverage rate was nearly 100% for poultry in Hong Kong and the lowest national coverage was less than 0.01% for poultry in Israel and the Netherlands. Inactivated AI vaccines accounted for 95.5% and live recombinant virus vaccines for 4.5% of the vaccines used. Most of these vaccines were used in the H5N1 HPAI panzootic, with more than 99% employed in the People's Republic of China, Egypt, Indonesia and Vietnam. Implementation of vaccination in these four countries occurred after H5N1 HPAI became enzootic in domestic poultry and vaccination did not result in the enzootic infections. Vaccine usage prevented clinical disease and mortality in chickens, and maintained rural livelihoods and food security during HPAI outbreaks. Low-pathogenicity notifiable avian influenza (LPNAI) became reportable to the World Organisation for Animal Health in 2006 because some H5 and H7 low-pathogenicity avian influenza (LPAI) viruses have the potential to mutate to HPAI viruses. Fewer outbreaks of LPNAI have been reported than of HPAI and only six countries used vaccine in control programmes, accounting for 8.1% of the total H5/H7 AI vaccine usage, as compared to 91.9% of the vaccine used against HPAI. Of the six countries that have used vaccine to control LPNAI, Mexico, Guatemala, El Salvador and Italy have been the biggest users. In countries with enzootic HPAI and LPNAI, development and implementation of exit strategies has been difficult. KeywordsAnimal disease -Avian disease -Avian influenza -Avian influenza virus -High-pathogenicity avian influenza -Immunity -Low-pathogenicity avian influenza -Low-pathogenicity notifiable avian influenza -Poultry -Vaccination -Vaccine -Vaccine bank.

Flock-Based Surveillance for Low Pathogenic Avian Influenza Virus in Commercial Breeders and Layers, Southwest Nigeria

“…In addition, high pathogenic avian influenza (HPAI) viruses in domestic poultry are thought to have evolved from low pathogenic avian influenza (LPAI) viruses through mutations or re-combinations (Alexander, 2007). According to Swayne et al (2011), LPAI is a reportable disease caused by H5, H7 and H9 subtype viruses that have become a major source of concern to the global poultry industry. Most LPAI viruses (LPAIVs) produce mild to moderate disease in commercial rearing settings, especially when complicated by secondary pathogens, immunosuppression, and stress factors in the environment.…”

Antibody Titer Has Positive Predictive Value for Vaccine Protection against Challenge with Natural Antigenic-Drift Variants of H5N1 High-Pathogenicity Avian Influenza Viruses from Indonesia

“…In the field, this translates into reduced environmental contamination and reduced farm-to-farm spread (1,(10)(11)(12)(13). Furthermore, the integration of H5N1 vaccine usage with other control components in poultry has been associated with a reduction in human cases in Vietnam and Hong Kong and a lack of H5N1 HPAI outbreaks on farms on which poultry were fully vaccinated (10).…”

Epidemiological parameter changes of global Avian Influenza H5N1 over two decades, from 1997 to 2017

“…Therefore, it should be considered for all H5N1 cases [26][27][28], and many affected countries has implemented vaccination for domestic poultry to control H5N1 in poultry, especially in countries where influenza H5N1 viruses have become enzootic in poultry and wild birds. [29,30].…”