24 research outputs found
Avian influenza vaccination of poultry and passive case reporting, Egypt
We investigated the infl uence of a mass poultry vaccination campaign on passive surveillance of highly pathogenic avian infl uenza subtype (H5N1) outbreaks among poultry in Egypt. Passive reporting dropped during the campaign, although probability of infection remained unchanged. Future poultry vaccination campaigns should consider this negative impact on reporting for adapting surveillance strategies. (Résumé d'auteur
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Modelling influenza A H5N1 vaccination strategy scenarios in the household poultry sector in Egypt
Highly pathogenic avian influenza (AI) due to H5N1 virus was first reported in Egypt in February 2006; since then, the government has allowed avian influenza vaccination in poultry. The present study evaluated the impact of AI vaccination in terms of cumulative annual flock immunity (CAFI): the percentage of bird × weeks protected by immunity. This evaluation took account of the combined effects of vaccination coverage, vaccine efficacy (VE), and different characteristics of household poultry production on the effectiveness of the adopted vaccination strategy (VS), and provided alternative options for improvement. The evaluation used a population and vaccination model that calculates the CAFI. Participatory approaches were employed in 21 villages to develop the vaccination and flock parameters required for the model. The adopted VS were compared in the model with three alternative VS scenarios in terms of the CAFI. Vaccination coverage varied among villages but was generally low (between 1 and 48 %; median 14 %). Under the adopted VS, the CAFI predicted for the villages ranged from 2 to 31 %. It was concluded that despite the enormous effort put into rural household poultry AI vaccination by the Egyptian government, village CAFI is unlikely to be maintained at the levels required to significantly reduce the virus load and restrict transmission. In HPAI-endemic countries that consider AI vaccination as one of the disease control options, the high cost of mass AI vaccination campaigns and their achievable benefits must be compared with other available control measures, which may include targeted vaccination. Achievable vaccination coverage, VE and the different characteristics of commercial and household (village) poultry production are key parameters determining the feasibility and cost-effectiveness of different AI vaccination strategies
Protective efficacy of recombinant turkey herpes virus (rHVT-H5) and inactivated H5N1 vaccines in commercial Mulard ducks against the highly pathogenic avian influenza (HPAI) H5N1 clade 2.2.1 virus
In Egypt, ducks kept for commercial purposes constitute the second highest poultry population,
at 150 million ducks/year. Hence, ducks play an important role in the introduction and
transmission of avian influenza (AI) in the Egyptian poultry population. Attempts to control
outbreaks include the use of vaccines, which have varying levels of efficacy and failure. To
date, the effects of vaccine efficacy has rarely been determined in ducks. In this study, we
evaluated the protective efficacy of a live recombinant vector vaccine based on a turkey
Herpes Virus (HVT) expressing the H5 gene from a clade 2.2 H5N1 HPAIV strain (A/Swan/
Hungary/499/2006) (rHVT-H5) and a bivalent inactivated H5N1 vaccine prepared from
clade 2.2.1 and 2.2.1.1 H5N1 seeds in Mulard ducks. A 0.3ml/dose subcutaneous injection
of rHVT-H5 vaccine was administered to one-day-old ducklings (D1) and another 0.5ml/
dose subcutaneous injection of the inactivated MEFLUVAC was administered at 7 days
(D7). Four separate challenge experiments were conducted at Days 21, 28, 35 and 42, in
which all the vaccinated ducks were challenged with 106EID50/duck of H5N1 HPAI virus (A/
chicken/Egypt/128s/2012(H5N1) (clade 2.2.1) via intranasal inoculation. Maternal-derived
antibody regression and post-vaccination antibody immune responses were monitored
weekly. Ducks vaccinated at 21, 28, 35 and 42 days with the rHVT-H5 and MEFLUVAC vaccines
were protected against mortality (80%, 80%, 90% and 90%) and (50%, 70%, 80%
and 90%) respectively, against challenges with the H5N1 HPAI virus. The amount of viral
shedding and shedding rates were lower in the rHVT-H5 vaccine groups than in the MEFLUVAC groups only in the first two challenge experiments. However, the non-vaccinated
groups shed significantly more of the virus than the vaccinated groups. Both rHVT-H5
and MEFLUVAC provide early protection, and rHVT-H5 vaccine in particular provides protection
against HPAI challenge.S1 Table. Weekly mean HI titres (log2 ± SD) using A/Swan/Hungary/4999/2006) rHVT/Ag
that indicate the immune response to the rHVT-H5 vaccination. S1 Table legend: Different
upper case letters in a row denote the presence of statistically significant (p 0.05) differences.
Group I (vaccinated with rHVT-H5 vaccine at 1 day old), Group II (vaccinated with inactivated
KV-H5 vaccine at 8 days old), Group III (unvaccinated control).S2 Table. Weekly mean HI titres (log2 ± SD) measured using (A/chicken/Egypt/Q1995D/
2010) V/H5N1/Ag that indicates the immune response to the KV-H5 vaccination. S2
Table legend: Different upper case letters in a row denote the presence of statistically significant
(p 0.05) differences. Group 1 (vaccinated with rHVT-H5 vaccine at 1 day old), Group II (vaccinated with inactivated KV-H5 vaccine at 8 days old), Group III (unvaccinated control).S3 Table. Weekly mean HI titres (log2 ± SD) measured using (A/chicken/Egypt/128S/2012)
C/H5N1/Ag that indicates the immune response to the challenge virus. S3 Table legend: Different
upper case letters in a row denote the presence of statistically significant (p 0.05) differences.
Group 1 (vaccinated with rHVT-H5 vaccine at 1 day old), Group II (vaccinated with
inactivated KV-H5 vaccine at 8 days old), Group III (unvaccinated control).This work was supported by the United
States Agency for International Development
(USAID) under a grant (AID-263-IO-11-00001, Mod.
#3) and within the framework of OSRO/EGY/101/
USA, which applies to projects jointly implemented by
the FAO, GOVS and NLQP.http://www.plosone.orgam2016Production Animal StudiesVeterinary Tropical Disease
Protective efficacy of recombinant turkey herpes virus (rHVT-H5) and inactivated H5N1 vaccines in commercial Mulard ducks against the highly pathogenic avian influenza (HPAI) H5N1 clade 2.2.1 virus
In Egypt, ducks kept for commercial purposes constitute the second highest poultry population,
at 150 million ducks/year. Hence, ducks play an important role in the introduction and
transmission of avian influenza (AI) in the Egyptian poultry population. Attempts to control
outbreaks include the use of vaccines, which have varying levels of efficacy and failure. To
date, the effects of vaccine efficacy has rarely been determined in ducks. In this study, we
evaluated the protective efficacy of a live recombinant vector vaccine based on a turkey
Herpes Virus (HVT) expressing the H5 gene from a clade 2.2 H5N1 HPAIV strain (A/Swan/
Hungary/499/2006) (rHVT-H5) and a bivalent inactivated H5N1 vaccine prepared from
clade 2.2.1 and 2.2.1.1 H5N1 seeds in Mulard ducks. A 0.3ml/dose subcutaneous injection
of rHVT-H5 vaccine was administered to one-day-old ducklings (D1) and another 0.5ml/
dose subcutaneous injection of the inactivated MEFLUVAC was administered at 7 days
(D7). Four separate challenge experiments were conducted at Days 21, 28, 35 and 42, in
which all the vaccinated ducks were challenged with 106EID50/duck of H5N1 HPAI virus (A/
chicken/Egypt/128s/2012(H5N1) (clade 2.2.1) via intranasal inoculation. Maternal-derived
antibody regression and post-vaccination antibody immune responses were monitored
weekly. Ducks vaccinated at 21, 28, 35 and 42 days with the rHVT-H5 and MEFLUVAC vaccines
were protected against mortality (80%, 80%, 90% and 90%) and (50%, 70%, 80%
and 90%) respectively, against challenges with the H5N1 HPAI virus. The amount of viral
shedding and shedding rates were lower in the rHVT-H5 vaccine groups than in the MEFLUVAC groups only in the first two challenge experiments. However, the non-vaccinated
groups shed significantly more of the virus than the vaccinated groups. Both rHVT-H5
and MEFLUVAC provide early protection, and rHVT-H5 vaccine in particular provides protection
against HPAI challenge.S1 Table. Weekly mean HI titres (log2 ± SD) using A/Swan/Hungary/4999/2006) rHVT/Ag
that indicate the immune response to the rHVT-H5 vaccination. S1 Table legend: Different
upper case letters in a row denote the presence of statistically significant (p 0.05) differences.
Group I (vaccinated with rHVT-H5 vaccine at 1 day old), Group II (vaccinated with inactivated
KV-H5 vaccine at 8 days old), Group III (unvaccinated control).S2 Table. Weekly mean HI titres (log2 ± SD) measured using (A/chicken/Egypt/Q1995D/
2010) V/H5N1/Ag that indicates the immune response to the KV-H5 vaccination. S2
Table legend: Different upper case letters in a row denote the presence of statistically significant
(p 0.05) differences. Group 1 (vaccinated with rHVT-H5 vaccine at 1 day old), Group II (vaccinated with inactivated KV-H5 vaccine at 8 days old), Group III (unvaccinated control).S3 Table. Weekly mean HI titres (log2 ± SD) measured using (A/chicken/Egypt/128S/2012)
C/H5N1/Ag that indicates the immune response to the challenge virus. S3 Table legend: Different
upper case letters in a row denote the presence of statistically significant (p 0.05) differences.
Group 1 (vaccinated with rHVT-H5 vaccine at 1 day old), Group II (vaccinated with
inactivated KV-H5 vaccine at 8 days old), Group III (unvaccinated control).This work was supported by the United
States Agency for International Development
(USAID) under a grant (AID-263-IO-11-00001, Mod.
#3) and within the framework of OSRO/EGY/101/
USA, which applies to projects jointly implemented by
the FAO, GOVS and NLQP.http://www.plosone.orgam2016Production Animal StudiesVeterinary Tropical Disease