Dataset Information

Influenza surveillance on 'foie gras' duck farms in Bulgaria, 2008-2012.

ABSTRACT: OBJECTIVES:Ducks can shed and spread influenza A viruses (IAVs) while showing no disease signs. Our objective was to clarify the role of 'foie gras' ducks in the circulation of IAVs in Bulgaria. METHODS:Monthly avian influenza surveillance was conducted on 63 'foie gras' duck farms, 52 of which were surveyed throughout the study between November 2008 and April 2012. Virologic and serologic samples were collected and tested. During this time, wild bird samples were collected at major wild bird-resting areas near the Black Sea coast and Danube River. RESULTS:The study showed high isolation frequency of low-pathogenicity avian influenza viruses. In the raising population (<75 days old), subtypes H3, H4, and H6 were detected monthly and H5 LPAIV, sporadically. Different subtypes (H1, H10, H11) were isolated from the fattening premises (75- to 100-day-old ducks), suggesting different routes of introduction. Only 6 of the 52 farms that were surveyed both virologically and serologically were influenza-free throughout the study, possibly due to higher biosecurity measures implemented. No evidence of direct transmission of IAV from wild birds was found. Wild bird surveillance showed low isolation frequency of IAV. IAV prevalence of 0·55% for migratory ducks and 0·53% for migratory geese was estimated in November-December 2011 and January-February 2012, respectively, at two ornithologically important locations near the Black Sea coast. CONCLUSIONS:The 'foie gras' duck farms in Bulgaria are an optimal niche where Eurasian-like IAVs are maintained and reassorted unapparent to farmers and veterinarians.

SUBMITTER: Marinova-Petkova A

PROVIDER: S-EPMC4746559 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature

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Influenza surveillance on 'foie gras' duck farms in Bulgaria, 2008-2012.

Marinova-Petkova Atanaska A Georgiev Georgi G Petkov Todor T Darnell Daniel D Franks John J Kayali Ghazi G Walker David D Seiler Patrick P Danner Angela A Graham Allison A McKenzie Pamela P Krauss Scott S Webby Richard J RJ Webster Robert G RG

Influenza and other respiratory viruses 20160301 2

<h4>Objectives</h4>Ducks can shed and spread influenza A viruses (IAVs) while showing no disease signs. Our objective was to clarify the role of 'foie gras' ducks in the circulation of IAVs in Bulgaria.<h4>Methods</h4>Monthly avian influenza surveillance was conducted on 63 'foie gras' duck farms, 52 of which were surveyed throughout the study between November 2008 and April 2012. Virologic and serologic samples were collected and tested. During this time, wild bird samples were collected at maj ...[more]

PMID: 26663739

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Project description:BACKGROUND: Indonesia is one of the countries most severely affected by H5N1 highly pathogenic avian influenza (HPAI) virus in terms of poultry and human health. However, there is little information on the diversity of H5N1 viruses circulating in backyard farms, where chickens and ducks often intermingle. In this study, H5N1 virus infection occurring in 96 smallholder duck farms in central Java, Indonesia from 2007-2008 was investigated and the molecular and antigenic characteristics of H5N1 viruses isolated from these farms were analysed. RESULTS: All 84 characterised viruses belonged to H5N1 clade 2.1 with three virus sublineages being identified: clade 2.1.1 (1), clade 2.1.3 (80), and IDN/6/05-like viruses (3) that did not belong to any of the present clades. All three clades were found in ducks, while only clade 2.1.3 was isolated from chickens. There were no significant amino acid mutations of the hemagglutinin (HA) and neuraminidase (NA) sites of the viruses, including the receptor binding, glycosylation, antigenic and catalytic sites and NA inhibitor targets. All the viruses had polybasic amino acids at the HA cleavage site. No evidence of major antigenic variants was detected. Based on the HA gene, identical virus variants could be found on different farms across the study sites and multiple genetic variants could be isolated from HPAI outbreaks simultaneously or at different time points from single farms. HPAI virus was isolated from both ducks and chickens; however, the proportion of surviving duck cases was considerably higher than in chickens. CONCLUSIONS: The 2.1.3 clade was the most common lineage found in this study. All the viruses had sequence characteristic of HPAI, but negligible variations in other recognized amino acids at the HA and NA proteins which determine virus phenotypes. Multiple genetic variants appeared to be circulating simultaneously within poultry communities. The high proportion of live duck cases compared to chickens over the study period suggests that ducks are more likely to survive infection and they may better suit the role of long-term maintenance host for H5N1. As some viruses were isolated from dead birds, there was no clear correlation between genetic variations and pathogenicity of these viruses.

Project description:BACKGROUND:Influenza is a major cause of respiratory illness resulting in 3-5 million severe cases and 291,243-645,832 deaths annually. Substantial health and financial burden may be averted by annual influenza vaccine application, especially for high risk groups. METHODS:We used an active facility-based surveillance platform for acute respiratory diseases in three hospitals in Guatemala, Central America, to estimate the incidence of laboratory-confirmed hospitalized influenza cases and identify risk factors associated with severe disease (defined as admission to the intensive care unit (ICU) or death). We enrolled patients presenting with signs and symptoms of acute respiratory infection (ARI) and obtained naso- and oropharyngeal samples for real-time reverse transcriptase polymerase chain reaction (RT-PCR). We used multivariable logistic regression to identify risk factors for ICU admission or death, adjusted for age and sex. RESULTS:From May 2008 to July 2012, among 6326 hospitalized ARI cases, 446 (7%) were positive for influenza: of those, 362 (81%) had influenza A and 84 (18%) had influenza B. Fifty nine percent of patients were aged ??5?years, and 10% were aged ??65?years. The median length of hospitalization was 5?days (interquartile range: 5). Eighty of 446 (18%) were admitted to the ICU and 28 (6%) died. Among the 28 deaths, 7% were aged ??6?months, 39% 7-60?months, 21% 5-50?years, and 32% ??50?years. Children aged ??6?months comprised 19% of cases and 22% of ICU admissions. Women of child-bearing age comprised 6% of cases (2 admitted to ICU; 1 death). In multivariable analyses, Santa Rosa site (adjusted odds ratio [aOR]?=?10, 95% confidence interval [CI]?=?2-50), indigenous ethnicity (aOR?=?4, 95% CI?=?2-13, and radiologically-confirmed pneumonia (aOR?=?5, 95% CI?=?3-11) were independently associated with severe disease. Adjusted for hospital utilization rate, annual incidence of hospitalized laboratory-confirmed influenza was 24/100,000 overall, 93/100,000 for children aged <?5?years and 50/100,000 for those ??65?years. CONCLUSIONS:Influenza is a major contributor of hospitalization and death due to respiratory diseases in Guatemala. Further application of proven influenza prevention and treatment strategies is warranted.

Dataset Information

Influenza surveillance on 'foie gras' duck farms in Bulgaria, 2008-2012.

Publications

Influenza surveillance on 'foie gras' duck farms in Bulgaria, 2008-2012.

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