Lack of evidence of avian adenovirus infection among turkey workers

Are adenoviruses zoonotic? A systematic review of the evidence

Adenoviruses (AdVs) are major contributors to clinical illnesses. Novel human and animal AdVs continue to be identified and characterized. Comparative analyses using bioinformatic methods and Omics-based technologies allow insights into how these human pathogens have emerged and their potential for host cross-species transmission. Systematic review of literature published across ProQuest, Pubmed, and Web of Science databases for evidence of adenoviral zoonotic potential identified 589 citations. After removing duplicates, 327 citations were screened for relevance; of which, 74 articles received full-text reviews. Among these, 24 were included here, of which 16 demonstrated evidence of zoonotic transmission of AdVs. These documented instances of AdV crossing host species barriers between humans and non-human primate, bat, feline, swine, canine, ovine, and caprine. Eight studies sought to but did not find evidence of zoonosis. The findings demonstrate substantial evidence suggesting AdVs have previously and will continue crossing host species barriers. These have human health consequences both in terms of novel pathogen emergence and epidemic outbreaks, and of appropriate and safe use of non-human adenoviruses for therapeutics. As routine human clinical diagnostics may miss a novel cross-species adenovirus infection in humans, next generation sequencing or panspecies molecular diagnostics may be necessary to detect such incursions.

Haemorrhagic enteritis of turkeys - current knowledge

Haemorrhagic enteritis virus (HEV), an adenovirus associated with acute haemorrhagic gastro-intestinal disease of 6-11-week old turkeys predominantly hampers both humoral and cellular immunity. Affected birds are more prone to secondary complications (e.g. colibacillosis and clostridiosis) and failure to mount an effective vaccine-induced immune response. HEV belongs to the new genus Siadenovirus. Feco-oral transmission is the main route of entry of the virus and it mainly colonizes bursa, intestine and spleen. Both naturally occurring virulent and avirulent strains of HEVs are serologically indistinguishable. Recent findings revealed that ORF1, E3 and fib genes are the key factors affecting virulence. The adoption of suitable diagnostic tools, proper vaccination and biosecurity measures have restrained the occurrence of disease epidemics. For diagnostic purposes, the best source of HEV is either intestinal contents or samples from spleen. For rapid detection highly sensitive and specific tests such as quantitative real-time PCR based on Taq man probe has been designed. Avirulent strains of HEV or MSDV can be effectively used as live vaccines. Novel vaccines include recombinant hexon protein-based subunit vaccines or recombinant virus-vectored vaccines using fowl poxvirus (FPV) expressing the native hexon of HEV. Notably, subunit vaccines and recombinant virus vectored vaccines altogether offer high protection against challenge or field viruses. Herein, we converse a comprehensive analysis of the HEV genetics, disease pathobiology, advancements in diagnosis and vaccination along with appropriate prevention and control strategies.

Review of Nonfoodborne Zoonotic and Potentially Zoonotic Poultry Diseases

Emerging and re-emerging diseases are continuously diagnosed in poultry species. A few of these diseases are known to cross the species barrier, thus posing a public health risk and an economic burden. We identified and synthesized global evidence for poultry nonfoodborne zoonoses to better understand these diseases in people who were exposed to different poultry-related characteristics (e.g., occupational or nonoccupational, operational types, poultry species, outbreak conditions, health status of flocks). This review builds on current knowledge on poultry zoonoses/potentially zoonotic agents transmitted via the nonfoodborne route. It also identifies research gaps and potential intervention points within the poultry industry to reduce zoonotic transmission by using various knowledge synthesis tools such as systematic review (SR) and qualitative (descriptive) and quantitative synthesis methods (i.e., meta-analysis). Overall, 1663 abstracts were screened and 156 relevant articles were selected for further review. Full articles (in English) were retrieved and critically appraised using routine SR methods. In total, eight known zoonotic diseases were reviewed: avian influenza (AI) virus (n = 85 articles), Newcastle disease virus (n = 8), West Nile virus (WNV, n = 2), avian Chlamydia (n = 24), Erysipelothrix rhusiopathiae (n = 3), methicillin-resistant Staphylococcus aureus (MRSA, n = 15), Ornithonyssus sylvarium (n = 4), and Microsporum gallinae (n = 3). In addition, articles on other viral poultry pathogens (n = 5) and poultry respiratory allergens derived from mites and fungi (n = 7) were reviewed. The level of investigations (e.g., exposure history, risk factor, clinical disease in epidemiologically linked poultry, molecular studies) to establish zoonotic linkages varied across disease agents and across studies. Based on the multiple outcome measures captured in this review, AI virus seems to be the poultry zoonotic pathogen that may have considerable and significant public health consequences; however, epidemiologic reports have only documented severe human cases clustered in Asia and not in North America. In contrast, avian Chlamydia and MRSA reports clustered mainly in Europe and less so in North America and other regions. Knowledge gaps in other zoonoses or other agents were identified, including potential direct (i.e., nonmosquito-borne) transmission of WNV from flocks to poultry workers, the public health and clinical significance of poultry-derived (livestock-associated) MRSA, the zoonotic significance of other viruses, and the role of poultry allergens in the pathophysiology of respiratory diseases of poultry workers. Across all pathogens reviewed, the use of personal protective equipment was commonly cited as the most important preventive measure to reduce the zoonotic spread of these diseases and the use of biosecurity measures to reduce horizontal transmission in flock populations. The studies also emphasized the need for flock monitoring and an integrated approach to prevention (i.e., veterinary-public health coordination with regard to diagnosis, and knowledge translation and education in the general population) to reduce zoonotic transmission.

A national study of US bird banders for evidence of avian influenza virus infections

BACKGROUND

Previously we have found that Midwestern US wildlife biologists, poultry farmers, veterinarians, and duck hunters have had evidence of avian influenza virus infections (AIVs).

OBJECTIVES

We sought to evaluate a national sample of US bird banders for previous evidence of AIV infection.

STUDY DESIGN

Controlled, cross-sectional serological survey.

RESULTS

In 2009 and 2010 we enrolled 157 registered bird banders from 40 US states and compared their enrollment data and serological results with 78 adult age-group matched controls from Iowa. On average, the bird banders had 15 years of wild bird exposure, banded 20 days per year, worked chiefly in 1 of the 4 North American flyways, and banded 300 individual birds of 5 different species per season. While handling birds, only 15% of banders reported wearing gloves. Three bird banders and 1 control had evidence of previous infection (1 AIV each) with A/BWTE/Ohio/07/495762-6(H7N3), A/Ty/MN/38391-6/95(H9N2) or A/CK/NJ/7290-2/95(H11N3) by microneutralization assay. There was no evidence of previous infection with a representative sample of H4, H5, H6, H8, or H10 AIVs. Participants were followed for influenza-like-illness for a median of 7 months and 4 (3 bird banders) submitted self-collected eye, nasal, and throat influenza-like-illness swab specimens, 1 of which collected in November of 2009, yielded a pandemic H1N1 influenza A virus.

CONCLUSION

Despite reports of conjunctivitis and upper respiratory symptoms while bird banding, we found sparse evidence that US bird banders had infections with AIVs.