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PIC Update: July 2009

Inclusion Body Hepatitis


June 22, 2009
By PIC

Topics

Fowl adenoviruses (FAdVs) are ubiquitous in domesticated fowl and
natural infections with many FAdVs cause no clinical problems. However,
some FAdVs have been associated with inclusion body hepatitis (IBH).
Most cases of IBH in broiler flocks occur between 2 and 4 weeks of age
and mortality usually ranges between 5 and10 per cent, but can reach as
high as 30 per cent per cent.

By Drs. Babak Sanei, Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), and Davor Ojkic, Animal Health Laboratory (AHL), University of Guelph

Fowl adenoviruses (FAdVs) are ubiquitous in domesticated fowl and natural infections with many FAdVs cause no clinical problems. However, some FAdVs have been associated with inclusion body hepatitis (IBH). Most cases of IBH in broiler flocks occur between 2 and 4 weeks of age and mortality usually ranges between 5 and10 per cent, but can reach as high as 30 per cent per cent.

During the past few years, IBH outbreaks in many Canadian provinces have resulted in significant economic losses. The incidence of IBH cases in Ontario has fluctuated over the past few years but there seems to be a trend of increasing IBH diagnosis.

In order to get a better grasp on the prevalence, causal factors and effects of IBH in Ontario broiler flocks, Dr. Babak Sanei at the Ontario Ministry of Agriculture, Food and Rural Affairs and Dr. Davor Ojkic and his research team at the Animal Health Laboratory (AHL), have been examining a variety of factors associated with patterns of exposure to different serotypes of adenoviruses associated with IBH. The researchers followed up 52 outbreaks of IBH with additional laboratory testing and a questionnaire to broiler producers.

Their findings?  FAdVs were isolated from all 52 outbreaks, and three main types of isolates were found.  The most common isolate during outbreaks was FAdV11, followed by FAdV08a and FAdV02.The average mortality rate in affected flocks was 3.01 per cent and ranging from 0.37 per cent to 11.29 per cent. Based on information received from broiler producers, 30.8 per cent of the farms had a previous history of IBH. One-third of broiler breeder flocks associated with IBH outbreaks were 30 weeks of age or younger, with the average age of affected broilers being 15 days.
 
The average farm population was around 35,000, but ranged from 15,000 to 97,000 broilers. In this study, serum samples were collected from broiler breeder flocks before egg production and after outbreaks in which their chicks were involved.  Almost all of the breeder flocks were exposed to one or more FAdV strains before production and remained positive for FAdV for most of their lifetimes. For the first time, AHL was able to establish a Microneutralization test that can be used at the field level in future to identify the serotype(s) of FAdVs that the breeder flocks have been exposed to prior to the production. This knowledge can be valuable for potential immunization of breeder flocks.

This study serves as a starting point for further investigations related to pathogenic properties, vaccine development and control of diseases caused by and associated with FAdVs. To read more on this study please visit www.poultryindustrycouncil.ca .



Featured Researcher

davor  

Dr. Davor Ojkic obtained his doctor of veterinary medicine degree at the University of Zagreb, Croatia, in 1990.  He spent some time in private practice, then immigrated to Canada where he completed an M.Sc. in molecular virology at Brock University in 1997.  Following that, Ojkic continued on with a PhD in veterinary virology at the Ontario Veterinary College. Upon graduation in 2001, Ojkic joined the Animal Health Laboratory (AHL) as a virologist. He is also adjunct professor and associated graduate faculty in the departments of pathobiology and population medicine, OVC, University of Guelph.  Ojkic has authored/coauthored 27 manuscripts, 29 papers in conference proceedings, and 45 other publications. He has also reviewed articles for several journals including Avian Pathology; Canadian Journal of Microbiology; Canadian Journal of Veterinary Research; Canadian Veterinary Journal; Infection, Genetics and Evolution; Journal of Veterinary; and Diagnostic Investigation and Vaccine.



Research Day Highlights

By Tim Nelson

The focus of our annual Research Day was food safety, specifically the research that has been undertaken to better understand the disease organisms that cause the problems and how to manage them. To kick the day off we had a really interesting talk from Dr. Niko Buddiger (Hybrid Turkeys) on the logistical difficulties and costs involved in developing and maintaining a salmonella-free flock. It was clear from his talk this is not an endeavour to be taken lightly and that there has to be a significant economic driver (in the case of Hybrid, the European market) for it to be worthwhile at this stage. The other point he stressed was that it is vitally important for everyone involved to strictly adhere to biosecurity protocols. He concluded by telling us that benefits far outweigh the negatives for their business despite the fact that they really have no choice if they are to sustain an export market. Dr. Scott McEwen from the Faculty of Population Medicine,  University of Guelph discussed how he and his team are undertaking a systematic review of the current approaches being taken in order to minimize the risk of salmonella organisms reaching the human population from poultry – a massive literature review. To make sense of this and come up with some concrete conclusions, the team is also undertaking a quantitative microbiological risk assessment of the reported interventions between farm and processing. By understanding what has been done elsewhere and its relative effectiveness and the efficacy of various interventions being used here in Canada are (such as the Safe, Safer, Safest program) his team hopes to develop a decision-making tool for industry based on the an optimal combination of interventions. Last speaker was a guest from the Department of Food Science and Human Nutrition at Iowa State University, Dr. Byron Brehm-Stecher. He’s an assistant professor in the rapid microbial detection and control laboratory of the department. Like many of the preceding talks his work focuses on trying to detect Salmonella sp. as quickly as possible from a range of samples. The sampling method he described is the use of adhesive tape, which provides a simple non-destructive means of sample preparation. It involves the removal of cells from the sample surface, quite simply by sticking the tape onto the surface of whatever you want to sample and pulling it off again, then laying the tape in a pre-prepared protective medium for transport to the laboratory. This not only provides a simple means of taking samples but also provides a means whereby the sample (the micro-organisms stuck on the tape) are held in position for presentation and analysis. The cells are effectively concentrated at the surface of the tape and made available in a two-dimensional format on an optically clear substrate so the researcher can observe the pattern and distribution of the organisms as if they were in situ on the product being sampled. The tape sample can then be combined with culture independent methods for molecular detection.

Dr. Brehm-Stecher gave an interesting talk on the pros and cons of the tape method and in summary concluded that the potential use of the tape-FISH method on a variety of surfaces holds great potential, particularly in poultry production around poultry barns – both simple and brilliant.

All talks given at the Research Day are on the PIC website.



PIC’s Picks

It was heavy going for those of us attending the Research Day who are not scientists, and even for those of us who are, if you’re not familiar with the field, it was still a tough afternoon. But this is important work and the complexity of the microsystems involved in foodborne disease underlines the difficulties we as an industry face in combatting these diseases.

Our food production system (and the way we live) lends itself to the rapid movement of disease organisms and there is no better example of this than the recent outbreak of H1N1, which as we know is an international traveller with potentially devastating impact. Recent data from the Canadian Integrated Program for Antimicrobial Resistance Surveillance indicates that while one common strain of salmonella (S. Heidelberg), has been in decline across the chicken food chain since 2002, others (S. enteritidis and S. Kentucky) have been detected as
being on the rise.

Why? Nobody knows. Does this pose an increased threat to our industry? Again nobody knows. We do know that a break within our food safety and biosecurity systems can be disastrous not only for individual organizations, but for entire industries and that is why we continue to invest in and hear reports from the likes of those who addressed us at Research Day this year.

On a lighter note, don’t forget to earmark the PIC golf tournament in your diaries – this year it’s being held on Sept. 9 at the Foxwood golf course to accommodate the higher number of players and also – even though it’s early days – make sure you get your reservations in at the Sheraton Niagara Falls for Nov. 9 and 10 for the Poultry Innovations Conference. For more information on these events, please don’t hesitate to contact PIC or visit our website www.poultryindustrycouncil.ca .


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