Variability in practices for drinking water vaccination of meat chickens against infectious laryngotracheitis

Context: Drinking water vaccination of young meat chickens with Infectious Laryngotracheitis (ILT) vaccine is problematic. Vaccine failure and adverse vaccine reactions are frequently reported. Variations in the technique of applying ILT vaccines by this mass vaccination method need to be understood to contribute to improving the success of vaccination. Aims: This study aimed to examine variations in the techniques of application of Infectious Laryngotracheitis vaccines via drinking water for young meat chickens. Methods: Drinking water vaccination techniques were observed and recorded across 52 broiler flocks during ILT outbreaks in three geographic areas of Australia. Descriptive statistics for all variables were computed and variations between integrator company procedures were statistically compared. Key results: Despite rigorous standard operating procedures, wide variations were observed in time of water deprivation prior to vaccination (3–15 min), time drinking water was stabilised prior to addition of vaccine and the type of stabiliser product used, time to activate the flock following filling of the water lines with vaccine (10–127 min), time for the vaccine to be consumed (36–226 min) and the volume of drinking water per bird used to provide the vaccine (11–48 mL/bird). Conclusions: Variation in vaccination technique can affect the success of drinking water vaccination against ILT in young meat chickens. Implications: Understanding the importance of the variable factors in vaccine application method can improve the success of water vaccination against ILT

Comparison of tracheal and choanal cleft swabs and poultry dust samples for detection of Newcastle disease virus and infectious bronchitis virus genome in vaccinated meat chicken flocks

This study assessed different methods (tracheal and choanal cleft swabs from individual birds, and poultry dust as a population level measure) to evaluate the shedding kinetics of infectious bronchitis virus (IBV) and Newcastle disease virus (NDV) genome in meat chicken flocks after spray vaccination at hatchery. Dust samples and tracheal and choanal cleft swabs were collected from four meat chicken flocks at 10, 14, 21 and 31 days post vaccination (dpv) and tested for IBV and NDV genome copies (GC) by reverse transcriptase (RT)-PCR. IBV and NDV GC were detected in all sample types throughout the study period. Detection rates for choanal cleft and tracheal swabs were comparable, with moderate and fair agreement between sample types for IBV (McNemar's = 0.27, kappa = 0.44) and NDV (McNemar's = 0.09; kappa = 0.31) GC respectively. There was no significant association for IBV GC in swabs and dust samples (R2 = 0.15, P = 0.13) but NDV detection rates and viral load in swabs were strongly associated with NDV GC in dust samples (R2 = 0.86 and R2 = 0.90,

Assessment of A20 infectious laryngotracheitis vaccine take in meat chickens using swab and dust samples following mass vaccination in drinking water

Infectious laryngotracheitis, caused by the alphaherpesvirus infectious laryngotracheitis virus (ILTV), is an important disease of chickens. Partial control of this disease in meat chickens is commonly achieved by mass vaccination with live virus in drinking water. There is a need for a practical test to evaluate vaccination outcomes. For the Serva ILTV vaccine, quantitative real-time PCR (qPCR) enumeration of ILTV genome copies (GC) in flock level dust samples collected at 7-8 days post vaccination (dpv) can be used to differentiate flocks with poor and better vaccine take. This study aimed to validate this approach for A20, another widely used ILT vaccine in Australia. In four meat chicken flocks vaccinated with A20 in water using two different water stabilization times (20 or 40 min), swabs from the trachea and choanal cleft and dust samples were collected at 0, 7, 14 and 21 dpv. ILTV GC detection in swabs and dust was highest at 7 dpv and at this time ILTV GC load in dust was strongly and positively associated with vaccine take in individual birds assessed by swab samples. Choanal cleft swabs provided significantly fewer ILTV positive results than paired tracheal swab samples but the level of ILTV GC detected was similar. Water stabilization time had only minor effects on vaccination response in favour of the shorter time. Location of dust collection had no effect on viral load measured in dust samples. Dust samples collected at 0 and 7 dpv can be used to assess the vaccination status of flocks

Turkey Haemorrhagic Enteritis: Australian Situation

Turkey haemorrhagic enteritis (HE) is caused by a group II avian adenovirus known as Haemorrhagic Enteritis Virus (HEV). HE is an acute disease of young growing turkeys with a sudden onset of depression, bloody faeces and a potentially high death rate (Pierson and Fitzgerald, 2008) but HEY may be more important as a cause of subclinical immunosuppression, splenomegaly and increased E. coli infections. An indistinguishable virus causes marble spleen disease (MSD) in pheasants and avian adenovirus splenomegaly (AAS) in chickens and these viruses are able to transmit between the host species. HE is controlled by live virus vaccination with avirulent strains of the virus in most major turkey producing regions of the world, but not Australia although a relatively avirulent strain HEV086 was isolated 30 years ago. HE is present in Australia (Tham and Critchley 1981; Tham and Thies 1988; Arzey and Cross 1990) with Tham and Critchley (1981) describing outbreaks in 7-8 week old broilers with mortality of 0.5-1% over a week. HEY is also considered to be a historical cause of loss of 01 production, illness and mortality in commercial turkey operations typically causing splenomegaly, mortality and increased E. coli infections at around 8-12 weeks of age. The recent status of the disease in Australia is uncertain with few diagnostic tools readily available to investigate it. With funding from the Poultry CRC we sought to • Develop or obtain suitable serological and molecular tests for HEY • Use these in field studies to assess the prevalence and importance of HEV • Develop a vaccine for HEY based on strain HEV08