For the first time in Bangladesh, 2 strains of IBH virus identified in chickens

For the first time in Bangladesh, two serotypes (8b and 11) of the fowl adenovirus responsible for causing Inclusion Body Hepatitis (IBH) in broiler chickens have been identified. The discovery was made by Professor Dr. Md. Alimul Islam and his research team from the Department of Microbiology and Hygiene at Bangladesh Agricultural University (BAU).

The study, funded by BAS-USDA, was led by Dr. Alimul Islam, with Professor Dr. Md. Ariful Islam from the same department serving as co-principal investigator. Several postgraduate students from BAU were also involved in the research.

According to Dr. Alimul Islam, around 2018, Bangladesh experienced a sudden spike in the mortality of young broiler chickens (aged 3–6 weeks), causing significant losses for poultry farmers. At the time, large commercial poultry farms had their chickens tested in various labs using histopathology and molecular detection techniques. The tests confirmed that it was neither bird flu nor Newcastle disease but a new type of virus. Although the virus was identified, it had not been isolated. Given that broiler meat is a key source of animal protein for the general population, this research was initiated to help address the issue. The findings have recently been published in the journal Frontiers in Microbiology.

Dr. Alimul Islam explained that Inclusion Body Hepatitis (IBH) is a newly emerging disease caused by the fowl adenovirus. The virus has 11 serotypes and five genotypes, with serotypes 8b and 11 being the most lethal. It primarily affects commercial broiler chickens, though it can also infect layers.

Regarding the symptoms observed in infected chickens, Dr. Islam noted that the disease is particularly prevalent in young birds, especially 14-day-old broilers. Starting from day 15, affected chickens show reduced appetite, movement, and growth. By day 21, full symptoms become evident. These include lethargy, weakness, and diarrhea, and many chickens die by the time they are 3–4 weeks old. Postmortem examinations reveal that the inner layer of the gizzard becomes soft and easily peels off. Focal nodular growths appear in the liver and kidneys, and hydropericardium is observed in the heart. The virus kills the chickens before they reach market size, causing significant financial losses for farmers.

Dr. Islam added that the virus spreads both vertically (through eggs) and horizontally (from one chicken to another within the farm).

Describing the research methodology, he said the team used conventional PCR and RT-PCR for virus detection and isolated the virus using avian embryos. Partial genome sequence analysis was completed, while whole genome sequencing is still underway.

Dr. Islam further stated that their vaccine, administered in two doses to chickens, was found to be highly effective against the disease when tested against field virus challenges. The vaccinated chickens were monitored over the course of a year, and none showed signs of IBH infection during that period.

However, he emphasized the need for further research, noting that two trial runs of the vaccine have been completed. A third trial is planned, after which the vaccine study will be submitted to an international journal. Still, more research is necessary to finalize and commercialize the vaccine.