IB, Infectious Bronchitis Field Case Study
A broiler chicken farm has a very high daily mortality rate at the age of 24 days due to a respiratory disease. The highest mortality rate is 3,200 broilers per day from 18 houses with a total population of 105,000 chickens. The peak of daily mortality rate in the house that suffered the most severe symptoms is 550 chickens from a population of about 5800 birds and total mortality rate reaches 40% for the house/cycle. The total farm mortality rate is almost 20% until the chicken reaches the age of 30 days. This is a very high number.
Such cases often occur in commercial broiler farms, openside house system. Cases of respiratory disease are the number one problem in conventional broiler farms. But sometimes there is a very significant mortality rate. At the peak of death chicken with the highest number occurred, up to thousands of chickens die per day, many breeders ask, whether their chickens attacked by Avian influenza or vvND ?. Because they assume only HPAI and vvND viruses can kill their chickens in large numbers.
If we do not come to the farm, look at data on mortality patterns, we might assume too, the chickens may die from both viruses. But the reality is not always like that. High mortality is not always caused by malignant viruses such as High pathogenic avian influenza or Newcastle Disease. There are many other causes that can cause a high mortality rate. Infectious and non-infectious. Each cause has different characters and patterns.
Infectious Bronchitis or IB is the most popular respiratory disease in chickens. Acute, highly contagious. The virus has the ability to spread faster than avian influenza virus and also with other viruses. However, IB virus does not have the same killing ability as Avian influenza, vvND or Gumboro virus. But some of the variant strains can cause death in chickens, certainly not as fierce as HPAI virus. Because IB virus has the ability to spread faster, then the impact is also enormous.
The disease can spread rapidly to another house in just a few days. Within a week, 18 houses contained in the farm can already be found the same case. In the case of avian influenza in the tropics, the spread of the disease is not so fast. We can still save the other houses. But not for Infectious Bronchitis.
See video: Infectious Bronchitis Symptoms in Broiler
Clinical symptoms, chickens may cough, sneeze, and have tracheal rales for 10–14 days.
Chicken beak becomes dirty due to the feed that attaches to the exudate around the nostrils and the beak. Other viral diseases are also present in vvND, but in HPAI (by H5N1 virus), respiratory symptoms such as coughing and sneezing and nasal discharge are rare. In HPAI chickens die abruptly before exudate is formed.
Dyspnea may be seen, and sometimes facial swelling, particularly with concurrent bacterial infection of the sinuses and supraorbital. Secondary infections by various bacteria have the greatest contribution to the cause of high mortality. E. coli and Mycoplasma bacteria are important agents that always follow the primary disease. This will aggravate the condition of the chicken. Complex infection between viruses and bacteria makes antibiotic treatment does not provide satisfactory results. So a high mortality rate is certain.
There are no symptoms and very distinctive lesions for infectious bronchitis in broiler chickens that occur at a young age. Rapid disease spread and lower tracheal lesion lesions may be an indicator for diagnosing Infectious Bronchitis, IB.
Infectious viral bronchitis can cause many lesions and symptoms. Symptoms and lesions vary widely, respiratory symptoms and decreased egg production are common symptoms. But some variants of the IB virus may cause renal lesions that can lead to death and permanent lesions of the reproductive organs in laying hens causing false layers.
Tymus, Infectious Bronchitis, IBLesions of the thymus are a common symptom if there is an infection of the respiratory tract by various disease agents.
Lesions in the kidneys are also not a typical lesion for infectious bronchitis, some other diseases can cause similar lesions. Gumboro, vvND, AI can cause similar symptoms. Respiratory symptoms, patterns of disease spread and patterns of death can be used as indicators to distinguish these diseases in addition to using the findings of pathological lesions.
E. coli bacteria cause high mortality in cases of infectious bronchitis. In the tropics, the conventional farm with open-side house system, environmental conditions in the house is very dependent on external environmental conditions, the temperature inside the house during the day is very high. Chicken with conditions of airsacculitis and pericarditis will not be able to survive. In healthy chickens physiologically, when the condition of high temperature during the day normally chicken will panting. However, in chickens with severe lesions on the heart membrane and airsac will not be able to breathe normally. Environmental conditions become the greatest executor to accelerate the killing of sick chickens.
At this farm, clinical symptoms are observed on day 8 only in one house (H4). On day 2, clinical symptoms begin to be found in the house located next to it (H2 & H5). Until a week later, all the houses on the farm have been found respiratory symptoms. However, the mortality rate increases at the time of entering week 3. Bacterial infection begins to play a role. At 30 days, there was significant seroconversion against IB virus, and after isolation, IB QX virus was found. This farm does not vaccinate against Infectious Bronchitis before.
The biggest problem is the high incidence of infectious bronchitis cases in laying hens farms. Decreased production, respiratory symptoms, and cystic oviduct are the symptoms that are easily found in farm-layer farms. The existence of IB virus in farm layer with the multiage system is a certainty. The problem is, many commercial broiler farms are located adjacent to the layer chicken farms. Then the chances of spreading the virus from the layer farm are very high.
Hopefully, this article can be a subject of discussion in the classroom for veterinary students, case study materials for professionals, and to provide inspiration for all. I am very happy if you are willing to share this article with others via social media as a learning material. Thank you.