Summary of avian infectious laryngotracheitis virus (AILTV)

Avian Infectious Laryngotracheitis Virus (Avian Infectious Laryngotracheitis Virus comes, AILTV) is a kind of chicken cause upper respiratory tract infection pathogens, pose a serious threat to poultry industry. The virus belong to the herpes virus family with capsule membrane, nucleic acid for the two strands of DNA, virus particles are spherical. AILTV have different strains, all have differences in pathogenicity and antigenicity. Virus is sensitive to ethyl ether, chloroform and other fat solvents, easy reproduction in chicken embryo, the embryo infection 2 ~ 12 days after death.

The epidemiological characteristics of

AILTV mainly through respiratory and digestive tract infection, poisoned disease chicken and chicken are the main source of transmission. Virus spread in the henhouse, spread, and spread to the whole chicken farm, make become infectious laryngotracheitis often hair. Healthy chickens infection mainly upper respiratory and eye conjunctiva, through the digestive tract can be infection, virus infection after long-term exists in the larynx, trachea mucosa epithelial cells, the poison to the world and become a new source of infection, forming cycle.

Clinical symptoms and pathological changes

AILTV clinical symptoms include dyspnea, cough, cough up blood exudate, laryngeal and tracheal mucosa swelling, bleeding and erosion. Sick chicken may appear stretched neck symptoms of gas, this is a typical symptom of AILT. Early onset, the chickens infected fast, symptoms usually only a few chickens on the first day, the second day will spread to the whole group. Serious when stretched neck gas pull phenomenon, and respiratory tract with frogs called snoring sound. In addition, in the early AILT egg quality will drop, but drop. After a period of time, if not effective treatment measures, the crowd will AILT peculiar symptoms - blood, visible feathers or cages have shrugged off blood phlegmy, generally is a thumb size, more fine. This is because after the onset of 5 ~ 6 d, tracheal mucosa bleeding is more, condenses into bloody sputum plugging in trachea, resulting in the chicken group stretched neck pull out gas. At this point, the chicken's mortality rate increased significantly, autopsy chickens will find death, sputum or blood, or peritonitis. AILT killing chickens there are two main causes, one is due to the trachea blocked by blood phlegmy, causing difficulty in breathing, choked to death, this is the most common cause of death in AILT; Another reason is because the AILT induced disease yolk to fall into the abdominal cavity, the formation of eggs peritonitis, which can lead to death.

Prevention and control measures

Prevention and control measures including strengthen management, improve the tunnel ventilation, fight disease and the introduction of poisoned chicken, chicken strict disinfection measures to prevent the pathogen invasion. For never happened this ill chicken is not advocating a vaccination. Happened to chicken infectious laryngotracheitis outbreak of epidemic area case or within the area of health chicken, should be immunized. Eyedrops and anorectal immunization with the attenuated vaccine can be used for immunization. For commercial broiler farms, vaccination is generally not recommended. When chicken farms nearby outbreaks of the disease or the chicken farms have outbreaks of the disease and lack of effective measures, can use genetically engineered vaccine carrier or vaccinations. For the affected flocks, the healthy flocks should be urgently vaccinated with live infectious laryngotracheitis vaccine by eye drops or anal application. At the same time, the disease should be isolated feeding chicken, with reference to relevant standards for symptomatic treatment.

The main routes of transmission of avian infectious laryngotracheitis virus

The main routes of transmission of avian infectious laryngotracheitis virus (ILTV) include:

• Respiratory transmission: The virus is present in the trachea and secretions of the upper respiratory tract and is transmitted via the upper respiratory tract by coughing up blood and mucus. This is the most common mode of transmission, especially in densely packed, poorly ventilated environments.
• Eye conjunctiva spread: the virus can also enter the chicken body through eye conjunctiva, especially infectious respiratory secretions in the chickens was overflowing or coughed, easily by eye conjunctiva is transmitted to other susceptible chicken.
• Indirect contact transmission: virus can through contaminated feed, water, basket and other transmission through the digestive tract. In addition, in the hen house dust, feathers and other media can also be a virus.
• Vertical transmission: although generally think chicken infectious laryngotracheitis cannot pass the breeder eggs vertical transmission, but in some cases, if the infected hens lay eggs during the disease, may also pass the virus to the next generation.

In order to effectively control and prevent the spread of avian infectious laryngotracheitis, recommend the following measures:

• Strengthen management, to ensure that the hen house well ventilated, avoid overcrowding.
• Regularly to cleaning and disinfection of the henhouse, the survival time of reduce the virus in the environment.
• The chicken of newly introduced in quarantine, confirmation of health can be incorporated into groups.
• Implement an all-in, all-out feeding management system to reduce the risk of cross infection.
• When necessary, can use the vaccine immunization, to improve the chicken group of disease resistance.

Avian infectious laryngotracheitis and other poultry disease symptoms

Avian infectious laryngotracheitis (ILT) is an acute respiratory infectious diseases, mainly affects chickens, especially adults. Its characteristic symptoms include dyspnea, cough, stretched his neck out, tracheal secretions in the mixed with blood. Pathological changes mainly concentrated in the larynx and trachea, has the characteristics of the transmission is fast, high fatality rate.

The difference from avian influenza

Bird flu is caused by type A influenza virus A deadly infectious diseases, symptoms and pathological changes, there are many similarities with ILT, such as difficulty in breathing, trachea ring hemorrhage and secretions, diseased fever, rate decline is larger, soft shell eggs, sometimes see salpingitis. However, the symptoms of avian influenza are usually more severe, may be associated with a high mortality rate, and the causative agent of avian influenza is the influenza virus, not the specific virus of ILT.

Differences from chicken Newcastle disease

Newcastle disease (ND) is caused by the new town of a highly contagious disease, symptoms include stretched neck breathing, cough, head, grunting, torticollis failed, feet, limb paralysis, laying down; Autopsy found larynx, trachea mucous, tracheal mucous membrane annular thickening bleeding, lung, brain haemorrhage. ILT, by contrast, focus more on the symptoms of respiratory symptoms, such as cough, difficulty breathing, quick, quick mouth stretched neck, death, cough with mucus blood.

The difference between with infectious bronchitis

Infectious bronchitis (IB) is an acute respiratory infectious disease caused by the infectious bronchitis virus that primarily affects young chickens. Symptoms include cough, sneeze, transmission is fast, abnormal breathing sound, throat, bronchial mucus, since on trachea by the bleeding obvious, sometimes with embolization. The ILT symptoms tend to adult chicken, characterized by cough, difficulty breathing, quick, quick mouth stretched neck, death, cough with mucus blood.

The difference from infectious rhinitis

Infectious rhinitis is a kind of disease, caused by deputy haemophilus symptoms include left nose, sneezing, difficulty breathing, high morbidity, mortality is low, nasal symptoms, nasal fluid, tears; Autopsy nasal cavity and sinuses mucosa red or yellow caseous material, face swollen but soft. The symptoms of ILT are more focused on respiratory symptoms, such as cough, dyspnea, rapid onset, opening of the mouth and neck, rapid death, and coughing up bloody mucus.

The difference from infectious Bursal disease in chicken

Chicken infectious bursal disease symptoms include muscle pale, see more at chicks, and the ILT is more focused on the symptoms of respiratory symptoms, such as cough, difficulty breathing, quick, quick mouth stretched neck, death, cough with mucus blood.

To sum up, the symptoms of avian infectious laryngotracheitis and several other diseases is different, mainly reflected in the chicken group age, severity of the symptoms of the disease, as well as on the part of the pathological changes. By looking at these characteristics, can help the differential diagnosis of veterinary or aquaculture preliminarily.

Types of avian infectious laryngotracheitis vaccines

Avian infectious laryngotracheitis (ILT) is caused by infectious laryngotracheitis virus an acute and contact of the upper respiratory tract infection, main effect in a crowd. In order to prevent and control the disease, at present there are many types of vaccines are available. Here are some commonly used vaccine types:

• Source of chicken embryos live vaccine (CEO) : the vaccine using a specific strains inoculated into chicken embryo, after a period of training, collected and made the vaccine virus. Commonly used vaccine strains including K317 strains, A - 96 strains, CHP50 strains and Serva strains, etc. These vaccines are usually through the eye way to chickens inoculated, has a good protective effect, but there may be some side effects.
• Source of tissue cell vaccine (TCO) : the vaccine is through online vaccine virus in certain cells, then collect the virus. LT - IVAX strains, for example, is a source of tissue cells live vaccine, it is also through the eye, with low toxicity and less side effects.
• Genetic engineering vaccine: this vaccine using modern biological technology, the key to the virus gene inserted into other organisms, so as to produce a vaccine. Chicken infectious laryngotracheitis restructuring chicken pox virus, for example, bigeminal vaccine and chicken infectious laryngotracheitis recombinant chicken pox virus gene engineering vaccine belong to this kind of vaccine, they through the patagium kind of way of vaccination, under whose wings can prevent chicken pox and can prevent the chicken infectious laryngotracheitis, and no side effects.

When choosing the vaccine, should according to the characteristics of the actual situation of chickens and vaccines, choose suitable products and inoculated in the correct method, to ensure the safety and effectiveness of immunity. Vaccines should be paid attention to at the same time, storage and use conditions, avoid vaccine failure or adverse reaction.