Infectious Sinusitis in Poultry

 

 

Dr. Majid Hamid Al-Sayegh / Australia

Introduction

Infectious sinusitis is an acute respiratory disease of poultry caused by the bacterium Avibacterium paragallinarum. The disease is characterized by symptoms such as nasal discharge, sneezing, and facial swelling. The disease is prevalent worldwide, especially in poultry flocks in low- and middle-income countries. The disease usually occurs in young poultry (about 3 weeks of age), but can also affect older poultry. Although infectious sinusitis is not a zoonotic disease and does not affect human health, it can cause significant economic losses in the poultry industry due to reduced productivity.

 

Cause

The main causative agent of infectious sinusitis is Avibacterium paragallinarum, a Gram-negative, non-motile, pleomorphic bacterium. These bacteria are facultative aerobes, meaning they require low levels of oxygen to grow, and are dependent on the vitamin nicotinamide adenine dinucleotide (V-factor) for growth in the laboratory. A. paragallinarum forms characteristic satellite colonies when grown on blood agar with a host colony of staphylococci that produce V-factor. There are three strains of A. paragallinarum (A, B, and C), which differ in immunological characteristics. The distribution of strains varies worldwide, with specific strains reported in some countries.

 

Epidemiology

Susceptible hosts

Poultry of all ages can be affected by A. paragallinarum, with young birds being most susceptible. Infection may persist in carrier birds that are asymptomatic but are a source of infection. The incubation period for the disease is 1–3 days, and the disease usually lasts 2–3 weeks, but may be longer if there is a concomitant infection such as mycoplasma.

 

Modes of Transmission

The disease is transmitted through direct contact with infected birds, airborne droplets, or contaminated water. The disease is not transmitted through eggs. Biosecurity practices such as the “group entry/group exit” system have helped to limit the spread of infectious sinusitis in commercial poultry farms. However, outbreaks still occur in farms with multi-age flocks or those that lack biosecurity measures.

 

Symptoms and signs

Clinical symptoms

The incubation period for infectious sinusitis ranges from 1-3 days, and the disease usually lasts for 2-3 weeks. Symptoms vary from mild to severe depending on the age of the poultry:

Mild form: occurs in young birds, and symptoms include lethargy, depression, serous nasal discharge, and slight facial swelling.

Severe form: occurs in older birds, and is characterized by facial swelling, severe nasal discharge (mucoid or purulent), conjunctivitis, and lacrimation. Birds may have difficulty opening their eyes due to swelling. Breath sounds may also occur due to pneumonia and air sacculitis.

 

Physical lesions

Affected birds typically show swelling and congestion of the nasal passages, sinuses, and lungs. Bleeding and mucus accumulation in the trachea and other organs may be observed. In some cases, secondary infection may aggravate the condition.

 

Histopathological examination

Microscopic examination reveals keratinization (thickening) and vascular congestion of the nasal mucosa, as well as pulmonary lesions due to inflammation. These findings are consistent with previous studies of infectious sinusitis.

 

Diagnosis

Infectious sinusitis is diagnosed using several methods, including PCR testing, bacterial culture, and clinical observation. Swabs are taken from the nasal passages and sinuses of affected birds, cultured on blood agar, and the presence of A. paragallinarum is confirmed using molecular techniques or the production of characteristic satellite colonies. Serological tests such as the clotting inhibition (HI) test are also used to detect antibodies.

 

Treatment

Early treatment is vital to reduce the severity and duration of the disease. Antibiotics such as erythromycin, oxytetracycline and sulfonamides are commonly used for treatment. In severe outbreaks, drugs such as enrofloxacin and newer generation antibiotics may also be effective. Treatment may result in improvement, but relapse may occur if treatment is stopped prematurely. Supportive care is essential, and secondary infections, particularly with mycoplasma species, may require additional treatment.

 

Prevention and control

The primary method of control is prevention through good biosecurity practices. A ‘mass entry/mass exit’ management system, where birds are removed and replaced simultaneously, is effective in reducing outbreaks. Replacement birds should come from disease-free flocks, and vaccination can help reduce the impact of the disease. Vaccination should be given approximately 4 weeks before the expected outbreak to ensure protection. Vaccines are available but may not provide cross-protection against all strains.

 

Conclusion

Infectious sinusitis is a serious respiratory disease of poultry, causing significant economic losses in the poultry industry. Although vaccines and antibiotics are available, prevention through strict biosecurity measures is the most effective strategy to reduce the spread of the disease. Early diagnosis and prompt treatment, combined with appropriate farm management practices, can help mitigate the impact of infectious sinusitis on animal production.