1. Respiratory System Diseases Physiology, Prevalence, Diagnosis and Treatment

2. Physiology  Respiratory diseases in commercial flocks are usually predisposed to by sub-optimum environmental conditions such as inadequate ventilation, high litter moisture content or concurrent disease problems.  The respiratory tract of the bird demonstrates unique adaptations that have evolved to accommodate high metabolic rates and highly energetic activities such as flight.  the bird has an increased pulmonary capillary blood volume and a much thinner blood/gas exchange barrier than mammals, which result in a greater pulmonary diffusing capacity for oxygen. The avian erythrocyte is also more efficient in oxygen uptake. If all these factors are included in calculations, the bird may have up to an 82%increase in efficiency of oxygen uptake compared to a mammal.

3.  The lung of the bird is of a fixed volume and does not expand and contract appreciably during the respiratory cycle. The lung is not divided into lobes or lobules like the mammalian lung, but is closely associated with the thoracic rib cage. Airflow is unidirectional coupled with a counter current or cross current blood flow, which maximizes the oxygen uptake gradient in the avian lung. Therefore, the air flow pattern influences the distribution of respiratory disease, as inhaled particles or pathogens are deposited in the caudal air sacs of the lungs.  the respiratory tract of the bird fulfills several important functions including: exchange of gases (i.e.. intake of oxygen and elimination of carbon dioxide); regulation of acid/base balance; filtration of dust, molds and other particulate material; temperature regulation of incoming air; also plays a highly significant role in the control of body temperature and in the regulation of body water balance.

5. Prevalence of Disease  Size and prevalence of poultry units has increased the incidence of respiratory diseases the world over.  Secondary bacterial invaders predominate.  Result is high mortality in young birds, poor growth and food conversion.  Prevention of Newcastle and/or Infectious Bronchitis through vaccines is dependent on the local challenge strains that predominate and the parental immunity of the chicks derived from infection in the parent flock or from a suitable vaccination policy.  Additionally, protection from secondary bacterial infections is provided by good husbandry methods, including warmth, air flow, lighting and litter control.  Infectious Bronchitis is prevalent worldwide and is the most widely experienced virus. It primarily affects the respiratory system, but can also cause a serious effect on the kidneys, known as uremia.  Newcastle Disease Virus occurs world over in large poultry populations. First reported in 1927 in Newcastle, England. Usually the more virulent outbreaks occur in warmer climates

6. Infectious Bronchitis- the Coronavirus * helical capsid, enveloped, with club-shaped spikes (peplomers) * single-stranded, positive sense RNA

7. * produce respiratory and intestinal infections * often have short incubation period Infectious Bronchitis- the Coronavirus

8. Newcastle Disease Virus- the Paramyxovirus * single stranded, -ve sense RNA, NON-segmented helical nucleocapsid, enveloped HN F Helical nucleocapsid Envelope

9.  Infectious Bronchitis Virus is most noticeable by respiratory noise, I.e. sneezing, gasping, etc. Worsening includes eye- watering, nasal discharge and increasing mortality and secondary infections, predominantly e. coli.  In older birds, Bronchitis has the profound effect on the female egg laying ability. The oviduct swells, trapping the egg and stopping production. Egg quality is poor, shape of egg is strange and the shells are ridged and lack pigment. The white of the egg is watery.  Post-mortem signs in chicks include catarrh of the trachea, congested lungs and cloudy air sacs. If the kidneys are affected, they will be white and enlarged with urate deposits. Symptoms of Disease- Bronchitis

10.  Newcastle Disease Virus has an incubation of 2-7 days but can prolong to 3 weeks. Signs include an indifference to food and water. Respiratory distress signs, such as struggling for breath and wheezing. Also watch for nervous disorders such as drooping wings, lack of coordination, and twitching.  Symptoms can also include hemorrhagic enteritis and tracheitis, encephalitis  In adults, the signs are not so obvious with only occasional drops in egg production accompanied with recovery.  Post-mortem signs include and inflamed respiratory tract, cloudy air sacs, small hemorrhages known as ‘petechiae’ on the heart and proventriculus. Symptoms of Disease- Newcastle

11.  Infectious Bronchitis and Newcastle Disease both have prominent post-mortem signs, but immunological testing should be performed to validate the agent affecting the birds and to eliminate the possibility of progression of illnesses due to secondary infections or other agents playing a role in the disease.  Testing methods include virus isolation, or hemagglutination inhibition or ELISA. Diagnosis

12. * highly contagious respiratory disease of young chickens  significant economic losses Acute tracheitis Infectious Bronchitis virus (coronavirus)

13. * causes loss of egg production/quality and nephrosis in older birds Nephrosis in 6 week-old bird Infectious Bronchitis virus (coronavirus)

14. * causes severe, generalized disease with high morbidity and mortality rates, in chickens * birds die acutely with respiratory, intestinal and nervous signs; hemorrhagic enteritis and tracheitis, encephalitis Newcastle disease virus (Avian paramyxovirus 1) Hepatic necrosis and hemorrhage

15.  Vaccinate all parent flocks thoroughly.  Vaccinate immediately after hatching if possible. In large numbers, odds are some chicks will not have maternal immunity.  Early vaccination allows for less stress later, therefore eliminating the results of undue stress.  For Newcastle, there are three widely used vaccines, two being live (Hitchner B1 and LaSota) and one an inactivated oil-based vaccine. The first two are administered by spray, drinking water, or occasionally eye-drop, while the oil-based vaccine is given intra-muscularly. Hitchner provides a gentle, immediate vaccine, but only lasts for a few weeks. LaSota is a little more stressful, but is still mild enough and protects for up to 12 weeks. Treatment and Control

16.  The Oil-based Newcastle vaccine is mostly administered to older birds, commonly at point of lay, protecting through the laying season, but does not give immediate protection.  Infectious Bronchitis vaccinations are usually administered to immature birds by the use of live vaccine, e.g. H-120 and H-52 as a coarse spray or in the drinking water.  Adults may be vaccinated for bronchitis by injection with inactivated vaccines.  To curb secondary infections, use chlortetracycline or potentiated sulphonamides. Examples of treatments for secondaries are oxytetracycline or chlortetracycline. Treatment and Control-cont.

17. Vaccination Schedule