Newcastle Disease Past Paper PDF

Made with Xodo PDF Reader and Editor Newcastle Disease Newcastle Disease Introduction ‫( ﻫﻮ ﻣﺮض ﻓﻴﺮوﺳﻲ ﻷﻧﻮاع ﻛﺜﻴﺮة ﻣﻦ اﻟﺪواﺟﻦ واﻟﻄﻴﻮر‬ND) ‫ﻣﺮض ﻧﻴﻮﻛﺎﺳﻞ‬ ‫اﻟﺒﺮﻳﺔ واﻷﻗﻔﺎص اﻟﺘﻲ ﺗﺘﻤﻴﺰ ﺑﺘﺒﺎﻳﻦ ﻣﻠﺤﻮظ ﻓﻲ اﻟﻤﺮاﺿﺔ...

Made with Xodo PDF Reader and Editor Newcastle Disease Newcastle Disease Introduction ‫( ﻫﻮ ﻣﺮض ﻓﻴﺮوﺳﻲ ﻷﻧﻮاع ﻛﺜﻴﺮة ﻣﻦ اﻟﺪواﺟﻦ واﻟﻄﻴﻮر‬ND) ‫ﻣﺮض ﻧﻴﻮﻛﺎﺳﻞ‬ ‫اﻟﺒﺮﻳﺔ واﻷﻗﻔﺎص اﻟﺘﻲ ﺗﺘﻤﻴﺰ ﺑﺘﺒﺎﻳﻦ ﻣﻠﺤﻮظ ﻓﻲ اﻟﻤﺮاﺿﺔ واﻟﻮﻓﻴﺎت واﻟﻌﻼﻣﺎت‬ Definition ‫واﻵﻓﺎت‬ Newcastle disease (ND) is a viral disease of many kinds of poultry, wild and cage birds characterized by marked variation in morbidity, mortality, signs and lesions. ‫ ﺳﻨﻮات‬10 ‫ وﻓﻲ ﻏﻀﻮن‬.1926 ‫ ﻷول ﻣﺮة ﻓﻲ ﺟﺎوة وإﻧﺪوﻧﻴﺴﻴﺎ وﻧﻴﻮﻛﺎﺳﻞ أﺑﻮن ﺗﺎﻳﻦ ﺑﺈﻧﺠﻠﺘﺮا ﻓﻲ ﻋﺎم‬ND ‫ﻇﻬﺮت‬ History ‫ ﻛﺎن ﻫﻨﺎك داء ﺑﺎﻧﺴﻴﻮﺗﻴﻚ ﻟﻠﻤﺮض‬، ‫ ﺧﻼل أواﺧﺮ اﻟﺴﺘﻴﻨﻴﺎت‬.‫اﻧﺘﺸﺮت إﻟﻰ اﻟﻌﺪﻳﺪ ﻣﻦ اﻟﺒﻠﺪان ﻓﻲ ﺟﻤﻴﻊ أﻧﺤﺎء اﻟﻌﺎﻟﻢ‬ ‫ ﻓﻲ اﻟﻌﺮاق‬AG68 ‫ ﺗﻢ ﻋﺰل اﻟﺴﻼﻟﺔ‬، ‫ ﺧﻼل ﻫﺬا اﻟﺒﺎﻧﺰوﺗﻴﻚ‬.‫ﻓﻲ اﻟﺸﺮق اﻷوﺳﻂ‬ ND first appeared in Java, Indonesia and Newcastle-upon-Tyne, England in 1926. Within 10 years it had spread to many countries throughout the world. During the late 1960s, there was a panzootic of the disease in the Middle East. During this panzootic, the strain AG68 was isolated in Iraq. Etiology Classification Family: Paramyxoviridae, Genus: Avulavirus include 11 serotypes or species (APMV-1 to APMV-11) Species: paramyxoviruse-1 (APV-1) or Newcastle Disease Virus (NDV) ‫ أﺣﺎدي‬RNA ‫ وﻓﻴﺮوس‬، ‫ ﻏﻴﺮ ﻣﺠﺰأ وﺳﻠﺒﻲ‬RNA ‫ ﻫﻮ ﻓﻴﺮوس‬NDV ‫ﺟﻴﻨﻮم‬ Virion properties ‫اﻟﺸﺮﻳﻄﺔ ﻣﻊ ﺗﻨﺎﻇﺮ ﻗﻔﻴﺼﺔ ﺣﻠﺰوﻧﻲ وﻫﻮ ﻓﻴﺮوس ﻣﻐﻠﻒ‬ NDV genome is a non-segmented, negative sense, single-stranded RNA viruse with helical capsid symmetry and it’s an enveloped virus. Pathotypes ‫ إﻟﻰ ﺧﻤﺴﺔ أﻧﻤﺎط ﻣﺮﺿﻴﺔ‬APMV-1 ‫ ﺗﻢ ﺗﺼﻨﻴﻒ ﺳﻼﻻت‬،‫ﺑﻨﺎء ﻋﻠﻰ اﻟﻌﻼﻣﺎت اﻟﺴﺮﻳﺮﻳﺔ ﻓﻲ اﻟﺪﺟﺎج اﻟﻤﺼﺎب‬ ً Based on clinical signs in infected chickens strains of APMV-1 have been grouped into five pathotypes: 1. Viscerotropic velogenic (Doyle’s form): hemorrhagic intestinal lesions are frequently seen with high mortality. 2. Neurotropic velogenic (Beach’s form): respiratory and nervous signs with high mortality hence it is also named Pneumoencephalitis. 1  Made with Xodo PDF Reader and Editor Newcastle Disease 3. Mesogenic (Beaudette’s form) : respiratory signs and occasional nervous signs with low mortality. 4. Lentogenic or respiratory (Hitchner’s form) : mild respiratory infection. 5. Asymptomatic enteric: subclinical enteric infection Epizootiology Distribution The disease occurs in all poultry-raising countries. According to the OIE (2015) there are 16 countries where the disease has never occurred. Hosts The disease usually occurs in chickens or (less often) in turkeys, although most poultry and many wild and cage birds are susceptible. All age groups are susceptible. Natural or experimental infection has been demonstrated in at least 241 bird species. Transmission Horizontal Newcastle disease virus transmits horizontally from infected to susceptible birds. Birds can be infected by virus inhalation, ingestion and contact with mucus membrane like conjunctiva. Shedding of the virus from infected birds depend on the organ in which the virus replicates. Birds manifesting respiratory signs shed the virus in respiratory secretions. On the other hand, birds shed the virus in feces when they suffer from digestive pathotypes. Vertical NDV is known not to be able to transmit vertically (because it kills the embryos), although there are some reports of isolation of the virulent virus from embryonated eggs, day-old chicks, and dead-in-shell birds. Carriers Any bird can be infected with NDV of low virulence, mount an immune response, be subsequently infected with vNDV, and without demonstrating clinical signs shed the vNDV to susceptible birds, acting as a carrier of the ND. 2  Made with Xodo PDF Reader and Editor Newcastle Disease Vectors and Spread Evidence that humans, mammals, or insects are biological vectors of spread of ND is lacking. spread by humans is more likely mediated by transport of contaminated fomites. NDV contaminated equipment, clothing, shoes, feed, water, vaccines, and poultry products, and NDV-infected birds (wild or domestic) moved or placed into contact with susceptible birds where virus can be inhaled or ingested can lead to the spread of ND. Clinical signs Incubation period The incubation period of ND can vary from two to fifteen days and averages from four to six days in natural infection. The length of incubation period? depends on several factors: species, immune status and age of the host; virulence and dose of the virus; and even route of infection. In cases of experimental infections, the incubation period ranges from one to four days. These factors also result in variation in the resulting clinical signs. Signs 1. When non-vaccinated birds are infected with viscerotropic isolate of NDV, they will become depressed and listless 2 days after the infection. Three to four days post infection there will be high mortality reaching 100%. When the bird gets the infection from the oculonasal rout, the clinical presentation could be bilateral conjunctivitis with facial swelling. A clear mucous could be seen dropping from the mouth when the bird tilts its head downwards. The feces may be green and watery and there may be cyanosis of the comb. 2. In cases of infection with virulent neurotropic strain, the birds become excitable. After 5 days, there may be tremor of the head, torticollis, and paralysis of a wing or a leg. In such infection, death is mainly due to inability to access food and water. The mortality may reach up to 50%. 3. Adult layers that are vaccinated properly may show decreased egg production one week after infection. After a month, the hen may lay misshapen and bleached eggs and continue to lay these types of eggs for the rest of its life. 3  Made with Xodo PDF Reader and Editor Newcastle Disease Pathology Gross lesions 1. The most common lesions in viscerotropic NDV infection are necrosis and hemorrhagic lesions involving lymphoid organs such as Peyer’s patches, cecal tonsils and harderian gland. Moreover, there may be hemorrhage in the thymus and proventriculus with splenomegaly. 2. With velogenic neurotropic NDV infection, there are occasionally mild splenic congestion and simple atrophy in the thymus. Gross pathological lesions in the central nervous system are not seen. 3. Lesions in the respiratory system are rare with the exception of thickening of the air sacs due to secondary infections. 4. Egg yolk peritonitis with atrophied follicles and degenerated oviduct may appear during birds in lay. Histopathology 1. necrosis with lymphoid depletion of cecal tonsils, spleen, thymus, eyelid, and bursa. 2. histiocytic airsacculitis. 3. lymphohistiocytic airsacculitis. 4. gliosis with perivascular cuffing; medulla, cerebellum, and brainstem. 5. yolk peritonitis with foamy macrophages of subserosal space of oviduct. 6. necrotic myocarditis. 7. bone marrow necrosis. 8. pancreatic, thymic, hepatic necrosis. 9. necrosis and ulceration of epithelium of intestine. 10.hemorrhagic, ulcerative tracheitis Diagnosis 1. Clinical diagnosis based on history, signs, and lesions may establish a strong 4  Made with Xodo PDF Reader and Editor Newcastle Disease index of suspicion. 2. Virus isolation and subsequent pathogenicity testing, 3. RT-PCR – demonstration of viral RNA and subsequent typing, 4. Serology - demonstration of increasing titer of Newcastle antibody in the flock from onset to convalescence by ELISA or HI. Differential Diagnosis The clinical presentation of other diseases, such as aspergillosis, mycoplasmosis, infectious laryngotracheitis, fowl cholera, infectious bronchitis, and highly pathogenic avian influenza, can be confused with ND. Control 1. Chickens and turkeys can be immunized against ND by proper vaccination. The method of vaccine administration has considerable influence on the immune response. Low-virulence live-virus vaccines are administered by a variety of routes and schedules from hatching through grow-out. Killed-virus oil- emulsion vaccines are administered parentally as a final vaccine prior to the onset of egg production. Although proper vaccination protects the birds from serious clinical disease it does not prevent virus replication and shed, which could be a source of infection to other flocks. 2. Stringent laws are in effect pertaining to the importation of poultry, poultry products, and cage birds. However, enforcement is often a difficult and nebulous problem. 3. ND is a reportable disease. All suspected outbreaks of ND must be reported to animal health authorities immediately. Treatment No treatment available. 1. No effective treatment of ND is known although broad-spectrum antibiotics may control the complications. 2. For baby chicks with NDV, it may be helpful to increase the room temperature, encourage the birds to eat by using a warm moist mash, and correct any apparent management deficiencies. 5