BACKGROUND: Serological survey of NDV infection from LBMs would give a good picture of Newcastle disease ecology in a country.OBJECTIVES: This cross-sectional study was carried out to evaluate the seroprevalence of Newcastle disease in live bird markets, bird parks, and zoos in Iran.METHODS: From July to December 2016, blood samples were collected from different bird species in each unit. The serum samples were evaluated via Hemagglutination inhibition test. The seropositive sample was considered a serum with antibody titer 4 or more (1.16) in HI, and units with at least one seropositive bird were considered as the contaminated unit. In this study, the serum samples were taken from various bird species (N=2292) selected from 127 bird markets, bird parks, and zoos distributed in 22 Iranian provinces.RESULTS: Among the 127 sampled units, 70 (55.12 %) were found to be seropositive. In addition, among the 2292 sampled birds, the number of seropositive birds were found to be 495. Among different bird species, the highest sero-positive prevalence belonged to chickens and turkeys with 38.7 % and 32.89 %, respectively.CONCLUSIONS: The results of this study suggested a high prevalence of Newcastle disease in the live bird markets, bird parks, and consequently, across our country. Given the importance of this infectious disease, it is essential to apply appropriate controlling measures, including continuous surveillances of circulating viruses and vaccination programs with conventional vaccines, such as heat-resistant vaccines. On account of the important role of rural poultry and wild birds in Newcastle disease distribution, controlling the disease in rural poultry and continuous surveillance in both can prevent the spread of NDV, particularly to the commercial poultry.

BACKGROUND:  Among infectious diseases, Newcastle disease, due to being highly contagious and its rapid spread among poultry and other bird species, is a deadly viral disease and is considered a global threat to the poultry industry. Objectives: To determine the occurrence of Newcastle disease in poultry broiler farms reported to the Iranian veterinary organization during the study period. Methods: This is a cross-sectional study from September 2013 to March 2015. During this study, from 185 farms and a total of 3700 bird sera, cloacal and tracheal swabs were sampled and tested using a haemagglutination inhibition test and reverse transcriptase polymerase chain reaction respectively. Results: In this study, of a total of 185 farms reported to the Iranian Veterinary Organization, 115 farms (62.16%, 95%CI: 55.17-69.14) were positive for Newcastle disease viruses and then using specific primers, 69 farms (37.3%, 95%CI: 30.33-44.26) had vaccinal pathotype (non-acute) and 46 farms (25%, 95%CI: 18.76-31.23) had acute pathotype (field virus). The mean±SD age of infected poultry was 24.63±5.38 days and antibodies titer against Newcastle disease virus was 5.97±1.21. The highest mortality rates were observed in the spring (32.34%) and winter (26.9%), respectively. Mazandaran (37%) and Isfahan (22%) province had the highest percentage of farms with Newcastle disease. Conclusions: The findings of this study suggested virulent Newcastle virus strains are circulating in the Iranian commercial broiler farms in the mentioned time and with high occurrence. Therefore, the relevant authorities need to make correct decisions to reduce the risk of Newcastle disease in the Iranian poultry industry and its control.

Newcastle Disease (ND) is a highly infectious disease of poultry causing huge economic loss to the poultry farmers. Newcastle Disease is controlled by vaccination of commercial or backyard poultry using inactivated or live ND vaccines. In the present study, safety and humoral antibody response in birds vaccinated with Newcastle disease virus oral pellet vaccine (NDV OPV) was studied in field conditions. A total of 300 backyard poultry (n=100/ farm) from three different farms were vaccinated with NDV OPV. The vaccinated birds were monitored for any adverse reactions or mortality up to 28 days post vaccination (dpv). There were no untoward reactions or mortality in the vaccinated birds in all the three farms up to 28 dpv. Blood samples (n=8/farm) were collected randomly from vaccinated birds on 0 and 28 dpv in each farm and were subjected to heamagglutination inhibition (HI) test. The mean HI titre was 66, 56 and 25 in farm 1, farm 2 and farm 3 respectively at 28 dpv. All the vaccinated birds had protective HI titre of ≥16 at 28 days post vaccination. In conclusion, Newcastle disease virus oral pellet vaccine (NDV OPV) is safe and induces good protective humoral antibody response and can be used to control ND in backyard poultry.

Vaccination against Newcastle disease (ND) is the most effective means of controlling the disease, and these vaccines are commercialized only after their safety and effectiveness have been verified through tests that comply with Korean Standards of National Lot Release for Veterinary Biologics. This study investigated whether a relatively convenient and safe serological test can be used in place of the challenge test using highly virulent ND virus. Hemagglutination inhibition (HI) assay and enzyme-linked immunosorbent assay (ELISA) were considered positive of log2 2 or more and cutoff value of 200 or more, respectively, in both live and inactivated vaccines. However, when the antibody levels of the live and inactivated vaccines induced using the Ulster 2C, KBNP-C4152R2L, and K148/08 strains were compared, the antibody titers for inactivated vaccines were significantly higher than those for live vaccines in both the HI assay and ELISA. A strong positive correlation was observed between HI and ELISA antibody titers. The live vaccines corresponded to a survival rates of ≥ 80% and the inactivated vaccines corresponded to 100% survival rates. This study confirmed that standard efficacy tests can serve as serological tests, and can replace the challenge test and that the vaccine approval process can be improved.

A total of 18 Newcastle disease virus (NDV) isolates that were recovered from 1949 through 1997 were characterized and pathotyped. All viruses were highly virulent as determined by intracerebral pathogenicity indices greater-than or equal to 1.81 in day-old. These pathotypes are typical for viscerotropic velogenic NDV (VVNDV) pathotype viruses. Some differences were observed for the chicken red blood cell elution rate and thermostability of the hemagglutinin at 56℃. Three antigenic groups were identified by a hemagglutination-inhibition assay using NDV monoclonal antibodies. And the predominant gross lesions were as follows: discharge from the nasal cavity, tracheal mucus, petechial hemorrhage in the heart fat, kidney urates and hemorrhage with or without necrosis in the gastrointestinal tract. Severe hemorrhagic or necrotic lesions were also noted in the lymphoid organs and were localized primarily in the spleen and cecal tonsil. However, differences in the occurrence and frequency of the gross lesions were observed between the virus strains. Among them, NDV strains that induced neurological symptoms belonged only to genotype Ⅵ. This strain had spread throughout Korea during the late 1980s to the 1990s, which suggests that specific VVNDVs genotypes might result in neurological symptoms.

Newcastle disease (ND) is a highly contagious disease of poultry that can cause severe economic losses throughout the world. Vaccination has been used for a long time and proved as one of the most effective method to reduce the economic loss due to ND virus infection. The measurement of antibody titer such as hamagglutination-inhibition (HI) test with sera has been used as a useful method to evaluate the immunity leve of host. However, HI test is gradually being replaced by the enzyme linked-immunosorbent assay (ELISA).

Many viruses can infect different types of birds, with poultry being the most susceptible. These viral diseases have a direct negative impact on the poultry industry, with significant economic losses. This study examined a group of the most important viruses that infect backyard chickens in 2 specific areas of Basrah Governorate, south of Iraq. The study analyzed avian influenza viruses (AIVs), Newcastle disease virus (NDV), and infectious bronchitis virus (IBV). Two hundred and ninety oropharyngeal swabs, 150 from Abu Al-Khasib and 140 from Shatt Al-Arab regions in the Basrah governorate, were obtained from backyard chickens with clear respiratory signs. The samples were subjected to viral RNA extraction, and the viral nucleic acids were detected using a reverse transcriptase polymerase chain reaction technique. The overall rate of viral infections was 74.8%, which varied depending on the type of virus: 15.8%, 31.3%, and 27.5% for AIV, NDV, and IBV, respectively. The NDV and IBV had much higher infection rates than that of AIV. In addition, the prevalence of AIV in the Shatt Al Arab district was significantly higher than in the Abul Khasib district. Moreover, there were no significant differences between the NDV and the IBV distributions in either of the targeted regions in this study.

 Newcastle disease (ND) is an endemic viral illness in Iraq and has four types: viscerotropic velogenic, neurotropic velogenic, mesogenic, and lentogenic. The virulence of the virus continuously increases, and it is widely spread in wild and domestic birds. Backyard and poultry farm chickens are mainly affected, causing significant economic losses, as the disease is famous for high morbidity and mortality, which may reach 100%. An outbreak of velogenic ND spread in poultry farms in Sulaymaniyah/Iraq in early 2023, causing high mortality rates. Hence, this study was conducted to isolate and identify the virus and determine its median embryo lethal dose (ELD50) in embryonated chicken eggs (ECEs). Samples were taken from chickens suspected of ND, and NDV identification was made by molecular techniques by amplifying part of the 535-base pair-F gene. The virus was passaged three times in ECEs, and the collected allantoic fluid was used to determine the ELD50. After that, fifty ECEs were used to calculate the ELD50. Allantoic fluid dilutions of 10–107 resulted in the death of all embryos after 2-3 days, with distinctive signs of bleeding and hemorrhage. Dilutions of 108, 109, and 1010 resulted in the death of four, two, and one embryo, respectively, and the PCR test revealed NDV infection. The ELD50 was 6.3 ×108 times the allantoic fluid dilution, showing that the virus was very velogenic and necessitated a strict control plan to prevent the disease's further spread.