1
|
Eid AAM, Hussein A, Hassanin O, Elbakrey RM, Daines R, Sadeyen JR, Abdien HMF, Chrzastek K, Iqbal M. Newcastle Disease Genotype VII Prevalence in Poultry and Wild Birds in Egypt. Viruses 2022; 14:v14102244. [PMID: 36298799 PMCID: PMC9607356 DOI: 10.3390/v14102244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 10/05/2022] [Accepted: 10/11/2022] [Indexed: 11/16/2022] Open
Abstract
Newcastle Disease Virus (NDV) genotype VII is a highly pathogenic Orthoavulavirus that has caused multiple outbreaks among poultry in Egypt since 2011. This study aimed to observe the prevalence and genetic diversity of NDV prevailing in domestic and wild birds in Egyptian governorates. A total of 37 oropharyngeal swabs from wild birds and 101 swabs from domestic bird flocks including chickens, ducks, turkeys, and pelicans, were collected from different geographic regions within 13 governorates during 2019–2020. Virus isolation and propagation via embryonated eggs revealed 91 swab samples produced allantoic fluid containing haemagglutination activity, suggestive of virus presence. The use of RT-PCR targeted to the F gene successfully detected NDV in 85 samples. The geographical prevalence of NDV was isolated in 12 governorates in domestic birds, migratory, and non-migratory wild birds. Following whole genome sequencing, we assembled six NDV genome sequences (70–99% of genome coverage), including five full F gene sequences. All NDV strains carried high virulence, with phylogenetic analysis revealing that the strains belonged to class II within genotype VII.1.1. The genetically similar yet geographically distinct virulent NDV isolates in poultry and a wild bird may allude to an external role contributing to the dissemination of NDV in poultry populations across Egypt. One such contribution may be the migratory behaviour of wild birds; however further investigation must be implemented to support the findings of this study. Additionally, continued genomic surveillance in both wild birds and poultry would be necessary for monitoring NDV dissemination and genetic diversification across Egypt, with the aim of controlling the disease and protecting poultry production.
Collapse
Affiliation(s)
- Amal A. M. Eid
- Department of Avian and Rabbit Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| | - Ashraf Hussein
- Department of Avian and Rabbit Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| | - Ola Hassanin
- Department of Avian and Rabbit Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| | - Reham M. Elbakrey
- Department of Avian and Rabbit Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44511, Egypt
| | - Rebecca Daines
- The Pirbright Institute, Ash Road, Pirbright, Woking GU24 0NF, UK
- Pathobiology and Population Sciences, Royal Veterinary College, Hatfield AL9 7TA, UK
| | | | - Hanan M. F. Abdien
- Department of Avian and Rabbit Medicine, Faculty of Veterinary Medicine, Suez Canal University, Ismailia 41622, Egypt
| | | | - Munir Iqbal
- The Pirbright Institute, Ash Road, Pirbright, Woking GU24 0NF, UK
- Correspondence:
| |
Collapse
|
2
|
Khan JS, Provencher JF, Forbes MR, Mallory ML, Lebarbenchon C, McCoy KD. Parasites of seabirds: A survey of effects and ecological implications. ADVANCES IN MARINE BIOLOGY 2019; 82:1-50. [PMID: 31229148 PMCID: PMC7172769 DOI: 10.1016/bs.amb.2019.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Parasites are ubiquitous in the environment, and can cause negative effects in their host species. Importantly, seabirds can be long-lived and cross multiple continents within a single annual cycle, thus their exposure to parasites may be greater than other taxa. With changing climatic conditions expected to influence parasite distribution and abundance, understanding current level of infection, transmission pathways and population-level impacts are integral aspects for predicting ecosystem changes, and how climate change will affect seabird species. In particular, a range of micro- and macro-parasites can affect seabird species, including ticks, mites, helminths, viruses and bacteria in gulls, terns, skimmers, skuas, auks and selected phalaropes (Charadriiformes), tropicbirds (Phaethontiformes), penguins (Sphenisciformes), tubenoses (Procellariiformes), cormorants, frigatebirds, boobies, gannets (Suliformes), and pelicans (Pelecaniformes) and marine seaducks and loons (Anseriformes and Gaviiformes). We found that the seabird orders of Charadriiformes and Procellariiformes were most represented in the parasite-seabird literature. While negative effects were reported in seabirds associated with all the parasite groups, most effects have been studied in adults with less information known about how parasites may affect chicks and fledglings. We found studies most often reported on negative effects in seabird hosts during the breeding season, although this is also the time when most seabird research occurs. Many studies report that external factors such as condition of the host, pollution, and environmental conditions can influence the effects of parasites, thus cumulative effects likely play a large role in how parasites influence seabirds at both the individual and population level. With an increased understanding of parasite-host dynamics it is clear that major environmental changes, often those associated with human activities, can directly or indirectly affect the distribution, abundance, or virulence of parasites and pathogens.
Collapse
Affiliation(s)
- Junaid S Khan
- Canadian Wildlife Service, Environment and Climate Change Canada, Gatineau, QC, Canada
| | - Jennifer F Provencher
- Canadian Wildlife Service, Environment and Climate Change Canada, Gatineau, QC, Canada.
| | - Mark R Forbes
- Department of Biology, Carleton University, Ottawa, ON, Canada
| | - Mark L Mallory
- Department of Biology, Acadia University, Wolfville, NS, Canada
| | - Camille Lebarbenchon
- Université de La Réunion, UMR Processus Infectieux en Milieu Insulaire Tropical, INSERM 1187, CNRS 9192, IRD 249, GIP CYROI, Saint Denis, La Réunion, France
| | - Karen D McCoy
- MIVEGEC, UMR 5290 CNRS-IRD-University of Montpellier, Centre IRD, Montpellier, France
| |
Collapse
|
3
|
Rahman AU, Habib M, Shabbir MZ. Adaptation of Newcastle Disease Virus (NDV) in Feral Birds and their Potential Role in Interspecies Transmission. Open Virol J 2018; 12:52-68. [PMID: 30288195 PMCID: PMC6142666 DOI: 10.2174/1874357901812010052] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 03/14/2018] [Accepted: 06/11/2018] [Indexed: 12/19/2022] Open
Abstract
Introduction: Newcastle Disease (ND), caused by Avian avulavirus 1 (AAvV 1, avulaviruses), is a notifiable disease throughout the world due to the economic impact on trading restrictions and its embargoes placed in endemic regions. The feral birds including aquatic/migratory birds and other wild birds may act as natural reservoir hosts of ND Viruses (NDVs) and may play a remarkable role in the spread of the virus in environment. In addition, other 19 avulaviruses namely: AAvV 2 to 20, have been potentially recognized from feral avian species. Expalantion: Many previous studies have investigated the field prevailing NDVs to adapt a wide range of susceptible host. Still the available data is not enough to declare the potential role of feral birds in transmission of the virus to poultry and/or other avian birds. In view of the latest evidence related to incidences of AAvVs in susceptible avian species, it is increasingly important to understand the potential of viruses to transmit within the domestic poultry and other avian hosts. Genomic and phylogenomic analysis of several investigations has shown the same (RK/RQRR↓F) motif cleavage site among NDV isolates with same genotypes from domestic poultry and other wild hosts. So, the insight of this, various semi-captive/free-ranging wild avian species could play a vital role in the dissemination of the virus, which is an important consideration to control the disease outbreaks. Insufficient data on AAvV 1 transmission from wild birds to poultry and vice versa is the main constraint to understand about its molecular biology and genomic potential to cause infection in all susceptible hosts. Conclusion: The current review details the pertinent features of several historical and contemporary aspects of NDVs and the vital role of feral birds in its molecular epidemiology and ecology.
Collapse
Affiliation(s)
- Aziz-Ul- Rahman
- Department of Microbiology, University of Veterinary and Animal Sciences, 54000, Lahore, Pakistan
| | - Momena Habib
- Department of Microbiology, University of Veterinary and Animal Sciences, 54000, Lahore, Pakistan
| | - Muhammad Zubair Shabbir
- Quality Operations Laboratory, University of Veterinary and Animal Sciences, 54000, Lahore, Pakistan
| |
Collapse
|
4
|
Spillover of Newcastle disease viruses from poultry to wild birds in Guangdong province, southern China. INFECTION GENETICS AND EVOLUTION 2017; 55:199-204. [PMID: 28935610 DOI: 10.1016/j.meegid.2017.09.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 09/12/2017] [Accepted: 09/17/2017] [Indexed: 12/29/2022]
Abstract
Despite intensive vaccination programs in many countries, including China, Newcastle disease has been reported sporadically and is still a significant threat to the poultry industry in China. Newcastle disease virus (NDV) is infectious for at least 250 bird species, but the role of wild birds in virus epidemiology remains largely unknown. Fourteen NDV isolates were obtained from 2040 samples collected from wild birds or the environment in Guangdong province, southern China, from 2013 to 2015. The isolation rate was the highest in the period of wintering and lowest during the periods of spring migration, nesting, and postnesting. A maximum clade credibility phylogenetic analysis revealed that at least four genotypes circulate in southern China: three class II genotypes (II, VI, and IX) and one class I (1b). We also demonstrated that most isolates from wild birds were highly similar to isolates from poultry, and two isolates were linked to viruses from wild birds in northern China. These data suggested that wild birds could disseminate NDV and poultry-derived viruses may spillover to wild birds. Accordingly, vaccine development and poultry management strategies should be considered to prevent future NDV outbreaks, particularly given the strength of the poultry industry in developing countries, such as China.
Collapse
|
5
|
Liu J, Zhu J, Xu H, Li J, Hu Z, Hu S, And XW, Liu X. Effects of the HN Antigenic Difference between the Vaccine Strain and the Challenge Strain of Newcastle Disease Virus on Virus Shedding and Transmission. Viruses 2017; 9:v9080225. [PMID: 28809802 PMCID: PMC5580482 DOI: 10.3390/v9080225] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 07/31/2017] [Accepted: 08/03/2017] [Indexed: 11/29/2022] Open
Abstract
Newcastle disease (ND) leading to heavy economic losses to the poultry industry worldwide is caused by Newcastle disease virus (NDV). Even though intensive vaccination programs have been implemented in many countries, virulent NDV can still be frequently isolated in well-vaccinated flocks. We compared the protection efficiency of LaSota and two sub-genotype VIId vaccines, NDV/AI4 and NDV O/AI4, in which NDV O/AI4 was constructed by replacing the hemagglutinin–neuraminidase (HN) gene of the vaccine strain NDV/AI4 with that from the variant NDV strain JS-14-12-Ch by the cross hemagglutination inhibition test and immune protection test. The number of birds shedding the virus and the titer of the shedding virus from the challenged birds were tested to evaluate the protection efficiency in the immune protection test. The cross hemagglutination inhibition and neutralization tests between JS-14-12-Ch and the three vaccines displayed a significant antigenic difference between JS-14-12-Ch and LaSota or NDV/AI4, but not between JS-14-12-Ch and NDV O/AI4. The results of the immune protection test showed that NDV O/AI4 could provide improved protection as determined by a significant decrease in both the number of birds shedding the virus and the titer of the shedding virus from the challenged birds. The results in this study indicated that the antigenic similarity between the vaccine strain and the challenge strain is important in reducing the shedding of virulent virus in which the congruence of the NDV HN protein may play a critical role.
Collapse
Affiliation(s)
- Jingjing Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
| | - Jie Zhu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
| | - Haixu Xu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
| | - Juan Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
| | - Zenglei Hu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
| | - Shunlin Hu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
| | - Xiaoquan Wang And
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
| | - Xiufan Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China.
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
| |
Collapse
|
6
|
Phylogenetic analysis of Newcastle disease viruses from Bangladesh suggests continuing evolution of genotype XIII. Arch Virol 2017; 162:3177-3182. [DOI: 10.1007/s00705-017-3479-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/09/2017] [Indexed: 01/01/2023]
|
7
|
Ayala AJ, Dimitrov KM, Becker CR, Goraichuk IV, Arns CW, Bolotin VI, Ferreira HL, Gerilovych AP, Goujgoulova GV, Martini MC, Muzyka DV, Orsi MA, Scagion GP, Silva RK, Solodiankin OS, Stegniy BT, Miller PJ, Afonso CL. Presence of Vaccine-Derived Newcastle Disease Viruses in Wild Birds. PLoS One 2016; 11:e0162484. [PMID: 27626272 PMCID: PMC5023329 DOI: 10.1371/journal.pone.0162484] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 08/23/2016] [Indexed: 01/28/2023] Open
Abstract
Our study demonstrates the repeated isolation of vaccine-derived Newcastle disease viruses from different species of wild birds across four continents from 1997 through 2014. The data indicate that at least 17 species from ten avian orders occupying different habitats excrete vaccine-derived Newcastle disease viruses. The most frequently reported isolates were detected among individuals in the order Columbiformes (n = 23), followed in frequency by the order Anseriformes (n = 13). Samples were isolated from both free-ranging (n = 47) and wild birds kept in captivity (n = 7). The number of recovered vaccine-derived viruses corresponded with the most widely utilized vaccines, LaSota (n = 28) and Hitchner B1 (n = 19). Other detected vaccine-derived viruses resembled the PHY-LMV2 and V4 vaccines, with five and two cases, respectively. These results and the ubiquitous and synanthropic nature of wild pigeons highlight their potential role as indicator species for the presence of Newcastle disease virus of low virulence in the environment. The reverse spillover of live agents from domestic animals to wildlife as a result of the expansion of livestock industries employing massive amounts of live virus vaccines represent an underappreciated and poorly studied effect of human activity on wildlife.
Collapse
Affiliation(s)
- Andrea J. Ayala
- College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
- Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, United States National Poultry Research Center, Agricultural Research Service, United States Department of Agriculture, Athens, Georgia, United States of America
| | - Kiril M. Dimitrov
- Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, United States National Poultry Research Center, Agricultural Research Service, United States Department of Agriculture, Athens, Georgia, United States of America
- National Diagnostic Research Veterinary Medical Institute, Sofia, Bulgaria
| | - Cassidy R. Becker
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
| | - Iryna V. Goraichuk
- Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, United States National Poultry Research Center, Agricultural Research Service, United States Department of Agriculture, Athens, Georgia, United States of America
- National Scientific Center Institute of Experimental and Clinical Veterinary Medicine, Kharkiv, Ukraine
| | - Clarice W. Arns
- Laboratory of Animal Virology, Institute of Biology, University of Campinas-UNICAMP, Campinas, Brazil
| | - Vitaly I. Bolotin
- National Scientific Center Institute of Experimental and Clinical Veterinary Medicine, Kharkiv, Ukraine
| | - Helena L. Ferreira
- Department of Veterinary Medicine, College of Animal Science and Food Engineering and Graduate Program in Experimental Epidemiology of Zoonosis, University of São Paulo, São Paulo, Brazil
- Post-Graduate Program in the Experimental Epidemiology of Zoonoses, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Anton P. Gerilovych
- National Scientific Center Institute of Experimental and Clinical Veterinary Medicine, Kharkiv, Ukraine
| | | | - Matheus C. Martini
- Laboratory of Animal Virology, Institute of Biology, University of Campinas-UNICAMP, Campinas, Brazil
| | - Denys V. Muzyka
- National Scientific Center Institute of Experimental and Clinical Veterinary Medicine, Kharkiv, Ukraine
| | - Maria A. Orsi
- National Agricultural Laboratory of São Paulo, Lanagro/SP, Campinas, Brazil
| | - Guilherme P. Scagion
- Laboratory of Animal Virology, Institute of Biology, University of Campinas-UNICAMP, Campinas, Brazil
| | - Renata K. Silva
- Post-Graduate Program in the Experimental Epidemiology of Zoonoses, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Olexii S. Solodiankin
- National Scientific Center Institute of Experimental and Clinical Veterinary Medicine, Kharkiv, Ukraine
| | - Boris T. Stegniy
- National Scientific Center Institute of Experimental and Clinical Veterinary Medicine, Kharkiv, Ukraine
| | - Patti J. Miller
- Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, United States National Poultry Research Center, Agricultural Research Service, United States Department of Agriculture, Athens, Georgia, United States of America
| | - Claudio L. Afonso
- Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, United States National Poultry Research Center, Agricultural Research Service, United States Department of Agriculture, Athens, Georgia, United States of America
| |
Collapse
|
8
|
Temporal, geographic, and host distribution of avian paramyxovirus 1 (Newcastle disease virus). INFECTION GENETICS AND EVOLUTION 2016; 39:22-34. [PMID: 26792710 DOI: 10.1016/j.meegid.2016.01.008] [Citation(s) in RCA: 185] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 01/08/2016] [Accepted: 01/09/2016] [Indexed: 12/16/2022]
Abstract
Newcastle disease is caused by virulent forms of avian paramyxovirus of serotype 1 (APMV-1) and has global economic importance. The disease reached panzootic proportions within two decades after first being identified in 1926 in the United Kingdom and Indonesia and still remains endemic in many countries across the world. Here we review information on the host, temporal, and geographic distribution of APMV-1 genetic diversity based on the evolutionary systematics of the complete coding region of the fusion gene. Strains of APMV-1 are phylogenetically separated into two classes (class I and class II) and further classified into genotypes based on genetic differences. Class I viruses are genetically less diverse, generally present in wild waterfowl, and are of low virulence. Class II viruses are genetically and phenotypically more diverse, frequently isolated from poultry with occasional spillovers into wild birds, and exhibit a wider range of virulence. Waterfowl, cormorants, and pigeons are natural reservoirs of all APMV-1 pathotypes, except viscerotropic velogenic viruses for which natural reservoirs have not been identified. Genotypes I and II within class II include isolates of high and low virulence, the latter often being used as vaccines. Viruses of genotypes III and IX that emerged decades ago are now isolated rarely, but may be found in domestic and wild birds in China. Containing only virulent viruses and responsible for the majority of recent outbreaks in poultry and wild birds, viruses from genotypes V, VI, and VII, are highly mobile and have been isolated on different continents. Conversely, virulent viruses of genotypes XI (Madagascar), XIII (mainly Southwest Asia), XVI (North America) and XIV, XVII and XVIII (Africa) appear to have a more limited geographic distribution and have been isolated predominantly from poultry.
Collapse
|
9
|
Genetic diversity of newcastle disease virus in wild birds and pigeons in West Africa. Appl Environ Microbiol 2013; 79:7867-74. [PMID: 24123735 DOI: 10.1128/aem.02716-13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In West and Central Africa, virulent Newcastle disease virus (NDV) strains of the recently identified genotypes XIV, XVII, and XVIII are enzootic in poultry, representing a considerable threat to the sector. The increasing number of reports of virulent strains in wild birds at least in other parts of the world raised the question of a potential role of wild birds in the spread of virulent NDV in sub-Saharan Africa as well. We investigated 1,723 asymptomatic birds sampled at live-bird markets and sites important for wild-bird conservation in Nigeria and 19 sick or dead wild birds in Côte d'Ivoire for NDV class I and II. Typical avirulent wild-type genotype I strains were found in wild waterfowl in wetlands in northeastern Nigeria. They were unrelated to vaccine strains, and the involvement of inter- or intracontinental migratory birds in their circulation in the region is suggested. Phylogenetic analyses also revealed that genotype VI strains found in pigeons, including some putative new subgenotype VIh and VIi strains, were introduced on multiple separate occasions in Nigeria. A single virulent genotype XVIII strain was found in a dead wild bird in Côte d'Ivoire, probably as a result of spillover from sick poultry. In conclusion, screening of wild birds and pigeons for NDV revealed the presence a variety of virulent and avirulent strains in West Africa but did not provide strong evidence that wild birds play an important role in the spread of virulent strains in the region.
Collapse
|