LanguageAvian paramyxovirus infections in birds are produced by nine distinguishable serotypes [1]. Among them, the avian paramyxovirus type 1 or Newcastle disease virus (NDV), has been the most widely studied due to its economic importance in poultry [2]. However, avian paramyxovirus type 3 (PMV-3) is also very important, mainly for the turkey industry [2, 3].
Since the first discovery of a turkey PMV-3 in 1967, turkeys have been considered as the primary natural hosts, however, other species, such as chickens, some psitaccines and some passerines are susceptible to infection [2].
Clinical signs
Natural infections in turkeys with PMV-3 are characterized by the presence of respiratory signs, severe drops in egg production and poor egg quality, with loss of shell pigmentation [2, 3]. The presence of mild coughing and tracheal rales has been observed in adult turkeys two days after an experimental infection [4]. Drops in egg production, as high as 60%, have been described, with production returning to normal levels several weeks after infection [4].
Other clinical signs of PMV-3 infections include:
- Depression
- Coughing
- Inflammation of the infraorbital sinus
- Tracheal rales
- Complete anorexia
- Drastic reduction in water consumption (up to 50%)
- Nervous symptoms (psittaccines)
- High mortality (caged birds)
Transmission
Since PMV-3 has been isolated from tracheal and cloacal swabs of domestic poultry, viral transmission seems to occur through aerosols and ingestion of fecal contaminated materials [2, 3]. Furthermore, since the first clinical manifestation of a PMV-3 infection is the presence of respiratory signs, the respiratory tract seems to be the primary site of infection.
PMV-3 infections can also be transmitted by direct contact with infected wild birds and fomites. In affected facilities, the spread of the infection in a turkey flock is usually slow and viral transmission from affected to adjacent flocks is unpredictable [5]. No transovarian transmission of PMV-3 has been reported, however, since PMV-3 may be shed from the respiratory and intestinal tracts, contamination of the egg shell could occur [3].
Control
Since even uncomplicated infections with PMV-3 in turkeys produce a sufficient economic impact to render the birds unprofitable, the use of inactivated vaccines in association with a strict biosecurity are recommended [6, 7]. Oil-emulsion vaccines against PMV-3 have been available for several years in Europe and the United States [3, 6, 7]. As in Newcastle disease, the presence of PMV-3 antibodies after vaccination against the fusion and haemagglutinin-neuraminidase proteins provide an adequate protection against challenge in turkey poults and young chickens [8]. After inoculation of oil emulsion vaccines, the presence of a strong and long lasting humoral immune response which can prevent the serious egg production losses in laying turkeys should be expected.
References
1. Alexander, D.J., The classification, host range and distribution of avian paramyxoviruses., in Acute virus infections of poultry., J.B. McFerran and M.S. McNulthy, Editors. 1986, Martinus Nijhoff: Dordrecht. p. 52-56.
2. Awang, I.P.R. and P.H. Russell, Turkey avian paramyxovirus type 3 infections in poultry. World's Poult. Sci. J., 1990. 46: p. 213-218.
3. Alexander, D.J., Avian Paramyxoviruses 2 - 9., in Diseases of Poultry, Y.M. Saif, et al., Editors. 2003, Blackwell Publishing. p. 88-92.
4. Tumova, B., J.H. Robinson, and B.C. Easterday, A hitherto unreported paramyxovirus of turkeys. Res. Vet. Sci., 1979. 27: p. 135-140.
5. Alexander, D.J., M. Pattison, and I. McPherson, Avian paramyxoviruses of PMV-3. Avian Path., 1983. 12: p. 469-482.
6. Box, P., PMV3 disease of turkeys. Int. Hatch. Prac, 1987. 2: p. 4-7.
7. Eskelund, K.H. Vaccination of turkey breeder hens against paramyxovirus type 3 infection. in West Poult. dis. Conf. 1988.
8. Russell, P.H., et al., The pathogenicity of PMV-3/Turkey/Midland PoultryHoldings/1981 for chickens and turkeys of different ages. Avian Path., 1989. 18: p. 125-134.