NEWCASTLE DISEASE VACCINATION OF PSITTACINES FOLLOWING
AN OUTBREAK IN COCKATIELS
Bendheim U1., Pokamunski S2. and Kass N3.
1. Koret School of Veterinary Medicine, Hebrew University of Jerusalem.
2. Veterinary Services, Bet-Dagan, Israel
3. Regional Poultry Disease Laboratory, Birya, Israel.
* Presented at the 5th Scientific Meetings of ECAMS, Tenerife, 2003.
A case of NCD in cockatiels with 100% mortality is reported. The presumed source of infection was from visitors from a commercial poultry flock. The disease did not spread to other psittacines, even in the same room.
Vaccination of several psittacine species with inactivated NCDV vaccine produced antibodies which could be diagnosed by ELISA (Immunocomb®) for three months. Vaccination with live NCDV vaccine by eye-drop or spray did not produce such antibodies in the majority of the tested birds .
Newcastle disease virus (NCDV) was introduced to poultry farms in several countries through imported psittacines. In 1970-71 it was introduced to California through infected psittacines from Mexico.
In the past, NCD in psittacines had been diagnosed in Israel only in newly imported birds. In January 2002, 18 cockatiels (Nymphicus hollandicus) housed in an aviary located in a closed building were infected with NCDV. All of them died. After necropsy a highly pathogenic NCDV was isolated from their spleens and brains using embryonated SPF eggs.
The ICPI (Intra-Cerebral Pathogenic Index) of the isolate was 1.9. An ICPI higher than 0.7 is considered by the OIE as pathogenic. The vaccine virus (VH strain) used in Israel produces an ICPI of 0.15.
Budgerigars (Mellopsittacus undulatus) and lovebirds (Agapornis roseicollis) were not infected: no clinical symptoms, mortality, antibodies were not detected for one month by ELISA (Immunocomb®) and NCDV was not isolated from cloacal swabs.
The budgerigars and lovebirds were separated from the cockatiels only by a wire fence. Rice finches caged in the same room were not infected, either.
The outbreak took place in the Western Galilee, an area where most of the NCDV outbreaks in the country had been diagnosed during the past two-and-a-half years (127 out of 135 in chickens).
The cockatiels were kept in a kibbutz bordering on a village in which two chicken flocks (one backyard flock and one commercial broiler flock) were infected with NCDV two weeks previously and had been culled. People from this village used to buy psittacines at the kibbutz.
A broiler farm in a settlement located two kilometers from the village was also infected and its 80,000 broilers were culled. This farm was managed by a person living in the infected village.
The ICPIs of the three isolated cases were similarly pathogenic: 1.91 for the cockatiels; 1.95 for the backyard flock; 1.83 from the commercial boiler flock in the settlement.
All isolates were sent to Dr. Alexander, OIE NCDV Reference Laboratory, Weybridge for classification.
Following the outbreak psittacines in some collections in the area were vaccinated once with inactivated NCDV vaccine (108EID50 per bird i.m. VH strain vaccine). Vaccination with live vaccine was not recommended due to poor results in a previously published trial.
NCDV antibodies were tested with Immunocomb®in conures (Aratinga and Pyrrhura), black-headed caiques (Pionites melanocephala), Ringnecks (Psittacula krameri) and blue-headed pionus for three months, and in grey parrots (Psittacus erithacus), cockatiels (Nymphicus hollandicus), Bourke’s (Neophema bourkii) and spectacled amazons (Amazona albincons) for one month. The birds were Immunocomb negative before vaccination. All became Immunocomb positive after vaccination.
Six birds were tested four months after vaccination; two of them were already Immunocomb negative.
Twenty budgerigars vaccinated once with inactivated vaccine showed no NDV antibodies after one, two and three months (Immunocomb and HI). Twenty-four cockatiels and twelve budgerigars vaccinated with a lentogenic live NCDV vaccine (107EID50, VH strain per bird) remained Immunocomb and HI negative.
Thirteen birds from a psittacine breeder collection in which the birds had been spray— vaccinated every six months for years with live NCDV vaccine were tested four months after the last vaccination. Eight birds were Immunocomb negative.
SEEING THE INVISIBLE
Based on the hypothesis that diurnal avian species which appear as sexually monochromatic to the trichromatic human eye might be dichromatic if the avian visual range (320-700 nm) and capabilities (tetrachromacy) are considered, this study was designed to reveal concealed plumage sexual dichromatism using reflectance spectrometry.Reflectance spectrometry is an objective method for colour assessment that has the advantage of including parts of the spectrum to which humans are blind (UV 320-400 nm) and is independent of the observer's visual capabilities.Feathers and plumage are non-uniform rough surfaces. Therefore, their physical characteristics have to be considered when choosing a colour assessment technique. Angle dependency (influence of illumination and observation angles on the reflectance spectrum) is expected in both structurally coloured and pigmented feathers. In Chapter 2, angle dependency of spectrometric results was shown to be significant, both for iridescent (as visually detectable) and non-iridescent feathers feathers. The results of this preliminary study emphasized the need for a plumage colour assessment technique superior to the commonly used single angle reflectance spectrometry. In the studies that followed, multiple angle spectrometry was used to explore sexual dichromatism in five different bird species previously classified as sexually "monochromatic".In Chapter 3, we have explored sex differences on a group of blue-fronted Amazon parrots (Amazona aestiva). Based on these findings a model that enabled 100% correct sex prediction based on one particular body region measured with different angle geometries was proposed.In Chapter 4, the plumage of the long-tailed finch (Poephila acuticauda) was chosen as a study object since this species had been previously classified by single reflectance spectrometry as monochromatic by others (Langmore and Bennett 1990). Sexual dichromatism of this species was revealed by multiple angle spectrometry. Moreover, a model for sex discrimination was proposed based on the use of multiple angle geometries for a particular body region (grey crown).In Chapter 5, a comparison between sexual dichromatism results obtained with both individual feathers and plumage was made using the most commonly used angles for plumage colour assessment. Both plumage and individual feathers revealed sexual dichromatism, but occasionally at different illumination and observation angles. Whichever method was used, the reflectance spectrum changed significantly when the angles of illumination and observation were changed, which resulted in sexual dichromatism being visible at one angle and not at another angle.In Chapters 6 and 7, respectively, the sexual dichromatism of the Java finch (Padda oryzivora) and European magpie (Pica pica) was explored and verified by multiple angle spectrometry. Additionally, in the European magpie, the proposed sex determination technique was confirmed with a new set of birds.Finally in Chapter 8, intraspecific co-evolution of the UV visual system and UV plumage sexual dichromatism was hypothesized for the studied species, based on the simultaneous presence of a spectral peak, sexual dichromatism in the UV range and the presence of a mutation for the UV sensitive opsin. From this study we can conclude that certain plumage colour characteristics can be missed by the use of single angle, rather than multiple angle spectrometry. Single angle spectrometry may occasionally lead to erroneous conclusions both in regards to morphological characteristics of birds, and in related fields of biology, such as taxonomy, behaviour or evolution.So far our initial hypothesis that all diurnal birds are sexually dichromatic, even when not visible to the relatively colour blind human eye, has not been rejected.