Paramyxovirus - What is it?

http://www.pigeon-aid.org.uk/pa/html/paramyxovirus__pmv_.php

Some may be wondering exactly what this latest pigeon disease is and how it related to our chickens or other birds. It's all very vague at the moment.

Some facts might be helpful here. I'm no expert, but I can read a textbook as well as anyone and I'll make some notes as I go through. The experts can correct when necessary. What is not going to be ok in this thread is any criticisms of other people or events in relation to their decisions. This is about the disease and its management.

Firstly, What is it and Where does it Fit?

A bit for the scientifically educated:

Paramyxoviridae

The family Paramyxoviridae has been divided into two subfamilies: Paramyxovirinae and Pneumovirinae. The subfamily Paramyxovirinae is divided into five genera:

* Morbilliviris. The type species is measles virus, the genus includes canine distemper and rinderpest viruses
* Respirovirus. The type species is Human Parainfluenza virus 1; the genus includes bovine and human parainfluenza 3 and Sendai virus
* Henipavirus. Formed from Nipah virus and Hendra virus
* Rubulavirus. The type species is mumps virus, the genus includes some other mammalian parainfluenza viruses
* Avulavirus. Newcastle disease virus (NDV or APMV-1), the type species, and the other avian paramyxoviruses (APMV-2 to APMV-9) are placed in this genus. The name is derived from 'avian Rubulavirus' as at one time the avian paramyxoviruses were placed in the same genus as mumps virus.

So we are interested in the 'Avulavirus' subfamily. The members of this genus show all the typical properties of their family but I'll skip the details unless anyone particularly wants them.

APMV-1 (Newcastle disease virus) is hosted by numerous bird types. It varies from extremely pathogenic to inapparent, depending on the strain and host that's infected. At the moment, my guess is that the DPI don't really know much about the current strain.


Poultry Diseases (2008) 6th Edition by Pattison, McMullin, Bradbury & Alexander

Already it's seems obvious that this family of diseases is very wide with multiple strains. Going on then ....

Newcastle Disease Virus was first isolated in 1926 from chickens in Newcastle-upon-Tyne, from which the name was derived, and for 30 years remained the only known avian paramyxovirus. However since the early 1970s a lot more of them have been isolated. Now we have APMV-1 to APMV-9 (APMV-1 being NDV). At 2008, with the exception of APMV-6 viruses, which have been occasionally been isolated from turkeys, and APMV-7 viruses, which have been isolated from turkeys and ostriches in the USA, disease in poultry has been associated only with viruses of APMV-1, APMV-2 and APMV-3 serotypes.

It seems from reports that what we have here in Australia is APMV-1. Although a slight variation it's close enough for our purposes to understand it as Newcastle Disease Virus. APMV-1 encompasses a group of closely related viruses that form that serotype. The thing to note is that vaccination for one strain of APMV-1 doesn't necessarily give protection for another strain and that would appear to be the problem at the moment. We don't seem to know enough about it. Different strains can cause quite distinct signs and degrees of severity, even in the same host species.

In chickens the strains of APMV-1 are ranked in five categories from those that don't cause apparent symptoms right up to those that are highly virulent and cause haemorhagic leesions characteristically present in the intestinal tract. For interest, I'll put up the rankings here:

1. Viscerotropic velogenic NDVs cause a highly virulent form of disease in which haemorrhagic lesions are characteristically present in the intestinal tract.
   
2. Neurotropic velogenic NDVs cause high mortality following respiratory and nervous signs.
   
3. Mesogenic NDVs cause respiratory and sometimes nervous signs with low mortality.
   
4. Lentogenic respiratory NDVs cause mild or inapparent respiratory infection
   
5. Asymptomatic enteric NDVs cause inapparent enteric infection.

These groups are a guide only, but when you read them, you can see that just because a strain causes devastation in pigeons, it does not necessarily follow that it's going to devastate hobby poultry fanciers. We just don't know.

[size=150]What Gets it?[/size]

Over 250 species of bird have been reported to be susceptible to natural or experimental infections of NDV and it seems probably that many more if not all species are susceptible to infection. NDV strains have been shown to infect all the major and minor species of domestic poultry, although some species (e.g. ducks) tend to show few signs of disease even when infected with the strains of NDV more virulent for chickens.

GOOD NEWS FOR THE DUCK PEOPLE!

How Does it Spread?

The way that it spreads from bird to bird is dependent on the organs in which the virus multiplies. Birds showing respiratory disease shed virus in droplets and aerosols of mucus which may be inhaled by other birds. Viruses that are mainly replicating in the intestine may be transferred by ingestion of contaminated faeces, either directly or in food or water. In some cases NDV can be airborne and spread over large distances, but not always. For NDV to be airborne at all it requires specific conditions.

Usually, humans play the central role in the spread of NDV, usually by the movement of live birds, or material associated with the birds.

Feral birds and other wildlife also contribute to the spread of disease during outbreaks, but their exactly role hasn't been fully evaluated.

There one interesting case detailed here:

PPMV-1 was introduced into the UK in 1984 probably by stray racing pigeons. The virus proceeded to spread rapidly among UK racing pigeons and from these to feral pigeons. This resulted in the infection of a flock of pigeons living on food stored at a dockyard. Food contaminated with pigeon faeces from these stores was fed untreated to fowls, who subsequently developed disease. There was relatively little secondary spread but where it was seen it was related to the agency of humans, contaminated vehicles and unfumigated eggs.

A key to the successful spread of NDV is the ability of the virus to survive in the dead host or excretions. In infected carcasses NDV may survive for several week at a cool temperature or several years if frozen. Faeces in which the virus may be present in high amounts, even at 37C can remain infective for over a month. NDV can be destroyed by cooking. Heating at a fairly high temperature for a number of minutes may reduce virus survival.

I am eventually going to get to the clinical signs. :wink:


http://www.lionsgrip.com/chickensnewcastle.html

What Does it Look Like?

This disease can vary greatly depending on the strain of virus, the species of bird, the immune status of the bird, age and conditions under which they are reared and other infections can all alter what it looks like and how bad it is.

The highly virulent viruses may produce peracute infections of fully susceptible chickens and the first you know about it is when the suddenly die. More typically, you would see signs like depression, prostration, diarrhoea, swelling of the head and nervous signs. The appearance of shell-less or soft-shelled eggs, often laid outside the nest boxes, followed by complete cessation of egg laying, may be an early sign in adult fowl. Flock mortality may reach 100%.

The moderately virulent viruses usually cause severe respiratory disease, followed by nervous signs, with flock mortality up to 50% or more. In some cases there are no respiratory symptoms, but diarrhoea and nervous signs are the main indication, along with catastrophic drops in egg production in laying hens.

The viruses of low virulence may cause no disease, or mild respiratory distress for a short time in chickens and turkeys. However in the presence of other disease or poor husbandry it may present more severely.

Lesions?

Lesions can vary. Viruses causing respiratory disease may cause inflammation of the trachea often with bleeding. The air sacs may be inflamed and appear cloudy and congested. There may be haemorrhagic lesions of the intestinal tract, particularly the proventriculus. Lesions may vary greatly in size and severity. The highly virulent viruses cause necrotic lesions, frequently with haemorrhages, in a range of organs of infected chickens. There can be exudative lung lesions. Where nervous signs have been an issue examination of the CNS have resulted in reports of neuronal degeneration, perivascular cuffing of lymphocyte cells and proliferation of the endothelial cells.


Depression
http://partnersah.vet.cornell.edu/avian-atlas/search/disease/507


Abnormal Righting Reflex
http://partnersah.vet.cornell.edu/avian-atlas/search/disease/507

For a truckload of images showing clinical signs of Newcastle Disease, go to the Atlas of Avian Diseases HERE and scroll through the pictures. It will give you an understanding of what it can look like.

What Does a Sick Pigeon Look Like When they Have This?


http://www.pigeonrescue.co.uk/pigeonparamyxovirus.htm

As I don't have pigeons and this disease has never been seen around here, I have quoted a list of possible signs from this site. If you see any pigeons hanging around your yard looking like this, then it's time to make the call.

PIGEON PARAMYXOVIRUS is a viral disease that does not affect man or animals, but a human that handles a pigeon with PMV or the live vaccine can develop conjunctivitis if sensible precautions are not taken (eg, do not touch your eyes immediately after handling a pigeon with PMV or the live vaccine).

Incubation period can vary from a few days to several weeks.
It is most often of moderate virulence with 5% to 10% mortality, but rarely highly virulent strains can cause 90% mortality.
Mortality rates are significantly higher if supportive care is not given (eg. when the virus is injected experimentally in a laboratory).
Water deprivation and stress increase mortality.
Spontaneous recovery within 6 - 12 weeks is common, but recovery can take longer.
Nervous symptoms can persist for life or return in times of stress.
Some pigeons will suffer from persistent diarrhoea after recovery.
SYMPTOMS:

Diarrhoea is often the first symptom, but feral pigeons will not often come to the attention of a rescuer until the nervous signs appear. Not all symptoms will be present at the same time. All symptoms are aggravated by excitement.

The most common symptoms seen by the rescuer will be:

Thin broken solid droppings in a pool of liquid
Fine tremor of eyes or head
Staggering
Somersaulting in flight
Crash landing
Difficulty picking up seed, pecking and missing.
Tossing seed backwards
Twisting neck, head upside down (torticollis, star gazing) - see photo.
Paralysis of legs or wings
Spiralling in flight
Flying backwards
Turning in circles
Having fits

http://www.pigeon-aid.org.uk/pa/html/paramyxovirus__pmv_.php

Still no poultry cases and pigeon cases confined to the Melbourne area.

Current infected properties.

Here is a youtube video showing what it looks like when a pigeon has paramyxovirus.