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In rock pigeons, nervous signs are characteristic with pigeon paramyxovirus type-1 infection (pigeon PMV-1; closely related to Newcastle Disease Virus) and may sometimes be seen with classic NDV infection in these birds. However, |
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Clinical signs of Newcastle disease in adult mallards (Anas platyrhynchos) that were experimentally infected with a velogenic form of NDV:
(A) leg paralysis and inability of two of the birds to hold their heads erect.
(B) torticollis and
(C) wing droop. Photographs by Milton Friend |
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not all individuals show nervous signs. Affected birds may be generally weak, and often have both polyuria and diarrhoea, with droppings consisting of a pool of clear liquid around a core of green material, sometimes bloody (haemorrhagic). Nervous signs include inability to pick up grain (the pigeon pecks at the wrong place), torticollis (twisting round of the head and neck), paralysis of the legs and/or wings (one or both sides), circling, loss of righting reflex (i.e. unable to get up if placed on their back), somersaulting, circling, flying backwards, head and neck tremors, and falling out of roosts. Additionally, birds may produce less or deformed eggs, and hatchability of eggs which are laid is reduced. Rapid breathing, and oedema (fluid swelling) around the head and eyes may be noted.
Birds may recover from diarrhoea and mild nervous signs over a period of three to four weeks; some birds with severe nervous signs may recover. The disease usually causes few deaths in adults, but many young pigeons may die from kidney failure or malnutrition.
In ostriches, depression and nervous signs may occur, or respiratory signs, or peracute death (death without any previous clinical signs). Disease and deaths are usually seen particularly in young birds (e.g. under six months old – but this has varied between outbreaks), with less disease in older or adult birds (Alexander, 2000). |
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In emus, infection may result in decreased appetite and green droppings (Heckert, 1999).
In rheas, rare reports of infection describe mainly nervous signs but also respiratory and gut-associated signs (Alexander, 2000).
In humans, severe inflammation (reddening) of one or both eyes can be seen, and sometimes a mild ‘flu-like illness. The disease can last three days to three weeks. It is seen mainly in poultry workers, pigeon fanciers, poultry abattoir workers, laboratory personnel and people applying live vaccines to birds. |
