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SIGNIFICANCE AND IMPLICATIONS FOR ANIMAL HEALTH

The effect of chlamydial infection on wild bird popula­tions has yet to be assessed. Clearly outbreaks of disease with relatively high morbidity and mortality have been described in passerines, particularly garden passerines and corvids, and in members of the pigeon family.

The nature of the disease in these species often appears to be chronic, and birds found dead and submitted for examination are few compared with the estimates of birds seen ill. It is therefore likely that sick birds die in areas unseen, or are removed by predators. Mortality in these reported out­breaks is probably underestimated, and increasingly there appear to be associations with concurrent disease. For example, a corvid respiratory disease syndrome has been noted in the UK for nearly a decade, consisting of airsac- culitis and pericarditis, but only from a small number of individuals has chlamydia been detected. In this syndrome Pasteurella multocida is considered to be aetiologically important and chlamydial infection considered to be inci­dental. The frequency of clinical disease in collared doves has suggested that this species may be the source of infec­tion for other wild birds — for example, robins (Erithacsu rubecula)(19). In a large serological study it was found that housed chickens were seronegative, but low and consistent titres were found in poultry raised outdoors, suggesting that infection in outdoor poultry originated from exposure to wild birds(4).

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Source: Gavier-Widen D., Meredith A., Duff Paul J. (eds.). Infectious Diseases of Wild Mammals and Birds in Europe. London: Wiley-Blackwell,2012. — 568 p.. 2012
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