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TurkeyPoult Enteritis

The turkey industry in Indiana ranks seventh in the US with 15 million turkeys (5.1% of US turkeys) in production yearly and a market value of $140.4 million.   Turkeypoult enteritis (also referred to as "spiking mortality of turkey poults") has contributed to significant economic losses encountered by a large number of turkey producers in Indiana for the last several years.   As an example of the magnitude of losses due to this disease, the estimated cost (mortality, stunting, and medication) in DuBois County alone in 1994 was $19.26 million. A similar disease has also been identified in western and eastern North Carolina, South Carolina, Georgia, Virginia, New York and other states.   Outbreaks of this disease have resulted in major economic hardships for turkey farmers in North Carolina in 1995 and 1996.

The clinical signs of turkey poult enteritis usually appear at 7 to 28 days of age and have diarrhea, chirping, litter eating, decreased feed efficiency, decreased weight gain, and uneven flock growth.   The morbidity is usually high and mortality may be low; however, mortality over 40 to 50% occasionally occurred in Indiana flocks in 1993. Diagnosticians at ADDL and SIPAC have shown that turkey poult enteritis can be experimentally induced by gavaging turkey poults with intestinal contents from affected poults. Electron microscopic examination of intestinal contents from affected turkey poults often revealed coronavirus.  In addition, intestines were often positive for coronavirus by fluorescent antibody testing.   However, attempts to isolate turkey coronavirus using various cell lines have not been successful. Turkey embryos have been used for the isolation, propagation and characterization of turkey coronavirus.   Turkeycoronavirus from affected intestinal contents filtered at 0.22 microns has been successfully passaged and propagated in turkey embryos. This is the only in vivo system available in propagating turkey coronavirus.

Fluorescent antibody testing and electron microscopic examination of the intestines from the passaged turkey embryos have revealed the presence of turkey coronavirus.   The infected intestines were often dilated and contained gas and greenish-brown fluid. By the fifth passage, the intestines had slight villous blunting, increased villous epithilialvacuolation, and multifocaldilation of crypts  histologically.     Turkeycoronavirus has also been purified from the intestines of infected turkey embryos in the fifth passage    by    sucrose    density    gradient ultracentrifugation.   The virions banded at a buoyant density of 1.18 to 1.20 g/ml and that of 1.14 g/ml in sucrose gradients, similar to reports for the other turkey coronaviruses isolated at Minnesota and Canada previously. In addition, sucrose density gradient purified material has been demonstrated to contain turkey coronavirus by electron   microscopy   and   immunoelectronmicroscopy. The purified turkey coronavirus also proved to be infectious to turkey embryos.

Diagnosticians at ADD1 and SIPAC conducted a study in an attempt to experimentally reproduce turkey poult enteritis in seven-day-old turkey poults using sucrose density gradient purified embryo intestinal material from serially passaged turkey embryos.  Clinically, the infected turkey poults showed ruffled feathers, acute enteritis, and decreased weight gain. Microscopically, the villi, particularly in the jejunum and ileum, revealed marked villous atrophy.  It appears that turkey poult enteritis can be caused by turkey coronavirus.

Although there is no effective treatment for turkey poult enteritis, strict biosecurity and use of crumble feed are helpful in reducing the severity of the disease. In order to effectively diagnose and control  turkey  poult   enteritis,   continuous monitoring of turkey poult intestines and sera from the field by fluorescent antibody testing, further characterization of turkey coronaviral protein, production of monoclonal antibody to turkey coronavirus   development   of  eruyme-linked immunosorbent  assay  (ELISA)  for  turkey coronaviral antibody or turkey coronavirus, genomic   sequence   comparison   of  turkey coronavirus isolate from Indiana with that from Minnesota, Canada, North Carolina, and other states and application of polymerase chain reaction (PCR) for the detection of turkey coronavirus are under way.

- prepared by Tsang Long Lin,DVM,PhD




ADDL-West Lafayette:
406 S. University
West Lafayette, IN 47907
Phone: 765-494-7440
Fax: 765-494-9181

11367 E. Purdue Farm Road
Dubois, IN 47527
Phone: (812) 678-3401
Fax: (812) 678-3412

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