A Diagnostic Dilemma: Turkey
Coronaviral Enteritis in Southern Indiana
T.A. Bryan1*, D. Hermes2,
T.A. Hooper1, C. L. Kanitz3, T.L. Lin3,
D.A. Murphy1,
R.E. Porter3, Jr., D.L. Schrader3,
H. L. Thacker3, M.M. Woodruff3
Enteritis in southern Indiana turkeys had been a serious
problem in Dubois County. Summer after summer affected flocks
were shrill and uneasy, marching the house, refusing feed
and water, acting chilled, but managing to impact their gizzards
with litter. Dead birds were dehydrated, light in weight,
with dark beaks and shanks. Grossly the cecae were distended
with pale, syringable fluid. Usually young flocks were affected.
The size uniformity in the flock quickly disappeared. It was
noted by Dr. Hermes that flocks on crumbles had much lower
mortality but similar morbidity than those fed mash. In the
fall and winter mortality was not a problem but weight gain
and feed conversion were economically unacceptable.
For a number of years, enteric virus detection has depended
upon electron microscopy. In our experience, electron microscopy
yielded varying results. There was no consistency within a
flock. Electron microscopy results improved when naïve,
test poults were exposed to field cecal material, followed
by harvest of cecal contents after 2-3 days. Poult inoculation
definitely improved electron microscopy results.
A literature search of Minnesota's TCE experience suggested
an avenue for FA work that Dr. Kanitz had initiated at ADDL-SIPAC
for other species. Dr. Y.M. Saif of OSU provided TCE antisera
produced in SPF turkeys. Tom Hooper adapted the test procedure
for use in several trials with inoculated and uninoculated
poults of 5-7 days of age. In the direct immunoflorescence
procedure composite sections of fresh frozen intestines taken
from the yolk stalk to cecal pouch were stained with conjugated
antisera. TCE FA+ diagnosed flocks continued to provide FA+'s
for about 4 weeks after the first FA+ result.
For handling large numbers of serological tests, Tom
Hooper propagated known antigen into 24 day old turkey embryos,
harvested intestines 2 days later, and mounted the frozen
intestine sections on glass slides. By testing convalescent
sera from 6 poults within a suspect flock, incubating with
previously prepared intestinal slides, washing, and staining
with conjugated goat anti-turkey globulin, lab time was reduced
as well as providing a greater window of opportunity for testing
convalescent, suspect flocks.
In conclusion, our experiences suggest that the IFA test
for turkey coronavirus has advantages over the EM and FA tests
for diagnosing TCE because it produces more consistent results
and is less labor intensive.
*Presenter
1Animal Disease Diagnostic Laboratory, Purdue
University, Southern Indiana Purdue Agricultural Center, Dubois,
Indiana.
2Perdue Farms, Inc., Washington, IN 47501.
3Animal Disease Diagnostic Laboratory, Purdue
University, West Lafayette, IN 47907.
NCCVLD ABSTRACT
Equine Protozoal Myelitis:
Current Knowledge About Etiologic Agent Life Cycle, Prevalence,
Diagnosis and Treatment
M. Levy1*
EPM is a debilitating neurologic disease of horses. It can
affect the brain, brainstem, spinal cord or any combination
of these three areas of the central nervous system. Clinical
signs may suggest focal or multifocal disease, which means
the disease may affect a very small (focal) part of the central
nervous system (CNS) or many parts of the CNS (multifocal).
Therefore, the disease may present itself with a variety of
different clinical signs, dependent on the location of the
damage caused by the organism within the CNS.
Although EPM has been recognized since the 1970's, it
was not until 1991 that the organism (protozoan parasite)
was cultured from a horse and given the name Sarcocystis
neurona. Opossum feces (definitive host) are the source
of the infection for horses. Opossums acquire the infection
by eating infected birds (intermediate host).
EPM occurs in much of North America. Surveys conducted
in central Kentucky, one county in Pennsylvania and the entire
states of Ohio and Oregon have revealed that approximately
50% of the horses have been exposed to this parasite. We know
that a positive serum test indicates exposure to the parasite
not necessarily the presence of disease.
EPM can affect a horse of any age, breed, or sex. The
youngest horse reported affected was 2 months of age, and
the eldest in its 30's. Clinical signs may be triggered or
worsened by physiologic stress or the administration of corticosteroids.
In most cases, affected horses are bright and alert with
a normal appetite although some horses are dysphagic and may
act as if they are choked.
Ante mortem diagnosis of EPM is based on clinical signs
and on testing of the horse's cerebrospinal fluid (CSF) by
the western blot test. If blood contaminates the CSF sample,
a false positive test may result.
Treatment of horses with EPM is expensive. The average
range of treatment is 90 to 120 days, and may exceed 6 months
in some instances. The current approaches to treatment for
EPM includes pyrimethamine in combination with a sulfonamide
antimicrobial with or without trimethoprim. It would appear
that early detection and therapy increases the chance of successful
treatment.
*Presenter
1Department of Veterinary Clinical Sciences, School
of Veterinary Medicine, Purdue University, West Lafayette,
IN.
NCCVLD ABSTRACT
Defining Proliferative
Enteritis As A Cause of Protein Losing Enteropathy in Foals
C. Fishman1* and C. Gebhart2
Lawsonia intracellularis (LI) is an obligate intracellular,
bacillary bacterium which has been established as the cause
of proliferative enteritis (PE) in swine. PE associated with
LI infection has been documented as an uncommon to rare disease
in the hamster, guinea pig, rabbit, ferret, dog, fox, horse,
deer, ostrich and non-human primate. There are currently two
published reports describing the pathology of PE in the foal.
There are no reports describing the clinical aspects of PE
in foals, and reviews of causes of enteritis in foals do not
include this disease. PE as the cause of protein losing enteropathy
was diagnosed in a six month old, quarterhorse colt presented
to the Animal Disease Diagnostic Laboratory at Purdue University,
West Lafayette, IN. The animal had been admitted to the Large
Animal Teaching Hospital, School of Veterinary Medicine at
Purdue University with the clinical history of sudden onset
of diarrhea and anorexia. The animal was febrile and dehydrated.
Clinical laboratory data revealed hypoproteinemia with comparable
decreases in albumin and globulin, mild normocytic, normochromic
anemia, mild leukocytosis with neutrophilia, left shift and
toxic neutrophils and lymphocytosis with reactive lymphocytes,
hyperfibrinogenemia, mild azotemia, hypocalcemia, hypomagnesemia,
hyponatremia and metabolic acidosis with compensatory respiratory
alkalosis. The animal failed to respond to treatment, which
included plasma transfusions, intravenous fluids, corticosteroids,
bismuth subsalicylate and cimetidine, and over a three week
period became increasingly cachectic, developed subcutaneous,
dependent edema and was euthanized. Gross necropsy revealed
diffuse thickening of the jejunum and ileum with a variably
corrugated or multinodular expansion of the mucosa, submucosal
edema and muscular hypertrophy. The affected mucosa was multifocally
ulcerated, and in one focus, a transmural ulcer resulted in
intestinal perforation and septic peritonitis. The microscopic
lesions in the affected small intestine closely resembled
that of porcine PE, including villous blunting and deepening
of crypts which were tortuous with complex branching patterns.
Crypts were lined by crowded, multilayered enterocytes with
vesicular nuclei containing prominent nucleoli and a moderate
amount of cytoplasm with increased basophilia and a lack of
mucus vacuoles. A Warthin-Starry stain revealed myriads of
curved bacilli in the apical cytoplasm of the hyperplastic
enterocytes. The mitotic index in crypt enterocytes was increased.
Crypts were "herniated" into the submucosa, particularly in
the area of Peyer's patches. In ulcerated foci, the intestinal
wall was partially to fully replaced by granulation tissue.
Immunohistochemical stains of paraffin-fixed tissue were positive
for LI using a specific monoclonal antibody. The DNA of the
bacterium in this case was shown to be homologous to that
of swine isolates using extraction, PCR amplification and
gel electrophoresis. Transmission electron microscopy revealed
bacillary bacteria, measuring 2-4 x 0.2 microns, with a wavy
trilaminar cell wall, free within the apical cytoplasm of
enterocytes and often adjacent to mitochondria. The clinical
signs and response to therapy of this foal were inconsistent
with other commonly reported causes of enteritis. If an index
of suspicion of PE exists, LI can be detected using PCR on
feces and by serum antibody tests. Ante mortem identification
of PE cases in foals will allow for estimates of prevalence
and will provide epidemiologic information. This is the first
case report to correlate clinical and clinical pathologic
findings with gross and microscopic morphology in a horse
with LI infection.
*Presenter/Graduate Student
1Animal Disease Diagnostic Laboratory, Purdue
University, West Lafayette, IN 47907.
2Department of Veterinary Pathobiology, University
of Minnesota, St. Paul, MN 55108.
NCCVLD ABSTRACT
Pneumonic Pasteurellosis
Associated with Pasteurella hemolytica Biotype A6 in
American Bison (Bison bison)
N.W. Dyer1* and Alton C.S. Ward2
Three buffalo bulls (Bison bison) with a clinical
history of respiratory distress and sudden death were submitted
to the North Dakota State University Veterinary Diagnostic
Laboratory (NDSU-VDL) for post mortem examination. The owner
maintained a herd of forty-eight animals to which he had recently
added twenty, sale-purchased, eight month old bull calves.
The first calf died on December 25, 1996 followed by a second
on December 27. Formalin-fixed and fresh tissues from the
second calf reached the NDSU-VDL on December 30. In addition,
the carcasses of a calf which developed signs of respiratory
disease on December 29, and a calf which died acutely on January
1, 1997, were submitted on January 3. Grossly, lung tissue
showed variable amounts of bilateral, cranioventral hemorrhage
and consolidation, pleural adhesions, and diffuse fibrinous
pleuritis and pericarditis. Histologically, the pleura and
interlobular septa were markedly expanded by focally intense
clusters of neutrophils, fibrin strands and extravasated red
blood cells. A similar inflammatory exudate was diffusely
present within alveoli, bronchioles and bronchi. Curvilinear
bands of streaming leukocytes frequently outlined these areas
of fibrinosuppurative inflammation. Numerous pulmonary vessels
showed vasculitis and thrombosis. Fluorescent antibody examination
of lung tissue from all three animals was negative for IBR,
BVD, BRSV and PI3. Culture of lung tissue from all three animals
yielded a moderate to heavy growth of Pasteurella hemolytica
biotype A serotype 6.
*Presenter
1Departments of Veterinary and Microbiological
Sciences, North Dakota State University, Fargo, ND.
2Caine Veterinary Teaching and Research Center,
University of Idaho, Caldwell, ID.
NCCVLD ABSTRACT
Case Report: Atypical PRRS
Outbreak in Illinois Swine Herd
Dale M. Webb1*
A well-managed, 2,200 sow herd began experiencing illness
characterized by inappetence, lethargy, fever, abortion, stillbirths,
and sow death in early June, 1996. The average parity in the
herd at the time of the outbreak was 3.2. Illness did not
correlate with parity nor was it correlated with stage of
gestation. Moving or treating sick animals resulted in exacerbation
of clinical signs and, in some cases, death of the sow. The
herd had prior natural exposure to porcine reproductive and
respiratory syndrome (PRRS), and was routinely vaccinated
with RespPRRSâ (NOBL Laboratories).
Abortions occurred in 8-10% of the affected sows and sows
that did not abort had a high occurrence of stillbirths and
mummified fetuses. Live-born piglets were often small and
weak. Abortions and stillbirths also did not appear to correlate
with parity.
Transmission of the disease was slow with neighboring
sows becoming ill as long as several weeks apart. Affected
animals generally returned to feeding and normal activity
within 72 hours of first showing signs of illness. A few sows
did not return to normal feeding and activity quickly. These
animals were often found not to be pregnant even though they
did not appear to cycle. The referring veterinarians2
indicated the disease appeared to have affected 95% of the
sows in the facility by the end of July (8-9 weeks from the
onset of disease in the first animals).
Early in the course of the outbreak, two sows were submitted
alive to the Illinois Department of Agriculture Animal Disease
Laboratory in Galesburg, IL, for necropsy. The sows were in
excellent physical condition and pregnant with near-term fetuses.
There were no significant grossly evident findings. No bacterial
growth was obtained from aerobic cultures of brain, lung,
and pooled liver, kidney, and spleen. Salmonellae were not
isolated from culture following enrichment techniques (tetrathionate
broth). Both sows were leukopenic and had slightly increased
hematocrits and total proteins, suggesting mild dehydration.
Fibrinogen was less than 400 mg/dl in both animals, and total
protein/fibrinogen ratios were 21 and 27, respectively. No
antibody titers were detected to the routinely pathogenic
serovars of Leptospira interrogans, except one sow
ha a 1:100 titer against the brataslava serovar. One
sow was seropositive for exposure to encephalomyocarditis
virus at 1:32. One sow had a PRRS ELISA S/P ratio of 0.62;
the other sow was seronegative.
Significant histologic alterations were limited to the
lung and liver. The lungs had mild diffuse interstitial pneumonia.
The liver had randomly distributed, disseminated foci of hepatic
necrosis involving small groups of hepatocytes with variable
(generally minimal), accompanying inflammatory infiltrates
consisting of macrophages, lymphocytes, and neutrophils.
Attempts at virus isolation were unsuccessful at our
laboratory (MARC 145 cells, swine testicular cells, and baby
hamster kidney cells), the National Veterinary Services Laboratory
(NVSL; fetal porcine kidney cells, swine testicular cells,
and MARC 145 cells), and Iowa State University (ISU). Subsequent
passage of liver homogenate into cesarean-derived , colostrum
deprived piglets resulted in all piglets producing PRRS virus
antibodies and PRRS virus was isolated from all piglets.3
Based on these findings, this diagnostically challenging
case was eventually believed to be an atypical PRRS-virus
infection. A novel feature of the disease in this herd was
the presence of necrotizing hepatitis, which had not been
described previously, but has been seen subsequently in other
outbreaks of atypical PRRS. Why this (and other) well-vaccinated
herd broke with clinical disease is currently under further
investigation at ISU and NVSL.
*Presenter
1Illinois Department of Agriculture, Animal Disease
Laboratory, Galesburg, IL.
2Terry L. Bolton, DVM and James R. Lehman, DVM,
Bolton and Lehman, Ltd., Atlanta, IL.
3Thanks to Pat Halbur, Veterinary Diagnostic Laboratory,
Iowa State University, and Kelly Lager, National Veterinary
Services Laboratory, Ames, IA.
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