In
August 2008, twin goat fetuses (a 1.3 kg female and a 1.2 kg male), along with
their placentas, were submitted to the Animal Disease Diagnostic Laboratory with
a clinical history of premature abortion. The owner reported that two groups
of goats were combined into a single flock; one a group of crossbred goats
that were purchased the previous winter, and the second, a group of registered
purebred goats that were purchased in the spring. Abortions reportedly occurred
only in the purebred Boer goats.
At gross necropsy, the male fetus was moderately autolytic (suggesting
intrauterine fetal death) and was still covered with fetal membranes. The
female fetus was fresh and well preserved with little evidence of autolysis,
was separated from the placenta, and was presumably alive just prior to
abortion. Both had complete fetal atelectasis of the lungs. No other gross
lesions were found in either fetus. The placenta had extensive areas that were
slightly dry and leathery and had abundant white muco-purulent exudates on the
surface of the intercotyledonary areas (suppurative placentitis).
Cytology impression smears of affected intercotyledonary placenta stained with
Diff-Quik had large numbers of degenerating neutrophils. A separate smear of
the placental cotyledon had large numbers of bacteria, comprised primarily of
large cocci, but with lesser numbers of small cocci and bacilli.
Histologically, the placenta had multifocal to
extensive areas of necrosis of superficial placental epithelium in both
cotyledons and intercotyledonary areas. Within the necrotic epithelial debris
were scattered cells swollen with basophilic granular material (suspected
intracellular bacteria. These bacteria stained with Giemsa, but not with
acid-fast. The underlying submucosal reaction in affected placenta was
surprisingly mild, consisting only of mild lymphocytic infiltrates, and
placental vessels had no evidence of vasculitis. No histologic lesions were
present in the fetal tissues.
Bacterial culture of the fetal tissues was negative. Culture of the placental
surface was not attempted due to gross examination of the tissue. Placenta was
submitted to the Colorado State molecular diagnostics laboratory for Coxiella
burnetii PCR analysis, and Coxiella DNA was detected in the
placental tissues. [Note: since this case was submitted the Purdue ADDL has
developed a PCR test for Coxiella - see information on page 8 of this edition
of Diagnostic Forum].
Other laboratory tests were negative for leptospirosis (FA and serology)
brucellosis (culture and serology), Campylobacter (culture), listeriosis
(culture), BVD (FA and VI), IBR (FA and VI), toxoplasmosis (serology), and
chlamydiosis (PCR).
Diagnosis of Q fever (coxiellosis) in this case was based upon gross
suppurative placentitis, histologic superficial necrotizing placentitis with
intracellular organisms, and the presence of Coxiella DNA within affected
placenta. Because of the fastidious nature of intracellular pathogens,
bacterial culture is not a suitable method for diagnosing Coxiella infection.
The National Veterinary Services Laboratory at Ames, Iowa, does have a
serologic test for Coxiella burnetii (not utilized in this case). This
test is maintained for regulatory import/export purposes, and is useful for
diagnosing coxiellosis on a herd basis, but is not considered sensitive enough
to reliably diagnose Coxiella infection in an individual animal.
Because Coxiella has traditionally been difficult to diagnose, it has
probably been underdiagnosed in the past. Once PCR testing for Coxiella became routine in Colorado, it was found to be more prevalent in that state
than had been previously believed. To our knowledge, this is the first
diagnosis of Coxiella burnetii infection in Indiana livestock but, with
the development of our own PCR test, we may also find that it is more common in
Indiana than previously thought.
Coxiella is an obligate intracellular bacterium in the family
Rickettsiaceae. It typically causes rare sporadic abortion in
endemically-infected groups of sheep, goats, and dairy cows but, as in this
case, can cause abortion storms when first introduced to naïve, non-immune animals. Large numbers of organisms are
shed into fetal fluids and milk, and infection occurs when contaminated dust or
fluids are inhaled by other animals (or humans). Recovered animals may not
abort again, but become carriers and continue to shed organisms in their fetal
fluids. Active infection can reportedly be treated with tetracycline and
related antibiotics. Quinolone antibiotics are also reportedly effective.
Q fever is zoonotic, causing flu-like symptoms in humans with a fever that can
last 7-14 days. Rarely, it may progress to pneumonia, chronic hepatitis, or
chronic endocarditis. It has been associated with spontaneous abortion
(miscarriage), and it is prudent for pregnant women to limit contact with
infected animals, especially with fetal fluids and unpasteurized milk.
-by
Dr. Duane Murphy, Heeke ADDL
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