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Final Diagnosis:  Q fever (Coxiella burnetii) in an
Indiana Goat Herd

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

 

Q fever.jpg
Suppurative exudate on the surface of the placenta


References:

  1. Jubb KVF, Kennedy PC, Palmer N eds: 1993.  Pathology of Domestic Animals, 4th ed.  Academic Press, New York.  Vol 3, pp 417-419.

  2. Van Campen H: 2008.  Colorado State University (personal communication)

  3. Berri M, Rousset E, Champion J et al: 2007.  Goats may experience reproductive failures and shed Coxiella burnetii at two successive parturitions after a Q fever infection.  Res Vet Sci 83(1): 47-52.

  4. Centers for Disease Control website http://www.cdc.gov/ncidod/dvrd/qfever/

  5. Raoult D, Fenollar F, Stein A: 2002.  Q Fever During Pregnancy.  Arch Intern Med 162: 701-704.

 

 

 

 

 

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