JPC SYSTEMIC PATHOLOGY
Signalment (JPC #1758839): African pygmy goat
HISTORY: Multiple near term abortions occurred in a research herd of African pygmy goats. Placentas were covered with tan mucoid exudates, cotyledons were hemorrhagic, and necrotic villi were noted. Cultures of fetal stomach contents were negative for bacterial growth.
HISTOPATHOLOGIC DESCRIPTION: Slide A: Chorioallantois: Diffusely, there is effacement of the chorioallantoic villar architecture with degeneration, necrosis and loss of the chorionic epithelium andreplacement by abundant necrotic debris, mineral, hemorrhage (lytic necrosis) and scattered sloughed cytotrophoblast and syncytiotrophoblast cells, admixed with numerous degenerate neutrophils, with fewer macrophages, lymphocytes and plasma cells. Multifocally abundant necrotic debris, degenerate neutrophils, fibrin, hemorrhage and edema expand the space between villi. Multifocally, there are numerous 1.0 um pleomorphic coccoid to rod-shaped organisms expanding the cytoplasm of trophoblasts, and less commonly, macrophages. The chorioallantoic stroma is multifocally expanded by eosinophilic or basophilic, finely granular material (mineral), clear space and ectatic lymphatics (edema), and moderate numbers of lymphocytes, plasma cells and fewer macrophages. Multifocally within the intercotyledonary chorion the surface is ulcerated with loss of the epithelium and replacement by degenerate neutrophils, fibrin, hemorrhage and necrotic debris, or the remaining epithelium is hypertrophic and hyperplastic with the cytoplasm being distended by abundant 1um basophilic pleomorphic coccid bacteria.
Slide B, Giemsa: Intratrophoblastic coccobacilli stain purple to magenta.
MORPHOLOGIC DIAGNOSIS: Chorioallantois: Placentitis, necrotizing and suppurative, subacute, diffuse, severe, with numerous intratrophoblastic and intrahistiocytic coccobacilli, African pygmy goat, caprine.
ETIOLOGIC DIAGNOSIS: Coxiella placentitis
CAUSE: Coxiella burnetii
CONDITION: Q Fever (“Query fever”) in man
- Gram negative, obligate intracellular intracytoplasmic organism of the order Legionellales (formerly Rickettsiales), the gamma subdivision of Proteobacteria; worldwide distribution; causes late gestational abortion in ruminants
- Phylogenetically related to Legionella, Francisella, and Rickettsia spp
- Vertebrate hosts include most wild and domestic mammals, birds, man, reptiles and arthropods
- Ruminants (dairy cows, goats, sheep) are the most common reservoir
- Identified in most tick species (facilitates sylvan cycle with reservoirs)
- Usually transmitted by inhalation of environmentally resistant organisms (can travel up to 10 miles via wind), ingestion, direct contact with body fluids and vectors
- Large numbers of organisms are present in infected placenta and fetal membranes; organisms also present in wool, feces, and milk
- Sporulates; resistant to heat (pasteurization temperature targeted to kill this organism), drying, and to physical and chemical agents; survives for long periods
- Infection persists indefinitely in sheep and cattle
- Two life cycle stages:
- Large cell form is metabolically active intracellular vegetative stage
- Small-cell extracellular variant is metabolically inactive, environmentally resistant stage
- Predilection for placental and fetal tissues; replicates in trophoblasts, epithelial cells, endothelial cells and macrophages
- Entry into cells via “induced phagocytosis” – active role of host cell
- C. burnetii has been shown to inhibit apoptosis in host macrophages as a survival strategy- since trophoblasts (like macrophages) also have a phagocytic function and apoptosis of trophoblasts is a normal part of placental growth/separation, there may be a similar mechanism of survival within these cells
- Altered expression of apoptosis genes as well as increasing/blocking production of anti/proapoptotic proteins
- C. burnetii (and Ehrlichia sp.) enters host cell lysosomes/phagolysosomes
- Survives and multiplies in the acidic environment of the phagolysosome
- Abortions usually follow initial exposure; abortions are less common in endemically infected herds/flock
- Cell mediated immunity is important in elimination of infection; circulating antibodies assist phagocytosis via opsonization
TYPICAL CLINICAL FINDINGS:
- Inapparent infection in most animals
- Abortions in last trimester, usually following initial exposure
- Retained placenta
- Weak and stillborn neonates
TYPICAL GROSS FINDINGS:
- Thickened, leathery placenta, with coalescing areas of mineralization
- Copious, off-white exudate covers intercotyledonary areas
- Cotyledons may have white outer ring with central scattered white flecks
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Acute, diffuse, suppurative placentitis with extensive necrosis of cotyledonary villi and intercotyledonary epithelium (both cotyledonary and intercotyledonary)
- Acute inflammatory infiltration most severe in intercotyledonary areas (and cotyledon periphery)
- Lymphoplasmacytic infiltrate in the chorioallantoic interstitium
- Vasculitis is not usually a feature (vs. Chlamydophila infection)
- Hypertrophic trophoblasts filled with microcolonies of Coxiella organisms
- Cells containing organisms frequently have a characteristic foamy appearance with multiple unstained vacuoles within finely granular blue cytoplasm (vs. Chlamydophila inclusions which stain poorly and appear more homogenous)
- Fetal lesions are usually mild and include a granulomatous hepatitis and nonsuppurative pneumonia with occasional focal peribronchiolar lymphoid accumulations
- Organisms have two trilaminar membranes separated by a periplasmic space; the inner plasma membrane often is in close association with peripheral ribosomes.
- Numerous ribosomes peripherally in the cytoplasm
- Nucleoid filaments centrally in either a dispersed state or packed together to form a dense mass
ADDITIONAL DIAGNOSTIC TESTS:
- Culture (BSL-3 lab required because of zoonotic potential)
- Giemsa, Gimenez, Macchiavello, Warthin-Starry, Brown & Hopps, modified Ziehl‑Neelsen acid-fast positive (not specific and poor sensitivity, especially with vaginal swabs and is not accurate for milk or fecal samples); stain poorly with H&E
- Placental immunohistochemistry: Antigen present in cytoplasmic vacuoles of trophoblasts, especially along the base of the chorionic villi and in neutrophils, degenerate cells and extracellularly in the intervillous spaces
- Fluorescent antibody staining of tissue or smears of placental exudate
- Serologic titers from dam; complement‑fixation; indirect fluorescent antibody; ELISA
- PCR assays
Abortions in sheep:
- Necrotizing placentitis associated with intra-trophoblastic organisms:
- Brucella ovis: Caramel colored sticky exudate on the placenta, thick leathery placenta, and vasculitis
- Chlamydophila abortus: Vasculitis common; coccoid organisms
- Toxoplasma gondii: Affects primarily cotyledons
- Campylobacter fetus: Placental lesions are more severe over the placentomes; vasculitis; characteristic targetoid lesions on fetal liver (hepatic necrosis)
- Listeria monocytogenes: Severe placental lesions; necrotic tips of villi covered by purulent exudate in which many bacteria are present
- Sarcocystis cruzi: Abortion in cattle, goats, sheep; acute necrotizing endometritis; zoite-containing cysts; multiple foci of necrosis in fetal soft tissues
- Bovine fetuses also abort due to Coxiella infection; placental lesions similar to sheep and goats
- Intralesional burnetii has been found within macrophages of cows with endometritis in the absence of other pathogens (De Biase et al., 2018)
- C. burnetii has been reported in the semen of a Saharawi Dorcas gazelle, suggesting possible venereal transmission in captive wild species
- C. burnetii in scid-bg mice xenotransplanted with fetal bovine tissue
- Infections in dogs and cats usually subclinical, but can transmit to humans
- Avian Coxiella-like infections have been described in psittacines- hepatic necrosis and disseminated intrahistiocytic infection; report of Coxiella-like organism in eclectus parrot with additional tropism for heart, biliary epithelium, exocrine pancreas
- C. burnetii has been found in marine mammals (seals, sea lions); however clinical significance is unknown
- De Biase, Costagliola A, Del Piero F, et al. Coxiella burnetii in infertile dairy cattle with chronic endometritis. Vet Pathol. 2018; 55(4):539-542.
- Emery MP, Ostlund EN, Schmitt BJ. Comparison of Q fever serology methods in cattle, goats and sheep. J Vet Diagn Invest. 2012; 24(2):379-382.
- Foster RA. Female reproductive system and mammae. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:1183.
- Garcia-Seco T, Perez-Sancho M, Martinez-Nevado E, et al. Detection of Coxiella burnetii in a Saharawi dorcas gazelle (Gazella dorcas neglecta). J Zoo Wildlife Med. 2016; 47(1):939-941.
- Greene CE. Francisella and Coxiella In: Greene CE, ed. Infectious Diseases of the Dog and Cat. 4th ed. St. Louis, MO: Elsevier Saunders; 2012:482-484.
- Kelly PJ. Q fever. In: Coetzer JAW, Tustin RC, eds. Infectious Diseases of Livestock. Vol 1. 2nd ed. Oxford, UK: Oxford University Press; 2004:565-572.
- Schlafer DH, Foster RA. Female genital system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Elsevier; 2016:416-7.
- Myers E, Ehrhart EJ, Charles B, Spraker T, Gelatt T and Duncan C. Apoptosis in normal and Coxiella burnetii-infected placentas from Alaskan northern fur seals (Callorhinus ursinus). Vet Pathol. 2013; 50(4):622-625.
- Vapniarsky N, Barr BC, Murphy B. Systemic Coxiella-like infection with myocarditis and hepatitis in an Eclectus parrot (Eclectus roratus). Vet Pathol. 2012; 49(4):717-724.
- Gonzalez-Barrio D, Maio E, Vieira-Pinto M, Ruiz-Fons F. European rabbits as reservoir for Coxiella burnetii. Emerg Infect Dis. 2015; 21(6):1055-1058.