Yersinia pseudotuberculosis and Y. enterocolitica abortions in sheep and goats in California: a series of cases diagnosed at CAHFS laboratories, 2002-2023

Abstract

Abortion in small ruminants poses a significant economic threat and can have zoonotic risk. Although the association between yersiniosis and reproductive complications is known, systematic studies and case series on abortion in sheep and goats are scarce. Here we describe epidemiologic and pathologic findings in 34 cases of Yersinia pseudotuberculosis- and Y. enterocolitica-associated abortions in sheep and goats, contributing to the understanding of these zoonotic diseases in California. We conducted a 22-y retrospective study to examine microbiologic and pathologic findings in abortion submissions, as well as the geographic and seasonal distribution of the analyzed cases. Yersiniosis-induced abortion was diagnosed in 22 goats and 12 sheep, with all abortions occurring in the last third of gestation. Samples from lung, liver, placenta, and abomasal contents were submitted for aerobic culture; the highest recovery of Yersinia spp. was from abomasal contents. Microscopically, there was severe necrotizing and suppurative inflammation in the lung, liver, spleen, kidney, and, when present, the placenta, with intralesional bacterial colonies. All cases were received from northern and central California in the winter and spring. Our study provides epidemiologic and pathologic features of Yersinia spp.-induced abortions in small ruminants and provides critical data to pave the way for future research, surveillance, and preventive strategies.

Keywords: California; abortion; epidemiology; pathology; small ruminants; yersiniosis.

Figure 1.

Gross findings of Yersinia pseudotuberculosis abortion. A. Purulent exudate present on the surface of intercotyledonary areas (asterisks) and over the cotyledons (arrows) of the placenta in a goat. B. Myriad necrotic foci throughout the hepatic parenchyma (arrows) in a sheep.

Figure 2.

Histopathologic features of yersiniosis-induced abortion in goats. A. Necrotizing pneumonia. B. Hepatitis. C. Splenitis. The lesions efface the lung, hepatic, and splenic parenchyma multifocally, and have prominent central eosinophilic necrotic foci with bacterial colonies (bacilli) surrounded by dense degenerate nuclei and light eosinophilic necrotic parenchyma. H&E. D. Necrosuppurative placentitis. Dense inflammatory infiltrates within the decidual plate (asterisk), and basophilic bacterial colonies are visible (arrow). H&E. E. Gram-negative, pink coccobacilli (asterisk) within the placenta of Fig. 2D. Gram stain.

Figure 3.

Geographic distribution of 34 cases of Yersinia pseudotuberculosis and Y. enterocolitica abortion in goats and sheep in California. Black triangles represent caprine abortion cases caused by Y. pseudotuberculosis, red triangles represent caprine abortion cases caused by Y. enterocolitica, and circles represent ovine abortion cases caused by Y. pseudotuberculosis.