Environment and Offspring Surveillance in Porcine Brucellosis

Sponge-based environmental DNA detection as a useful tool in monitoring Mycobacterium tuberculosis complex markers in European bison (Bison bonasus)

The European bison (Bison bonasus), also called wisent, is the largest terrestrial mammal in Europe, classified by the International Union for Conservation of Nature (IUCN) as a "Near Threatened" species. Tuberculosis (TB) represents a well-known threat to wisent, especially nowadays when infectious diseases are emerging to this species, due to locally high population density and frequent translocation (and consequently increased exposure to infectious diseases). There is an urgent need to control the TB-epidemiological situation in the European bison environment. This study aimed to assess the usefulness of the sponge-based environmental-DNA (eDNA) for monitoring TB in free-ranging and captive European bison herds based on the knowledge of the TB-epidemiological situation in the past. Between 2022 and 2024, eDNA samples (n = 84) were collected from European bison or their environment in eight herds from different regions of Poland. The real-time PCR techniques with IS6110, IS1081, and MPB70 as targets were used to detect MTC DNA markers in the samples. The MTC DNA IS6110 and IS1081 were simultaneously detected in 17/84 (20.2%) samples. No sample was positive for MPB70. The highest number of positive results for both markers (IS6110 and IS10081 targets) was in the captive herd in Bieszczady-Muczne, followed by the free-ranging herd in the nearby Bieszczady Mountains. Even though detecting nucleic acid, especially at low eDNA signal, does not necessarily indicate viable pathogens, our results suggest this new approach could represent a suitable complementary tool for TBC surveillance in wildlife-livestock interface of particular interest in endangered species.

Detection of Brucella in Dermacentor Ticks of Wild Boar with Brucellosis

Brucellosis is a sanitary and economically relevant disease affecting humans, livestock, and wildlife. Ticks have been suggested as vectors, long-term carriers, and amplifiers of Brucella. In this study, ticks from wildlife ungulate hosts living in hunting reserves of a central region of Spain were collected during a 6-year period, pooled, and screened for Brucella spp. by PCR. Aiming to correlate Brucella spp. DNA presence in ticks with Brucella spp. infections in wildlife ungulate hosts, liver samples from deceased wildlife ungulates coming from the hunting reserves showing a positive result for Brucella in ticks were tested using a commercial ELISA. In total, 229 tick pools from wild boar (Sus scrofa, n = 176; 76.8%, 95% CI 70.9%-81.8%), red deer (Cervus elaphus, n = 40; 17.4%, 95% CI 13.1%-22.9%), mouflon (Ovis orientalis musimon, n = 7; 3.06%, 95% CI 1.49%-6.17%), and fallow deer (Dama dama, n = 6; 2.62%, 95% CI 1.21%-5.60%) were analyzed. PCR results showed that 3.93% (95% CI 2.08%-7.30%) tick pools (9/229) from 16.6% hunting reserves (7/41) screened yielded a positive PCR result for Brucella. All positive ticks were Dermacentor (Dermacentor marginatus or Dermacentor reticulatus) collected from wild boar. Ticks collected from wild boars were positive to Brucella in a relative percentage of 5.10% (95% CI = 1.61-11.4) in 2018 and of 7.59% (95% CI = 2.79-15.6) in 2021 (6-year prevalence of 5.17%, 9/176). ELISA showed positive results in three wild boars coming from two out of seven hunting reserves (28.5%) with a positive PCR for Brucella in ticks. To conclude, Brucella spp. DNA can be detected in Dermacentor ticks parasitizing wild boars living in hunting reserves harboring Brucella spp.-seropositive wild boars. This study provides evidence that the contribution of arthropod vectors should be considered in the epidemiology of brucellosis in wildlife.

Histopathologic and immunohistochemical findings in the placentas and fetuses of domestic swine naturally infected with Brucella suis biovar 2

Porcine brucellosis, which is caused by Brucella suis biovar (bv) 2, is a re-emerging disease that causes reproductive problems in pigs in Europe. The pathogenesis and lesions of B. suis intrauterine infection are poorly characterized; characterization could facilitate the diagnosis and investigation of porcine brucellosis. We collected samples of placentas and fetuses for histologic and microbiologic studies during an outbreak of abortions on a pig-breeding farm in Spain. Brucella was cultured from the vaginal swabs obtained from sows that had aborted, some placentas, and fetal tissues (spleen, liver, lung, gastric content); molecular testing confirmed B. suis bv 2 infection. Histologically, there was necrotizing and hemorrhagic placentitis; suppurative hepatitis; lymphoid depletion and sinusoidal histiocytosis in the spleen, lymph nodes, and thymus; and bronchointerstitial pneumonia. Hemorrhages were observed in the umbilical cord, heart, kidneys, and brain. We detected Brucella by immunohistochemistry (IHC) in all of the placentas and fetal organs studied, specifically in the trophoblasts of the chorionic epithelium, in the cytoplasm of macrophages in the chorionic stroma, and extracellularly in necrotic debris. Furthermore, we assessed the lymphocyte population in the placentas through the use of IHC (anti-CD3, anti-Pax5 antibodies), revealing that the lymphocytic response was composed of T cells but not B cells.