Lucía María Campero

The invasive wild boar (Sus scrofa) is commonly hunted for human consumption and meat commercialization both in native and introduced ranges worldwide. Due to its foraging behavior, potential ingestion of Toxoplasma gondii and Neospora caninum parasites are highly likely, making it an ideal sentinel species for parasitic surveillance. This study evaluated the presence and prevalence of T. gondii and N. caninum in wild boars introduced in Northern Patagonia, Argentina, using molecular and multiple serological methods. Samples were collected from 71 wild boars (69 brains; 71 liver, heart, and lung samples; 46 sera). Molecular analysis detected Toxoplasma gondii in only one brain sample (1.4%), while all other tissue samples were negative for both parasites. Additionally, we compared an in-house modified agglutination test (MAT), an indirect fluorescence antibody test (IFAT), and immunoblotting (IB) for toxoplasmosis, and an IFAT, a commercial competitive ELISA (ELISAc), and IB for neosporosis. The seroprevalence of T. gondii, based on agreement among all three tests, was 15.2% (7/46). The in-house MAT showed near-perfect agreement (k= 0.846) with the relative standard of comparison (RSC = IFAT + IB). Conversely, IFAT yielded false-positive results for N. caninum as proved by IB and ELISAc. This study confirms T. gondii infection in Patagonian wild boars at a higher seroprevalence than previously reported, and represents the first investigation of neosporosis in wild boars established in Argentina. Due to its practicality, high specificity (100%), adequate sensitivity (77.8%), and species-independent conjugate need, MAT is a useful tool for serological surveillance of toxoplasmosis in wild boars.

La neosporosis es una enfermedad parasitaria causada por el protozoo Neospora caninum. En los bovinos provoca principalmente abortos y raramente signos neurológicos y lesiones neuromusculares en terneros neonatos infectados congénitamente. En el presente trabajo un ternero recién nacido que presentaba dificultad para incorporarse, pérdida de la propiocepción y lesiones microscópicas incluyendo meningoencefalitis multifocal linfohistiocítica severa, mielitis linfohistiocítica difusa severa con perivasculitis y vacuolización severa del neuropilo resultó positivo a N. caninum mediante inmunohistoquímica y PCR. Se considera relevante incluir como diagnóstico diferencial a la neosporosis congénita en los terneros neonatos que presentan signología neurológica.

Background: Toxoplasma gondii is a globally distributed protozoan parasite with major implications for human and animal health. In sheep, infection can cause reproductive failure and represents an important source of zoonotic transmission through contaminated meat. While cell-mediated immunity is the main protective mechanism, the contribution of humoral responses, particularly against individual recombinant antigens (rAGs), remains poorly characterized in ovine toxoplasmosis. Methods: We analyzed the humoral response of lambs experimentally infected with two reference strains of T. gondii (RH and Me49) using different inoculation doses. Recombinant antigens rGra4Gra7, rGra8, rRop2, rCST9, and rBCLA were tested by IgG-ELISA to evaluate their kinetics during infection. Histopathological analyses of brain tissues were performed to assess lesion severity and cyst presence. Additionally, sera from naturally infected sheep were evaluated to test diagnostic performance. Results: An early IgG response against rGra4Gra7 and rGra8 was detected, consistent with markers of acute infections. Anti-rBCLA, rRop2, and rCST9 IgG responses were associated with the chronic phase and correlated with cyst burden. Notably, stronger anti-rGra4Gra7 IgG responses tended to associate with lower lesion scores, suggesting a potential protective role. In naturally infected sheep, IgG-ELISA against rGra4Gra7 and rGra8 demonstrated the highest diagnostic performance, outperforming total lysate antigen (TLA)-based assays. Conclusion: Our findings highlight distinct kinetics of specific antibody responses against selected T. gondii antigens in sheep, suggesting their value as markers of infection stage and pathology. rGra4Gra7 and rGra8 appear particularly promising both as diagnostic candidates and for exploring mechanisms of humoral modulation in ovine toxoplasmosis.

Intracellular pathogens such as Neospora caninum, Brucella abortus, and Bovine Viral Diarrhea Virus (BVDV) are major contributors to bovine abortions, yet many cases remain without a definitive etiological diagnosis despite inflammatory evidence. This study aimed to characterize the immune response in bovine fetuses aborted due to these intracellular agents, comparing them with fetuses showing inflammatory lesions of probable infectious origin and with negative controls. We analyzed cytokine expression (IFN-γ, TNFα, IL-4, IL-8, IL-12) and haptoglobin levels in mid- and late-gestation fetuses. Mid-gestation fetuses infected with intracellular agents exhibited elevated IFN-γ and IL-8 expressions, suggesting a Th1-type immune response, while late-gestation fetuses showed decreased of these cytokines, indicating a shift toward a Th2-type response. Probable infectious abortions at late gestation also showed downregulation of IFN-γ. No significant differences were observed in TNF-α and IL-12 expressions. Additionally, haptoglobin levels were lower in mid-gestation infected fetuses compared to controls. These findings highlight gestational age-dependent immune modulation in response to intracellular infections and suggest that other unidentified pathogens may contribute to abortions with inflammatory lesions but no confirmed etiology. This study enhances our understanding of fetal immune responses in bovine abortions and may support improved diagnostic approaches for reproductive losses in cattle.

Los parásitos apicomplejos utilizan diversos vertebrados como hospedadores, incluido el ser humano. La detección de estos protozoarios en la fauna silvestre evidencia la contaminación biológica del medio y la existencia de ciclos silvestres, lo que relacionaría su contacto con animales domésticos/seres humanos, debido al avance antropogénico sobre los ambientes naturales. El objetivo del presente trabajo consistió en recopilar información sobre estudios parasitológicos, serológicos y moleculares de los géneros Sarcocystis, Toxoplasma, Neospora y Cryptosporidium en especies de la fauna silvestre presente en Argentina. Se seleccionaron 48 trabajos en los que se analizaron especies silvestres de roedores, cánidos, cérvidos, marsupiales, primates, camélidos sudamericanos, cingulados, félidos, mustélidos, suinos, herpéstidos, lagomorfos, aves psitaciformes y gecónidos. El género parasitario reportado en mayor cantidad de provincias fue Sarcocystis, seguido de T. gondii, N. caninum y por último, Cryptosporidium. La condición de vida libre o en cautiverio y los hábitos etológicos de los animales silvestres, entre otros factores, influyeron en la dinámica de la interacción parásito-hospedador y en la presentación de estas infecciones.

We describe the occurrence of dystocia and stillbirths in Brangus and Aberdeen Angus cows and heifers within the context of mineral deficiencies in a beef farm located in Buenos Aires province, Argentina. Water, forage, and blood samples were collected for chemical, serology, and mineral quantification, respectively. Birth weight, sex and presentation of calves were monitored at birth, and calving ease was evaluated. A stillborn Aberdeen Angus female was examined postmortem. The occurrence of dystocia and subsequent stillbirths was recorded in 6.11% (32 out of 523) of dams with subclinical hypomagnesemia. During calving, dystocic animals exhibited prolonged labor, stillbirths, and delivery assistance. No difference in birth weight was registered between dystocic and eutocic births. A postmortem examination of a stillborn calf revealed low hepatic copper concentrations and congenital Neospora caninum infection. However, no histopathological findings consistent with N. caninum infection were observed, confirming only the congenital infection. Maternal hematological analyses indicated suboptimal levels of calcium, magnesium, and copper. Mineral supplementation with MgCl2 + MgO reduced the likelihood of dystocic calvings in cows. Additionally, non-infectious causes of perinatal deaths were serologically identified in the dams. Dietary analysis showed no mineral-interfering factors. While dystocia is common, its association with mineral deficiencies is likely underreported. Further research is needed to better understand and mitigate the negative impact of mineral deficiencies on the sustainability of beef production systems in the region.