Quantification of vertical transmission of Neospora caninum in dairy cows in Minas Gerais, Brazil

Combined control evaluation for Neospora caninum infection in dairy: Economic point of view coupled with population dynamics

Neospora caninum infection is regarded as one of the most important infectious causes of abortion in dairy cattle. To intervene in its spread, four potential controls including test-and-cull, medication, vaccination, and selective breeding are considered and assessed in this study. The cost of each control, together with the inevitable annual loss due to population dynamics, is adopted as an assessment criterion from an economic point of view. By performing simulation and sensitivity analysis, our results demonstrate that compared with each single control, combined controls are worthwhile with better financial outcomes. For farm affected with significant prevalence (equal to or greater than 30%), vaccine treatment is the most effective and economical option among all control strategies. On the other hand, for farm where prevalence is relatively low (around 10%), combined control, by applying vaccination followed with test-and-cull, medication or selective breeding, could be alternative treatment to provide better financial outcome against single control in an observed period.

Meta-analysis of the prevalence and risk factors associated with bovine neosporosis

Neospora caninum is one of the main infectious agents that cause reproductive disorders in cattle. However, knowledge about the prevalence and causal factors of bovine neosporosis is needed in order to establish control measures. The purpose of this study was to estimate the pooled prevalence and determine the risk factors of bovine neosporosis using meta-analytic methods. Searches for data on N. caninum seroprevalence and potential risk factors were conducted in the PubMed, LILACS, and SciElo databases. The random effects model was used for the meta-analysis of the included studies. The pooled prevalence of N. caninum in cattle was 24% (95% confidence interval (CI), 19-29) in North and Central America, 24% (95% CI, 20-28) in South America, 18% (95% CI, 14-21) in Asia, 15% (95% CI, 12-18) in Europe, 13% (95% CI, 11-16) in Africa, and 8% (95% CI, 4-14) in Oceania. A significant correlation was found between N. caninum infection and abortion in cows (odds ratio (OR) = 2.66, 95% CI, 1.97-3.59). The following risk factors were signicantly associated with N. caninum seroprevalence: presence of dogs on the farm (OR = 2.84; 95% CI, 1.40-5.80) and the type of cattle production system, with dairy cattle being more susceptible to bovine neosporosis (OR = 1.60; 95% CI, 1.16-2.19) than beef cattle. The adoption of measures to prevent the dissemination of N. caninum in cattle herds is suggested, aiming to reduce the economic losses incurred to the dairy and beef industry.

Extracellular Vesicles Secreted by Neospora caninum Are Recognized by Toll-Like Receptor 2 and Modulate Host Cell Innate Immunity Through the MAPK Signaling Pathway

Neospora caninum is an obligate intracellular parasite, which causes significant economic losses in the cattle industry. However, the immune mechanism of the parasite–host interaction is not yet fully understood. Extracellular vesicles (EVs) have emerged as a ubiquitous mechanism by which almost all cells, especially immune and tumor cells, participate in intercellular communications. Although studies have indicated that EVs secreted by Toxoplasma gondii or Trypanosoma brucei promote exchanges of biological molecules important for the host–parasite interplay, however, EVs and their biological activities in N. caninum is not clear. Here, we used multiple methods, including electron microscopy, nanoparticle tracking analysis, RT-PCR, immunofluorescence, western blot, proteomics, and cytokine analyses, to examine the properties of N. caninum EVs. We found that N. caninum produced EVs that are similar to mammalian exosomes, which generally range from 30 to 150 nm in diameter. It was shown that N. caninum EVs could remarkably increase the production of pro-inflammatory cytokines IL-12p40, TNF-α, IL-1β, IL-6, and IFN-γ by wild-type (WT) mouse bone marrow-derived macrophages (BMDMs) whereas the secretion of IL-12p40, TNF-α, and IFN-γ was very strongly downregulated in TLR2^−/− mouse BMDMs. The levels of IL-6 were not affected, but the secretion of IL-10 was upregulated. We found that the phosphorylation levels of P38, ERK, and JNK were significantly reduced in the TLR2^−/− cells compared with those in WT mouse BMDMs and that treatment with chemical inhibiters of P38, ERK, and JNK resulted in upregulation of IL-6, IL-12p40, and IL-10 production. Together, these results demonstrated that N. caninum EVs could be rapidly internalized to deliver proteins to the host cells and modulate the host cell immune responses through MAPK signaling pathway in a TLR2-dependent manner. Our study is the first to reveal potential roles for N. caninum EVs in host communication and immune response in parasite–host interactions.

Assessment of transplacental transmission of Neospora caninum in dairy cattle in the Agreste region of Pernambuco

Abstract The transplacental transmission is the primary route of Neospora caninum infection in bovine herds around the world. This study aimed to determine the frequency of transplacental transmission of the parasite in dairy cattle of Agreste region of Pernambuco through serological tests (IFAT and ELISA). Three hundred sixteen serum samples from cows and heifers and their offspring were analyzed. The transplacental transmission rate was 72.22% (13/18) for cows and 69.23% (9/13) for heifers by IFAT. ELISA test showed transplacental transmission rate of 43.58% (17/39) for cows and 50% (9/18) for heifers. The transplacental transmission rates were similar, in both groups in test, but a higher seropositivity was found in cows by IFAT. Data were statistically analyzed using the chi-square and Fisher’s exact test. A significant relationship of dependence between seropositivity of mothers and their offspring was found. The more frequent IFAT antibody titers and ELISA levels for N. caninum were, respectively, 200 and between four (cows) and five (heifers and offspring). In the Spearman correlation, no association was found between the magnitude of antibody titers for N. caninum between mothers and their offspring. The kappa test showed an index of 0.35, indicating a mild correlation between the serological tests used. The study suggests that cows and heifers are the main transmitters of N. caninum in the studied region and that vertical transmission is the major form of transmission in dairy herds of the Agreste region of Pernambuco.