Neospora caninum infection in dairy cattle in Egypt: a serosurvey and associated risk factors

Global Prevalence of Neospora caninum in Domestic Pigs (Sus domesticus) and Wild Boars (Sus scrofa): A Systematic Review and Meta-Analysis

BACKGROUND

Neospora caninum (Apicomplexa, Sarcocystidae) is a protozoan parasite regarded as a major cause of reproductive failure in cattle. Swine are susceptible to N. caninum infection; however, the role of these animals in the circulation, maintenance, and transmission of N. caninum remains unclear. Therefore, we aimed to estimate the global seroprevalence of N. caninum in domestic pigs (Sus domesticus) and wild boars (Sus scrofa).

METHODS

Online databases including PubMed, Web of Science, Scopus, and Google Scholar were systematically searched to identify relevant studies up to 30 April 2024. A random-effects meta-analysis model was used to estimate the overall and subgroup-pooled prevalence of N. caninum across studies. The Cochrane test (Q) and the I2 index were employed to heterogeneity. Funnel plots and Egger's regression test were used to evaluate publication bias, year of publication, and sample size.

RESULTS

A total of 11,124 animals from 26 eligible studies were included. The pooled seroprevalence of N. caninum in swine was 17% (95% CI: 7%-26%) with a prevalence of 17% in domestic pigs and 16% in wild boars. In the subgroup analysis, the highest prevalence was observed among female animals, with a pooled seroprevalence of 17% (95% CI: 7%-26%). The pooled seroprevalence of N. caninum was nearly equal in adult and sub-adult swine (18% and 14%, respectively). The overall seroprevalence of N. caninum in swine, based on sample size and year of publication, showed no statistically significant correlations.

CONCLUSION

The present study showed that domestic swine are suitable intermediate hosts of N. caninum based on serological findings. However, further studies are needed to describe the epidemiology of the N. caninum and to isolate the parasite from swine to confirm this hypothesis.

Epidemiology of Bovine Neosporosis in Relation to Socioeconomic, Demographic, and Transmissibility Factors in Dual-Purpose Production Systems in Colombia

INTRODUCTION

Bovine neosporosis represents a significant threat to reproduction and production in livestock systems worldwide. This disease is caused by the protozoan Neospora caninum, resulting in abortions of cows and neurological signs in newborn calves. This leads to significant economic losses, decreasing meat and milk production, especially in tropical regions. The infection has an endogenous and exogenous cycle of transmission involving dogs that shed the oocysts, with the highest transmission successes in humid areas. Similarly, there is a lack of knowledge about the epidemiological risk factors and management practices involved in the transmission success in tropical humid regions.

METHODS

In this sense, a cross-sectional epidemiological survey was conducted on 150 farms from 24 municipalities of the Huila area. A total of 360 cattle were sampled, and information about the production system was collected using a structured poll with 128 questions.

RESULTS

In these cattle, 53% (191/360) were positive for antibodies against Neospora caninum using ELISA. The logistic regression analysis using the information collected from the poll identified the presence of flooring type, water access, production systems, and feed management as risk factors. Among the protective factors were identified the geographical area, molasses supplementation, and biosecurity practices such as animal separation and access control.

DISCUSSION

This study identified for the first time the epidemiological risk factors associated mainly with the exogenous cycle of neosporosis. The present study contributes to the design of intervention strategies oriented to minimize the impact of parasitism in Colombian herds.

Immunization with the NcMYR1 gene knockout strain effectively protected C57BL/6 mice and their pups against the Neospora caninum challenge

Neospora caninum is an important protozoan parasite that causes abortion in cattle and nervous system dysfunction in dogs. No effective drugs and vaccines for neosporosis are available. Further elucidation of proteins related to N. caninum virulence will provide potential candidates for vaccine development against neosporosis. In the present study, N. caninum c-Myc regulatory protein (NcMYR1) gene knockout strains (ΔNcMYR1-1, ΔNcMYR1-2, and ΔNcMYR1-3) were generated using the CRISPR-Cas9 gene editing system to investigate phenotype changes and the potential of the ΔNcMYR1-1 strain as an attenuated vaccine, and this is the first time of using the N. caninum CRISPR-Cas9 gene knockout strain as an attenuated vaccine. NcMYR1 was determined to be a cytoplasmic protein in N. caninum tachyzoites. The deficiency of NcMYR1 decreased the plaque area and the rate of invasion, replication, and egression of the parasites. ΔNcMYR1-1 strain-infected C57BL/6 mice had 100% survival rate, reduced parasite burden, and alleviated pathological changes in tissues compared with those in Nc-1 strain-infected mice. Immunization with ΔNcMYR1-1 tachyzoites increased the productions of cytokines in mice, with a survival rate reaching 80%, and the parasite burdens in the liver and spleen were greatly reduced when challenged with the Nc-1 strain with a lethal dose after 40 days of ΔNcMYR1-1 tachyzoite immunization. ΔNcMYR1 immunization could decrease the abortion rate of female mice from 71.4% to 12.5% and increase the survival rate of pups from 12.5% to 83.3% against the N. caninum challenge. Above all, NcMYR1 is a virulence factor and the ΔNcMYR1-1 strain could be used as a candidate vaccine against N. caninum infection and vertical transmission.

Seroprevalence and assessment the associated risk factors for Fasciola hepatica infection in water buffaloes in Egypt

Fasciolosis is a zoonotic neglected parasitic disease that affects a variety of hosts, resulting in substantial economic losses. The epidemiological information about fasciolosis in water buffaloes in Egypt is very scarce. Hence, the present study aimed to determine the seroprevalence of F. hepatica in water buffaloes using commercial ELISA kits in three governorates at north of Egypt and to estimate the associated risk factors for F. hepatica infection. The total seroprevalence of F. hepatica in buffaloes was 15.4% (63/410), with a higher seroprevalence in Kafr Elsheikh governorates 17.9% (25/140) than in other areas. Fasciolosis was more likely in older buffaloes (OR = 3.4, 95%CI:1.5-7.8), throughout the winter season (OR = 5.3, 95%CI:1.9-14.7). Moreover, the absence of prophylactic treatment (OR = 2.3, 95%CI:1.2-4.2) increased the risk of F. hepatica infection in buffaloes, particularly in animals suffered from diarrhea (OR = 3.8, 95%CI:1.4-10.6). The present study confirmed the prevalence of F. hepatica in water buffaloes in north of Egypt. Consequently, the implementation of preventive and control for the parasite and its intermediate host are very necessary to decrease the economic losses and public health hazard.

Seroprevalence and associated risk factors for Neospora caninum infection in dairy cattle in South Africa

Bovine neosporosis is a widespread parasitic disease associated with significant economic losses. Its effects on the reproductive performance of cows have resulted in losses that run into the hundreds of millions of US dollars in dairy industries in various countries (Reichel et al., Int J Parasitol 43:133-142, 2013). Due to outdated and scant information on the occurrence of Neospora caninum infection in South Africa, the study aimed to determine the seroprevalence and risk factors associated with infection in dairy cattle in South Africa. A total of 1401 blood samples were randomly collected from cattle on 48 dairy farms in seven of the nine provinces in South Africa. A close-ended questionnaire was used in a cross-sectional study to obtain farm-level and animal-level data. Serological testing was done using a commercial IDvet Screen® Neospora caninum Indirect ELISA. An overall seroprevalence, adjusted for test sensitivity and specificity, of 2.3% (95% CI, 1.3-4.1) was detected and 48% (23/48) of sampled farms had at least one animal testing positive. The highest seroprevalence of N. caninum was in the KwaZulu-Natal province with 7.5% (95% CI, 3.8-14.3), and the lowest in Western Cape with 0.1% (95% CI, 0-1.2). The highest within-farm seroprevalence of 25% was detected on a farm in the North West Province. In a multivariable logistic regression model, the odds of N. caninum seropositivity were higher in Holstein-Friesian cattle when compared to other breeds. Good hygiene was identified as a protective factor. Cattle left out on pasture had increased odds of testing positive for N. caninum compared to those that were penned. The odds of testing seropositive for N. caninum was higher on farms that practised segregation of cattle into different age groups. The purchase of replacement animals was a significant risk factor, as open herds had increased odds of N. caninum seropositivity. Cattle on farms that did not have a specific calving location were more likely to be seropositive. This is the first such study in South Africa and shows that N. caninum is widely distributed in the country at a low seroprevalence, but it may be a cause of concern on certain farms.

Evaluation of Immunodiagnostic Performances of Neospora caninum Peroxiredoxin 2 (NcPrx2), Microneme 4 (NcMIC4), and Surface Antigen 1 (NcSAG1) Recombinant Proteins for Bovine Neosporosis

Bovine neosporosis is among the main causes of abortion in cattle worldwide, causing serious economic losses in the beef and dairy industries. A highly sensitive and specific diagnostic method for the assessment of the epidemiology of the disease, as well as it surveillance and management, is imperative, due to the absence of an effective treatment or vaccine against neosporosis. In the present study, the immunodiagnostic performance of Neospora caninum peroxiredoxin 2 (NcPrx2), microneme 4 (NcMIC4), and surface antigen 1 (NcSAG1) to detect IgG antibodies against N. caninum in cattle were evaluated and compared with that of the indirect fluorescent antibody test (IFAT). The results revealed that NcSAG1 had the highest sensitivity and specificity, with values of 88.4% and 80.7%, respectively, followed by NcPrx2, with a high sensitivity of 87.0% but a low specificity of 67.0%, whereas NcMIC4 showed sensitivity and specificity of 84.1% and 78.9%, respectively, when compared with IFAT. A high degree of agreement was observed for NcSAG1 (k = 0.713) recombinant protein, showing the highest diagnostic capability, followed by NcMIC4 (k = 0.64) and NcPrx2 (k = 0.558). The present study demonstrates that NcSAG1 is helpful as an antigen marker and also demonstrates the potential immunodiagnostic capabilities of NcPrx2 and NcMIC4, which could serve as alternative diagnostic markers for detecting N. caninum infection in cattle. These markers may find utility in future treatment management, surveillance, and risk assessment of neosporosis in livestock or other animal host species. Further research should be directed toward understanding the in vivo immune response differences resulting from immunization with both recombinant proteins.

Serosurvey and associated risk factors for Neospora caninum infection in Egyptian water buffaloes (Bubalus bubalis)

Neosporosis is a parasitic disease that causes reproductive disorders in animals, making it a barrier to maximum efficiency. The purpose of this study was to determine the seroprevalence of Neospora caninum (N. caninum) antibodies in water buffaloes from four governorates in northern Egypt. A commercial indirect-ELISA test was used to detect antibodies against N. caninum in the serum of 450 water buffaloes. The total seroprevalence of N. caninum in water buffaloes from Egypt was 31.3%, and the highest prevalence was observed in Gharbia governorate. The identified risk factors for N. caninum infections in water buffaloes were sex (OR = 1.96, 95%CI: 1.22-4.17), buffaloes more than 4 years of age ( OR = 5.80, 95%CI: 2.26-14.86), abortion in second trimester (OR = 16.48, 95%%CI: 2.99-34.03), history of abortion (OR = 3.45, 95%CI: 1.58-7.52) and contact with dogs (OR = 2.55, 95%CI: 1.51-4.32). Thus, more studies are needed to determine the role of buffaloes in the epidemiology of neosporosis in Egypt.