Occurrence of antibodies against Neospora caninum in water buffaloes (Bubalus bubalis) on four ranches in Corrientes province, Argentina

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.

Neosporosis in Argentina: Past, present and future perspectives

Neosporosis, caused by the protozoan Neospora caninum, was first diagnosed in Argentinean cattle in the 90's. With a national bovine stock of approximately 53 million head, the cattle industry is socially and economically relevant. Severe economic losses have been estimated at US$ 33 and 12 million annually in dairy and beef cattle, respectively. Approximately 9% of bovine abortions in the Buenos Aires province are caused by N. caninum. In 2001, the first isolation of N. caninum oocysts from feces of a naturally infected dog was performed in Argentina and named as NC-6 Argentina. Further strains were isolated from cattle (NC-Argentina LP1, NC-Argentina LP2) and axis deer (Axis axis, NC-Axis). Epidemiological studies revealed a high distribution of Neospora-infections not only in dairy but also in beef cattle, with seroprevalence rates of 16.6-88.8% and 0-73%, respectively. Several experimental infection studies in cattle have been carried out, as well as attempts to develop effective vaccines to avoid Neospora-abortions and transmission. However, no vaccine has proven successful for its use in daily practice. Reduction of seroprevalence, vertical transmission and Neospora-related abortions have been achieved in dairy farms by the use of selective breeding strategies and embryo transfer. Neospora-infections have been also detected in goats, sheep, deer, water buffaloes (Bubalus bubalis) and gray foxes (Lycalopex griseus). Moreover, Neospora-related reproductive losses were reported in small ruminants and deer species and could be more frequent than previously thought. Even though diagnostic methods have been improved during the last decades, control of neosporosis is still not optimal. The development of new strategies including new antiprotozoal drugs and vaccines is highly needed. This paper reviews the information from the previous 28 years of research of N. caninum in Argentina, including seroprevalence and epidemiological studies, available diagnostic techniques, experimental reproduction, immunization strategies, isolations and control measures in domestic and non-domestic animals from Argentina.

Serosurveillance and risk factors for Neospora caninum infection in water buffaloes (B. bubalis) from central and southern Mexico

The water buffalo (B. bubalis) is an alternative to cattle ranching in several regions of southern Mexico. Here we report seroprevalence and risk factors associated with the protozoan parasite, Neospora caninum, in water buffaloes in six buffalo production units, in municipalities from central and southern Veracruz, Mexico. Antibodies to N. caninum were assessed in serum samples of 543 buffaloes by a commercial ELISA-kit, and 44.8% (243/543; 95% CI 40.5-49.0) were seropositive. Questionnaires were used to collect epidemiological data and to identify risk factors associated with N. caninum infection. Data analysis indicated that older buffaloes (≥7 year) exhibited the highest seroprevalence for neosporosis 62.3% (38/61; 95% CI 49.7-73.4) (P ≤ 0.05). Buffaloes that were in close contact with cattle had higher seroprevalence 47.6% (168/353; 95% CI 42.3-52.9) (P < 0.01) than those that were not in contact 36.8% (70/190; 95% CI 30.0-44.1). Our findings provide important information to implement preventive measures in the buffalo farms.

A Review of Toxoplasmosis and Neosporosis in Water Buffalo (Bubalus bubalis)

Toxoplasmosis and neosporosis are diseases with worldwide distribution that are associated with reproductive problems in livestock and responsible for economic losses. This review presents an overview of the current knowledge relative to these diseases in water buffalo (Bubalus bubalis). In general, buffalo are considered resistant to clinical toxoplasmosis because there are studies only reporting serological evidence of natural infection in these animals. Studies have described age, poor hygienic status of the farm, and presence of cats as risk factors for the development of Toxoplasma gondii infection in buffalo. It must be highlighted that buffalo meat, which does not receive adequate freezing treatment, could be a potential source for toxoplasmic human infection as well as the importance of raw buffalo milk in the transmission of toxoplasmosis to human beings. Neospora caninum is considered one of the major causes of abortion and responsible for huge economic losses in cattle. Vertical transmission is the main route to infect calves, and is responsible for maintaining the parasite within a herd. In buffalo, vertical transmission is also described; moreover, although there are indications that N. caninum may be associated with abortion in dairy buffalo, the reproductive importance of neosporosis is apparently lower in buffalo relative to cattle. Most studies have identified a higher time of exposition to N. caninum oocysts relative to age. The household system was also described as a risk factor for infection, possibly due to persistent contact between the home-raised buffalo and canids. The fetal immune competence of buffalo is similar to bovine, and buffalo fetus are highly susceptible to infection during the first trimester of pregnancy, indicating that N. caninum may be an abortigenic agent in buffaloes. Alternatively, it is interesting to note there is evidence that the inflammatory response in pregnant buffalo infected with N. caninum is mild enough to avoid abortion in most cases. It is proposed that the possible transmission of toxoplasmosis through unprocessed milk and buffalo meat may occur, which is important in terms of public health. Additionally, there is strong evidence to suggest that N. caninum may be associated with abortion in buffalo.

An investigation of the concurrency of anti-Neospora antibody and parasitemia in water buffalo (Bubalus bubalis) in northwest of Iran

Neospora caninum is an obligate intracellular parasite causing abortion and reproductive failure in ruminants. Here, the seroprevalence of Neospora DNA and anti-Neospora antibodies and the correlation between the DNA and the antibody using polymerase chain reaction (PCR) and a new developed whole cell-based enzyme-linked immunosorbent assay (ELISA) in water buffalo (Bubalus bubalis) were investigated. To determine the level of anti-Neospora antibody, 83 serum samples were collected from buffaloes in the northwest of Iran. Plates were coated with 2 × 10⁶ whole Neospora tachyzoites and the anti-Neospora antibody level was determined by calculating the ratio of sample/positive control (S/P) optical densities (ODs) in the ELISA. All samples with the ration of 0.50 or above were accounted as positive. To confirm the presence of Neospora DNA, the serum samples were directly subjected to PCR and nested PCR for detection of Neospora NC5 gene without the DNA isolation process. A total number of 83 buffalo serum samples were examined for the presence of anti-N. caninum immunoglobulin G and Neospora DNA. All samples with the S/P ratio of 0.50 or above (16 samples, 19.27%) were also positive for Neospora DNA. All samples with OD less than 0.50 (34 samples, 40.96%) were negative for Neospora DNA. However, 33 samples with the S/P ratio of bellow 0.50 (39.75%) showed a significant level of antibody. A 100% correlation was observed between high levels of the anti-Neospora antibody and Neospora DNA in the serum of water buffalo, and the whole N. caninum tachyzoites have the potency to be used as antigens for detection of the parasite in ELISA.

Prevalence and associated factors with Neospora caninum infection in female water buffaloes (Bubalus bubalis) from Pernambuco, Brazil

Neosporosis is one of the major parasitic diseases that causes reproductive problems, making it a limitation for optimal efficiency in livestock. The aim of the present study was to conduct a seroepidemiological survey for bubaline neosporosis and to analyse associated factors associated with N. caninum infection in female water buffaloes in the State of Pernambuco, northeast Brazil. The prevalence of N. caninum infection in the bubaline herds examined was 35.4% (122/345; 95% CI: 30.4%-40.7%), at least 1 Neospora-positive animal was found in each farm. Associated factors for N. caninum infection identified in this study were exclusive pasture feeding (OR: 5.91, p <0.001) and purchase of animals of free fair and from reputable sellers (OR: 1.85; p =0.045). In this survey, we document the occurrence of neosporosis in female water buffaloes. Associated factors should be controlled in order to reduce the risk of N. caninum infection in these herds.

Seroepidemiology of Infection with Neospora Caninum, Leptospira, and Bovine Herpesvirus Type 1 in Water Buffaloes (Bubalus Bubalis) in Veracruz, Mexico

We aimed to determine the seroprevalence of infection with Neospora caninum, Leptospira, and bovine herpesvirus type 1 and risk factors associated with these infections in water buffaloes in Veracruz State, Mexico. Through a cross-sectional study, 144 water buffaloes (Bubalus bubalis) raised in 5 ranches of Veracruz were examined for anti-N. caninum and anti-bovine herpesvirus type 1 antibodies by enzyme immunoassays, and anti-Leptospira interrogans antibodies by microscopic agglutination test.

Of the 144 buffaloes studied, 35 (24.3%) were positive for N. caninum, 50 (34.7%) for Leptospira, and 83 (57.6%) for bovine herpes virus. The frequencies of leptospiral serovars in buffaloes were as follows: 18.7% for Muenchen (n = 27), 10.4% for Hardjo LT (n = 15), 9.0% for Pyrogenes (n = 13), and 4.8% for Icterohaemorrhagiae (n = 7). Seropositive buffaloes were found in all 5 ranches studied. Logistic regression showed that cohabitation of buffaloes with cows was associated with infection with Leptospira (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.04–4.5; P = 0.03) and bovine herpesvirus (OR, 12.0; 95% CI, 4.0–36.2; P < 0.01).

This is the first study that provides serological evidence of N. caninum, Leptospira, and bovine herpesvirus type 1 infections in water buffaloes in Mexico. Our findings could be used to enhance preventive measures against these infections.

Serological survey of Neospora caninum and Toxoplasma gondii in cattle (Bos indicus) and water buffaloes (Bubalus bubalis) in ten provinces of Brazil

The objective of this study was to determine the prevalence of antibodies to Neospora caninum and Toxoplasma gondii among 500 cattle (Bos indicus) and 500 buffaloes (Bubalus bubalis) using the indirect fluorescent antibody test (IFAT) technique. Blood samples from were collected from water buffalo and cattle in 10 municipalities in the northern region of Brazil. The frequency of cattle and water buffaloes seropositive for Neospora caninum in Pará state, Brazil, was 55% and 44%, respectively, and the frequency of cattle and water buffaloes seropositive for Toxoplasma gondii was 52% and 39%, respectively. Seropositivity for both N. caninum and T. gondii was detected in 10.6% of the cattle samples and 14.8% of the buffalo samples. The frequency of cattle positive for N. caninum and T. gondii was significantly (p<0.05) higher than that of buffalo in two and three provinces, respectively. Buffaloes had a lower seroprevalence for N. caninum or T. gondii in all of the provinces studied. These results suggest that both species, when exposed to the same risks for N. caninum and T. gondii infection, have a high serological prevalence. Cattle showed a higher probability of being seropositive when exposed to the same risks for N. caninum and T. gondii. Our study, which included an extensive number of blood samples, provides important epidemiological information pertinent to buffalo production in tropical countries that can be used as a basis for disease-management practices in Latin America.

Antibodies against Neospora caninum, Sarcocystis spp. and Toxoplasma gondii detected in buffaloes from Rio Grande do Sul, Brazil

ABSTRACT: The presence of antibodies against Neospora caninum, Sarcocystis spp. and Toxoplasma gondii was evaluated in buffaloes (Bubalus bubalis) from Rio Grande do Sul state (RS), southern Brazil. Serum samples (n=220) were analyzed for antibodies by indirect fluorescent antibody test (IFAT). Antibody presence was considered when the titers were equal or higher than 100 for these protozoa. A total of 60.5% (133/220) buffalo serum samples were positive for at least one of the protozoa evaluated in this study. Antibodies for N. caninum, Sarcocystis spp. and T. gondii were found in 36.4% (80/220), 25.5% (56/220) and 16.8% (37/220) of the buffaloes respectively, indicating a higher frequency of N. caninum infection (p=0.0133). The IFAT is a suitable method to diagnose N. caninum, Sarcocystis spp. and T. gondii infection in buffaloes for detecting IgG antibodies. This study demonstrates the presence of these three protozoa in buffalo herds in RS, Brazil, which may be source of infection to other animals. The high frequency of animals positive for N. caninum is important and could be related to reproductive problems. Additionally, the presence of Sarcocystis spp. and T. gondii in buffaloes can be a possible public health issue.

A review of Neospora caninum in water buffalo (Bubalus bubalis)

A number of countries in the world have reported infections with Neospora caninum in water buffalo (Bubalus bubalis), from Africa to Asia, Europe and South America and recently Australia. In general, clinical manifestations (such as abortion) seem rare, which has raised the prospect that buffalo may be inherently resistant to clinical effects of N. caninum infection. Worldwide, the seroprevalence of N. caninum infection (as a measure of exposure determined by the detection of antibody) in buffalo is high, at approximately 48%. This reported seroprevalence is three or four times higher than that reported from the world's cattle populations, which have collective seroprevalence rates of 16.1% for dairy cattle and 11.5% for beef cattle. However, there is a lack of standardisation in seroprevalence studies and some studies may well under-estimate the true level of infection. Epidemiologic evidence supports post-natal transmission, and in utero transmission has also been demonstrated. The causes for water buffalo to have markedly higher seroprevalence but apparently lower neosporosis abortion rates than cattle warrant further investigation.

Abortion and foetal lesions induced by Neospora caninum in experimentally infected water buffalos (Bubalus bubalis)

The water buffalo (Bubalus bubalis) is an important species in several countries for its milk and meat production, as well as for transport and other agricultural activities. It is, in general, considered more resistant than cattle to different parasitic diseases, also less demanding for forage quality. It has been postulated that buffalo may be resistant to abortion caused by neosporosis, because of high serological prevalences found in buffalo herds from different localities, with no description of Neospora caninum-related abortion. Recent studies have demonstrated the potential impact of neosporosis in pregnant water buffalo cows. In this work, three pregnant buffalo cows were experimentally infected with Nc-1 strain of N. caninum, and abortion was detected 35 days post-infection. Molecular and histopathological results found in post-mortem tissues are described and discussed, confirming the susceptibility of water buffalos to abortion caused by N. caninum.

Neospora caninum serostatus is affected by age and species variables in cohabiting water buffaloes and beef cattle

The aim of this study was to investigate how Neospora caninum serostatus may be affected by variables such as host species (water buffaloes or cattle) and age in animals cohabiting in the same ranch. A convenience cross-sectional study was performed on four ranches in the Northeast of Argentina, where water buffalo are cohabitating with beef cattle. Blood samples were collected from 1350 female water buffaloes (Bubalus bubalis) and 880 female beef cattle (Bos taurus and Bos indicus crossbreeds) from four ranches. Calving and weaning percentages at herd level for each ranch were also recorded. N. caninum antibody levels were measured by an indirect fluorescent antibody test (IFAT) (reciprocal antibody titers ≥ 100). Serological results were classified into 2 categories (0: negative; 1: positive). A logistic regression model was used to describe the relationship between N. caninum serostatus and specie (water buffalo or cattle), age or ranch and their interactions. Likelihood ratio tests were used to assess the significance of the model and their terms. Odds ratios were estimated and 95% profile likelihood (LR) and Wald confidence intervals (CI) obtained. Overall, specific antibody titers were found in 43.3% (584/1350) of water buffaloes and 28.6% (252/880) of cattle. Seropositive water buffaloes and cattle were observed on all ranches. Age was statistically significant (p=0.01) with an overall estimate of logit (log odds) of age of 0.03 for both species. This indicates that for every one year increase in age, the expected change in log odds of being seropositive increased by 0.03. On three of four ranches a water buffalo was 4.48, 1.54 and 2.25 times more likely to be seropositive than cattle for animals of the same age. The N. caninum serostatus was affected by age in the first place, but also by species on at least three of the four ranches. Calving and weaning percentages were higher in water buffaloes than in beef cattle (p<0.05). Even though the low pathogenicity that N. caninum seems to have in water buffaloes, this study reinforces the importance of this specie as maintenance of the disease.

Prevalence survey of selected bovine pathogens in water buffaloes in the north region of Brazil

Although the largest buffalo herd in the occident is in the north region of Brazil, few studies have been conducted to assess the prevalence of selected parasitic diseases in buffalo herd. The present study was therefore conducted to investigate the epidemiological of Toxoplasma gondii, Neospora caninum, Anaplasma marginale, Babesia bigemina, and Babesia bovis in water buffaloes in the north region of Brazil. A total of 4796 buffalo blood samples were randomly collected from five provinces and simultaneously analyzed by the IFAT and ELISA. The serological prevalence of T. gondii and N. caninum was 41.3% and 55.5% in ELISA and 35.7% and 48.8% in IFAT, respectively. The overall prevalence of A. marginale, B. bovis, and B. bigemina was 63%, 25%, and 21% by ELISA and 50.0%, 22.5%, and 18.8% by IFAT, respectively. This study shows valuable information regarding the serological survey of selected bovine pathogens in water buffaloes in the north region of Brazil which will likely be very beneficial for the management and control programs of this disease.

Prevalence of Neospora caninum antibodies in dairy cattle and water buffaloes and associated abortions in the plateau of Southern Peninsular India

A seroprevalence study of bovine neosporosis was conducted among 1,927 dairy cattle and 341 water buffaloes from Karnataka and Andhra Pradesh states in plateau of southern peninsular India by employing competitive enzyme-linked immunosorbent assay. Overall, 12.61 and 9.97 % sera samples were found positive for the presence of Neospora caninum antibody, respectively, among cattle and water buffaloes. Out of 1,927 sera samples from cattle, 912 and 1,015 samples were collected from unorganized and organized herds, respectively. The cattle screened were of upgraded Holstein-Friesian and water buffaloes were of graded Surti breed. Significantly (p < 0.05) higher prevalence was found in the cattle in unorganized herds (16.66 %) in comparison to organized herds (8.96 %). The highest seroprevalence was recorded in the age group of 4 years and above in both type of cattle herds and water buffaloes. There was a significant variation of seroprevalence (p < 0.05) observed between different age groups of cattle. The rate of seroprevalence increased with the increment in the age of the animals suggesting a possibility of horizontal mode of transmission of the infection from the environment. The percentage of abortion history was more in seropositive group (51.65 %) in comparison to the seronegative group (5.84 %) and the seropositive cattle were 8.84 times more likely to experience abortion than the seronegative cattle. The occurrence of abortion among different age groups varied significantly (p < 0.05). The findings revealed the presence of neosporosis in the southern peninsular India among cattle and water buffaloes and a strong association between the seroprevalence and abortion.

Experimental inoculation of Neospora caninum in pregnant water buffalo

The aim of this study was to characterize the pathogenesis of Neospora caninum in experimentally inoculated pregnant water buffalo (Bubalus bubalis). Twelve Mediterranean female water buffaloes ranging in age from 4 to 14 years old and seronegative to N. caninum by indirect fluorescent antibody test (IFAT) were involved. Ten females were intravenously inoculated with 10(8) tachyzoites of NC-1 strain at 70 (n=3) or 90 (n=7) days of pregnancy (dp). Two control animals were inoculated with placebo at 70 and 90 dp, respectively. Serum samples were obtained weekly following inoculation to the end of the experiment. Three animals inoculated at 70 dp were slaughtered at 28 days post inoculation (dpi), three animals inoculated at 90 dp were slaughtered at 28 dpi and the remaining four animals inoculated at 90 dp were slaughtered at 42 dpi. Fetal fluids from cavities and tissue samples were recovered for IFAT and histopathology, immunohistochemistry and PCR, respectively. Genomic DNA from fetal tissues was used for parasite DNA detection and microsatellite genotyping in order to confirm the NC-1 specific-infection. Dams developed specific antibodies one week after the inoculation and serological titers did not decrease significantly to the end of the experiment. No abortions were recorded during the experimental time; however, one fetus from a dam inoculated at 70 dp was not viable at necropsy. Specific antibodies were detected in only two fetuses from dams inoculated at 90 dp that were slaughtered at 42 dpi. No macroscopic changes in the placentas and organs of viable fetuses were observed. Nonsuppurative placentitis was a common microscopic observation in Neospora-inoculated specimens. Microscopic fetal lesions included nonsuppurative peribronchiolar interstitial pneumonia, epicarditis and myocarditis, interstitial nephritis, myositis and periportal hepatitis. Positive IHC results were obtained in two fetuses from dams inoculated at 70 dp and slaughtered at 28 dpi. N. caninum DNA was detected in placentas and fetuses from all inoculated animals. The pattern of amplified microsatellites from placental and fetal tissues resembled the NC-1 strain. Water buffaloes, like cattle, are susceptible to experimental inoculation with N. caninum at early pregnancy.

Anticorpos IgG anti-Neospora caninum e Toxoplasma gondii em búfalas (Bubalus bubalis) criadas no estado do Pará

Para determinar a ocorrência de anticorpos IgG anti-Neospora caninum e Toxoplasma gondii em 14 unidades produtivas de búfalos, situadas em 13 municípios no estado do Pará, foram coletadas amostras de soro sanguíneo de 374 fêmeas adultas. Os soros foram submetidos à reação de imunofluorescência indireta (RIFI), utilizando-se os títulos 200 e 64, respectivamente como ponto de corte para N. caninum e T. gondii. Obteve-se 153 (40,9%) de animais soropositivos para N. caninum com 100% das propriedades com focos da infecção, enquanto que quatro búfalas (1,1%) foram soropositivas em quatro fazendas para T. gondii e uma búfala (0,27%) foi soropositiva para ambos parasitos. A presença de anticorpos é um indicativo da circulação desses protozoários em búfalos das propriedades estudadas, representando uma fonte de infecção para outros animais, assim como o possível envolvimento em distúrbios reprodutivos nessa espécie.