Seroprevalence of antibodies to Neospora caninum in dogs and raccoon dogs in Korea

Neospora caninum is an important cause of abortion in cattle, and dogs are its only known definitive host. Its seroprevalence among domestic urban and rural dogs and feral raccoon dogs (Nyctereutes procyonoides koreensis) in Korea was studied by indirect fluorescent antibody test (IFAT) and by the neospora agglutination test (NAT), respectively. Antibodies to N. caninum were found in 8.3% of urban dogs and in 21.6% of dogs at dairy farms. Antibody titers ranged from 1:50 to 1:400. Antibodies to N. caninum were found in six (23%) of 26 raccoon dogs. However, the potential role of raccoon dogs as a source of horizontal transmission of bovine neosporosis needs further investigation. The results of this study suggest that there is a close relationship between N. caninum infection among dairy farm dogs and cattle in Korea. This study reports for the first time upon the seroprevalence of N. caninum infection in raccoon dogs in Korea.     

Prevalence of Neospora caninum infection in dogs from beef-cattle farms, dairy farms, and from urban areas of Argentina

Prevalence of anti-Neospora caninum antibodies was determined in sera of 320 dogs from Argentina using the indirect fluorescent antibody test (IFAT). Antibodies to N. caninum were found in 121 of 320 (37.8%) sera with titers of 1:50 (21 dogs), 1:100 (23 dogs), 1:200 (23 dogs), 1:400 (17 dogs), 1:800 (23 dogs), and > or = 1:1.600 (14 dogs). The seropositivity (IFAT, > or = 1:50) was higher in dogs from dairy (48% of 125) and beef (54.2% of 35) farms than in dogs from urban areas (26.2% of 160). Prevalence of anti-N. caninum antibodies was higher in dogs more than 12 mo of age (47.7%, 105 of 222) versus in 12-mo-old or younger dogs (12.7% of 86), suggesting postnatal exposure of N. caninum infection in dogs.     

Seroprevalence of Neospora caninum antibodies in cattle and water buffaloes in India

Neospora caninum is now recognized as a major cause of abortion in cattle worldwide, but there is no report of N. caninum infection in cattle in India. Serum samples from 427 dairy cattle and 32 dairy water buffaloes from 7 organized dairy farms located in Punjab, India, were tested for N. caninum antibodies using a commercial monoclonal antibody-based competitive enzyme-linked immunosorbent assay (ELISA). Antibodies to N. caninum were found in 35 of 427 cattle from 6 of the 7 farms; 9.6% of cows, 5.1% of heifers, and 5.0% of calves were seropositive, suggesting postnatal transmission of N. caninum on the farm. Antibodies to N. caninum were found in 16 of 32 buffaloes tested from 2 dairy farms. In total, 64 cattle and 16 buffalo sera already tested by ELISA were also evaluated by an indirect fluorescent antibody test (IFAT) to verify ELISA results. Of the 64 cattle samples, 29 sera were negative by both tests and of the 35 ELISA-positive sera, 12 had IFAT titers of 1:100 or higher (1 had IFAT titer of 100, 2 had IFAT titer of 200, and 9 had IFAT titers of 400 or higher). Of the 16 buffalo sera positive by ELISA, 1 had an IFAT titer of 1:400. Thus, antibodies to N. caninum were demonstrated in cattle sera by 2 serologic methods. To our knowledge this is the first report of N. caninum infection in cattle and buffaloes in India.     

Prevalence of agglutinating antibodies to Neospora caninum in raccoons, Procyon lotor.

Neospora caninum is an apicomplexan parasite that causes neonatal neuromuscular disease in dogs and abortions in cattle. Dogs are the only proven definitive host. Little is known about the prevalence of antibodies to this parasite in wildlife. Sera from 99 raccoons (Procyon lotor) were examined for agglutinating antibodies to N. caninum using the modified agglutination test employing formalin-fixed tachyzoites as antigen. Raccoons originated in Florida (n = 24, collected in 1996), New Jersey (n = 25, collected in 1993), Pennsylvania (n = 25, collected in 1999), and Massachusetts (n = 25, collected in 1993 and 1994). Ten (10%) had antibodies to N. caninum; 9 had titers of 1:50, and 1 (1%) had a titer of 1:100. The present study indicates that raccoons have minimal exposure to N. caninum. The sera were also tested for agglutinating antibodies to Toxoplasma gondii and 46 (46%) were positive; 16 had titers of 1:50, 8 had titers of 1:100, and 22 had titers of > or = 1:500.     

Seroepidemiological evidence for a relationship between Neospora caninum infections in dogs and cattle

Dogs from dairy farms with a known prevalence of Neospora caninum antibodies in the cattle were examined for the presence of N. caninum antibodies using an ELISA. Data of farm dogs were compared with those of dogs examined at a university clinic, which originated mainly in urban areas. Of the 152 farm dogs, 36 (23.6%) were seropositive to N. caninum, which was significantly higher than the proportion of seropositives in the clinic dog population (19 of 344, 5.5%). Seroprevalence was significantly higher (P = 0.01) in female dogs than in male dogs. Seroprevalence in dogs increased with age, indicating postnatal infection. Seropositivity to N. caninum in farm dogs was strongly correlated with a high prevalence of N. caninum antibodies in the cattle. At farms where no dogs were present, the seroprevalence to N. caninum in the cattle was significantly lower (P = 0.0002) than in farms where dogs were present. These findings suggest that there is a relationship between N. caninum infection of farm dogs and cattle. Since dogs have been shown to be definitive hosts of N. caninum, cattle may be infected by exposure to canine oocysts. Further research is needed to find out whether and how dogs may acquire the infection from cattle.     

Neospora caninum infections in bovine foetuses and dairy cows with abortions in Argentina

Antibodies to Neospora caninum were measured in bovine foetuses, dairy cows and beef cows in Argentina using the IFAT, the N. caninum agglutination test, and the recombinant NCDG1 and NCDG2 ELISA. Serum antibodies (IFAT titre 1:80) were found in 20 of 82 (24.4%) dairy cow foetuses and one of 22 (4.5%) beef cow foetuses. Microscopic lesions suggestive of neosporosis were seen in brains of seven of eight foetuses with IFAT titres of 1:80. Antibodies (IFAT) were found in 122 of 189 (64.5%) dairy cows that aborted. Serum antibody titres (IFAT) of 189 dairy cows that aborted were: < 1:25 (67 cows), 1:25 (four cows), 1:50 (16 cows), 1:200 (seven cows), 1:> or = 800 (95 cows). Of the 87 sera with IFAT titres of < or = 1:50, 57 had no antibodies in 1:40 dilution and 30 had titres of 1:40 in the N. caninum agglutination test. Thus, sera from at least 56 dairy cows which had aborted were seronegative both in the N. caninum agglutination test and the IFAT. The distribution of positive and negative sera was similar when measured by ELISA, except that, depending on cut-off titre, the ELISA indicated a greater number of seropositive cows that were negative by the IFAT and N. caninum agglutination test. These results suggest that transplacental transmission of N. caninum in dairy cows in Argentina is frequent.     

Significance of Neospora caninum in British dairy cattle determined by estimation of seroprevalence in normally calving cattle and aborting cattle

A case control study was conducted to evaluate the significance of Neospora caninum infections in cattle in England and Wales. The prevalence of N. caninum in normally calving cattle (the control group; n = 418) and aborting cattle (n = 633) was estimated using a commercial antibody-detection ELISA. Prevalence estimates for bovine virus diarrhoea virus, infectious bovine rhinotracheitis virus and Leptospira hardjo were also obtained by serology. The prevalence of N. caninum was significantly higher (P < 0.0001) in the aborting group (18%; 95% confidence interval: 15%, 21%) than in the control group (6%; 95% confidence interval: 4%, 8%); the latter is the first estimate, to date, of the national seroprevalence of N. caninum in dairy cattle in England and Wales. Prevalence estimates for bovine virus diarrhoea virus, infectious bovine rhinotracheitis virus and L. hardjo were not found to be higher in the aborting cattle than in the control group. With N. caninum, a strong association between seropositivity and abortion was found, with seropositive cows being 3.5-times more likely to abort than seronegative cows (odds ratio = 3.49; 95% confidence interval: 2.16, 5.69). Furthermore, 12.5% of abortions in dairy cattle in England and Wales may be attributable to N. caninum, as indicated by estimation of the population aetiological fraction.     

Toxoplasma gondii and Neospora caninum antibodies in dogs from Grenada, West Indies

Toxoplasma gondii and Neospora caninum are structurally similar parasites with many common hosts. The prevalence of antibodies to T. gondii and N. caninum was determined in sera from dogs in Grenada, West Indies. Using a modified agglutination test, antibodies to T. gondii were found in 52 (48.5%) of the 107 dogs, with titers of 1:25 in 17, 1:50 in 19, 1:100 in 7, 1:1,600 in 5, and 1:3,200 or higher in 4. Seroprevalence increased with age from 2.2% in dogs <6 mo old to 18.9% in dogs older than 2 yr, indicating postnatal transmission of T. gondii in this population of canines. There was no correlation between the health of the dogs and the seroprevalence or magnitude of the T. gondii titer. Antibodies to N. caninum were determined by the indirect immunofluorescent antibody test (IFAT). Two of the 107 dogs had N. caninum antibodies (IFAT titers 1:100 and 1:400); these dogs had T. gondii titers of 1:1,600 and 1:50, respectively. Results indicate that these 2 structurally similar protozoa are antigenically different.     

Seroprevalence of Neospora caninum infection in dairy cattle of Southern China

A seroepidemiological survey of Neospora caninum infection in dairy cattle was carried out in China's southern Guangdong Province between July 2009 and March 2010. A total of 370 serum samples of dairy cattle was collected from 5 farms and examined for antibodies to N. caninum by enzyme-linked immunosorbent assay. The overall seroprevalence of N. caninum in dairy cattle was 18.9% (70/370). The seroprevalence of N. caninum in aborting cows (22.7%) was higher than that in nonaborting cows (16.3%), but the difference was not statistically significant (P > 0.05). Five-yr-old dairy cattle had the highest seroprevalence (27.8%), followed by those that were 6-yr-old (20.4%). Dairy cattle with 4 pregnancies had the highest seroprevalence (29.2%). There was no apparent association of N. caninum seropositivity with age or number of pregnancies (P > 0.05). The results of the present survey indicated that the infection with N. caninum is prevalent in dairy cattle of all ages in southern China, which may be one of the causes of bovine abortion. This is the first report of seroprevalence of N. caninum in dairy cattle in southern China.     

Fetal infection with Neospora caninum in dairy and beef cattle in Belgium

Neospora caninum is a protozoan parasite, which causes fetal and neonatal mortality in livestock and companion animals. In 224 abortions in Belgian cattle, different diagnostic methods were used to demonstrate infection, and the presence of N. caninum. An indirect fluorescent antibody test (IFAT) was used to analyze fetal and maternal sera and immunohistochemistry (IHC) was performed when lesions consistent with neosporosis were observed in the brain, heart or liver. Twenty dairy cattle sera out of 70 (29%) and 13 beef cattle sera out of 93 (14%) were positive by IFAT. A positive titer to N. caninum was found in seven and three fetuses born to beef and dairy cows, respectively. Lesions consistent with N. caninum infection were observed in 17 fetuses. Of nine positive beef fetuses, five were confirmed by IHC while, all but one dairy fetus were confirmed using the same technique.Age had no influence on the serological status of the mother (P = 0.486) whereas husbandry system had a borderline influence (P = 0.082). However, a strong association (P = 0.004) between the level of antibodies in the dam and the occurrence of lesions in the fetus was observed and lesions were more prominent in dairy than in beef fetuses. Additionally, the distribution of intra-cerebral lesions was more extensive in dairy than in beef fetuses (P < 0.0001). Age and serological status of the fetus were found to influence the occurrence of lesions in beef fetuses (both P < 0.001) but no such significant relationships could be demonstrated in dairy fetuses. The study indicated that N. caninum must be considered as an important cause of bovine abortion in Belgium.     

Seroprevalence of Neospora caninum and Brucella abortus in dairy cattle herds with high abortion rates

The protozoan Neospora caninum and the bacterium Brucella abortus are well-recognized causes of abortion in dairy cattle. Serum samples (n = 240) from aborting (n = 141) and at-risk (n = 99) animals from 5 herds with high abortion rates in Punjab Province, Pakistan, were tested for antibodies to N. caninum using monoclonal antibody-based ELISA and for antibodies to B. abortus using the serum agglutination test. Antibodies to N. caninum and B. abortus were detected in 105 (43.8%) and 135 (56.3%) cattle, respectively. Prevalences of antibodies to N. caninum and B. abortus were higher in aborting cows (46.8% and 76.6%, P < 0.05) than in animals at risk (39.4% and 27.3%, P > 0.05). Sixty-six animals (27.5%) were seropositive to both N. caninum and B. abortus , and results showed no significant difference (P > 0.05) with respect to geographical district, breed, and age. This is the first report of N. caninum infection among dairy cattle herds in Pakistan.     

Seroprevalence of Neospora caninum infection in dairy and beef cattle in Spain

In recent years, neosporosis has been identified as a major cause of abortion in dairy and beef cattle. Although the disease has been described worldwide, there is a Jack of information concerning the prevalence of this infection in different cattle production systems. The aim of this study was to investigate the seroprevalence of Neospora caninum infection in a representative area of beef and dairy cattle production in Spain. A cross-sectional study was undertaken in which herds constituted the initial sampling unit and two strata (dairy and beef herds) were considered. Using a 95% level of confidence and setting 5% (beef) and 5.4% (dairy) error limits, 216 beef and 143 dairy herds were randomly selected and sampled. Nine animals (> 1 year old) were randomly sampled in each herd to detect the presence of the infection. A herd was considered infected when at least one animal was seropositive. In total, serum samples from 1121 dairy and 1712 beef animals were collected and tested for specific anti-N. caninum IgG using an ELISA. Specific antibodies were detected in 55.1% (119/216) beef and 83.2% (119/143) dairy herds. Individual prevalences obtained were 17.9% (306/1712) for beef and 35.9% (402/1121) for dairy animals. Presence of N. caninum infection was higher in dairy than in beef herds and the association between infection and the cattle production system (dairy or beef) was statistically significant [(chi2)Y= 29.21, P < 0.001, OR = 4.04 (2.35-6.99)]. Herd size of dairy cattle did not appear to be associated with N. caninum infection. On the contrary, infection was associated with herd size in beef cattle (chi2 = 12.79, P < 0.01). Finally, no association was found between replacement or pasture management and infection in beef herds.     

Transmission of Neospora caninum between wild and domestic animals

To determine whether deer can transmit Neospora caninum, brains of naturally infected white-tailed deer (Odocoileus virginianus) were fed to 4 dogs; 2 of these dogs shed oocysts. Oocysts from 1 of the dogs were tested by polymerase chain reaction and found to be positive for N. caninum and negative for Hammondia heydorni. The internal transcribed spacer 1 sequence of the new strain (designated NC-deer1) was identical to N. caninum from domestic animals, indicating that N. caninum is transmitted between wild and domestic animals, often enough to prevent divergent evolution of isolated populations of the parasite. NC-deerl oocysts were administered to a calf that developed a high antibody titer, providing evidence that N. caninum from wildlife can infect cattle. In addition, N. caninum antibody seroprevalence was detected in 64/164 (39%) free-ranging gray wolves (Canis lupus), 12/113 (11%) coyotes (Canis latrans), 50/193 (26%) white-tailed deer, and 8/61 (13%) moose (Alces alces). These data are consistent with a sylvatic transmission cycle of N. caninum between cervids and canids. We speculate that hunting by humans favors the transmission of N. caninum from deer to canids, because deer carcasses are usually eviscerated in the field. Infection of canids in turn increases the risk of transmitting the parasite to domestic livestock.     

Seroprevalence of Neospora caninum infection on dairy cattle in farms from southern Romania

Neospora caninum, a coccidian parasite closely related to Toxoplasma gondii, is one of the major causes of abortion in cattle worldwide. Conventional serological techniques, such as the indirect fluorescent antibody test and enzyme-linked immunosorbent assay (ELISA), are routinely used in adult animals and aborted fetuses for the detection of anti- N. caninum antibodies. In Romania, infection with N. caninum in cattle has been reported recently, but only in limited areas from the north and central parts of the country. Therefore, the aim of this study was to obtain additional seroepidemiological data on infection with N. caninum on dairy farms from the south of Romania. A total of 258 blood samples was analyzed from 230 dairy cows and 28 calves from 9 dairy farms in southern Romania; the presence of specific IgG antibodies against N. caninum was determined using an indirect ELISA test. The average seroprevalence was 40.3%, but the within-herd prevalence ranged between 11.5 and 80.0%; the seroprevalence in dairy cows was 41.7%, while in calves it was 28.6%. Of the positive samples, 74.0% (77/104) had a high positive reaction (S/P ratio more than 1.0), while 26.0% (27/104) had a low positive reaction (S/P ratio between 0.5 and 1.0). This study indicates that N. caninum infection is widespread in the south of Romania, which could explain the causes of abortions registered in some herds in the studied area. However, a serological screening across the country is planned in order to assess the actual national prevalence of N. caninum infection, followed by implementation of a prevention and control program.     

Seroprevalence of Neospora caninum antibodies in dogs in India

Neospora caninum is one of most important causes of abortion in cattle worldwide, and dogs are an important risk factor for N. caninum infection in cattle. Antibodies to N. caninum were determined in 184 (126 rural, 58 urban) dogs from the Punjab State, India, using commercial monoclonal antibody-based competitive ELISA and found in 16.8% of the animals. The prevalence of N. caninum antibodies was significantly higher in rural dogs (21.4%, 27 of 126) than city dogs (6.9%, 4 of 58). To our knowledge this is the first report of N. caninum infection in canines from India.     

Neospora caninum and Toxoplasma gondii antibodies in dogs from Durango City, Mexico

Toxoplasma gondii and Neospora caninum are structurally similar parasites, with many hosts in common. The prevalence of antibodies to T. gondii and N. caninum was determined in sera from dogs from Durango City, Mexico. Using a modified agglutination test, antibodies to T. gondii were found in 52 (51.5%) of the 101 dogs with titers of 1:25 in 27, 1:50 in 11, 1:100 in 5, 1:200 in 4, 1:400 in 2, 1:800 in 2, and 1:3,200 or higher in 1. Antibodies to N. caninum were determined by the indirect immunofluorescent antibody test (IFAT) and the Neospora sp. agglutination test (NAT). Two of the 101 dogs had N. caninum antibodies; these dogs did not have T. gondii antibodies, supporting the specificity of the tests used. The N. caninum antibody titers of the 2 dogs were: 1:400 by IFAT and 1:200 by NAT in 1, and 1:25 by NAT and IFAT in the other. Results indicate that these 2 structurally similar protozoans are antigenically different.     

High prevalence of antibodies to Neospora caninum in white-tailed deer (Odocoileus virginianus)

Serum samples of 400 white-tailed deer (Odocoileus virginianus) from 16 preserves in northeastern Illinois were tested for Neospora caninum antibodies in the N. caninum agglutination test using mouse-derived N. caninum tachyzoites and mercaptoethanol. Antibodies were found in 162 deer with titres of 1:40 (47 deer), 1:80 (32 deer), 1:160 (17 deer), 1:200 (eight deer), 1:400 (19 deer), 1:800 (17 deer) and > or = 1:1600 (22 deer). There were no significant differences in prevalence between age or sex of the deer. The high prevalence of N. caninum infection in deer is consistent with a sylvatic cycle of N. caninum.     

Occurrence of Neospora caninum antibodies in capybaras (Hydrochaeris hydrochaeris) from São Paulo State, Brazil

Capybara (Hydrochaeris hydrochaeris) is a large rodent distributed throughout tropical America. Antibodies to Neospora caninum in 213 feral capybaras from 11 counties of the State of S?o Paulo, Brazil, were assessed using the indirect immunofluorescent antibody test (titer >or=1:25) and found in 20 (9.4%), with titers of 1:25 in 4, 1:50 in 7, and 1:100 in 9 animals. This is the first report of occurrence of N. caninum antibodies in capybaras.     

Prevalence of antibodies to Neospora caninum in white-tailed deer,Odocoileus virginianus,from the southeastern United States

Serum samples from 305 white-tailed deer (Odocoileus virginianus) from 14 states in the southeastern United States were examined for antibodies to Neospora caninum using a direct agglutination test. Positive agglutination titers were found in 145 (48%) of the white-tailed deer examined: 21 (7%) had titers of 1:25, 92 (30%) had titers of 1:50, and 32 (10%) had titers of > or = 1:500. These findings that antibodies to N. caninum are common in white-tailed deer support the concept that a sylvatic cycle might exist for this economically important parasite of domestic cattle.     

Low seroprevalence of Neospora caninum infection associated with the limousin breed in cow-calf herds in Andorra, Europe

Neospora caninum seroprevalence and risk factors affecting seroprevalence in beef cattle in Andorra were investigated. Antibodies to N. caninum were evaluated by enzyme-linked immunosorbent assay performed on a yearly basis in 1,758 animals older than 6 mo, belonging to 26 herds. Mean seroprevalence of antibodies to N. caninum for the herds was 7.4 +/- 1.2% (130/1,758). Logistic regression analyses were performed on data from each animal, considering N. caninum seropositivity as the dependent variable, and herd, grazing area, year of sampling, repeat-test animal (animals sampled twice or more), sex, breed, age (animals <4 yr old or > or =5 yr old), and country of birth as possible risk factors. Based on the odds ratio, the prevalence of infection was 2.1 times higher (P < 0.01) in animals from the Ordino grazing area, 1.64 times higher in animals older than 5 yr (P < 0.01), and 6.7 times (1/0.15) lower in Limousin-mixed Limousin cattle (P < 0.002). The results suggest that the particular grazing location could promote the horizontal transmission of this parasite and that certain breeds are less susceptible to N. caninum infection than others.