Prevalence of anti-Neospora caninum antibodies in cattle and dogs from Western Amazon, Brazil, in association with some possible risk factors

For evaluation of the prevalence of anti-Neospora caninum antibodies and its associated risk factors, serum samples from 2109 cattle (11 beef, 50 dairy and 25 mixed farms) and 174 dogs were examined in the State of Rond?nia, Western Amazon, Brazil. An inquiry was applied in each farm. Sera were examined by the Indirect Fluorescence Antibody Test (IFAT) using cut off dilution of 1:25 for cattle and 1:50 for dogs. Statistical association between the serologic status and several variables were analyzed by linear and logistic regression. The overall herd prevalence of anti-N. caninum antibodies for 86 farms was 72% (61.3-81.2%). Prevalence values were 100, 70 and 64% in beef, dairy and mixed herds, respectively. Herd prevalence in beef herds was significantly different (P<0.05) from dairy and mixed herds. The overall animal prevalence of N. caninum in cattle was 8.8%. Prevalence values by animal were similar in different production types (P>0.05), with values of 9.5, 11.2 and 9.7% for beef, dairy or mixed cattle, respectively. Antibodies were found in 12.6% of the 174 examined dogs. Sixteen (22.8%) out of 70 farms with dogs had at least one dog with anti-N. caninum antibodies. The occurrence of antibodies in cattle was statistically associated with farms having more than 25 cows (OR 9.7, 95% IC 2.9-32.2; P=0.0002). There was no significant association between the presence of the dogs, jungle contact or reproductive variables with the occurrence of antibodies in cattle.     

Occurrence of anti-Neospora caninum antibodies in Brazilian cervids kept in captivity

Neospora caninum is a coccidian parasite that causes disease in captive and domesticated animals and has been found in wild animals such as cervids. Sera from 150 cervids of the genus Mazama, were collected from 31 captive herds and 16 zoos from different Brazilian regions and analyzed by indirect fluorescent antibody test for anti-N. caninum antibodies. Positive reactions were found in 42% (63) of the samples and the titers varied from 50 to 51,200. Of the 86 cervids from the captive herds, 38 (44.2%) had anti N. caninum antibodies and of the 64 samples from the zoo, 25 (39.1%) were positive. No significant difference (p>0.05) was found for the occurrence values observed between the animals from captive herds and zoos as well as within the values documented for each one of the species analyzed. Therefore, the results indicate that the agent is prevalent from cervids in captivity in Brazil.     

Dynamics of anti-Neospora caninum antibodies during gestation in chronically infected dairy cows

The dynamics of antibody production against Neospora caninum during the gestation period was examined in chronically infected dairy cows. Data were obtained from 86 pregnant parous dairy cows, 21 of which had suffered abortion. The cows belonged to two herds in which a diagnosis of N. caninum infection had been previously confirmed in aborted foetuses. Pregnancy diagnosis and blood collection were performed on post-insemination Days 40, 90, 120, 150, 180, 210, and at parturition or until the time of abortion detection. Blood plasma was tested for antibodies against N. caninum using ELISA. The non-aborting cows were divided into two groups according to whether their antibody values in the second half of gestation had increased or not, while aborting cows were classified as those showing an antibody peak before abortion or those not showing a pre-abortion peak. Differences in antibody values throughout pregnancy in each group of non-aborting and aborting cows were analysed by GLM repeated measures of analysis of variance. While 32 non-aborting cows (49%) showed a significant and consistent increase in anti-Neospora antibody values during the second half of gestation, antibody values in the remaining 33 non-aborting cows were practically constant throughout gestation. An antibody peak around abortion was observed in 11 aborting cows (52%), while antibody values in the remaining 10 aborting cows were similar before and at abortion. Seroprevalence fluctuations, defined as seronegative blood samples at some point during the gestation period, were, furthermore, observed in 2 aborting and 11 non-aborting cows. Our results indicate two clearly distinguishable types of humoral immune dynamics throughout gestation: an increased or flat production of antibodies during the second half of gestation in non-aborting animals and before abortion in aborting cows. The observation that some Neospora-infected dams can exhibit negative antibody values at any time during gestation, particularly at parturition or abortion, prompts future studies designed to explore the use of new ELISA strategies at the farm level.     

Detection of specific antibodies anti-Neospora caninum in the fallow deer (Dama dama)

Sera from 335 farmed fallow deer (Dama dama) at the breeding station in Kosewo Górne in the Mazurian Lake District, North-East Poland, were investigated for the presence of antibodies against Neospora caninum. The distribution of age groups was as follow: >4 years - 154 animals; 2 years - 76 animals; 1 year - 105 animals. Ten sera with the optical density exceeding 0.159 absorbance units (i.e., cut-off value) in ELISA test were also analyzed by Western blot. Western blot analysis revealed seroreactivity against immunodominant N. caninum antigens of 37, 25, and 16kDa; however, in some sera additional bands were also visible. This is the first screening studies for antibodies against N. caninum in farmed fallow deer in Poland, in the region where neosporosis was confirmed in cattle and in farmed and free-ranging European red deer (Cervus elaphus).     

Environmental effect on the occurrence of anti-Neospora caninum antibodies in pampas-deer (Ozotoceros bezoarticus)

Sera obtained from pampas-deer (Ozotoceros bezoarticus) captured in two different Brazilian environments were analyzed for the presence of anti-Neospora caninum antibodies by the indirect fluorescent antibody test (IFAT). Samples were collected from 23 animals from a savanna area in the National Park of Emas, in the state of Goiás, Brazil. This area is surrounded by cultivated lands and allows very little contact between wild and domestic animals. Another batch of samples was collected from 16 animals from the Pantanal region, in the state of Mato Grosso, Brazil. This area is a flood plain where domestic animals have intensive contact with cervids. The 39 samples were analyzed (IFAT> or =1:50), and the values for the occurrences found in the animals from each region were compared by the test for comparison of two proportions. Of the 39 cervids examined, 38.46% (15) had anti-N. caninum antibodies. Three (13%) of the 23 samples from the National Park of Emas, and 12 (75%) of the 16 samples from the Pantanal were positive, with significant differences between regions (p<0.001). These results suggested that the presence of domestic animals, mainly dogs and cattle, may be responsible for the greater occurrence of N. caninum in the Pantanal cervids. Thus, as a recommendation of the Conservation Units that care for the pampas-deer, attention should be taken to carefully monitor the flow of diseases between the domestic animals and this species.     

Prevalence of antibodies to Neospora caninum in dogs from Amazon,Brazil

Neospora caninum is an important cause of abortion in dairy cattle worldwide. Dogs are important in the epidemiology of this parasite because they are the only hosts known to excrete N. caninum oocysts. Antibodies to N. caninum were assayed in serum samples from 157 dogs from Monte Negro, Rond?nia, Amazon, Brazil using the indirect fluorescent antibody test. Antibodies to N. caninum were found in 13 (8.3%) of dogs in titers of 1:50 in 1, 1:100 in 2, 1:200 in 5, 1:800 in 1, 1:1600 in 2, and 1:3200 in 2 dogs. These data indicate that N. caninum infection is prevalent even in remote areas of the Amazon.     

Seroprevalence of antibodies to Neospora caninum in Belgian dogs

Sera from 300 dogs from Ghent and Antwerp were tested for antibodies to Neospora caninurn using an Indirect fluorescent antibody test. Overall, 11 per cent (995 to 13 per cent; confidence interval of 95 per cent) of dogs were seropositive, at titres of 1:50 to 1:800. No sex or breed differences were detected, but there was an Increase In seropositivity with age.     

Prevalence of antibodies to Neospora caninum in dogs.

Serum samples from 1077 dogs suspected of having Neospora caninum infections from 35 states in the United States and 3 provinces in Canada were tested for N. caninum IgG antibodies by the indirect fluorescent antibody test. Antibodies to N. caninum were found in 75 of 1077 (7%) of the samples. Twenty of the positive dogs were females, 17 were males and the sex was not recorded on 38 dogs. Chi square analysis indicated no differences (P > 0.05) based on sex were present. Dogs from the Southeast and Midwest regions of the United States were more likely to be N. caninum antibody positive than were dogs from the Northeast or West regions.     

Serosurvey of antibodies against Toxoplasma gondii and Neospora caninum in white-tailed deer from Northern Mexico

The objective of this study was to determine the seroprevalence of Toxoplasma gondii and Neospora caninum in white-tailed deer from Northern Mexico. Sera from 532 white-tailed deer (Odocoileus virginianus) from three Northern states of Mexico were assayed for antibodies to T. gondii by ELISA and western blot. From these samples, 368 were available to test for N. caninum antibodies by ELISA. The overall prevalence for T. gondii antibodies was 13.9% (74/532; CI(95) 11-17) and for N. caninum 8.4% (31/368; CI(95) 6-12). There was a significant association between positive ELISA results for T. gondii, with management factors within ranches, such number of deer per hectare and geographic location of deer, but none for N. caninum. T. gondii infection in the deer from Guerrero, Coahuila had an increased risk than those from Nuevo Laredo, Tamaulipas (OR, 8.3; CI(95) 1.9-35.4; P<0.05) and ranches with one deer in 15ha had increased risk of positive association (OR, 2.61; CI(95) 1.5-4.4; P<0.05). These findings may have environmental or public health implications because venison can be an important meat source of T. gondii infections for humans and feral cats.     

Natural transmission routes of Neospora caninum between farm dogs and cattle

Twelve dairy herds with evidence of post-natal infection with Neospora caninum were compared with 21 control herds with no evidence of post-natal infection. On the former farms, dogs consumed placenta or licked uterine discharge in 75 and 67% of the farms, respectively, while on control farms these activities occurred in 38 and 24% of the farms, respectively. On all control farms and all but three post-natally infected farms the dogs were fed colostrum or milk. Defecation of dogs on the feeding alley was observed in 92% of the post-natally infected farms and in 24% of the control farms. The same trend was observed for defecation of dogs in grass silage, in 75% of the post-natally infected farms and in 19% of the control farms; and in corn silage, in 50% of the post-natally infected farms and in 10% of the control farms. Consumption of placenta, material of aborted foetuses or uterine discharge in combination with defecation on the feeding alley, storage of grass or corn silage was observed in 19% of the control farms and in 75% of the post-natally infected farms. This study supports the hypothesis that farm dogs may become infected by foetal fluids or placental material of infected cattle, and may subsequently cause a post-natal infection of cattle in the herd by shedding oocysts.     

Shedding of Neospora caninum oocysts by dogs fed different tissues from naturally infected cattle

Neospora caninum is one of the most important causes of abortion in dairy cattle worldwide. The distribution of N. caninum in tissues of adult cattle is unknown and the parasite has not been demonstrated histologically in tissues of cows. In the present study the distribution of N. caninum in different tissues of adult cattle was evaluated by bioassays in dogs. Seventeen dogs (2-3 month-old) were fed different tissues of 4 naturally exposed adult cattle (indirect fluorescent antibody test N. caninum titer ≥ 400): 5 were fed with masseter; 5 with heart, 3 with liver, 4 with brain, and 3 pups were used as non-infected control. Two dogs fed masseter, 2 fed heart, 1 fed liver, and 3 fed brain shed oocysts, and all dogs presented no seroconvertion to N. caninum during the observation period of 4 weeks. The oocysts were confirmed as N. caninum based on the detection of N. caninum-specific DNA by PCR and sequencing. The results indicate that dogs can be infected by N. caninum with different tissues of infected cattle.     

Prevalence of antibodies to Neospora caninum in Korean native beef cattle

A total of 438 sera from Korean native beef cattle in 9 provinces were tested for Neospora caninum antibodies using an immunofluorescent antibody test (IFAT). Eighteen (4.1%) cattle were positive by IFAT. The titers ranged from 1:200 (10 animals), 1:400 (5 animals), 1:800 (2 animals) to 1:1,600 (1 animal). Although the seroprevalence was slightly higher in Chungnam (8.9%), this was not significantly different from those noted in Kyunggi, Kangwon, Kyungbuk, Kyungnam, and Cheju provinces. Sera obtained from beef cattle in the provinces of Chungbuk, Jeonbuk and Jeonnam were all negative. Neospora positive sera were also tested for anti-Toxoplasma gondii antibodies using a commercial latex agglutination test (LAT). Antibody to T. gondii was detected in only 1 (5.6%) of 18 N. caninum positive sera. These results indicate that N. caninum and T. gondii infection are present at a low level in the Korean native beef cattle.     

Occurrence of antibodies to Neospora caninum and Toxoplasma gondii in dogs from Pernambuco, Northeast Brazil

A serological survey was carried out to assess the occurrence of anti-Neospora caninum antibodies in dogs from the State of Pernambuco. A total of 625 serum samples of dogs (289 from Paulista, 168 from Amaraji and 168 from Garanhuns) were tested by an immunofluorescence antibody assay for the detection of anti-N. caninum antibodies. A total of 177 (28.3%; IC 95%, 24.9-32.1) samples were positive. The seropositivity rates found in Paulista, Amaraji and Garanhuns were 26% (IC 95%, 21-31.4), 26.2% (IC 95%, 19.7-33.5) and 34.5% (IC 95%, 27.4-42.2), respectively. Of the 177 serum samples positive to anti-N. caninum antibodies, 170 were additionally tested for the presence of anti-Toxoplasma gondii antibodies and out of these 57.6% (IC 95%, 49.8-65.2) were positive. The results indicate that dogs from Amaraji, Paulista and Garanhuns are exposed to both N. caninum and T. gondii infections. The presence of dogs infected by N. caninum in Pernambuco represents a potential risk factor for the occurrence of outbreaks of abortion in cattle and small ruminants in this state. This study is the largest serological survey on the presence of anti-N. caninum antibodies in dogs carried out in Brazil and reports for the first time the exposure to N. caninum and T. gondii in dogs from Pernambuco.     

Serological survey of Neospora caninum infection in dairy cattle herds in Aguascalientes,Mexico

A serological survey for antibody activity to Neospora caninum was carried out in Aguascalientes, a state in the central part of Mexico. One-hundred and eighty-seven serum samples from 13 dairy herds were tested by the ELISA test. The herd prevalence was 100% and the overall prevalence was 59% (n=110). Seventy-six of 97 seropositive cows had previous records of abortion. There was a statistically significant difference between the groups (P<0.05). However, the odds ratio was 1.4, suggesting an association between abortion and seropositivity. Neosporosis in dairy cattle appears to be widespread in Mexico, warranting more epidemiological studies to determine the distribution of the causative protozoan.     

Survey of Neospora caninum antibodies in dairy and beef cattle from five regions of the United States

Serum samples from 4,907 cows from 93 dairy and five beef herds were analyzed for antibodies to Neospora caninum by commercially available ELISA. The herds were recruited from 20 states and the territory of Puerto Rico. A questionnaire assessed the herd's abortion history and exposure risks to N. caninum. Results showed that 788 (16%) cows tested positive for antibodies to N. caninum. At least one positive animal was detected in 90% of the herds tested. The prevalence of cows seropositive to N. caninum varied from 2% to 65% among herds. Abortion rates ranging from 2% to 19% were reported. The epidemiologic data collected from the questionnaire suggested that the presence of farm dogs does not increase the risk of exposure of cows to N. caninum.     

Seroprevalence of antibodies to Neospora caninum in urban and rural dogs in north-west Italy

Sera were collected from 490 dogs from north-west Italy. One hundred and eighty-eight dogs were urban, while 302 dogs were rural. Among the latter, 190 were shepherd dogs and 112 were cattle farm dogs. Sera were tested for the presence of antibodies against Neospora caninum using the Neospora agglutination test. Seroprevalence at 1/40, 1/80, 1/160 dilution titres was significantly higher in rural (36.4%, 19.5%, 9.9% respectively) than in urban dogs (20.2%, 10.6%, 4.8% respectively). Seroprevalence did not differ significantly in males and females. In shepherd dogs, prevalence increased according to dogs' age, thus suggesting a post-natal exposure by horizontal transmission. The observed higher seroprevalence in rural dogs suggests the importance of lifestyle and alimentary habits (i.e. aborted foetuses, placentas and small mammals) in the acquisition of N. caninum infection. Our results confirm that dogs are exposed to N. caninum and play an important role in the epidemiology of N. caninum.     

Anti-Neospora caninum antibodies in milk in relation to production losses in dairy cattle

A comprehensive field study was carried out with the following objectives: (a) to assess the usefulness of individual and bulk tank milk analysis for determining Neospora caninum serostatus in individual cows and herds, and (b) to study the associations between N. caninum infection status (based on milk testing), and several productive and reproductive parameters in the animals. Antibodies were detected with a commercially available ELISA test (Bio K 192/5). Analysis of paired serum and milk samples from 1134 lactating cows on 38 farms revealed that 97.6% of the ELISA results were coincident, irrespective of whether serum or milk samples were used. Moreover, multiple linear regression analysis revealed that 86.0% of the variations in ELISA values in milk were due to variations in the serum. The measurement of antibodies in bulk tank milk was a good estimator of the herd level status of N. caninum infection, and enabled detection of infection in 94.7% herds with ≥10.0% seropositive cows and/or in all herds with >4% highly seropositive cows. The odds ratio for abortion in seropositive animals was 9.1 times higher than in seronegative animals. The infection serostatus was also a significant risk factor, as the odds ratio for abortion was even higher (12.0 times) in cows categorized as highly seropositive. ELISA values for the bulk milk from 387 randomly selected herds were negatively associated with average milk production. Moreover, milk production losses mainly occurred on farms categorized as highly positive (i.e. herds with ≥20.0% seropositive cows).     

奶牛新孢子虫病血清流行病学调查

本研究用酶联免疫吸附试验（ELISA）对采集自北京地区的94份奶牛血清（随机采集）和河北地区的55份奶牛血清（有流产史奶牛），进行Neospora caninum血清抗体检测。结果发现，北京地区随机采集的奶牛血清N．caninum抗体阳性率为18．1％（17／94），河北地区有流产史的奶牛N．caninum血清抗体阳性率为23．6％（13／55）。采用牛奶记录体系（DHI）对北京地区17头N．caninum血清抗体阳性牛进行了日产奶量、乳中蛋白率和乳脂率的测定，并与同群牛中134头阴性牛比较。结果表明，N．caninum血清抗体阳性牛日产奶量比阴性牛降低9．7％，乳中蛋白率和乳脂率分别降低20％和15．4％。初步证明N．caninum血清抗体阳性奶牛产奶量降低及奶品质的下降。对不同N．caninum抗体滴度阳性牛的泌乳期主要生产性能比较发现，其生产性能的变化与抗体滴度无明显相关性。     

Prevalence of antibodies against Neospora caninum and Toxoplasma gondii in dogs and foxes in Austria

Sera from 1770 dogs and 94 red foxes from Austria were examined for antibodies against Neospora caninum using the indirect immunofluorescent antibody test (IFAT). 3.6% of the dogs were seropositive with titres ranging from 1:50 to 1:6400. Dogs from rural areas were significantly more often seropositive for N. caninum than those from the urban area of Vienna (5.3% versus 2.1%). There were no significant differences in sex or breed, but a slight increase in seropositivity with age was apparent, indicating postnatal infection. None of the foxes had antibodies against N. caninum. Additionally, sera from 242 dogs and 94 foxes were examined for antibodies against Toxoplasma gondii using the IFAT. Thirty-five percent foxes and 26% of the dogs were positive; 1.7% of the dogs were positive for both parasites. This is the first report of the prevalence of N. caninum infections in dogs and foxes in Austria.