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de Oliveira UV, de Magalhães VCS, Costa SCL, Allaman IB, Munhoz AD. Fluctuations of antibody serum titers for Toxoplasma gondii and Neospora caninum in naturally infected crossbred cows during gestation. BRAZILIAN JOURNAL OF VETERINARY MEDICINE 2023; 45:e003023. [PMID: 38162819 PMCID: PMC10756150 DOI: 10.29374/2527-2179.bjvm003023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 12/08/2023] [Indexed: 01/03/2024] Open
Abstract
This study aimed to assess the fluctuations of antibody serum titers for Toxoplasma gondii and Neospora caninum in naturally infected crossbred cows during gestation and to investigate transplacental transmission of T. gondii; 51 cows were monitored during pregnancy by monthly serologic testing by indirect fluorescent antibody test. 33 cows were seronegative for both N. caninum and T. gondii, 10 were seropositive only for N. caninum, 5 were seropositive only for T. gondii, and 3 were seropositive for both N. caninum and T. gondii. In both protozoan infections, great variation in antibody levels in pregnant cows was observed, and there was significant increase (p<0.05) in the comparison between the averages of serological titration per trimester. There was a significant correlation (p<0.05) between month and probability of seropositivity for T. gondii. We conclude that pregnancy influences antibody titers of crossbred cows naturally infected with N. caninum and/or T. gondii, and that serologic testing for T. gondii in pregnant cows from the sixth month of gestation onward may decrease the number of false negative results.
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Affiliation(s)
| | | | - Sônia Carmen Lopo Costa
- Veterinarian, Departamento de Agricultura e Meio Ambiente, Universidade Estadual de Santa Cruz (UESC), Ilhéus, BA, Brasil.
| | - Ivan Bezerra Allaman
- Zootechnics, Departamento de Ciências Exatas e Tecnológicas, UESC, Ilhéus, BA, Brasil.
| | - Alexandre Dias Munhoz
- Veterinarian, Departamento de Agricultura e Meio Ambiente, Universidade Estadual de Santa Cruz (UESC), Ilhéus, BA, Brasil.
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da Silva JB, Nicolino RR, Fagundes GM, Dos Anjos Bomjardim H, Dos Santos Belo Reis A, da Silva Lima DH, Oliveira CMC, Barbosa JD, da Fonseca AH. Serological survey of Neospora caninum and Toxoplasma gondii in cattle (Bos indicus) and water buffaloes (Bubalus bubalis) in ten provinces of Brazil. Comp Immunol Microbiol Infect Dis 2017; 52:30-35. [PMID: 28673459 DOI: 10.1016/j.cimid.2017.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 05/04/2017] [Accepted: 05/08/2017] [Indexed: 10/19/2022]
Abstract
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.
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Affiliation(s)
- Jenevaldo Barbosa da Silva
- Universidade Federal dos Vales do Jequitinhonha e Mucuri - ICA/UFVJM, Av. João Narciso, 1380-Cachoeira, 38610-000 Unaí, Minas Gerais, Brazil.
| | - Rafael Romero Nicolino
- Universidade Federal dos Vales do Jequitinhonha e Mucuri - ICA/UFVJM, Av. João Narciso, 1380-Cachoeira, 38610-000 Unaí, Minas Gerais, Brazil
| | - Gisele Maria Fagundes
- Universidade de São Paulo - USP, Av. Duque de Caxias Norte, 225, 13635-900 Pirassununga, São Paulo, Brazil
| | - Henrique Dos Anjos Bomjardim
- Universidade Federal do Pará - UFPA, Rodovia BR 316 Km 61, Bairro Saudade, 68740-970, Castanhal, Pará, Brazil(1)
| | | | | | - Carlos Magno Chaves Oliveira
- Universidade Federal do Pará - UFPA, Rodovia BR 316 Km 61, Bairro Saudade, 68740-970, Castanhal, Pará, Brazil(1)
| | - José Diomedes Barbosa
- Universidade Federal do Pará - UFPA, Rodovia BR 316 Km 61, Bairro Saudade, 68740-970, Castanhal, Pará, Brazil(1)
| | - Adivaldo Henrique da Fonseca
- Universidade Federal Rural do Rio de Janeiro - UFRRJ, Br 465, Km 07, 23890-000 Seropédica, Rio de Janeiro, Brazil
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McAllister MM. Diagnosis and Control of Bovine Neosporosis. Vet Clin North Am Food Anim Pract 2016; 32:443-63. [DOI: 10.1016/j.cvfa.2016.01.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Rodríguez AM, Maresca S, Cano DB, Armendano JI, Combessies G, Lopéz-Valiente S, Odriozola ER, Späth EJL, Odeón AC, Campero CM, Moore DP. Frequency of Neospora caninum infections in beef cow-calf operations under extensive management. Vet Parasitol 2016; 219:40-3. [PMID: 26921037 DOI: 10.1016/j.vetpar.2016.02.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 01/27/2016] [Accepted: 02/01/2016] [Indexed: 10/22/2022]
Abstract
The aim of this study was to evaluate the frequencies of Neospora caninum horizontal and vertical transmissions in beef cow-calf operations under three different extensive management systems: group A: 0.75 head per hectare pasturing on natural grass; group B: 1.1 head per hectare on natural grass and improved cultured pastures; and group C: 2 head per hectare on natural grass, improved cultured pasture and whole corn silage. Serum samples from 72 multiparous cows assigned to each beef cow-calf operations were obtained every 3 months during 2 years. A group of 30 replacement heifers from each group were tested similarly since they were 10-21 months old. Twenty four, 20 and 34 calves from groups A, B and C respectively, were bled before colostrum intake and again 6 months later. The samples were analyzed by indirect fluorescence antibody test (IFAT) for detection of total IgG against N. caninum at a serological titre ≥ 200 for multiparous cows and replacement heifers, and a serological titre ≥ 25 for calves. Serum samples from seropositive cows were assessed by ELISA to evaluate the avidity of their specific antibodies. There were no differences in the proportion of seropositive cows from groups A, B and C at the beginning of the trial (p>0.05). Interestingly, the lowest serological titres in seropositive cows from all groups were observed during the first trimester (p<0.05). Although seropositive cows had medium to high avidity antibodies, suggesting chronic infection; seroconversion associated with low antibody avidity was found in 2, 3 and 3 seropositive cows from groups A, B and C. All replacement heifers remained seronegative. No abortions were recorded but 2, 1, and 2 calves from groups A, B and C were seropositive before colostrum intake, respectively. Seropositive calves born from cows having intermediate or high avidity remained with the same serostatus at 6 months of age. Even under varying extensive management conditions, both N. caninum horizontal and vertical transmission methods do occur in beef cow-calf operations.
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Affiliation(s)
- A M Rodríguez
- Instituto Nacional de Tecnología Agropecuaria (INTA), Rauch CP7203, Argentina
| | - S Maresca
- Instituto Nacional de Tecnología Agropecuaria (INTA), Rauch CP7203, Argentina
| | - D B Cano
- Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce CP7620, Argentina
| | - J I Armendano
- Universidad Nacional de Mar del Plata, CP7600, Argentina
| | | | - S Lopéz-Valiente
- Instituto Nacional de Tecnología Agropecuaria (INTA), Rauch CP7203, Argentina
| | - E R Odriozola
- Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce CP7620, Argentina
| | - E J L Späth
- Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce CP7620, Argentina
| | - A C Odeón
- Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce CP7620, Argentina
| | - C M Campero
- Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce CP7620, Argentina
| | - D P Moore
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.
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Guido S, Katzer F, Nanjiani I, Milne E, Innes EA. Serology-Based Diagnostics for the Control of Bovine Neosporosis. Trends Parasitol 2015; 32:131-143. [PMID: 26711188 DOI: 10.1016/j.pt.2015.11.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/18/2015] [Accepted: 11/20/2015] [Indexed: 11/30/2022]
Abstract
The protozoan Neospora caninum is a primary infectious cause of abortion in cattle that causes significant economic losses worldwide. Because effective vaccines and licensed pharmacological treatments are currently unavailable, control measures rely on biosecurity and management practice. Serological diagnosis plays a crucial role in the identification of infected animals and several tests have been developed. However, owing to the particular dynamics of the host-parasite interaction and to the characteristics of the currently used diagnostic tools, a proportion of infected cattle may not be reliably identified, and can potentially undermine efforts towards the control of bovine neosporosis. Current diagnostic methods for N. caninum infection in cattle and the advances necessary to support effective control strategies are discussed.
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Affiliation(s)
- Stefano Guido
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZ, UK; The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Roslin, Midlothian, EH25 9RG, UK.
| | - Frank Katzer
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZ, UK
| | - Ian Nanjiani
- Westpoint Veterinary Group, Dawes Farm, Bognor Road, Warnham, West Sussex, RH12 3SH, UK
| | - Elspeth Milne
- The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Roslin, Midlothian, EH25 9RG, UK
| | - Elisabeth A Innes
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, EH26 0PZ, UK
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Transmission paths of Neospora caninum in a dairy herd of crossbred cattle in the northeast of Brazil. Vet Parasitol 2014; 202:257-64. [PMID: 24560936 DOI: 10.1016/j.vetpar.2014.01.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 01/10/2014] [Accepted: 01/21/2014] [Indexed: 11/23/2022]
Abstract
The aim of this study was to determine the transmission paths of Neospora caninum in a dairy herd of crossbred cattle. Two hundred and ninety animals were grouped according to the year of their birth to verify the distribution of infection according to age. The blood of 196 cattle was collected thrice, with an average interval of 210 days, to evaluate the existence of horizontal transmission in the herd. To evaluate vertical transmission, the blood of 64 calves was collected prior to ingestion of colostrum and from their mothers at parturition. Moreover, 63 family trees were built. The presence of anti-N. caninum antibodies was detected using an indirect fluorescent antibody test. The chi-square test (χ(2)) with Yates' correction or Fisher's exact test was used to evaluate the relation between the serology and age groups and between the serostatus of cows and their progeny in different calvings. A higher seropositivity (p=0.035) was found in animals born in 2008 compared to those born in 1997-2007. The serological status of only 13 animals presented changes, of which six (3.1%) became seropositive, indicating a low proportion of horizontal transmission. All seropositive cows gave birth to seropositive calves, resulting in 100% vertical transmission. Sixty-three family trees were constructed. In 29 (46%) of these families, there were animals seropositive for N. caninum. Congenital infection in relation to the number of births was estimated from the relation of Mother+ and Daughter+, without significant differences (p=0.84) between the number of births and the transmission of the parasite from infected cows to their progeny. The low proportion of horizontal transmission combined with the high proportion of vertical transmission allowed us to conclude that transplacental transmission is the principal route of N. caninum infection in the herd.
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Syed-Hussain SS, Howe L, Pomroy WE, West DM, Smith SL, Williamson NB. Adaptation of a commercial ELISA to determine the IgG avidity in sheep experimentally and naturally infected with Neospora caninum. Vet Parasitol 2014; 203:21-8. [PMID: 24582279 DOI: 10.1016/j.vetpar.2014.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 01/07/2014] [Accepted: 01/07/2014] [Indexed: 10/25/2022]
Abstract
Recent reports indicate Neospora caninum has a possible role in causing abortions in sheep in New Zealand. Knowledge about the epidemiology of neosporosis in sheep is limited. This study aimed to adapt and validate a commercially available ELISA assay as an IgG avidity assay to discriminate between acute (primary and re-inoculated) and chronic N. caninum infections in sheep. In addition, it was used to compare the antibody avidity values between lambs from ewes inoculated with N. caninum either during the pregnancy or in the previous year. The avidity assay was undertaken by using 6M urea for the first wash after incubation with the primary antibody in the commercial ELISA (Chekit* Neospora antibody test kit, IDEXX Laboratories, Australia). Sequential serum samples were obtained from naïve ewes (n=16) experimentally inoculated with live N. caninum tachyzoites. All ewes were seropositive by two weeks post-inoculation and remained seropositive for 20 weeks post-inoculation. There was a linear relationship between time after inoculation and avidity values (p<0.05) over the first 24 weeks. In Week 4, all animals had avidity values <35% and by Week 8, 8/16 animals had avidity values of >35%. These results suggest that an avidity value of <35% indicates a recent primary infection while a value of >35% is indicative of a chronic infection. The assay was then validated using samples from other groups of experimentally inoculated sheep as well as samples from naturally infected ewes. When comparing sample to positive ratio (S/P) and avidity values from lambs born from recently inoculated ewes with those from ewes inoculated the previous year and re-inoculated in the current year, it was possible to differentiate the lambs at 2 weeks of age. Lambs from recently inoculated ewes had low S/P and avidity values at 2 weeks of age which increased by 12 weeks of age. In comparison, lambs from re-inoculated ewes had high S/P and avidity values at 2 weeks of age, due to maternal antibody influence but values were similar to those from lambs that were born from recently inoculated ewes at 12 weeks of age. Avidity values for four naturally infected ewes were all >60% indicating chronic infection. These results suggest that the assay is able to discriminate between recent and chronic infection in sheep as well as able to differentiate lambs with maternal immunity compared to their own de novo immunity. As such it can be utilized to understand the kinetics of N. caninum infection in sheep.
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Affiliation(s)
- S S Syed-Hussain
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; Institute of Veterinary Animal and Biomedical Sciences, Massey University, Palmerston North 4412, New Zealand
| | - L Howe
- Institute of Veterinary Animal and Biomedical Sciences, Massey University, Palmerston North 4412, New Zealand
| | - W E Pomroy
- Institute of Veterinary Animal and Biomedical Sciences, Massey University, Palmerston North 4412, New Zealand.
| | - D M West
- Institute of Veterinary Animal and Biomedical Sciences, Massey University, Palmerston North 4412, New Zealand
| | - S L Smith
- Institute of Veterinary Animal and Biomedical Sciences, Massey University, Palmerston North 4412, New Zealand
| | - N B Williamson
- Institute of Veterinary Animal and Biomedical Sciences, Massey University, Palmerston North 4412, New Zealand
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Clinical outcome and vertical transmission variability among canine Neospora caninum isolates in a pregnant mouse model of infection. Parasitology 2013; 141:356-66. [PMID: 24148606 DOI: 10.1017/s0031182013001479] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We compared the clinical outcome and vertical transmission of six canine Neospora caninum isolates using a pregnant BALB/c model. Four of the isolates were obtained from oocysts of naturally infected dogs (Nc-Ger2, Nc-Ger3, Nc-Ger6 and Nc-6Arg) and two were from diseased dogs with neurological signs (Nc-Bahia and Nc-Liv). The dams were inoculated with 2×106 tachyzoites of each isolate at day 7 of pregnancy. Morbidity, mortality and the antibody responses were evaluated in both the dams and the offspring, as was parasite transmission to the progeny. The mortality rates varied from 100% in Nc-Bahia and Nc-Liv-infected pups to 19% or less for those infected with the isolates from oocysts. The vertical transmission rates varied from 9 to 53% for N. caninum from oocysts, compared with 100% for the Nc-Liv and Nc-Bahia isolates. All dams showed specific IgG responses against tachyzoite and rNc-GRA7 antigens, confirming Neospora infection. The highest IgG levels were detected in mice inoculated with the Nc-Liv and Nc-Bahia isolates. These results demonstrate marked differences in virulence between the N. caninum isolates obtained from oocysts and neurologically affected dogs. This variability could help us to explain the differences in the outcome of the infection in definitive and intermediate hosts.
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Cardoso JMS, Amaku M, dos Santos Araújo AJU, Gennari SM. A longitudinal study of Neospora caninum infection on three dairy farms in Brazil. Vet Parasitol 2012; 187:553-7. [DOI: 10.1016/j.vetpar.2012.01.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 01/05/2012] [Accepted: 01/11/2012] [Indexed: 10/14/2022]
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Munhoz AD, Pereira MJS, Flausino W, Lopes CWG. Neospora caninum seropositivity in cattle breeds in the South Fluminense Paraíba Valley, state of Rio de Janeiro. PESQUISA VETERINARIA BRASILEIRA 2009. [DOI: 10.1590/s0100-736x2009000100004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The infection by Neospora caninum of different cattle breeds in dairy properties in two municipalities of the South Fluminense Paraíba Valley, state of Rio de Janeiro, was evaluated. Considering a sampling universe of 2,491 cows, blood samples were collected from 563 dairy cows in 57 farms, which were randomically selected in proportion to the number of animals, using a random stratified sampling system. For each property the number of selected cows was proportional to the herd size. Abortion or other reproductive disorders were not considered as criteria for selecting the animals, and seropositivity was determined by indirect enzyme-linked immunosorbent assay (ELISA). A high association (p=0.006) between seropositivity and racial patterns was found. The analysis revealed that in comparison of pure black-and-white Holstein cows versus Zebu (p=0.0028), Holstein cows showed 2.65 times greater odds for seropositivity. In the same way, by comparing black-and-white Holstein versus Zebu + crossbreed Zebu/Holstein (p=0.01), it was noted that there is 2.23 times more chance for seropositivity in Holstein cattle. There were no significant differences concerning the comparison of Holstein cattle versus crossbreed Zebu/Holstein (p=0.08) or Zebu versus crossbreed Zebu/Holstein (p=0.11). This study supports the hypothesis that there is a close association between cattle breeds and the frequency of infection by N. caninum.
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Dijkstra T, Lam T, Bartels C, Eysker M, Wouda W. Natural postnatal Neospora caninum infection in cattle can persist and lead to endogenous transplacental infection. Vet Parasitol 2008; 152:220-5. [DOI: 10.1016/j.vetpar.2007.12.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 12/07/2007] [Accepted: 12/21/2007] [Indexed: 11/25/2022]
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Neospora caninum infection in Greek dairy cattle herds detected by two antibody assays in individual milk samples. Vet Parasitol 2008; 152:79-84. [DOI: 10.1016/j.vetpar.2007.11.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Revised: 08/15/2007] [Accepted: 11/13/2007] [Indexed: 10/22/2022]
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Bartels CJM, Huinink I, Beiboer ML, van Schaik G, Wouda W, Dijkstra T, Stegeman A. Quantification of vertical and horizontal transmission of Neospora caninum infection in Dutch dairy herds. Vet Parasitol 2007; 148:83-92. [PMID: 17640807 DOI: 10.1016/j.vetpar.2007.06.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Revised: 05/20/2007] [Accepted: 06/04/2007] [Indexed: 11/24/2022]
Abstract
Ninety-six of 108 randomly selected Dutch dairy herds had one or more cows with a positive serostatus for N. caninum. In these 96 herds, we have quantified the probabilities of vertical transmission (VT) and horizontal transmission (HT) of N. caninum infection by combining serostatus and pedigree data in 4091 dam-daughter pairs. The probability of animals infected by vertical transmission during pregnancy (Prob(VT)) was calculated as the proportion of seropositive daughters among daughters of seropositive dams. The probability of animals infected by horizontal transmission (Prob(HT)) was the proportion of seropositive daughters among daughters of seronegative dams. These probabilities were calculated after the frequencies of observed dam-daughter combinations were corrected for (1) imperfect test-characteristics, (2) underestimation of horizontal transmission in situations that seronegative dams were horizontally infected after the birth of their daughters and (3) overestimation of vertical transmission in situations that seronegative daughters born from seropositive dams were horizontally infected. The incidence rate for horizontal transmission was calculated based on Prob(HT) and the average age of the animals in these herds. Based on the analysis of dam-daughter serology, Prob(VT) was 61.8% (95% CI: 57.5-66.0%) and Prob(HT) was 3.3% (95% CI: 2.7-3.9%). After adjusting the observed frequencies for imperfect test-characteristics, underestimation of horizontal transmission and overestimation of vertical transmission, Prob(VT) decreased to 44.9% (95% CI: 40.0-49.9%) while Prob(HT) increased to 4.5% (95% CI: 3.9-5.2%). Prob(HT) corresponded with an incidence rate for horizontal transmission of 1.4 (95% CI: 1.2-1.7) infections per 100 cow-years at risk. When stratifying herds for the presence of farm dogs, Prob(HT) was higher (5.5% (95% CI: 4.6-6.4%)) in herds with farm dogs than in herds without farm dogs (2.3% (95% CI: 1.5-3.4%)). When stratifying for within-herd seroprevalence, Prob(HT) was higher (10.3% (95% CI: 8.6-12.2%)) in herds with high (> or =10%) within-herd seroprevalence compared with herds with low (<10%) within-herd seroprevalence (2.0% (95% CI: 1.5-2.6%)). Although there was this relation between Prob(HT) and within-herd seroprevalence (crude OR(PREV) = 5.7 (95% CI: 4.0-7.9)), in herds without farm dogs, this relationship was no longer statistical significant (OR(PREV|DOG-) = 1.9 (95% CI: 0.7-5.5)). It indicated that the association between seroprevalence and Prob(HT) depended largely on the presence of farm dogs. In addition, when looking for the presence of specific age-groups with significantly higher seroprevalence compared with the rest of the herd, there were 7 herds in which two or more horizontally-infected animals were present in specific age-groups. This was an indication of a recent point-source exposure to N. caninum. These results reiterate the current control strategies to apply strict dog-management measures as well as to minimize within-herd seroprevalence by monitoring serostatus of animals.
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Affiliation(s)
- Chris J M Bartels
- Animal Health Service Ltd., P.O. Box 9, 7400 AA, Deventer, The Netherlands.
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Chanlun A, Emanuelson U, Frössling J, Aiumlamai S, Björkman C. A longitudinal study of seroprevalence and seroconversion of Neospora caninum infection in dairy cattle in northeast Thailand. Vet Parasitol 2007; 146:242-8. [PMID: 17416467 DOI: 10.1016/j.vetpar.2007.02.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 02/09/2007] [Accepted: 02/09/2007] [Indexed: 10/23/2022]
Abstract
A long-term study was carried out in 11 dairy herds in the Khon Kaen province of northeast Thailand between August 2001 and November 2004. The objective was to investigate seroprevalence dynamics of Neospora caninum infection in the herds and to demonstrate patterns of seroconversion in individual cattle. Each herd was visited once a year, in total four times, and sera from cattle > 3 months of age and farm dogs as well as a sample from the bulk milk were collected. All samples were analysed for presence of specific antibodies by an N. caninum iscom ELISA. The overall percentage of antibody-positive cattle was constant and varied only between 10 and 13% over the 4 years, but the variation in within-herd seroprevalence between herds was substantial. Two herds had > or = 20% seropositive animals at all samplings and consistently high bulk milk OD, whereas two herds had no seropositive animal at the last two samplings and low bulk milk OD. Five herds had a decreasing trend of within-herd seroprevalence, whereas the remaining six herds had a higher portion of test-positive individuals at the end of the study. A total of 424 individuals were sampled more than once; 344 (81%) and 32 (8%) were consistently antibody-negative and antibody-positive, respectively. The proportions of animals that changed from being seronegative to seropositive and from being seropositive to seronegative between the years were 3.9-4.6% and 19-39%, respectively. Apparent vertical and horizontal transmission rates were 58% (95% CI; 44-71%) and 5% (95% CI; 3-7%), respectively. In conclusion, the overall percentage of N. caninum antibody-positive cattle was constant over the years, but the within-herd seroprevalence varied substantially between the herds. Seroconversions were likely to occur in individual cattle although most animals had consistent serological status throughout the study.
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Affiliation(s)
- Aran Chanlun
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, P.O. Box 7054, SE-750 07 Uppsala, Sweden.
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Dubey JP, Schares G, Ortega-Mora LM. Epidemiology and control of neosporosis and Neospora caninum. Clin Microbiol Rev 2007; 20:323-67. [PMID: 17428888 PMCID: PMC1865591 DOI: 10.1128/cmr.00031-06] [Citation(s) in RCA: 699] [Impact Index Per Article: 41.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neospora caninum is a protozoan parasite of animals. Until 1988, it was misidentified as Toxoplasma gondii. Since its first recognition in dogs in 1984 and the description of the new genus and species Neospora caninum in 1988, neosporosis has emerged as a serious disease of cattle and dogs worldwide. Abortions and neonatal mortality are a major problem in livestock operations, and neosporosis is a major cause of abortion in cattle. Although antibodies to N. caninum have been reported, the parasite has not been detected in human tissues. Thus, the zoonotic potential is uncertain. This review is focused mainly on the epidemiology and control of neosporosis in cattle, but worldwide seroprevalences of N. caninum in animals and humans are tabulated. The role of wildlife in the life cycle of N. caninum and strategies for the control of neosporosis in cattle are discussed.
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Affiliation(s)
- J P Dubey
- Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD 20705, USA.
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16
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Björkman C, Alvarez-Garcia G, Conraths FJ, Mattsson JG, Ortega-Mora LM, Sager H, Schares G. Neospora caninum IgG avidity tests: An interlaboratory comparison. Vet Parasitol 2006; 140:273-80. [PMID: 16750301 DOI: 10.1016/j.vetpar.2006.04.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 04/11/2006] [Accepted: 04/27/2006] [Indexed: 10/24/2022]
Abstract
Avidity tests can be used to discriminate between cattle that are acutely and chronically infected with the intracellular parasite Neospora caninum. The aim of this study was to compare the IgG avidity ELISA tests being used in four European laboratories. A coded panel of 200 bovine sera from well documented naturally and experimentally N. caninum infected animals were analysed at the participating laboratories by their respective assay systems and laboratory protocols. Comparing the numeric test results, the concordance correlation coefficients were between 0.479 and 0.776. The laboratories categorize the avidity results into the classes "low" and "high" which are considered indicative of recent and chronic infection, respectively. Three laboratories also use an "intermediate" class. When the categorized data were analysed by Kappa statistics there was moderate to substantial agreements between the laboratories. There was an overall better agreement for dichotomized results than when an intermediate class was also used. Taken together, this first ring test for N. caninum IgG avidity assays showed a moderate agreement between the assays used by the different laboratories to estimate the IgG avidity. Our experience suggests that avidity tests are sometimes less robust than conventional ELISAs. Therefore, it is essential that they are carefully standardised and their performance continuously evaluated.
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Affiliation(s)
- C Björkman
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
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17
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Dubey JP, Buxton D, Wouda W. Pathogenesis of bovine neosporosis. J Comp Pathol 2006; 134:267-89. [PMID: 16712863 DOI: 10.1016/j.jcpa.2005.11.004] [Citation(s) in RCA: 188] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Accepted: 11/28/2005] [Indexed: 11/29/2022]
Abstract
The protozoan parasite Neospora caninum is a major pathogen of cattle and dogs, being a significant cause of abortion in cattle in many countries. It is one of the most efficiently transmitted parasites, with up to 90% of cattle infected in some herds. The pathogenesis of abortion due to Neospora is complex and only partially understood. Losses occur after a primary infection during pregnancy but more commonly as the result of recrudescence of a persistent infection during pregnancy. Parasitaemia is followed by invasion of the placenta and fetus. It is suggested that abortion occurs when primary parasite-induced placental damage jeopardises fetal survival directly or causes release of maternal prostaglandins that in turn cause luteolysis and abortion. Fetal damage may also occur due to primary tissue damage caused by the multiplication of N. caninum in the fetus or due to insufficient oxygen/nutrition, secondary to placental damage. In addition, maternal immune expulsion of the fetus may occur associated with maternal placental inflammation and the release of maternal pro-inflammatory cytokines in the placenta. Thus N. caninum is a primary pathogen capable of causing abortion either through maternal placental inflammation, maternal and fetal placental necrosis, fetal damage, or a combination of all three. The question of how N. caninum kills the fetus exposes the complex and finely balanced biological processes that have evolved to permit bovine and other mammalian pregnancies to occur. Defining these immunological mechanisms will shed light on potential methods of control of bovine neosporosis and enrich our understanding of the continuity of mammalian and protozoal survival.
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Affiliation(s)
- J P Dubey
- Animal Parasitic Diseases Laboratory, United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, BARC-East, Building 1001, 10300 Baltimore Avenue, Beltsville, MD 20705-2350, USA
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18
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Corbellini LG, Smith DR, Pescador CA, Schmitz M, Correa A, Steffen DJ, Driemeier D. Herd-level risk factors for Neospora caninum seroprevalence in dairy farms in southern Brazil. Prev Vet Med 2006; 74:130-41. [PMID: 16343669 DOI: 10.1016/j.prevetmed.2005.11.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Revised: 10/28/2005] [Accepted: 11/04/2005] [Indexed: 10/25/2022]
Abstract
A cross-sectional study was used to test the relationship between herd seroprevalence to Neospora caninum and various potential herd-level risk factors in 60 dairy farms located in two distinct regions in southern Brazil. Thirty farms were randomly selected from within each region. A questionnaire was designed to summarize each farm's production system as it might relate to N. caninum transmission. The questionnaire contained 105 closed questions relating to general characteristics of the farms, farm facilities, management, source of food and water, herd health, environment and biosecurity, which included questions relevant to N. caninum transmission, including presence and number of dogs and other animals, purchase of animals and contact with man. Serum samples were collected from 40% of animals in each farm and N. caninum antibodies were detected by immunofluorescent antibody test (IFAT). The association between potential risk factors and the probability of an animal being seropositive was modeled using a generalized estimation equations (GEE) logistic regression model. The model accounted for multilevel correlation of data from multiple animals within herds. The mean (+/-S.D.) number of animals in the 60 herds was 64.5 (+/-45.6), ranging from 20 to 280 females. Blood samples were collected from 1549 animals. The size of the farms varied from 4 to 100 ha (mean 30.1+/-25.9 ha). At least one dog was found in 57 of the 60 dairy farms (95%). The mean number of dogs was 3.1 (+/-1.9), ranging from 0 to 10. All females were raised on pasture. For all cattle sampled, N. caninum seroprevalence was 17.8%. Overall, 93.3% of herds (56/60) had at least one seropositive animal identified. Four variables were significantly associated with N. caninum sero-response in the 57 dairy farms, which were included in the final multivariable model: the number of dogs on the farm, farm area (hectares), feeding pooled sources of colostrum and region. The odds of a cow being seropositive increased 1.13 times for each additional dog present on the farm (P=0.021). Cattle from farms that fed calves colostrum pooled from multiple cows had 1.79 times greater odds for being seropositive for N. caninum (P<0.003). The probability of being seropositive was inverse to the area of the farms, such that cattle had 0.92 times the odds to be seropositive (P=0.014) for each additional 10 ha of farmland. Finally, cattle from farms in region one had 0.71 times the odds to be seropositive than cattle from region two (P=0.035). Results of this study suggest that several risk factors may explain why dairy cattle in Brazil may become exposed to N. caninum. However, further investigation of these factors is necessary because the purpose of this study was to refine and generate hypotheses on N. caninum transmission.
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Affiliation(s)
- Luis G Corbellini
- Laboratory of Veterinary Pathology, Faculty of Veterinary, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9090, CEP 91540-000, Porto Alegre, RS, Brazil.
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19
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Abstract
AbstractNeospora caninum is considered a major cause of abortion in cattle. Appropriate techniques for diagnosis of bovine neosporosis, both in vivo and in aborted foetuses, have been developed in the last ten years and some of them are commercially available. For diagnosis in live animals, detection of antibodies in serum or milk has been shown to be the best option both at the herd and the individual level. These techniques are excellent tools to examine N. caninum-associated abortion problems and to adopt some basic herd-control measures. Concerning foetal diagnosis, detection of compatible lesions by histological examination and parasites by PCR in brain (as well as heart and liver) are the best choices. Diagnostic criteria to distinguish foetal infection and Neospora-associated abortion are based not only on the demonstration of the parasite in the foetus but also on the extent and severity of the lesions in the foetus, foetal age and the assessment of neosporosis at the herd level. In the near future, new tools to diagnose infection should help to detect animals with parasite reactivation by testing the immune response to stage-specific antigens and lead to the development of molecular typing methods to characterise different parasite isolates. Finally, uniform diagnostic procedures need to be established between laboratories and countries in order to standardise result interpretation. The role of National or Regional Reference Laboratories is essential in countries or regions where control programmes for the disease are being developed.
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20
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Caetano-da-Silva A, Ferre I, Collantes-Fernández E, Navarro V, Aduriz G, Ugarte-Garagalza C, Ortega-Mora LM. Occasional detection of Neospora caninum DNA in frozen extended semen from naturally infected bulls. Theriogenology 2005; 62:1329-36. [PMID: 15325558 DOI: 10.1016/j.theriogenology.2004.01.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2003] [Revised: 01/23/2004] [Accepted: 01/24/2004] [Indexed: 11/30/2022]
Abstract
Recently, the presence of Neospora caninum DNA in semen from naturally infected bulls was reported. In the present work, the presence and quantification of N. caninum by PCR techniques in frozen extended semen straws from naturally infected bulls was investigated. A total of 20 seropositive and five seronegative bulls raised for reproductive purposes in an AI centre were used. Ten extended semen straws from each bull obtained at different time-points during the previous 2 years were selected for Neospora testing. Eight of the seropositive bulls (40%) studied showed at least one positive straw to N. caninum DNA and 14 of their 180 semen straws examined (7.8%) were found to be positive. In all positive samples, N. caninum DNA was consistently detected in the cell fraction and not in the seminal plasma. However, the parasite number in each positive straw was under the detection level of real-time PCR. In parallel, 10 semen straws from each of the five seronegative bulls were also analyzed by the nested-PCR and no N. caninum DNA products were obtained. In order to check the consistent presence of N. caninum in a positive semen batch, three additional semen straws from the same batch of each positive straw from three seropositive bulls were analyzed but N. caninum DNA was only detected in one straw from one bull. In conclusion, we report the sporadic detection of N. caninum DNA in semen straws of naturally infected bulls but the low frequency of contaminated semen straws and the low parasite load observed indicate a minor chance of bovine neosporosis transmission by AI.
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Affiliation(s)
- Andrea Caetano-da-Silva
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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21
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Gondim LFP, McAllister MM, Anderson-Sprecher RC, Björkman C, Lock TF, Firkins LD, Gao L, Fischer WR. Transplacental transmission and abortion in cows administered Neospora caninum oocysts. J Parasitol 2005; 90:1394-400. [PMID: 15715235 DOI: 10.1645/ge-359r] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Neospora caninum infection is a common cause of bovine abortion. One method by which cattle can acquire infection is through ingestion of oocysts; however, this has not yet been proved to cause transplacental infection or abortion. In this study, 19 cows, pregnant between 70 and 176 days, were administered 1500 to 115,000 oocysts through an esophageal tube. Seventeen of the cows became seropositive, indicating acquisition of infection, whereas 8 negative control cows remained seronegative (P < 0.001). Offspring were examined using serology, histology, immunohistochemistry, parasite isolation, and polymerase chain reaction (PCR). Six offspring were infected and 1 of them was aborted. The aborted fetus had typical lesions and positive immunohistochemistry and PCR for N. caninum. All 6 cows with infected offspring had continuously rising antibody titers, whereas 10 of 11 infected cows with uninfected offspring had falling titers after an early apex. The risk of transplacental transmission was increased by later exposure times during gestation and by the dose of oocysts (P < 0.01 for the 2 combined variables). The lowest dose of oocysts, when administered after the 160th day of gestation, caused transplacental infection in 1 of 2 animals. This study demonstrates that infection with N. caninum oocysts can cause transplacental transmission and abortion in cattle.
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Affiliation(s)
- L F P Gondim
- Department of Veterinary Pathobiology, University of Illinois, 2001 South Lincoln Avenue, Urbana, Illinois 61802, USA.
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22
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Björkman C, Gondim LFP, Näslund K, Trees AJ, McAllister MM. IgG avidity pattern in cattle after ingestion of Neospora caninum oocysts. Vet Parasitol 2005; 128:195-200. [PMID: 15740856 DOI: 10.1016/j.vetpar.2004.11.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Revised: 11/15/2004] [Accepted: 11/26/2004] [Indexed: 10/25/2022]
Abstract
The avidity (functional affinity) of specific antibodies are being used to estimate duration of bovine Neospora caninum infection. Here, we report for the first time the avidity pattern in cattle orally inoculated with N. caninum oocysts. In all, 16 pregnant cows and 7 calves were administered N. caninum oocysts. In the cows, the avidity increased during the early course of infection. In all but one, the avidity was < or = 35 during the first 6 weeks after infection and no cow had an avidity value >50 until week 9. The calves were sampled either week 6 (n = 3) or week 9 (n = 9) after infection, and by then had avidities between 2 and 17. The results are in agreement with results from previous investigations of naturally infected cattle, and calves that were experimentally infected with tachyzoites. They further validate the ability of the N. caninum iscom avidity ELISA to accurately assess the duration of infection.
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Affiliation(s)
- C Björkman
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, P.O. Box 7019, SE-75007 Uppsala, Sweden.
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23
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Abstract
Although the majority of pregnancy failures occur during the embryonic period, reports indicate that approximately 5% of detected pregnancies are lost during the fetal period, underlining the fact that fetal death is a substantial cause of economic loss. However, examination for fetal development or death during pregnancy is not performed routinely in domestic animals, and reference curves for normal fetal growth are, therefore, scarce. In this paper, the numerous possible causes of fetal death are reviewed briefly, with emphasis on the role of placental problems in fetal death and impaired fetal viability. In this respect, the role of placental insufficiency as a cause of pregnancy loss in twin pregnancies in monotocous species is well known, whereas the abnormal placental development leading to retarded fetal growth during pregnancies in recipients of in vitro produced (IVP) or nuclear transfer (NT) embryos has been less extensively documented. Fetal viability or death can be evaluated using hormonal, chemical and ultrasonographic parameters. For example, the viability of the feto-placental unit can be examined by measuring maternal plasma concentrations of oestrone sulphate or the placental proteins, including pregnancy-associated glycoprotein (PAG) and pregnancy-specific protein B-60 (PSPB-60). Low concentrations of any of these three indicate either no pregnancy, or if pregnancy was confirmed earlier, fetal death and abnormally high or low levels can indicate fetal abnormality. Ultrasound can be used to examine the fetal heart rate (FHR), the incidence of fetal movements (FM), the appearance of fetal fluids and the development of the fetus and placenta. However, although abnormal FHRs have been correlated to subsequent fetal death, it is important to remember that there is a large physiological variation in FHR at the end of gestation, due to different behavioural states and differences in FM patterns. Although monitoring fetal viability and death using hormonal and ultrasonographic evaluations is possible during pregnancy in domestic animals, there is considerable physiological variations in the 'normal' values. Therefore, suitable combinations of tests need to be identified and more accurate reference values generated before such approaches can be considered reliable for monitoring the status of individual fetuses.
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Affiliation(s)
- F H Jonker
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, The Netherlands.
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Stenlund S, Kindahl H, Uggla A, Björkman C. A long-term study of Neospora caninum infection in a Swedish dairy herd. Acta Vet Scand 2003; 44:63-71. [PMID: 14650545 PMCID: PMC1831554 DOI: 10.1186/1751-0147-44-63] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A longitudinal study was performed in a Swedish dairy herd where Neospora caninum had been isolated from a stillborn calf. Starting in autumn 1994, blood samples from all female animals in the herd were collected once yearly until 1999. The sera were analysed for presence of IgG1 antibodies to N. caninum by the iscom ELISA, and by an avidity ELISA to establish the timing of infection. In addition, data on reproductive performance were compiled. During the study the percentage of seropositive female animals increased from 63% to 87%. In 1994 a large number of young animals tested seropositive although their dams were seronegative, indicating that a transmission of the parasite other than the vertical had recently occurred. Low avidity values supported this assumption. The annual abortion rate increased from a mean of 2% before the initiation of the study to 9% in 1994-1998. During the same time, as judged by the avidity data, a large proportion of the animals shifted from being recently to being chronically infected. The source of the external infection in the herd could not be identified.
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Affiliation(s)
- Susanne Stenlund
- Department of Obstetrics and Gynaecology, Centre of Reproductive Biology, Uppsala, Sweden.
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25
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Ortega-Mora LM, Ferre I, del-Pozo I, Caetano-da-Silva A, Collantes-Fernández E, Regidor-Cerrillo J, Ugarte-Garagalza C, Aduriz G. Detection of Neospora caninum in semen of bulls. Vet Parasitol 2003; 117:301-8. [PMID: 14637032 DOI: 10.1016/j.vetpar.2003.09.015] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In cattle, transplacental infection is the main route of Neospora caninum transmission, but postnatal transmission by the oral uptake of sporozoite-containing oocysts shed by dogs may also be possible. Other routes of horizontal transmission, such as the venereal route, have not been investigated. In this study, we evaluated the presence of N. caninum DNA by a nested-PCR in fresh non-extended semen and frozen extended semen straws of five Holstein-Friesian bulls with naturally-acquired neosporosis. The infection status was assessed by an immunofluorescent antibody test (IFAT) and confirmed by immunoblotting (IB). Because of inhibitory components of semen, a protocol was developed to purify N. caninum DNA from bovine semen. Sporadically, N. caninum DNA was detected in non-extended fresh semen samples and frozen extended semen straws of the five seropositive bulls. In all positive samples, specific DNA was consistently found in the cell fraction of semen and not in seminal plasma. The parasite mean load in positive fresh semen samples determined by a real-time PCR was low oscillating between 1 and 2.8 parasites/ml of semen (maximum parasite load detected in one sample was 7.5 parasites/ml of semen). In parallel, another three similar but uninfected bulls acted as controls and no N. caninum DNA was amplified in any of their fresh and straw semen samples assayed. Whether venereal transmission plays a role in the spread of bovine neosporosis needs to be determined.
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Affiliation(s)
- Luis Miguel Ortega-Mora
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain.
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