Seroprevalence and risk factors for Neospora caninum and Toxoplasma gondii in dairy cattle from São Paulo State, Brazil

Soroprevalência e fatores de risco para Neospora caninum e Toxoplasma gondii em bovinos leiteiros do Estado de São Paulo

Abstract

Neospora caninum is a major cause of reproductive loss in cattle worldwide as it leads to abortion and animal repositioning. Although Toxoplasma gondii does not cause a reproductive problem in cattle, consuming raw or uncooked beef poses the risk of transmission. This study aimed to evaluate the occurrence of anti-N. caninum and anti-T. gondii antibodies in dairy cattle in the West and Northwest regions of São Paulo State, Brazil. A total of 653 serum samples from dairy cows were analyzed using an indirect immunofluorescence assay (IFA). Epidemiological data from the farms were associated with the serological results of the animals by logistic regression based on the presence of antibodies. The frequencies of the antibodies against N. caninum and T. gondii were 41.6% (272/653) and 11.5% (75/653), respectively. A statistically significant association was observed between: the serum anti-N. caninum antibodies and breed, history of food supplementation for calves, introduction of outside animals that later presented reproductive problems, and history of reproductive problems by the trimester of gestation. The present study highlights the importance of neosporosis in dairy cattle in the study regions and that the inclusion of this parasite in the investigation of animals with reproductive disorders is important.

Keywords:
Neosporosis; toxoplasmosis; dairy cattle; seroprevalence; risk factors

Resumo

Neospora caninum é uma das principais causas de perda reprodutiva em bovinos em todo o mundo, pois leva ao aborto e ao reposicionamento animal. Embora o Toxoplasma gondii não cause problemas reprodutivos em bovinos, o consumo de carne bovina crua ou não cozida apresenta risco de transmissão. Este estudo teve como objetivo avaliar a ocorrência de anticorpos anti-N. caninum e anti-T. gondii em bovinos leiteiros nas regiões Oeste e Noroeste do Estado de São Paulo, Brasil. Um total de 653 amostras de soro de bovinos leiteiros, foi analisado utilizando-se o ensaio de imunofluorescência indireta (IFI). Os dados epidemiológicos das propriedades foram associados aos resultados sorológicos dos animais por meio de regressão logística. As frequências dos anticorpos contra N. caninum e T. gondii foram 41,6% (272/653) e 11,5% (75/653), respectivamente. Foi observada associação estatisticamente significativa entre: soropositividade para N. caninum e raça, histórico de suplementação alimentar para bezerros, introdução de animais externos que, posteriormente, apresentaram problemas reprodutivos e histórico de problemas reprodutivos no segundo trimestre de gestação. O presente estudo destaca a importância da neosporose em bovinos leiteiros, nas regiões de estudo, e a inclusão deste parasita na investigação de animais com distúrbios reprodutivos é fundamental.

Palavras-chave:
Neosporose; toxoplasmose; gado leiteiro; soroprevalência; fatores de risco

Introduction

Milk production is one of the major economic activities in Brazil. The country is the fifth largest milk producer in the world, with an annual yield of R$35 billion in 2019. The Southeast region is ranked the highest in milk production, accounting for 34.3% of the national yield, with 5% of the regional production from São Paulo State (Embrapa Gado de Leite, 2022).

Neospora caninum is a major cause of abortion in dairy cattle, and vertical transmission is considered the most relevant route (Dubey, 1999; Dubey et al, 2017; Reichel, et al., 2013). However, cattle can also be infected through horizontal transmission, which occurs through the ingestion of food or water contaminated with sporulated oocysts eliminated by the definitive hosts of the parasite, such as some species of canids (Dubey et al, 2017). In Brazil, N. caninum is widely distributed, with reports from 16 states (Cerqueira-Cézar et al, 2017).

Although T. gondii is not an important cause of abortion in cattle, it can be transmitted when the beef is consumed raw or undercooked (Santos et al., 2020). The herd can be infected through the consumption of pastures contaminated with oocysts eliminated by felines. Thus, establishing a real causal agent is important for promoting the efficiency of epidemiological knowledge and sanitation practices (Gomes et al., 2020).

The aim of this study was to investigate the occurrence of anti-N. caninum and anti-T. gondii antibodies in dairy cattle from the West and Northwest regions of São Paulo State, Brazil, and evaluate the factors associated with their seropositivity.

Material and Methods

Study location and ethics approval

The study was conducted on ten dairy farms in the municipalities of Tupã (four dairy farms), Iacri (one dairy farm), Queiroz (one dairy farm), Alto Alegre (two dairy farms), and Penápolis (two dairy farms), located in the West and Northwest regions of São Paulo State, Brazil. This study was approved by the Committee of Animal Ethics of the State University of Londrina (UEL) (CEUA 10/2019, number 23340.2018.90).

Sampling

Ten dairy cattle farms with semi-intensive production systems in municipalities, where seroprevalence of N. caninum and T. gondii had not been studied were selected for this study by convenience. Blood samples were collected from Holstein, Jersey, Gir, Girolando, Jersolando, Brown Swiss, and crossbred dairy cows between March and April, 2019. The sample inclusion criteria were male and female dairy cattle up to 10 years of age. Considering the most conservative and substantial sample size obtained in epidemiological studies, an infinite population was used as a reference to calculate the sample size (n), and a prevalence of 50% was assumed for both parasites. With a 95% confidence level, the admitted error was 4%, resulting in a sample size of 600 animals.

Blood samples were collected from the herds into tubes without anticoagulants and transported in isothermal boxes at 8 °C to the Center of Veterinary Medical Diagnosis (EMERGE, Tupã, São Paulo, Brazil). The samples were centrifuged at 3000 × g for 10 min in the laboratory, and the serum was then transferred to a 2 mL microtube and stored at -20 °C until serological analysis.

Serological analysis

The presence of antibodies against N. caninum and T. gondii was verified via an indirect immunofluorescence assay (IFA) using bovine anti-IgG marked with fluorescein (Fluoresceinisothiocyanate - Sigma- Aldrich, San Luis, Missouri, USA) for both parasites and slides fixed with tachyzoites from the NC-1 strain for N. caninum and the RH strain for T. gondii (Conrad et al., 1993; Camargo, 1974). One positive and one negative serum sample for antibody presence was added to each slide as a control. For N. caninum antibody screening, serum samples were diluted to 1:50 and 1:100. They were considered positive when calf and cow serum presented titers of ≥1:100 (Antonello et al., 2015). Similarly, for T. gondii antibody screening, samples were diluted to 1:16 and 1:64 and were considered positive when calf and cow serum presented titers of ≥1:64 (Santos et al., 2020). All the positive samples in the screening analysis had their titers determined by complete dilution of sera until no fluorescence reaction was observed.

Epidemiological Characterization

To obtain epidemiological data, a questionnaire regarding information on structures and managements of farms (variables: open or close market, crossbred or pure production system), zootechnical and health characteristics of animals (variables: sex; age; breed; history of food supplementation for calves; vaccines; history of trimester in which reproductive problems occurred; and history of reproductive, neurological, previous disease, and endo-ectoparasite problems), and environment (variables: presence of dogs, presence of cats, source of water for animals, destination of wastewater, and distance between water source and wastewater) was administered.

Statistics

Microsoft Excel® was used to tabulate the responses of producers with the variables of the epidemiological questionnaire, termed independent variables (IV), and the results of the diagnostic tests used, termed dependent variables (DV) (research results for N. caninum and T. gondii seroprevalence). Descriptive statistics were computed using Epi Info software (version 7.2.3.1).

Epi Info (version 7.2.3.1) and R environment (version 3.6.2) (epitools and epiDisplay packages) (Aragon et al, 2020; Chongsuvivatwong, 2018; Dean et al., 1996; R Core Team, 2019) were used to investigate the association between IV and DV. Significance was set at p<0.05, and the tests were chi-square corrected using Yates or Fisher's exact test or logistic regression. The strength of association was estimated using the odds ratio (OR) and its respective 95% confidence interval.

For georeferencing, the QGIS software (QGIS.org Association - Free Software Foundation, Massachusetts, New York, USA) was applied using geospatial data from the Brazilian Institute of Geography and Statistics (IBGE, 2010).

Results

Blood samples were collected from 653 animals (Table 1): 251 (38.4%) in the West and 402 (61.6%) in the Northwest region of São Paulo State (Table 2). Antibodies against N. caninum were verified in 41.6% (272/653; CI: 37.93–45.47%) of these animals. The prevalence of protozoan antibodies was 33.5% (84/251; CI: 27.66–39.67%) in the West region and 46.8% (188/402; CI: 41.94–51.65%) in the Northwest region (Figure 1). N. caninum was observed in 100.00% (10/10) of the farms studied (Tables 1 and 2). Farms showed a prevalence ranging from 22.5% to 92.8%, and the range of antibody titers was 100–6,400 (Table 1 and 3).

Table 1
Outcome of indirect immunofluorescence assay (IFA) for IgG against Neospora caninum in farms from São Paulo State, Brazil.

Farms	N	Sample (%)	IFA		Titer
			pos	neg	min	max
P1	26	3.98	9 (34.6%)	17	100	6,400
P2	17	2.60	9 (52.9%)	8	100	800
P3	66	10.11	19 (28.8%)	47	100	1,600
P4	40	6.13	9 (22.5%)	31	100	800
P5	72	11.03	21 (29.1%)	51	100	800
P6	173	26.49	79 (45.7%)	94	100	800
P7	30	4.59	17 (56.7%)	13	200	800
P8	110	16.85	35 (31.8%)	75	100	800
P9	91	13.94	48 (52.7%)	43	100	400
P10	28	4.29	26 (92.8%)	2	100	800
Total	653	100.00	272 (41.6%)	381	100	6,400

Table 2
Number of samples collected from cattle in West-Northwest and West regions of São Paulo State, Brazil, based on age.

Mesoregion	Age of animals (months)
	0-12 (%)	12-24 (%)	> 24 (%)
West-Northwest	40/653 (6.12)	41/653 (6.28)	170/653 (26.03)
West	41/653 (6.28)	66/653 (10.11)	295/653 (45.18)
Total	81/653 (12.40)	107/653 (16.39)	465/653 (71.21)

Figure 1
Frequency of anti-Neospora caninum antibodies detected via IFAT in bovine milk breeding cities in the Northwest region of Sao Paulo State, Brazil.

Table 3
Frequency of anti-Neospora caninum and anti-Toxoplasma gondii antibodies in dairy cattle from São Paulo State, Brazil.

Mesoregion	N. caninum farms Positive/Total (%)	N. caninum Animals Positive/Total (%)	T. gondii farms Positive/Total (%)	T. gondii Animals Positive/Total (%)
West-Northwest	6/6 (100.0)	84/251 (33.5)	6/6 (100.0)	32/251 (12,7)
West	4/4 (100.0)	188/402 (46.8)	3/4 (75.0)	43/403 (10.7)
Total	10/10 (100.0)	272/653 (41.6)	9/10 (90.0)	75/653 (11.5)

Although no statistical significance was observed among age and seroprevalence of parasites, majority of the prevalence occurred in those aged ≥24 months (44.1%, 205/465).

The model obtained via multivariate logistic regression demonstrated a significant association between seropositivity for N. caninum and the following factors: breed, history of food supplementation for calves, introduction of outside animals that later presented reproductive problems, and history of reproductive problems during the trimester of gestation (Table 4). Herds with crossbred cows were 2.08 [(Odds-ratio Confidence Interval (OR CI): 1.30–3.31)] times more prone to be seropositive to N. caninum compared with purebred animals. Similarly, animals from farms without supplementation for calves were 4.67 (OR CI: 2.93–7.45) times more likely to be seropositive to N. caninum, and each property followed the specific diets for the calves: the main supplements used were vitamins, minerals, and protein sources. Seventy percent (7/10) of the farms practiced open market management system, in which the cows bought later presented reproductive problems. Compared to others, the chances of the cows from these farms being seropositive were 5.02 (OR CI: 3.14–8.00) times higher (Table 4).

Table 4
Variables statistically associated with the prevalence of anti-Neospora caninum antibodies in bovine milk breeding farms in the West-Northwest and West region of São Paulo State, Brazil.

Variables	Positive/Total (%)	P 1	OR (CI 95%)	P 2	Adjusted OR (CI 95%)
Breed
Crossbred	153/292 (52.4)	<0.0001	2.23 (1.62-3.07)	0.0016	2.08 (1.30-3.31)
Pure Breed	119/361 (33.0)
Historic of food supplementation for calves
Yes	209/529 (39.5)	0.0223	1.58 (1.06-2.34)	< 0.0001	4.67 (2.93-7.45)
No	63/124 (50.8)
Bought animals that presented later reproductive problems
Yes	188/402 (46.8)	0.0007	1.74 (1.25-2.42)	0.0007	5.02 (1.91-13.19)
No	84/251 (33.5)
Historic of reproductive problem by trimester of gestation
Fisrt3	31/112 (27.7)	0.0034		0.0007
Second	208/468 (44.4)		1.03 (0.63-4.01)		1.12 (0.59-2.13)
Third	33/73 (45.2)		2.16 (1.16-4.01)		4.63 (4.02-4.98)

• ¹
  Bivariate; ²Multiple Logistic Regression; ³Reference Category; OR: Odds-ratio; CI: Confidence Interval.

In all the three trimesters of pregnancy, 272 (41.65%) showed a history of reproductive problems, such as abortion, retained placenta, and return to estrus. As demonstrated by the logistic model, based on the trimester of gestation, the history of reproductive problems in farms was associated with the presence of anti-N. caninum antibodies. Furthermore, cows with a history of reproductive problems in the third trimester of pregnancy were 4.63 times more likely to be seropositive to the protozoan compared to those with an abortion in the first trimester (Table 4). Second and third trimester of gestation had higher positivity than the first trimester of gestation (p=0.0034).

Antibodies anti-T. gondii was confirmed in 11.5% (75/653; CI: 9.26–14.16%) of the animals from 90% (9/10) of the farms studied (Table 3): 12.7% (32/251; CI: 8.89–17.52%) from the Northwest region and 10.7% (43/403; CI: 8.04–14.10%) from the West region. No factors were associated with the presence of T. gondii antibodies in the animals (Table 5).

Table 5
Variables statistically associated with the prevalence of anti-Toxoplasma gondii antibodies in bovine milk breeding farms of the West-Northwest and West region of São Paulo State, Brazil.

Variables	Positive/Total (%)	P1	OR (CI 95%)
Breed
Crossbred	37/292 (12.7)	0.4646	0.81 (0.50-1.31)
Pure Breed	38/361 (10.5)
Historic of food supplementation for calves
Yes	6/529 (12.5)	0.1378	1.82 (0.88-3.76)
No	9/124 (7.3)
Bought animals that presented later reproductive problems
Yes	43/402 (10.7)	0.5002	1.21 (0.74-1.98)
No	32/251 (12.7)
Historic of reproductive problem by trimester of gestation
First²	15/112 (13.4)	0.2396
Second	48/468 (10.3)		0.74 (0.40-1.37)
Third	12/73 (16.4)		1.27 (0.56-2.90)

• ¹
  Bivariate; ²Reference Category; OR: Odds-ratio; CI: Confidence Interval.

Discussion

In the Northwest region of São Paulo, Curci et al. (2017) used the IFA method and observed a N. caninum seroprevalence of 35.1% (332/945) in dairy herds from a family farming system, and this is consistent with our results.

The seroprevalence observed for N. caninum in this study was 41.6%, while the seroprevalence of N. caninum obtained via IFA ranged from 14.1% to 97.2% in Brazil (Guimarães et al., 2004; Albuquerque et al., 2005; Ogawa et al., 2005; Benetti et al., 2009; Camillo et al., 2010; Silva et al., 2015; Chiebao et al., 2015; Klauck et al., 2016; Katto et al., 2017; Fávero et al., 2017; Snak et al, 2018; Bastos et al., 2019; Santos et al., 2020; Azevedo et al., 2021; Souza et al., 2022) and 12.4% to 43.1% in other parts of the world (Moore et al., 2002, 2009; Puray et al., 2006; González-Warleta et al., 2008; Eiras et al., 2011; Qian et al., 2017; Serrano-Martínez et al., 2007). Some of these studies used different cut-offs in their IFA, and several studies that involved the use of IFA as a serological technique have been conducted in Brazil.

Seventy percent of the studied farms had an open market management system in which the animals purchased presented reproductive problems later. These purchased animals had five times higher chances of being seropositive for N. caninum compared to other animals, and this is an alert to veterinarians as a control tool. All farms with crossbred animals used open market management, whereas farms with European cattle used closed herd market management. Non-replacement of animals with those from other herds can be a protective factor against N. caninum infection in dairy farms. Gindri et al. (2018) reported that animal purchase and animal substitution were significantly correlated with anti-N. caninum antibodies. A study that analyzed the impact of N. caninum on the reproductive parameters of 434 Holstein dairy cows from a closed herd in Brazil reported an association between the age at first calving and the services by conception, suggesting that the low seropositivity of the animals were due to closed handling system (de Barros et al., 2021).

In this study, pregnancy was observed during blood collection in 23.3% (152/653) of the cows sampled, among which 17.1% (26/152) presented history of an abortion episode that was associated with the presence of anti-N. caninum antibody as previously described previously (Boas et al., 2015; Bruhn et al., 2013; Chiebao et al., 2015; Corbellini et al., 2002; Hein et al., 2012; Oshiro et al., 2007; Pessoa et al., 2016). Animals in the second and third trimesters of gestation showed higher positivity for neosporosis than those in the first trimester. According to Dubey et al (2017), the pathogenesis of abortion remains unclear. Abortion caused by Neospora spp. occurs more frequently in the second and third trimesters of pregnancy; however, transplacental infection is very common in this gestation phase, and miscarriage rarely occurs. Nishikawa et al. (2001) and Innes et al. (2005) affirmed that a seropositive cow could experience reactivation of N. caninum during pregnancy, owing to the modulation of the humoral and cellular pathways of the immune system. This modulation is explained by a decrease in cellular response, which causes a change from bradyzoites to tachyzoites, thereby resulting in the invasion of the placental barrier and infection of the fetus. We observed an association between history of reproductive problems by the trimester of pregnancy and N. caninum seroporsitivity. Stenlund et al. (1999) and Almería et al. (2009) showed higher IgG titers in the third trimester than in the other trimesters, suggesting that the most probable period of Neospora reactivation is between the fourth and sixth months of pregnancy.

Even with a wide range of animal ages, no statistically significant association with Neospora seropositivity was observed. Some studies have revealed an association between N. caninum infection and animal age (Dyer et al.,2000; Guimarães et al., 2004; Sanderson et al., 2000), hypothesizing that the cause of the infection is due to the exposure time of hosts to parasite forms. Previous studies showed that younger animals had a lower seroprevalence than animals above 24 months of age. The time period for which these animals had contact with a contaminated environment probably increased their chances of infection (Bastos et al., 2019; Dyer et al., 2000; Guimarães et al., 2004).

The calves without dietary supplementation had higher susceptibility to neosporosis than the other calves in this study. Bartels et al. (1999) reported an association between farm management and the risk of infection in dairy herds in the Netherlands. According to Tokarnia et al. (2000), unequilibrated management of nutrients may occur at many levels and cause metabolic disturbances, which may decrease productivity and immunity. These may lead to reactivation of the parasite and cause clinical signs. Compared to other calves, non-supplemented calves were 4.67 times more likely to be seropositive for N. caninum, and they were associated with farm management because farms with the best nutrition program for cattle had the most efficient sanitation parameters as well (Chiebao et al., 2015).

This study verified the seropositivity of T. gondii in 11.5% of the sampled animals. Ogawa et al. (2005) observed the seroprevalence of T. gondii and N. caninum in dairy cattle from 90 farms in 12 municipalities in the northern region of Paraná and reported that 26.0% (102/392) of the animals were seropositive for T. gondii. In Brazil, T. gondii seroprevalence in cattle varies with regions and diagnostic methodology. The seroprevalence amplitude of positive animals is approximately 1%–49%, and studies have shown that the resistance of cows to T. gondii may interfere with prevalence rates and transmission (Albuquerque et al., 2005; Daguer et al., 2003; Dubey, 1986; Costa & Costa, 1978; Garcia et al., 1999; Marana et al, 1995). There was no association between reproductive problems and T. gondii antibodies, and it was expected that this parasite would not be abortifacient in cattle (Barros et al., 2021).

Conclusion

Here, we observed a high frequency of antibodies against N. caninum in the studied farms; however, seropositivity was low for T. gondii. An association between N. caninum infection and history of reproductive problems was observed but not with T. gondii. This study shows the importance of neosporosis in dairy cattle from the study regions and including this parasite while discussing reproductive disorders in animals is fundamental for future diagnosis.

Acknowledgements

We would like to acknowledge the financial support of Nacional Institute on Science and Technology - INCT/Leite (number 465725/2014-7) and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) and to all those involved who contributed to the research.

• How to cite: Bernardes JC, Pinto-Ferreira F, Ladeia WA, Caldart ET, Paschoal ATP, Martins TA, et al. Seroprevalence and risk factors for Neospora caninum and Toxoplasma gondii in dairy cattle from São Paulo State, Brazil. Braz J Vet Parasitol 2024; 33(2): e006024. https://doi.org/10.1590/S1984-29612024034

References

• Albuquerque GR, Munhoz AD, Flausino W, Silva RT, Almeida CRR, Medeiros SM, et al. Prevalence of anti-Toxoplasma gondii antibodies in dairy cattle from Sul Fluminense Paraíba Valley, State of Rio de Janeiro. Rev Bras Parasitol Vet 2005; 14(3): 125-128. PMid:16229757.
• Almería S, Nogareda C, Santolaria P, Garcia-Ispierto I, Yániz JL, López-Gatius F. Specific anti-Neospora caninum IgG1 and IgG2 antibody responses during gestation in naturally infected cattle and their relationship with gamma interferon production. Vet Immunol Immunopathol 2009; 130(1-2): 35-42. http://doi.org/10.1016/j.vetimm.2009.01.003 PMid:19201036.
  » http://doi.org/10.1016/j.vetimm.2009.01.003
• Antonello AM, Camillo G, Weber A, Braunig P, Sangioni LA, Vogel FSF. Dinâmica sorológica de anticorpos contra Neospora caninum durante a gestação de vacas naturalmente infectadas. Cienc Anim Bras 2015; 16(4): 553-559. http://doi.org/10.1590/1089-6891v16i428127
  » http://doi.org/10.1590/1089-6891v16i428127
• Aragon TJ, Fay MP, Wollschlaeger D, Omidpanah A. Epitools: epidemiology tools. R package version 0.5-10.1 [online]. 2020 [cited 2023 Sep 10]. Available from: https://CRAN.R-project.org/package=epitools
  » https://CRAN.R-project.org/package=epitools
• Azevedo PCG Fo, Ribeiro-Andrade M, Santos JF, Reis AC, Pinheiro Júnior JW, Valença SRFA, et al. Neospora caninum infection in cattle in the state of Amazonas, Brazil: seroprevalence, spatial distribution and risk factors. Rev Bras Parasitol Vet 2021; 30(1): e020820. http://doi.org/10.1590/s1984-296120201083 PMid:33533797.
  » http://doi.org/10.1590/s1984-296120201083
• Barros LD, Bogado ALG, Furlan D, Jardim AM, Okano W, Silva LC, et al. Effects of Neospora caninum on reproductive parameters in dairy cows from a closed herd in Brazil. Vet Parasitol Reg Stud Rep 2021; 23: 100524. http://doi.org/10.1016/j.vprsr.2020.100524 PMid:33678379.
  » http://doi.org/10.1016/j.vprsr.2020.100524
• Bartels CJM, Wouda W, Schukken YH. Risk factors for Neospora caninum-associated abortion storms in dairy herds in The Netherlands (1995 to 1997). Theriogenology 1999; 52(2): 247-257. http://doi.org/10.1016/S0093-691X(99)00126-0 PMid:10734392.
  » http://doi.org/10.1016/S0093-691X(99)00126-0
• Bastos SB, Martins AT, Sammi AS, Martins FDC, Cunha IAL, de Barros LD, et al. Neospora caninum: seroepidemiology of cows and dogs from milk farms of Cunha, São Paulo, Brazil. Semina: Ciênc Agrár 2019;40(6 Suppl 2): 3123-3132. http://doi.org/10.5433/1679-0359.2019v40n6Supl2p3123
  » http://doi.org/10.5433/1679-0359.2019v40n6Supl2p3123
• Benetti AH, Schein FB, dos Santos TR, Toniollo GH, Costa AJ, Mineo JR, et al. Pesquisa de anticorpos anti-Neospora caninum em bovinos leiteiros, cães e trabalhadores rurais da região Sudoeste do Estado de Mato Grosso. Rev Bras Parasitol Vet 2009;18(Suppl 1): 29-33. http://doi.org/10.4322/rbpv.018e1005 PMid:20040187.
  » http://doi.org/10.4322/rbpv.018e1005
• Boas RV, Pacheco TA, Melo ALT, Oliveira ACS, Aguiar DM, Pacheco RC. Infection by Neospora caninum in dairy cattle belonging to family farmers in the northern region of Brazil. Rev Bras Parasitol Vet 2015; 24(2): 204-208. http://doi.org/10.1590/S1984-29612015035 PMid:26154960.
  » http://doi.org/10.1590/S1984-29612015035
• Bruhn FRP, Daher DO, Lopes E, Barbieri JM, Rocha CMBM, Guimarães AM. Factors associated with seroprevalence of Neospora caninum in dairy cattle in Southeastern Brazil. Trop Anim Health Prod 2013; 45(5): 1093-1098. http://doi.org/10.1007/s11250-012-0330-y PMid:23212838.
  » http://doi.org/10.1007/s11250-012-0330-y
• Camargo ME. Introdução as técnicas de imunofluorescência. Rev Bras Patol Clin 1974; 10(1): 143-171.
• Camillo G, Cadore G, Cezar AS, Toscan G, Bräunig P, Sangioni LA, et al. Anticorpos anti-Neospora caninum em bovinos de leite do sudoeste do estado do Paraná. Arq Bras Med Vet Zootec 2010; 62(6): 1511-1513. http://doi.org/10.1590/S0102-09352010000600033
  » http://doi.org/10.1590/S0102-09352010000600033
• Cerqueira-Cézar CK, Calero-Bernal R, Dubey JP, Gennari SM. All about neosporosis in Brazil. Rev Bras Parasitol Vet 2017; 26(3): 253-279. http://doi.org/10.1590/s1984-29612017045 PMid:28876360.
  » http://doi.org/10.1590/s1984-29612017045
• Chiebao DP, Valadas SYOB, Minervino AHH, Castro V, Romaldini AHCN, Calhau AS, et al. Variables associated with infections of cattle by Brucella abortus, Leptospira spp. and Neospora spp. in Amazon Region in Brazil. Transbound Emerg Dis 2015; 62(5): e30-e36. http://doi.org/10.1111/tbed.12201 PMid:26302373.
  » http://doi.org/10.1111/tbed.12201
• Chongsuvivatwong V. Epidemiological Data Display Package. R package version 3.5.0.2 [online]. 2018 [cited 2023 Sep 10]. Available from: https://cran.r-project.org/web/packages/epiDisplay/index.html
  » https://cran.r-project.org/web/packages/epiDisplay/index.html
• Conrad PA, Sverlow K, Anderson M, Rowe J, BonDurant R, Tuter G, et al. Detection of serum antibody responses in cattle with natural or experimental Neospora infections. J Vet Diagn Invest 1993; 5(4): 572-578. http://doi.org/10.1177/104063879300500412 PMid:8286457.
  » http://doi.org/10.1177/104063879300500412
• Corbellini LG, Driemeier D, Cruz CFE, Gondim LFP, Wald V. Neosporosis as a cause of abortion in dairy cattle in Rio Grande do Sul, Southern Brazil. Vet Parasitol 2002; 103(3): 195-202. http://doi.org/10.1016/S0304-4017(01)00600-8 PMid:11750112.
  » http://doi.org/10.1016/S0304-4017(01)00600-8
• Costa AJ, Costa EP. Freqüência de bovinos reagentes à imunofluorecência indireta para Toxoplasma gondii em Poços de Caldas, MG, Brasil. Arq Esc Vet UFMG 1978; 30(1): 47-51.
• Curci VCM, Morelli F, dos Santos LHR, de Moraes BA, Nogueira AHC, Okuda LH, et al. Soroprevalência da neosporose em bovinos de leite criados em sistema de agricultura familiar. Rev Acad (Pontif Univ Catól Paraná) 2017; 15(Suppl 2): S37-S38. http://doi.org/10.7213/academica.15.S02.2017.18
  » http://doi.org/10.7213/academica.15.S02.2017.18
• Daguer H, Hamann W, Vicente RT, Amendoeira MRR. Soropositividade para anticorpos anti-Toxoplasma gondii em bovinos da região Sudoeste do Paraná, Brasil. 2003. http://doi.org/10.1590/S0103-84782004000400026
  » http://doi.org/10.1590/S0103-84782004000400026
• Dean DJ, Abelseth MK, Atanasiu P. The fluorescent antibody test. In: Meslin FX, Kaplan MM, Koprowski H. Laboratory techniques in rabies 4th ed. Genebra: World Health Organization; 1996. p. 88-95.
• Dubey JP, Hemphill A, Calero-Bernal R, Schares G. Neosporosis in animals. Boca Raton: CRC Press; 2017. http://doi.org/10.1201/9781315152561
  » http://doi.org/10.1201/9781315152561
• Dubey JP. A review of toxoplasmosis in cattle. Vet Parasitol 1986; 22(3-4): 177-202. http://doi.org/10.1016/0304-4017(86)90106-8 PMid:3551316.
  » http://doi.org/10.1016/0304-4017(86)90106-8
• Dubey JP. Recent advances in Neospora and neosporosis. Vet Parasitol 1999; 84(3-4): 349-367. http://doi.org/10.1016/S0304-4017(99)00044-8 PMid:10456423.
  » http://doi.org/10.1016/S0304-4017(99)00044-8
• Dyer RM, Jenkins MC, Kwok OCH, Douglas LW, Dubey JP. Serologic survey of Neospora caninum infection in a closed dairy cattle herd in Maryland: risk of serologic reactivity by production groups. Vet Parasitol 2000; 90(3): 171-181. http://doi.org/10.1016/S0304-4017(00)00253-3 PMid:10841997.
  » http://doi.org/10.1016/S0304-4017(00)00253-3
• Eiras C, Arnaiz I, Álvarez-García G, Ortega-Mora LM, Sanjuánl ML, Yus E, et al. Neospora caninum seroprevalence in dairy and beef cattle from the northwest region of Spain, Galicia. Prev Vet Med 2011; 98(2-3): 128-132. http://doi.org/10.1016/j.prevetmed.2010.10.014 PMid:21145605.
  » http://doi.org/10.1016/j.prevetmed.2010.10.014
• Embrapa Gado de Leite. Centro de Inteligência do Leite - CILeite. Produção de leite no Brasil [online]. 2022 [cited 2022 Jan 8]. Available form: https://www.cileite.com.br/leite_numeros_producao
  » https://www.cileite.com.br/leite_numeros_producao
• Fávero JF, Silva AS, Campigotto G, Machado G, de Barros LD, Garcia JL, et al. Risk factors for Neospora caninum infection in dairy cattle and their possible cause-effect relation for disease. Microb Pathog 2017; 110: 202-207. http://doi.org/10.1016/j.micpath.2017.06.042 PMid:28666842.
  » http://doi.org/10.1016/j.micpath.2017.06.042
• Garcia JL, Navarro IT, Ogawa L, Oliveira RC. Soroprevalência do Toxoplasma gondii, em suínos, bovinos, ovinos e eqüinos, e sua correlação com humanos, felinos e caninos, oriundos de propriedades rurais do norte do Paraná- Brasil. Cienc Rural 1999; 29(1): 91-97. http://doi.org/10.1590/S0103-84781999000100017
  » http://doi.org/10.1590/S0103-84781999000100017
• Gindri PC, Mion B, Pradieé G, Bialves TS, Souza GN, Dellagostin AO, et al. Seroprevalence estimate and associated risk factors for neosporosis in dairy cattle in the Northwest region of Rio Grande do Sul State, Brazil. Cienc Rural 2018; 48(7): e20170921. http://doi.org/10.1590/0103-8478cr20170921
  » http://doi.org/10.1590/0103-8478cr20170921
• Gomes DFC, Krawczak FS, de Oliveira CHS, Ferreira Júnior Á, Fernandes ÉKK, Lopes WDZ, et al. Toxoplasma gondii in cattle in Brazil: a review. Rev Bras Parasitol Vet 2020; 29(1): e015719. http://doi.org/10.1590/s1984-29612019106 PMid:32049142.
  » http://doi.org/10.1590/s1984-29612019106
• González-Warleta M, Castro-Hermida JA, Carro-Corral C, Cortizo-Mella J, Mezo M. Epidemiology of neosporosis in dairy cattle in Galicia (NW Spain). Parasitol Res 2008; 102(2): 243-249. http://doi.org/10.1007/s00436-007-0753-y PMid:17899194.
  » http://doi.org/10.1007/s00436-007-0753-y
• Guimarães JS Jr, Souza SLP, Bergamaschi DP, Gennari SM. Prevalence of Neospora caninum antibodies and factors associated with their presence in dairy cattle of the north of Paraná state. Brazil. Vet Parasitol 2004; 124(1-2): 1-8. http://doi.org/10.1016/j.vetpar.2004.07.002 PMid:15350656.
  » http://doi.org/10.1016/j.vetpar.2004.07.002
• Hein HE, Machado G, Miranda ICS, Costa EF, Pellegrini DCP, Driemeier D, et al. Neosporose bovina: avaliação da transmissão vertical e fração atribuível de aborto em uma população de bovinos no Estado do Rio Grande do Sul. Pesq Vet Bras 2012; 32(5): 396-400. http://doi.org/10.1590/S0100-736X2012000500006
  » http://doi.org/10.1590/S0100-736X2012000500006
• Innes EA, Wright S, Bartley P, Maley S, Macaldowie C, Esteban-Redondo I, et al. The host-parasite relationship in bovine neosporosis. Vet Immunol Immunopathol 2005; 108(1-2): 29-36. http://doi.org/10.1016/j.vetimm.2005.07.004 PMid:16098610.
  » http://doi.org/10.1016/j.vetimm.2005.07.004
• Instituto Brasileiro de Geografia e Estatística - IBGE. Censo 2010 [online]. 2010 [cited 2022 Jan 8]. Available from: https://censo2010.ibge.gov.br
  » https://censo2010.ibge.gov.br
• Katto S, Cunha LFC Fo, Bogado ALG, Martins TA, Sammi AS, Santos JR, et al. Anti-Neospora caninum antibodies among dairy cattle in a rural settlement, Paraná, Brazil. Semina: Ciênc Agrár 2017; 38(1): 259-266. http://doi.org/10.5433/1679-0359.2017v38n1p259
  » http://doi.org/10.5433/1679-0359.2017v38n1p259
• Klauck V, Machado G, Pazinato R, Radavelli WM, Santos DS, Berwaguer JC, et al. Relation between Neospora caninum and abortion in dairy cows: risk factors and pathogenesis of disease. Microb Pathog 2016; 92: 46-49. http://doi.org/10.1016/j.micpath.2015.12.015 PMid:26747583.
  » http://doi.org/10.1016/j.micpath.2015.12.015
• Marana ERM, Venturini ACH, Freire RL, Vidotto O, Navarro IT. Ocorrência de anticorpos anti-Toxoplasma gondii em rebanhos de bovinos de leite do norte do Paraná- Brasil. Semina: Ciênc Agrár 1995; 16(1): 40-42. http://doi.org/10.5433/1679-0359.1995v16n1p40
  » http://doi.org/10.5433/1679-0359.1995v16n1p40
• Moore DP, Campero CM, Odeón AC, Posso MA, Cano D, Leunda MR, et al. Seroepidemiology of beef and dairy herds and fetal study of Neospora caninum in Argentina. Vet Parasitol 2002; 107(4): 303-316. http://doi.org/10.1016/S0304-4017(02)00129-2 PMid:12163242.
  » http://doi.org/10.1016/S0304-4017(02)00129-2
• Moore DP, Pérez A, Agliano S, Brace M, Cantón G, Cano D, et al. Risk factors associated with Neospora caninum infections in cattle in Argentina. Vet Parasitol 2009; 161(1-2): 122-125. http://doi.org/10.1016/j.vetpar.2009.01.003 PMid:19216028.
  » http://doi.org/10.1016/j.vetpar.2009.01.003
• Nishikawa Y, Inoue N, Xuan X, Nagasawa H, Igarashi I, Fujisaki K, et al. Protective efficacy of vaccination by recombinant vaccinia virus against Neospora caninum infection. Vaccine 2001; 19(11-12): 1381-1390. http://doi.org/10.1016/S0264-410X(00)00389-3 PMid:11163660.
  » http://doi.org/10.1016/S0264-410X(00)00389-3
• Ogawa L, Freire RL, Vidotto O, Gondim LFP, Navarro IT. Occurrence of antibodies to Neospora caninum and Toxoplasma gondii in dairy cattle from the northern region of the Paraná State, Brazil. Arq Bras Med Vet Zootec 2005; 57(3): 312-316. http://doi.org/10.1590/S0102-09352005000300006
  » http://doi.org/10.1590/S0102-09352005000300006
• Oshiro LM, Matos MFC, Oliveira JM, Monteiro LARC, Andreotti R. Prevalence of anti-Neospora caninum antibodies in cattle from the state of Mato Grosso do Sul, Brazil. Rev Bras Parasitol Vet 2007; 16(3): 133-138. http://doi.org/10.1590/S1984-29612007000300004 PMid:18078599.
  » http://doi.org/10.1590/S1984-29612007000300004
• Pessoa GA, Martini AP, Trentin JM, Dalcin VC, Leonardi CEP, Vogel FSF, et al. Impact of spontaneous Neospora caninum infection on pregnancy loss and subsequent pregnancy in grazing lactating dairy cows. Theriogenology 2016; 85(3): 519-527. http://doi.org/10.1016/j.theriogenology.2015.09.034 PMid:26542136.
  » http://doi.org/10.1016/j.theriogenology.2015.09.034
• Puray NC, Chávez AV, Casas EA, Falcón PN, Casas GV. Prevalencia de Neospora caninum en bovinos de una empresa ganadera de la sierra central del Perú. Rev Investig Vet Peru 2006; 17(2): 189-194.
• Qian W, Wang T, Yan W, Zhang M, Han L, Xue R, et al. Seroprevalence and first multilocus microsatellite genotyping of Neospora caninum in dairy cattle in Henan, central China. Vet Parasitol 2017; 244: 81-84. http://doi.org/10.1016/j.vetpar.2017.07.022 PMid:28917323.
  » http://doi.org/10.1016/j.vetpar.2017.07.022
• R Core Team. R: a language and environment for statistical computing [online]. Vienna: R Foundation for Statistical Computing; 2019 [cited 2024 Jan 26]. Available from: https://www.r-project.org
  » https://www.r-project.org
• Reichel MP, Ayanegui-Alcérreca MA, Gondim LFP, Ellis JT. What is the global economic impact of Neospora caninum in cattle - the billion dollar question. Int J Parasitol 2013; 43(2): 133-142. http://doi.org/10.1016/j.ijpara.2012.10.022 PMid:23246675.
  » http://doi.org/10.1016/j.ijpara.2012.10.022
• Sanderson MW, Gay JM, Baszler TV. Neospora caninum seroprevalence and associated risk factors in beef cattle in the Northwestern United States. Vet Parasitol 2000; 90(1-2): 15-24. http://doi.org/10.1016/S0304-4017(00)00234-X PMid:10828508.
  » http://doi.org/10.1016/S0304-4017(00)00234-X
• Santos JR, Grando L, Nino BSL, Langoni H, Cunha IAL, de Barros LD, et al. Neospora caninum and Toxoplasma gondii: seroprevalence and associated factors in cows from milk farms of Toledo, Parana, Brazil. Semina: Ciênc Agrár 2020; 41(5): 1581-1590. http://doi.org/10.5433/1679-0359.2020v41n5p1581
  » http://doi.org/10.5433/1679-0359.2020v41n5p1581
• Serrano-Martínez E, Ferre I, Martínez A, Osoro K, Mateos-Sanz A, del-Pozo I, et al. Experimental neosporosis in bulls: parasite detection in semen and blood and specific antibody and interferon-gamma responses. Theriogenology 2007; 67(6): 1175-1184. http://doi.org/10.1016/j.theriogenology.2007.01.010 PMid:17316779.
  » http://doi.org/10.1016/j.theriogenology.2007.01.010
• Silva CL, Freitas JA, Garcia JL, Araújo CV, Zulpo DL, Cunha IAL. Serological survey of Neospora caninum in dairy herds from Parauapebas, State of Pará. Semina: Ciênc Agrár 2015; 36(1): 231-238. http://doi.org/10.5433/1679-0359.2015v36n1p231
  » http://doi.org/10.5433/1679-0359.2015v36n1p231
• Snak A, Garcia FG, Lara AA, Pena HFJ, Osaki SC. Neospora caninum in properties in the west region of Paraná, Brazil: prevalence and risk factors. Rev Bras Parasitol Vet 2018; 27(1): 51-59. http://doi.org/10.1590/s1984-29612018001 PMid:29641794.
  » http://doi.org/10.1590/s1984-29612018001
• Souza GG, Amatti LZ, Garcia LV, Costa LR, Minutti AF, Martins TA, et al. Neospora caninum infection and reproductive problems in dairy cows from Brazil: A case-control study. Vet Parasitol Reg Stud Rep 2022; 28: 100683. http://doi.org/10.1016/j.vprsr.2021.100683 PMid:35115122.
  » http://doi.org/10.1016/j.vprsr.2021.100683
• Stenlund S, Kindahl H, Magnusson U, Uggla A, Björkman C. Serum antibody profile and reproductive performance during two consecutive pregnancies of cows naturally infected with Neospora caninum. Vet Parasitol 1999; 85(4): 227-234. http://doi.org/10.1016/S0304-4017(99)00120-X PMid:10488725.
  » http://doi.org/10.1016/S0304-4017(99)00120-X
• Tokarnia CH, Döbereiner J, Peixoto PV. Deficiências minerais em animais de fazenda, principalmente bovinos em regime de campo. Pesq Vet Bras 2000; 20(3): 127-138. http://doi.org/10.1590/S0100-736X2000000300007
  » http://doi.org/10.1590/S0100-736X2000000300007

Publication Dates

• Publication in this collection
  08 July 2024
• Date of issue
  2024

History

• Received
  17 Mar 2024
• Accepted
  16 Apr 2024