Antônio Marcos Guimarães

Universidade Federal de Lavras (UFLA), Lavras, Estado de Minas Gerais, Brazil

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Publications (12)7.27 Total impact

  • Article: Factors associated with seroprevalence of Neospora caninum in dairy cattle in southeastern Brazil.
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    ABSTRACT: Neosporosis is an infectious disease caused by Neospora caninum, an obligate intracellular cyst-forming protozoan considered a major cause of miscarriage in dairy cattle in many parts of the world. This cross-sectional study evaluated the relationship between reproductive abnormalities and seropositivity to N. caninum in 1,204 dairy cows from 40 farms located in the state of Minas Gerais, southeastern Brazil. Producers were interviewed, and blood samples were collected to perform indirect immunofluorescence tests (IFAT 1:200). Association between reproductive abnormalities and seropositivity in cattle was evaluated with generalized estimating equations. The true herd-level seroprevalence of N. caninum was 95 % (83.3-99.1), while the individual-level true seroprevalence was 21.6 % (19.2-24.2). Several reproductive abnormalities were significantly associated with seropositivity to N. caninum: occurrence of repeated estrus (p = 0.02; OR = 3.84; 95 % CI = 1.239-11.893), repeated miscarriages (p = 0.001; OR = 2.54; 95 % CI = 1.423-5.402), and temporary anestrus (p = 0.001; OR = 3.44; 95 % CI = 1.976-5.994). Furthermore, loose dogs (p = 0.041; OR = 2.20; 95 % CI = 1.033-4.672) when fed raw meat (p = 0.001; OR = 1.91; 95 % CI = 1.443-2.519) are risk factors for N. caninum infection. We observed that seropositivity to N. caninum in cattle increases risk of miscarriage by almost twice throughout the reproductive life of cows (p = 0.004; OR = 1.978; 95 % CI = 1.249-3.131). Serologic evidence in this study indicates that N. caninum infection is widely distributed among dairy herds and significantly associated with reproductive disorders, especially miscarriage, repeated estrus, and temporary anestrus.
    Tropical Animal Health and Production 12/2012; · 1.12 Impact Factor
  • Article: Quantification of vertical transmission of Neospora caninum in dairy cows in Minas Gerais, Brazil.
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    ABSTRACT: The objective of this cross-sectional study was to estimate the rate of vertical transmission and to investigate horizontal transmission of Neospora caninum and occurrences of reproductive abnormalities in seropositive dairy cows on two farms in the state of Minas Gerais, Brazil. The frequency of cows seropositive for N.caninum according to the indirect fluorescent antibody test (IFAT) was 39.4% (93/236) for Farm A and 31.4% (32/102) for the Farm B (p > 0.05). The mean vertical transmission rates for N. caninum were 29% and 9% for the herds of Farms A and B, respectively. No negative effects (p > 0.05) from infection by N.caninum were observed regarding milk production and occurrences of reproductive abnormalities in herds A and B.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 09/2012; 21(3):294-7. · 0.46 Impact Factor
  • Article: Principal component analysis on the perceptions of milk producers about Rhipicephalus (Boophilus) microplus control in Minas Gerais.
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    ABSTRACT: Milk producers in Lavras, Passos and Divinópolis, Minas Gerais, were interviewed with the aim of evaluating their perceptions and attitudes regarding control over Rhipicephalus (Boophilus) microplus. Multivariate correlation between the variables was done by means of principal component analysis. The producers' perceptions and attitudes regarding R. (B.) microplus were similar: most of them did not have any basic knowledge of tick biology or control, and they applied acaricide products through backpack spraying, without any defined technical criteria. Some of the results obtained were: I. a negative correlation between schooling level and the frequency of spraying cattle with acaricides; II. a positive correlation between milk production, quality of equipment for acaricide application and technological level of the farm; III. farm properties with greater production and technification tended to keep the intervals between acaricide applications constant over the course of the year. After applying principal component analysis, a positive correlation was observed between schooling level, technological level of the farm and perceptions regarding R. (B.) microplus, but without any correlation with attitudes towards controlling this tick. It was concluded that higher technological level and schooling level improved the producers' perceptions relating to the biology of the tick R. (B.) microplus, but did not achieve effectiveness with regard to using controls more rationally.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 09/2012; 21(3):224-31. · 0.46 Impact Factor
  • Article: Occurrences of Eimeria spp. and gastrointestinal nematodes in dairy calves in southern Minas Gerais, Brazil.
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    ABSTRACT: The aim of this cross-sectional observational study was to determine the frequency and factors associated with infection by Eimeria spp. and gastrointestinal nematodes in 356 calves on 20 dairy farms located in southern Minas Gerais, Brazil. Ten species of Eimeria spp. were identified, of which E. bovis (37.6%) and E. zuernii (17.9%) were the most frequent. From fecal cultures, four genera of gastrointestinal nematodes were recovered, of which Cooperia spp. (74.6%) and Haemonchus (19.4%) were the most frequent. Variables relating to higher levels of technology used on dairy farms showed a significant association (p < 0.05) with higher OPG and EPG counts, and are discussed in this study.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 06/2012; 21(2):171-5. · 0.46 Impact Factor
  • Article: Occurrence of anti-Neospora caninum antibodies in dogs in rural areas in Minas Gerais, Brazil.
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    ABSTRACT: The aim of this study was to determine the frequency of anti-Neospora caninum antibodies and risk factors associated with seropositivity in 240 dogs from rural areas of the Lavras, Belo Horizonte and Nanuque regions, state of Minas Gerais, Brazil. The indirect fluorescence antibody test (IFAT) with a cutoff of 50 was used to assess the frequency of seropositive dogs. The risk factor analysis was performed using the Chi-square test (χ2) and multiple logistic regression. The frequency of seropositivity for N. caninum was 15% of the dogs (36/240). Presence of dogs without defined breed (p = 0.018; OR = 5.9) and presence of cattle on the farm (p = 0.053, OR = 4.3) were associated with N. caninum seropositivity. Dogs in the Nanuque region had higher seropositivity for N. caninum (29.9%) than did those in the Lavras (6.2%) and Belo Horizonte (2.2%) regions (p < 0.05). The presence of seropositive dogs in rural areas of Minas Gerais demonstrates the potential risk of horizontal transmission of N. caninum to cattle, especially from dogs without defined breed, which were four times more likely to be seropositive than purebred dogs were.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 06/2012; 21(2):161-4. · 0.46 Impact Factor
  • Article: Neospora caninum in bovine fetuses of Minas Gerais, Brazil: genetic characteristics of rDNA.
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    ABSTRACT: Neosporosis is an important cause of abortion in cattle and information on their genetics and host parasite relationships are desirable. Neospora caninum samples obtained from 24 bovine fetuses from Minas Gerais, were genetically analyzed in part of the rDNA region, coding for rRNAs. Previously, brain, heart, liver, skeletal muscle, lung, kidney, spleen, thymus, lymph nodes, ovary or testis, uterus and skin of the ear were analyzed by conventional histopathology and immunohistochemistry. Of these, eight had lesions compatible in the brain and heart and two also in skeletal muscle and liver. Three brains showed antigen identification in immunohistochemistry. Brain and heart tissues were subjected to DNA extraction for PCR, whose product of 588 bp of ITS-1 region was sequenced in three samples. We obtained 96% similarity with dozens of sequences N. caninum deposited in GenBank. The phylogenetic tree showed great conservation among isolates of N. caninum in this study and those deposited in GenBank, while well-defined and specific branches were generated against other Apicomplexa. PCR for this region is useful as a diagnosis, with good analytical specificity, but the ITS-1 region is not suitable for genetic differentiation intra species because the sequences obtained were identical to the others analyzed.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 10/2011; 20(4):281-8. · 0.46 Impact Factor
  • Article: Perceptions about the biology of Rhipicephalus (Boophilus) microplus among milk producers in Divinópolis, Minas Gerais.
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    ABSTRACT: One hundred semi-systematized interviews were applied with the aim of surveying the perceptions of milk producers in the municipality of Divinópolis, Minas Gerais regarding the biology of the tick Rhipicephalus (Boophilus) microplus. Content analysis was conducted on each of the variables surveyed and their descriptions, highlighting the higher frequencies in order to construct profiles of perceptions about each of the matters surveyed. In addition, each of the producers was categorized regarding their readiness to proceed with efficient control, from the assessment of their responses. Among the variables surveyed were the tick lifespan, duration of parasitic life, time of greatest incidence, survival in pastures and egg-laying volume. These questions are considered important for defining the knowledge needed for rational combat. It was concluded that the information needed for adopting effective practices to combat ticks was insufficient among the milk farm properties in Divinópolis. Moreover, the producers interviewed had a good perception of what they observed in their daily routine, but did not have complementary information about the tick life cycle.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 10/2011; 20(4):289-94. · 0.46 Impact Factor
  • Article: Perceptions of milk producers from Divinópolis, Minas Gerais, regarding Rhipicephalus (Boophilus) microplus control.
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    ABSTRACT: Semi-systematized interviews were conducted with 100 dairy cattle producers in the municipality of Divinópolis, Minas Gerais, with the aim of ascertaining their perceptions regarding the importance of Rhipicephalus (Boophilus) microplus and of combating it. Content analysis was performed and the frequency distribution of each of the variables was used to construct profiles of the producers interviewed. The production losses caused by ticks were perceived incompletely by the producers, who were unaware of the pathogen transmission caused by the parasite and the indirect losses through combating it, such as the cost of acaricide and labor. The combat operations were performed in a traditional manner, with an excessive number of inefficient treatments that aimed to control the level of infestation at that moment. The quality of the acaricide dipping/spraying applied was affected by the quality of the equipment used to apply the products, lack of knowledge of the mode of action of these products, lack of the specific information needed and lack of motivation caused by unawareness of the disadvantages of chemical combat. It was concluded that the lack of knowledge about combat methods and the acceptance of endemicity of the parasitosis were impediments to changing the realities encountered.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 10/2011; 20(4):295-302. · 0.46 Impact Factor
  • Article: Frequency of species of Eimeria in females of the Holstein-Friesian breed at the post-weaning stage during autumn and winter.
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    ABSTRACT: The frequency of species of the genus Eimeria in a dairy herd in the municipality of Boa Esperança, Southern region of the State of Minas Gerais was assessed. From 37 females of the Friesian breed aged three to seven months, 259 feces samples were analyzed between May and September 2008. The examinations to quantify oocysts per gram of feces (OPG) and identify Eimeria species were conducted at the Veterinary Parasitology Laboratory of the Federal University of Lavras. Eleven species of Eimeria were identified, namely: E. bovis (23.2%), E. zuernii (22.6%), E. ellipsoidalis (20.3%), E. cylindrica (14.1%), E. subspherica (5.4%), E. canadensis (3.5%), E. alabamensis (2.4%), E. auburnensis (2.4%), E. pellita (2.1%), E. brasiliensis (2%) and E. bukidnonensis (1.9%). E. bovis, E. zuernii and E. ellipsoidalis were the most frequent and the ones with the highest oocyst shedding over time (p < 0.05). Differences in OPG counts were found between most months studied (p < 0.05). The large number of Eimeria species found, in particular E. bovis and E. zuernii, indicates that Eimeria sp. has significant pathogenic potential in dairy cattle in the South of Minas Gerais.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 10/2011; 20(4):303-7. · 0.46 Impact Factor
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    Article: [Factors associated the seropositivity for Babesia, Toxoplasma, Neospora e Leishmania in dogs attended at nine veterinary clinics in the municipality of Lavras, MG].
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    ABSTRACT: The aim of the present study was to determine the frequency and evaluate the infuence of age, sex and breed in seropositivity anti-Babesia canis, Toxoplasma gondii, Leishmania (L.) chagasi and Neospora caninum, by means of the indirect immunofuorescence antibody test (IFAT), in serum samples collected from dogs attended in nine private veterinary clinics in municipality of Lavras, Minas Gerais, Brazil, from August 2000 to April 2002. Of 300 dogs, 73.3% were seropositive (IFAT>or=1:80) to B. canis, and there was a signifcant increase (p<0.05) of the reagent in adult animals when compared with young. Only one dog (0.3%) from Belo Horizonte there was antibodies anti-L. (L.) chagasi (IFAT>or=1:40). T. gondii, of 218 dogs, 60.7% were positive (IFAT>or=1:16). In 228 serum samples, 3.1% were positive (IFAT>or=1:50) to N. caninum. Infections to B. canis and T. gondii occur as endemic form in dogs examined at private veterinary clinics in Lavras. Tere is no evidence that there are autochthonous cases of canine visceral leishmaniosis in Lavras. Besides this the infection by N. caninum is uncommon in dogs breed at the urbane zone of the municipality.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 12/2009; 18 Suppl 1:49-53. · 0.46 Impact Factor
  • Article: [Toxocara sp. eggs and Ancylostoma sp. larva in public parks, Brazil].
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    ABSTRACT: Visceral and cutaneous larva migrans are parasitic zoonoses caused by the infection of larval nematodes Toxocara sp. and Ancylostoma sp. respectively. The objective of this study was to investigate the contamination by Toxocara sp. eggs and Ancylostoma sp. eggs and larva of soil samples collected from public parks and children's playground areas in state of Minas Gerais, Brazil, using both Baermann's method and centrifugal flotation technique. Toxocara sp. and Ancylostoma sp. eggs were observed in soil samples collected from public squares in 17.4% (4/23) and 69.6 (16/23) respectively. In schools and child day care settings the contamination by Ancylostoma sp. larva in sand samples was 11.1% (2/18). Public parks are settings of more potential risk of Toxocara sp. eggs and Ancylostoma sp. infection. Stool parasitology testing of 174 stool samples showed 58% and 23% of Ancylostoma sp and Toxocara sp eggs infection respectively.
    Revista de Saúde Pública 05/2005; 39(2):293-5. · 1.33 Impact Factor
  • Article: [Frequency of intestinal parasites in samples of lettuce (Lactuca sativa) commercialized in Lavras, Minas Gerais State].
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    ABSTRACT: The aim of this study was to evaluate the parasitological contamination in samples of lettuce (Lactuca sativa) commercialized in Lavras city, Minas Gerais. The samples of lettuce showed low hygienic conditions, indicated by the presence of parasites of animal or human origin and high concentration of fecal coliforms.
    Revista da Sociedade Brasileira de Medicina Tropical 36(5):621-3. · 0.68 Impact Factor