Ricardo Augusto Dias

Prevalence of anti-Toxoplasma gondii and anti-Neospora caninum antibodies in sheep from Mossoró, Rio Grande do Norte, Brazil

Toxoplasma gondii is an obligate intracellular parasite with a variety of hosts, responsible for reproductive problems and economic losses in sheep flocks. Neospora caninum was recently identified and its clinical presentation in sheep is similar to that of toxoplasmosis, which can cause repeated abortions, though less frequently in this species. In order to confirm the prevalence of these agents in the city of Mossoró, Rio Grande do Norte, Brazil, 409 serum samples from adult sheep (364 females and 45 males) were tested by the indirect immunofluorescence antibody test, using cut-off point at a dilution of 1:64 and 1:50 for T. gondii and N. caninum, respectively. From the 35 properties examined, 23 (65.7%) had at least one seropositive animal for T. gondii and six (17.1%) for N. caninum. The prevalence of seropositive animals for T. gondii was 20.7% and for N. caninum 1.8%. There was no association between the presence of the agents antibody and gender, reports of reproductive problems and presence of dogs and/or cats in the properties. T. gondii is well distributed and N. caninum has low prevalence in sheep and in the properties of the studied region.

Study of the Seasonal Dynamics, Life Cycle, and Host Specificity of Amblyomma aureolatum (Acari: Ixodidae)

Abstract In the first part of this study, monthly infestation by ticks was evaluated on dogs from December 2000 to November 2002 in the rural area of Taiaçupeba, São Paulo. Adults of Amblyomma aureolatum (Pallas) were found on dogs in all months, with a mean prevalence per month of 46.9 ± 15.7% (range, 25–80%). The mean tick relative abundance per month was 2.4 ± 2.7 ticks (range, 0.5–14 ticks), and the mean tick mean intensity per month was 4.7 ± 4.2 ticks (range, 1.5–23.3 ticks). No A. aureolatum immature ticks were found on dogs. In the second part of this study, we studied the life cycle of A. aureolatum in the laboratory. We tested the suitability of six host species for the immature stages and dogs for the adult stage. Tick developmental periods were observed at different temperatures (23, 25, or 27°C), always with RH >95%, which were satisfactory for all free-living developmental stages of the tick life cycle. Chickens and guinea pigs were the most suitable hosts for larvae and nymphs (recovery rates, 18.4–52.2%). Dogs were highly suitable for adult ticks (all females exposed to them were recovered and laid eggs) but were unsuitable for the immature ticks (recovery rates, 0–10%). Based on published host records for A. aureolatum, our results indicate that dogs and birds are primary hosts for adult and immature stages, respectively, of A. aureolatum in nature. In addition, wild guinea pigs are indicated as another potential primary host for immature ticks.

Geographical distribution of Amblyomma cajennense (sensu lato) ticks (Parasitiformes: Ixodidae) in Brazil, with description of the nymph of A. cajennense (sensu stricto)

BackgroundUntil recently, Amblyomma cajennense (Fabricius, 1787) was considered to represent a single tick species in the New World. Recent studies have split this taxon into six species. While the A. cajennense species complex or A. cajennense (sensu lato) (s.l.) is currently represented by two species in Brazil, A. cajennense (sensu stricto) (s.s.) and Amblyomma sculptum Berlese, 1888, their geographical distribution is poorly known.MethodsThe distribution of the A. cajennense (s.l.) in Brazil was determined by morphological examination of all lots of A. cajennense (s.l.) in two large tick collections of Brazil, and by collecting new material during three field expeditions in the possible transition areas between the distribution ranges of A. cajennense (s.s.) and A. sculptum. Phylogenetic analysis inferred from the ITS2 rRNA gene was used to validate morphological results. Morphological description of the nymphal stage of A. cajennense (s.s.) is provided based on laboratory-reared specimens.ResultsFrom the tick collections, a total 12,512 adult ticks were examined and identified as 312 A. cajennense (s.s.), 6,252 A. sculptum and 5,948 A. cajennense (s.l.). A total of 1,746 ticks from 77 localities were collected during field expeditions, and were identified as 249 A. cajennense (s.s.), 443 A. sculptum, and 1,054 A. cajennense (s.l.) [these A. cajennense (s.l.) ticks were considered to be males of either A. cajennense (s.s.) or A. sculptum]. At least 23 localities contained the presence of both A. cajennense (s.s.) and A. sculptum in sympatry. DNA sequences of the ITS2 gene of 50 ticks from 30 localities confirmed the results of the morphological analyses. The nymph of A. cajennense (s.s.) is morphologically very similar to A. sculptum.ConclusionOur results confirmed that A. cajennense (s.l.) is currently represented in Brazil by only two species, A. cajennense (s.s.) and A. sculptum. While these species have distinct distribution areas in the country, they are found in sympatry in some transition areas. The current distribution of A. cajennense (s.l.) has important implications to public health, since in Brazil A. sculptum is the most important vector of the bacterium Rickettsia rickettsii, the etiological agent of Brazilian spotted fever.

Epidemiologia da Leptospirose em animais silvestres na Fundação Parque Zoológico de São Paulo

A Leptospirose e uma doenca bacteriana de carater zoonotico que afeta os animais domesticos, silvestres e o homem. Levantamentos sorologicos tem demonstrado o envolvimento de diferentes especies sinantropicas e silvestres na epidemiologia da doenca. Com o objetivo de conhecer melhor a epidemiologia da Leptospirose dentro da Fundacao Parque Zoologico de Sao Paulo, foi realizado um estudo sorologico nos animais silvestres mantidos em cativeiro, no periodo de 1996 a 1999. Foram colhidas amostras de sangue de 302 animais atendidos na rotina da Divisao de Veterinaria, das quais 59 apresentaram resultado positivo (19.5%) para a prova de Soroaglutinacao Microscopica. Os sorovares mais provaveis para o conjunto total de resultados foram : copenhageni (15/59=25.4%), pomona (13/59=22%) e castellonis (10/59=16.9%). Entre os animais silvestres examinados os sorovares mais provaveis foram : Familia Callithrichidae : castellonis (3/3=100%), Familia cebidae : copenhageni : (13/21=65%), grippotyphosa (2/21=9.5%) e castellonis (1/21=44.7%). Familia felidae : pomona (12/17=70.5%), icterohaemorrhagiae (2/17=11.7%) e grippotyphosa (1/17=5.8%), Familia canidae : castellonis (2/4=50%), cynopteri (1/4=25%) e mini (1/4=25%), Familia cervidae : mini (1/1=100%), Familia bovidae : copenhageni (2/3=66.6%), pomona (1/3=33.3%), Familia dasyproctidae : castellonis (2/3=66.6%), Familia macropodidae: sentot (1/1=100%), familia giraffidae : castellonis (1/1=100%). Animais de vida livre como ratos (Rattus norvegicus) e gambas (Didelphis marsupialis) tambem foram submetidos a prova de soroaglutinacao necroscopica e cultura bacteriologica. Foram encontrados testes positivos para o sorovar icterohaemorrhagiae em 42,8% dos ratos e 40% dos gambas estudados. As frequencias de positivos quando analisadas do ponto de vista da localizacao espacial dos recintos destes animais, permitiram a verificacao da existencia de areas criticas para exposicao a leptospira dentro da Fundacao Parque Zoologico de Sao Paulo. As frequencias de positivos para as varias areas examinadas foram : Setor extra (36/113=31.8%), Alameda dos felinos (10/20=50%), Ilhas+Alameda, Lago+Alameda Girafa (3/14=21.4%), Alameda Urso+Alameda Zebra (3/21=14.2%), Gaiolao II (1/21=14.2%), Planicie Africana (2/15=13.3%) e Alameda Bisao (1/2=50%). As razoes desta constatacao foram discutidas e medidas de profilaxia e controle para a Leptospirose no ambiente da Fundacao Parque Zoologico de Sao Paulo foram sugeridas. Tambem foi discutida a importância do monitoramento sorologico em ambientes de zoologico para acoes de vigilância.

Estimativa de populações canina e felina domiciliadas em zona urbana do Estado de São Paulo

OBJECTIVE Given the importance of assessing owned dog and cat populations to adequate planning and evaluation of rabies control measures in urban areas, it is proposed the use of an estimate of these populations based on human population parameters. METHODS The ratio between human population and owned animal (dogs and cats) population was calculated in the municipality of Taboão da Serra, state of São Paulo, Brazil. This municipality was divided into two distinct social and economic homogeneous areas through k-mean algorithm, allowing for comparison between the ratios of the two homogeneous areas. RESULTS A 5.14 ratio was calculated for human and dog populations and a 30.57 ratio for human and feline populations. A significant difference was not observed when comparing the ratios for human and animal populations of the two homogeneous areas. CONCLUSIONS An estimate of owned dog and cat populations based on the human population is the better choice for assessing the animal population instead of an animal census because it can be easily implemented.

Situação epidemiológica da brucelose bovina no Estado de São Paulo

A study to characterize the epidemiological situation of bovine brucellosis in the State of Sao Paulo was carried out. The state was stratified in seven cattle production regions and 150 herds with reproductive activity were randomly selected within each one. A total of 1,073 herds were sampled. In a second stage, 10 or 15 cows older than 24 month age (in herds with <100 cows and herds ≥100 cows, respectively) were bled at random. A total of 8,761 animals were bled. Sera were tested using a serial testing procedure with the Rose Bengal test as the screening method and the Complement Fixation as the confirmatory method. The estimated prevalence of herds with at least one positive animal was 9.7% [7.8-11.6%], whereas the estimated prevalence of positive cattle was 3.8% [0.7-6.9%] in Sao Paulo State. An epidemiological questionnaire was applied in each farm, allowing the evaluation of the association of selected risk factors with the disease. The characteristics associated with the brucellosis infected herds were farms with more than 87 bovines (OR= 2.25) and introduction of breeding cattle (OR= 1.56).

Situação epidemiológica da brucelose bovina no Estado de Rondônia

Realizou-se um estudo para caracterizar a situacao epidemiologica da doenca no Estado de Rondonia. O Estado foi estratificado em tres circuitos produtores. Em cada circuito produtor foram amostradas aleatoriamente cerca de 300 propriedades e, dentro dessas, foi escolhido, de forma aleatoria, um numero pre-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total, foram amostrados 9.717 animais, provenientes de 927 propriedades. Em cada propriedade amostrada foi aplicado um questionario epidemiologico para verificar o tipo de exploracao e as praticas zootecnicas e sanitarias que poderiam estar associadas ao risco de infeccao pela doenca. O protocolo de testes utilizado foi o da triagem com o teste do antigeno acidificado tamponado e o reteste dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo, se pelo menos um animal foi reagente as duas provas sorologicas. As prevalencias de focos e de animais infectados do Estado foram de 35,2% [32,1-38,4%] e 6,2% [4,9-7,6%], respectivamente. Os resultados para os circuitos pecuarios foram: circuito 1, 41,9% [36,3-47,6%] e 8,3% [5,9-10,8%]; circuito 2, 31,7% [26,5-37,2%] e 5,9% [4,3-7,6%]; circuito 3, 31,9% [26,7-37,4%] e 4,6% [2,5-6,6%]. Os fatores de risco (odds ratio, OR) associados a condicao de foco foram: historico de aborto (OR= 1,42 [1,04-1,95]) e exploracao de corte (OR= 1,75 [1,30-2,38]).

Situação epidemiológica da brucelose bovina no Estado do Mato Grosso do Sul

Realizou-se um estudo para caracterizar a situacao epidemiologica da brucelose bovina no Estado de Mato Grosso do Sul. Foram definidos tres estratos (regioes): Pantanal-corte, Planalto-corte e Planalto-leite, este ultimo subdividido em Bolsao, Campo Grande e Dourados. Em cada estrato foram amostradas aleatoriamente propriedades e, dentro dessas, foi escolhido, de forma aleatoria, um numero pre-estabelecido de animais, dos quais foi obtida uma amostra de sangue. No total, foram amostrados 14.849 animais, provenientes de 1.004 propriedades. Em cada propriedade amostrada foi aplicado um questionario epidemiologico para verificar suas caracteristicas e tambem para detectar transtornos reprodutivos que poderiam estar associados a infeccao brucelica. O teste utilizado foi o do antigeno acidificado tamponado. O rebanho foi considerado positivo se pelo menos um animal foi reagente a prova sorologica. Para o Estado, a prevalencia de focos foi de 41,5% [36,5-44,7%]. As prevalencias de focos e de animais infectados por estrato foram, respectivamente, de: 59,0% [52,8-64,9%] e 12,6% [9,1-17,2%] para o estrato Pantanal-corte, e 40,6% [35,8-45,5%] e 4,5% [2,1-9,0%] para Planalto-corte. No estrato Planalto-leite, a prevalencia de focos foi de 33,1% [28,4-38,1%]. Os fatores de risco (odds ratios, OR) associados a condicao de foco foram: ter ≥500 vacas (OR = 2,46 [1,81-3,34]), ocorrencia de bezerros fracos (OR = 1,20 [0,87-1,65]) e uso da inseminacao artificial (OR = 0,71 [0,50-1,01]).

Situação epidemiológica da brucelose bovina no Estado de Mato Grosso

A study to characterize bovine brucellosis in the State of Mato Grosso was carried out in 2003 in order to support the implementation of the National Program for the Control and Eradication of Bovine Brucellosis. The State was divided into four productive regions, and 13,684 bovines from 1,152 herds were sampled. The serum samples were screened for antibodies to Brucella spp. by the Rose-Bengal test (RBT) and all RBT-positive sera were re-tested by the 2-mercaptoethanol test (2-ME), and again by RBT for confirmation. The prevalence of infected herds and animals in the State of Mato Grosso were 41.2% [38.0-44.4%] and 10.2% [7.4-13.1%], respectively. In the productive regions, the prevalence of infected herds were 36.9% [29.2-45.2%], 27.2% [22.8-32.1%], 40.4% [38.8-46.2%], and 50.3% [44.5-56.1%], respectively; and the prevalence of infected animals were 7.9% [3.0-12.9%], 4.1% [2.8-5.4%], 8.1% [5.2-11.1%], and 15.3% [9.2-21.3%], respectively, for regions 1, 2, 3, and 4. The risk factors (odds ratio, OR) associated with the presence of the infection in the State were: beef cattle farming (OR=1.8 [1.2-2.5]), mixed (beef and dairy) cattle farming (OR=1.8 [1.2-2.7]), farms with 11 to 50 females (OR=4.8 [1.1-20.8]), farms with more than 51 females (OR=6.8 [1.6-29.0]), and occurrence of abortion (OR=1.7 [1.3-2.2]). Given that brucellosis is homogeneously distributed in the State, uniform sanitary measures might be adopted. As a homogeneous additional measure for the State, the intensification of female vaccination is suggested.

Situação epidemiológica da brucelose bovina no Estado de Santa Catarina

A study to characterize the brucellosis epidemiological situation in the State of Santa Catarina was carried out. The State was divided into five regions. Three hundred herds were randomly sampled in each region and a pre-established number of animals were sampled in each of these herds. A total of 7,801 serum samples from 1,586 herds were collected. In each herd, it was applied an epidemiological questionnaire regarding herd features and also husbandry and sanitary practices that could be associated with risk of infection. The serum samples were screened for antibodies to Brucella spp. by the Rose-Bengal Test (RBT), and all RBT-positive sera re-tested by the 2-mercaptoethanol test (2-ME). The herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalences of infected herds and animals in Santa Catarina State were, respectively: 0.32% [0.10-0.69%] and 0.06% [0.0-0.17%]. The prevalence of infected herds in the regions were: region 1, 0.33% [0.0-0.99%]; region 2, 0.33% [0.0-1.0%]; region 3, 0.25% [0.0-0.75%]; region 4, 0.66% [0.08-1.84%]; and region 5, 0.33% [0.0-1.00%].