The aims of the present study were to compare centrality and other measures of bovine movement networks in the state of Mato Grosso, Brazil, in 2007, by examination of the positive and negative herds identified in the brucellosis survey conducted in 2003. In addition, we aimed to examine the association between herd size (measured by the number of females older than 24 months, denoted FEM24+) and animal trade between herds. We found a statistical association between brucellosis occurrence and both the total degree (number of traded animals) and out-degree (for the number of animals sold and the number of neighboring herds). This finding suggests that positive herds in the 2003 survey were trading (particularly selling) more frequently in 2007 than negative herds, thereby presumably increasing the risk of disease spread. Statistical differences observed (p-values) in the network of movements for reproduction purposes were more significant than those observed in other networks for average herd size; degrees of animals, batches, and neighbors; outdegree of neighbors; and betweenness. We found positive associations (p < 0.001) between the following variables: number of traded animals and the FEM24+ herd size; FEM24+ herd size and FEM24+ herd size of neighbors within the network of cattle movement; FEM24+ herd size of neighbors and number of traded animals; and weighted degree (animals) of neighbors and degree (animals) of the herd of origin. A comparison of positive and negative herds stratified by herd size (≤ 10 FEM24+; and > 50 FEM24+), within the network of movements for reproduction purposes, revealed significant differences (p < 0.05) in the > 50 FEM24+ category only, for average herd size, total degree (animals, batches, and neighbors), outdegree (animals, batches, and neighbors), and outcloseness. Logistic regression analysis, in which average herd size and degree (animals) were both factors, showed that a tenfold increase in herd size and the number of animals traded would lead to an increased chance of a herd being positive by 41% (OR = 1.41 [1.01; 1.99]) and 39% (OR = 1.39 [1.05; 1.85]), respectively. We concluded that the presence of bovine brucellosis is associated with a larger herd size, which is consistent with other reports. We also found an association between the increased trade of bovines and the presence of bovine brucellosis. Furthermore, an association was noted between herd size and animal trade, both of which could contribute to the spread of brucellosis. ResumoO objetivo do presente estudo foi comparar medidas de centralidade e outras medidas da rede de trânsito bovino no estado de Mato Grosso, Brasil, em 2007, pela análise de rebanhos positivos e negativos identificados no levantamento de brucelose realizado em 2003. Além disso, examinamos a associação entre tamanho de rebanho (medido pelo número de fêmeas acima de 24 meses, denotado FEM24+) e o comércio animal entre rebanhos. Foi observada uma associação estatística entre brucelose e tanto o grau total (número de animais comerci...

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DEDICATÓRIASEsta dissertação marca uma fase e uma passagem muito importante na minha vida, a qual ficará registrada para sempre. Por esse motivo gostaria de aproveitar a oportunidade de deixar registrado o meu sentimento por aquelas pessoas que fizeram de mim o que sou hoje. Dedico este momento:Aos meus pais, William e Marta, pelo esforço e dedicação para me proporcionar a melhor educação possível, pelo apoio incondicional e pelo exemplo de como se viver.Ao restante da minha família, meu irmão Bruno, meus tios e tias, meus primos e primas pela ajuda e amizade. À Dea, meu grande amor, pelo companheirismo, amizade e amor em todas as situações, alegres ou tristes, durante não só o mestrado, mas durante toda a nossa união. Juntos, construiremos ainda mais capítulos da nossa vida. Amo você! E gostaria de dedicar e agradecer também à sua família (Marcos, Lúcia e Luciana) a minha segunda casa, obrigado por tudo.MEUS ETERNOS AGRADECIMENTOS... AGRADECIMENTOSMuitas pessoas contribuíram, direta ou indiretamente, com a realização desse trabalho e desde já agradeço a todas. Em particular gostaria de agradecer: Ao Prof. Dr. Marcos Amaku, excepcional orientador, pelos ensinamentos, amizade e sua dedicação ao trabalho que inspira todos ao seu redor. Ao Prof. Dr. Ricardo Augusto Dias, pelos ensinamentos e apoio desde o tempo da iniciação científica. Aos companheiros do LEB, Fernando Marques, Zé Grisi e Raul pela ajuda na execução deste trabalho, ideias e sugestões. A todos os colegas do LEB, Guilherme Braga, Gina, Oswaldo... pelo convívio de fundamental importância durante estes anos. À FAPESP, pelo apoio financeiro e o incentivo na área de pesquisa acadêmica. A todos que de qualquer forma ajudaram e participaram na concretização deste trabalho. MEU MUITO OBRIGADO...

Recently, studies have suggested an association between the Torque teno sus virus (TTSuV) and the Porcine circovirus-2 (PCV2) in PCV2-associated disease cases. The aim of this study was to verify TTSuVs loads in pig faeces from PCV2-positive animals with and without diarrhea from PCVADaffected and PCV2-unvaccinated herds. A total of 80 faecal samples were collected individually from nursery and grow-finish pigs with (n = 40) or without (n = 40) diarrhea. The samples were tested for PCV2 and TTSuVs by using DNA binding dye SYBR Green quantitative polymerase chain reaction (qPCR). Torque teno sus virus k2 (TTSuVk2) load in the faeces was significantly higher in the nursery pigs with diarrhea, and these pigs also exhibited significantly higher PCV2 (P < 0.01) faecal matter loads compared to the non-diarrheic animals from the same age group. Torque teno sus virus 1 (TTSuV1) viral loads were the same regardless of age group and disease condition. There were no correlations between PCV2 and TTSuV1 or TTSuVk2 and TTSuV1 viral loads; however, a weak correlation (r = 0.23, P = 0.03) was found between TTSuVk2 and PCV2 viral loads. In conclusion, TTSuVk2 viral loads were significantly higher in the diarrheic faeces from the nursery pigs. Additionally, the higher loads of PCV2 and TTSuVk2 in the nursery-diarrheic animals revealed that diarrhea might have an important role in the spread of both viruses in herds.

Our friends have more friends than we do. That is the basis of the friendship paradox. In mathematical terms, the mean number of friends of friends is higher than the mean number of friends. In the present study, we analyzed the relationship between the mean degree of vertices (individuals), k , and the mean number of friends of friends, k F F , in scale-free networks with degrees ranging from a minimum degree (k min ) to a maximum degree (k max ). We deduced an expression for k F F − k for scale-free networks following a power-law distribution with a given scaling parameter (α). Based on this expression, we can quantify how the degree distribution of a scale-free network affects the mean number of friends of friends.