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Trichostrongylus tenuis is a nematode that lives in the caeca of wild red grouse. It causes disease in red grouse and can cause fluctuations in grouse pop ulations. The aim of the work described in this thesis was to study aspects of the ecology of the infective-stage larvae of T.tenuis, and also certain aspects of the pathology and immunology of red grouse and chickens infected with this nematode. The survival of the infective-stage larvae of T.tenuis was found to decrease as temperature increased, at temperatures between 0-30 C? and larvae were susceptible to freezing and desiccation. The lipid reserves of the infective-stage larvae declined as temperature increased and this decline was correlated to a decline in infectivity in the domestic chicken. The occurrence of infective-stage larvae on heather tips at caecal dropping sites was monitored on a moor; most larvae were found during the summer months but very few larvae were recovered in the winter. The number of larvae recovered from the heather showed a good correlation with the actual worm burdens recorded in young grouse when related to food intake. Examination of the heather leaflets by scanning electron microscopy showed that each leaflet consists of a leaf roll and the infective-stage larvae of T.tenuis migrate into the humid microenvironment' provided by these leaf rolls. Scanning electron microscopy showed that the adult nematodes burrowed into the mucosa as well as lying on its surface and that the caecal mucosa of heavily infected grouse became disrupted in areas of nematode activity. The caecal mucosa of lightly infected grouse exhibited little damage and the caecal mucosa of grouse treated with an anthelmintic and shot 5-6 months later was similar to that of lightly infected birds. Some of the nematodes from these treated birds were covered in rosette-shaped cells which have been tentatively identified as adherent lymphocytes. The cuticle of adult T.tenuis was superficially annulated but did not possess cuticular ridges, as described in some other trichostrongyle nematodes. Primary and challenge infections with T.tenuis were established in the domestic chicken and these reached patency but nematodes were expelled in blood-stained balls of mucus and all adult nematodes had been expelled from the birds 30 days after dosing with infective-stage. Following trickle doses of larvae, there was a rise and then a fall in nematode egg output but larvae administered later in the trickle infection appeared to fail to establish. Light and scanning electron microscopy showed haemorrhagic lesions and blood spots on the caecal mucosa of infected chickens and nematodes were found to burrow beneath mucus secreted on the mucosal surface. There were significant increases in the proportions of circulating leucocytes in infected chickens, but only on certain days of infection. No antibodies to T.tenuis were detected in the blood of infected chickens. There was a decrease in the length of the caeca of infected chickens during the period when the Ill nematodes were being expelled from the caeca. Nematode egg output continued to rise during an infection in young red grouse and there was no expulsion of nematodes from these infected birds. Infective-stage larvae that had been attenuated by cobalt 60 irradiation stimulated some degree of resistance to challenge infection in the domestic chicken but not in the red grouse. It was concluded that immunization with irradiated larvae would be of little use in the control of T.tenuis in red grouse.

Since the Morris worm was released in 1988, Internet worms continue to be one of top security threats. For example, the Conficker worm infected 9 to 15 million machines in early 2009 and shut down the service of some critical government and medical networks. Moreover, it constructed a massive peer-to-peer (P2P) botnet. Botnets are zombie networks controlled by attackers setting out coordinated attacks. In recent years, botnets have become the number one threat to the Internet. The objective of this research is to characterize spatial-temporal infection structures of Internet worms, and apply the observations to study P2P-based botnets formed by worm infection. First, we infer temporal characteristics of the Internet worm infection structure, i.e., the host infection time and the worm infection sequence, and thus pinpoint patient zero or initially infected hosts. Specifically, we apply statistical estimation techniques on Darknet observations. We show analytically and empirically that our proposed estimators can significantly improve the inference accuracy. Second, we reveal two key spatial characteristics of the Internet worm infection structure, i.e., the number of children and the generation of the underlying tree topology formed by worm infection. Specifically, we apply probabilistic modeling methods and a sequential growth model. We show analytically and empirically that the number of children has asymptotically a geometric distribution with parameter 0.5, and the generation follows closely a Poisson distribution. Finally, we evaluate bot detection strategies and effects of user defenses in P2P-based botnets formed by worm infection. Specifically, we apply the observations of the number of children and demonstrate analytically and empirically that targeted detection that focuses on the nodes with the largest number of children is an efficient way to expose bots. However, we also point out that future botnets may self-stop scanning to weaken targeted detection, without greatly slowing down the speed of worm infection. We then extend the worm spatial infection structure and show empirically that user defenses, e.g., patching or cleaning, can significantly mitigate the robustness and the effectiveness of P2P-based botnets. To counterattack, we evaluate a simple measure by future botnets that enhances topology robustness through worm re-infection.

Este projeto teve o objetivo de avaliar, sobre as variáveis que compõe o eritrograma e leucograma, os impactos da administração de anti-inflamatório e antibiótico, concomitante ao uso de antiparasitários, e a influência exercida pela suplementação de ferro dextrano, sobre a resposta medular de ovinos com anemia verminótica. Foram utilizadas 45 ovelhas, com mais de 24 meses de vida, naturalmente infectadas. Os animais foram triados por exame clínico, coproparasitológico e hemograma. Após a seleção, foram alocados em 03 subgrupos experimentais. O grupo 01recebeu apenas tratamento com antiparasitários (controle); ao grupo 02, além dos antiparasitários, foi aplicada uma associação de antibióticos e antiinflamatórios; e o grupo03, além dos antiparasitários, recebeu suplementação com Ferro Dextrano. Os resultados obtidos para VCM e HCM indicam que houve diferença estatística entre os grupos (p<0.05), sugerindo que a suplementação de ferro contribuiu para melhora da resposta medular. O predomínio da ocorrência de anemia do tipo normocítico e normocrômico indica que os animais foram capazes de manter a homeostase no metabolismo de ferro. Sobre as variáveis que representam o leucograma, foi possível observar que houve variação significativa entre os tempos analisados (p<0.05), indicativo de evolução no processo de recuperação. Evidenciou-se normoleucocitemia, com existência de linfopenia e eosinopenia, além da ocorrência de neutrofilia com desvio à esquerda. Também, foi observada a inversão do padrão leucocitário, que passou de predominantemente linfocitário para neutrofílico, enquanto os animais permaneciam sob quadro de anemia intensa. Pela contagem de plaquetas, evidenciou-se diferença estatística entre os grupos (p<0.05), principalmente, no início do processo de avaliação, período de maior infestação parasitária. / The purpose of this project was to evaluate the impact of anti-inflammatory and antibiotic administration on the erythrogram and leukogram variables, concomitant with antiparasitic use, and the influence exerted by iron dextran supplementation on the spinal response of sheep with verminous anemia. Forty-five sheep, more than 24 months old, naturally infected, were used. The animals were screened by clinical, coproparasitological and hemogram. After the selection, they were allocated in 03 experimental subgroups. Group 01 received only antiparasitic treatment (control); to group 02, besides the antiparasites, an association of antibiotics and anti-inflammatories was applied; and Group 03, in addition to the antiparasitics, received supplementation with Iron Dextran. The results obtained for VCM and HCM indicate that there was a statistical difference between the groups (p<0.05), suggesting that the iron supplementation contributed to the improvement of the spinal response. The predominance of anemia of the normocytic and normochromic type indicates that the animals were able to maintain the homeostasis in iron metabolism. Regarding the variables that represent the leukogram, it was possible to observe that there was a significant variation between the times analyzed (p<0.05), indicative of evolution in the recovery process. There was evidence of normoleukocytemia, with lymphopenia and eosinopenia, besides the occurrence of neutrophilia with deviation to the left. In addition, the inversion of the leukocyte pattern, which changed from predominantly lymphocytic to neutrophilic, was observed, while the animals remained under severe anemia. The platelets count showed a statistically significant difference between the groups (p<0.05), mainly at the beginning of the evaluation process, the period of greatest parasitic infestation.

Este projeto teve o objetivo de avaliar, sobre as variáveis que compõe o eritrograma e leucograma, os impactos da administração de anti-inflamatório e antibiótico, concomitante ao uso de antiparasitários, e a influência exercida pela suplementação de ferro dextrano, sobre a resposta medular de ovinos com anemia verminótica. Foram utilizadas 45 ovelhas, com mais de 24 meses de vida, naturalmente infectadas. Os animais foram triados por exame clínico, coproparasitológico e hemograma. Após a seleção, foram alocados em 03 subgrupos experimentais. O grupo 01recebeu apenas tratamento com antiparasitários (controle); ao grupo 02, além dos antiparasitários, foi aplicada uma associação de antibióticos e antiinflamatórios; e o grupo03, além dos antiparasitários, recebeu suplementação com Ferro Dextrano. Os resultados obtidos para VCM e HCM indicam que houve diferença estatística entre os grupos (p<0.05), sugerindo que a suplementação de ferro contribuiu para melhora da resposta medular. O predomínio da ocorrência de anemia do tipo normocítico e normocrômico indica que os animais foram capazes de manter a homeostase no metabolismo de ferro. Sobre as variáveis que representam o leucograma, foi possível observar que houve variação significativa entre os tempos analisados (p<0.05), indicativo de evolução no processo de recuperação. Evidenciou-se normoleucocitemia, com existência de linfopenia e eosinopenia, além da ocorrência de neutrofilia com desvio à esquerda. Também, foi observada a inversão do padrão leucocitário, que passou de predominantemente linfocitário para neutrofílico, enquanto os animais permaneciam sob quadro de anemia intensa. Pela contagem de plaquetas, evidenciou-se diferença estatística entre os grupos (p<0.05), principalmente, no início do processo de avaliação, período de maior infestação parasitária. / The purpose of this project was to evaluate the impact of anti-inflammatory and antibiotic administration on the erythrogram and leukogram variables, concomitant with antiparasitic use, and the influence exerted by iron dextran supplementation on the spinal response of sheep with verminous anemia. Forty-five sheep, more than 24 months old, naturally infected, were used. The animals were screened by clinical, coproparasitological and hemogram. After the selection, they were allocated in 03 experimental subgroups. Group 01 received only antiparasitic treatment (control); to group 02, besides the antiparasites, an association of antibiotics and anti-inflammatories was applied; and Group 03, in addition to the antiparasitics, received supplementation with Iron Dextran. The results obtained for VCM and HCM indicate that there was a statistical difference between the groups (p<0.05), suggesting that the iron supplementation contributed to the improvement of the spinal response. The predominance of anemia of the normocytic and normochromic type indicates that the animals were able to maintain the homeostasis in iron metabolism. Regarding the variables that represent the leukogram, it was possible to observe that there was a significant variation between the times analyzed (p<0.05), indicative of evolution in the recovery process. There was evidence of normoleukocytemia, with lymphopenia and eosinopenia, besides the occurrence of neutrophilia with deviation to the left. In addition, the inversion of the leukocyte pattern, which changed from predominantly lymphocytic to neutrophilic, was observed, while the animals remained under severe anemia. The platelets count showed a statistically significant difference between the groups (p<0.05), mainly at the beginning of the evaluation process, the period of greatest parasitic infestation.