Nenhuma / O controle epidemiológico da leishmaniose visceral (LV) no Brasil envolve a eliminação de cães infectados, portanto, métodos diagnósticos confiáveis são essenciais para evitar a transmissão da doença ou o sacrifício desnecessário de animais. O programa de controle da LV no Brasil é baseado em inquéritos sorológicos. Os métodos sorológicos, no entanto, apresentam problemas de sensibilidade e especificidade. A Reação em Cadeia da Polimerase (PCR) demonstrou ser uma técnica rápida e sensível para a detecção de Leishmania, no entanto amostras não invasivas representam um instrumento essencial, neste contexto, uma vez que elas são mais simples, indolores e mais facilmente aceitas pelos proprietários de cães. Um método útil é o swab conjuntival (SC) que utiliza um swab estéril para a realização de um esfregaço das conjuntivas do cão. O SC mostrou-se altamente sensível para o diagnostico da LV por PCR. O objetivo deste estudo foi avaliar através do SC a prevalência de animais infectados em dois grupos de cães: assintomáticos e vacinados contra a LV. O primeiro grupo foi composto por 30 animais assintomáticos, positivos nos diagnósticos sorológico e parasitológico. Os resultados do SC foram comparados com os obtidos através de duas amostras pouco invasivas, sangue (S) e biopsia de pele (BP). As amostras foram analisadas por dois métodos diferentes de PCR: kDNA PCR-hibridização e ITS-1 nPCR. O volume de amostra de DNA utilizada para o kDNA PCR-hibridização foi de 1,0 &#61549;L e para o ITS-1 nPCR o volume foi de 10,0 L. Utilizando-se o SC o método kDNA PCR- hybridização detectou DNA de Leishmania em 24/30 cães (80%) através da conjuntiva direita (CD) e 23/30 cães (76,6%) utlizando-se a conjuntiva esquerda (CE), 17/30 cães (56,7%) por meio de BP e 4/30 cães (13.3%) com S. A positividade do SC obtida combinando-se ambas as conjuntivas foi de 90% (27/30 cães). A análise das amostras de SC pelo método ITS-1 nPCR revelou que 25/30 cães (83,3%) foram positivos utilizando-se a CD e 20/30 cães (66,6%) foram positivos via a CE. Pelo mesmo método 15/30 cães (50,0%) foram positivos através de BP e 17/30 cães (56,7%) com S. A positividade obtida combinando-se ambas as oculares foi de 83,3%. Para o método kDNA PCR- hybridização as positividades do SC para a CD e CE foram significantemente superiores (p<0.05) as obtidas com BP e S. Diferença estatística em relação a BP e S foi verificada pelo método ITS-1 nPCR apenas para CD. Os métodos kDNA PCR-hibridação e ITS-1 nPCR apresentaram sensibilidade semelhante para SC e amostras BP. Por outro lado, a positividade do ITS-1 nPCR para amostras de S, foi significativamente maior que a obtida pelo kDNA PCR-hibridização, indicando que a sensibilidade dos métodos de PCR pode variar de acordo com o tecido examinado. A melhor sensibilidade neste estudo (90%) foi obtido através de amostras SC (combinando-se as duas conjuntivas) associada ao kDNA PCR-hibridização. Este nível de sensibilidade foi semelhante ao obtido em outros estudos utilizando SC para o diagnóstico da LV em cães sintomáticos. O segundo grupo foi de 42 cães militares, todos vacinados contra a LV. Neste grupo os resultados do SC foram comparados aos obtidos por testes sorológicos. Os testes sorológicos foram realizados de forma independente por três laboratórios. Os laboratórios 1 e 2 (Lab1 e Lab2) foram laboratórios comerciais. O laboratório 3 (Lab3) foi o Laboratório de Referência Nacional. A primeira triagem sorológica realizada pelo Lab1 mostrou 15 cães reativos e 4 cães foram classificados como indeterminados. Devido à alta positividade encontrada neste ensaio, animais com sorologia reativa e indeterminada, diagnosticados pelo Lab1, foram submetidos a novos testes sorológicos pelos Lab2 e Lab3. O Lab2 confirmou apenas 3 cães reativos e 2 animais foram indeterminados. O Lab3 confirmou 7 cães reativos e 3 cães foram classificados como indeterminados. Os cães que foram confirmados como reativos no diagnóstico sorológico do Lab3 foram submetidos à eutanásia. O diagnóstico molecular por PCR, utilizando o SC em todos os 42 animais foi capaz de detectar o DNA de Leishmania em 17 cães. Comparando os resultados da PCR com os obtidos através do teste sorológico do Lab1, a PCR foi positiva para 10 casos reativos e um caso indeterminado, mas foi negativo para 5 reativos e 3 casos indeterminados. Além disso, a PCR foi positiva em 5 casos não reativos. Os casos reativos e indeterminados, de acordo com o Lab1 que foram PCR negativos, apresentaram resultados negativos nos testes sorológicos dos Lab2 e Lab3. Para o Lab2, a PCR confirmou os 3 casos reativos e foi positiva para os 2 casos indeterminados. Em relação ao Lab3, a PCR confirmou todos os 7 casos reativos e foi positiva para os 3 casos indeterminados. O ensaio de PCR confirmou todos os casos, simultaneamente reativos nos testes sorológicos de dois laboratórios. Nossos resultados mostraram que o SC é um método sensível e prático para coleta de amostra permitindo diagnósticos confiáveis por PCR, além de apresentar sensibilidade superior a outras amostras pouco invasivas. Concluímos que o uso do SC deve ser considerado para os inquéritos caninos rotineiros para a LV / The epidemiological control of visceral Leishmaniasis (VL) in Brazil involves the elimination of infected dogs. Therefore, reliable diagnostic tests are essential to prevent the transmission of the disease or unnecessary culling of dogs. The VL control in Brazil is based on serological surveys, nevertheless serologic assays present problems related to sensitivity and specificity. Polymerase chain reaction (PCR) proved to be a rapid and sensitive technique for detection of Leishmania. However, non-invasive samples are an essential tool in this context, since they are simpler, painless and more easily accepted by dog owners. A useful method is the conjunctival swab (CS) that uses a sterile swab to sample the dog conjunctiva. The SC was highly sensitive for the VL diagnosis by PCR. The objective of this study was to evaluate by CS the prevalence of infected animals in two groups of dogs: asymptomatic and vaccinated against VL. The first group had 30 asymptomatic dogs with positive serological and parasitological tests. The SC samples were compared with two non-invasive samples: blood (B) and skin biopsy (SB). The samples were analyzed by two different PCR methods: kDNA PCR-hybridization and ITS-1 nPCR. The volume of DNA sample used for kDNA PCR-hybridization was 1.0 &#61549; L and ITS-1 nPCR volume was 10.0 L. The DNA sample volume used was of 1.0 L and 10.0 L respectively. Using CS samples the kDNA PCR- hybridization was able to detected parasite DNA in 24/30 dogs (80%) using the right conjunctiva (RC) and 23/30 dogs (76.6%) with the left conjunctiva (LC), 17/30 dogs (56.7%) by means of SB and 4/30 dogs (13.3%) with B. The CS positivity obtained combining RC and LC results was of 90% (27/30 dogs). The assay of CS samples by ITS-1 nPCR revealed that 25/30 dogs (83.3%) were positive when using RC and 20/30 dogs (66.6%) were positive when using LC. Via the same method 15/30 dogs (50.0%) were positive by SB and 17/30 dogs (56.7%) with B. The CS positivity obtained by ITS-1 nPCR combining RC and LC was of 83.3%. The CS positivities for RC and LC were significantly higher (p<0.05) than SB and B for kDNA PCR- hybridization method. Statistical difference in relation to SB and B was verified by ITS-1 nPCR only for RC. Methods kDNA PCR-hybridization and ITS-1 nPCR showed similar sensitivities to CS and SB samples. Moreover, the positivity of ITS-1 nPCR 11 for B samples, was significantly higher than that obtained by kDNA PCR-hybridization, indicating that the sensitivity of the PCR may vary with the tissue examined. The best sensitivity in this study (90%) was obtained from CS samples (by combining both conjunctivas) associated with kDNA PCR-hybridization. This level of sensitivity was similar to that obtained in other studies using CS for the VL diagnosis in symptomatic dogs. The second group was of 42 military dogs, all of them vaccinated against VL. In this group CS and compared with the results obtained by serological tests. The serological tests were carried out independently by three laboratories. Laboratories 1 and 2 (Lab1 and Lab2) were private laboratories. Laboratory 3 (Lab3) was the National Reference Laboratory. The first serological screening performed by the Lab 1 showed 15 reactive dogs and 4 dogs were classified as indeterminate. Due to the high positivity found in this test, animals with reactive and indeterminate serology according Lab 1 were subjected to new serological tests by Lab 2 and Lab 3. Lab 2 confirmed only 3 reactive dogs and 2 animals were undetermined. The Lab 3 found 7 reactive dogs and 3 dogs were classified as indeterminate. Dogs that were confirmed as reactive by Lab 3 were euthanized. The molecular diagnosis by PCR, using CS, was performed in all 42 animals and was able to detect Leishmanial DNA in 17 dogs. Comparing the PCR results with those obtained by serological test of Lab 1, PCR was positive for 10 reactive and one indeterminate case, but was negative for 5 reactive and 3 indeterminate cases. In addition, the PCR was positive in 5 non-reactive cases. The reactive and indeterminate cases according to Lab 1 that were PCR negatives, tested negative in the serologic assays of Lab 2 and Lab 3. For the Lab 2, the PCR confirmed the 3 reactive cases and was positive for the 2 indeterminate cases. In relation to Lab 3, the PCR confirmed all 7 reactive cases and test positive for the 3 indeterminate cases. The PCR assay confirmed all cases simultaneously reactive in the serologic tests of two laboratories. Our results showed that the SC is a sensitive and practical method for collecting samples, allowing reliable diagnostic tests by PCR and showed higher sensitivity than other low invasive samples. We conclude that the use of CS for the regular screenings of dogs by PCR should be considered.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A leishmaniose visceral (LV) é um grave problema de saúde pública no Brasil. Na área urbana o cão é a principal fonte de infecção e o controle da LV no Brasil envolve a eliminação de cães infectados. Testes sorológicos são utilizados para os levantamentos rotineiros, mas estes apresentam problemas de especificidade e sensibilidade. Os métodos moleculares como a PCR são úteis tanto no diagnóstico como na identificação das espécies de Leishmania. São capazes de detectar animais infectados soronegativos e são mais sensíveis e específicos, particularmente no diagnóstico de cães assintomáticos. Um dos maiores obstáculos na implementação de ensaios moleculares é a falta de padronização. Mais de 400 publicações sobre o diagnóstico molecular da leishmaniose foram realizadas desde 1989, porém pouquíssimas compararam a eficiência das diversas técnicas disponíveis. O objetivo deste trabalho foi comparar diferentes métodos de PCR em diferentes amostras clínicas para o diagnóstico de leishmaniose visceral canina (LVC) em cães assintomáticos. Amostras clínicas de medula óssea, sangue periférico, swab conjuntival e biópsias de pele foram analisadas pelos métodos kDNA PCR hibridização, kDNA semi nested PCR (kDNA snPCR), Leishmania nested PCR (LnPCR) e Internal Transcribed Spacer 1 nested PCR (ITS-1 nPCR). Foram utilizados 30 cães assintomáticos positivos na sorologia e no exame parasitológico. Seis cães não infectados foram utilizados como controles. A extração de DNA a partir dos swabs foi realizada pelo método do Fenol-Clorofórmio. Para as amostras de sangue, medula e biópsias de pele foram utilizados kits comerciais. As análises pelo método kDNA PCR hibridização detectaram 5/30 (16,7%) cães positivos para as amostras de sangue periférico, 17/30 (57%) para pele, 19/30 (63,3%) para medula e 21/30 (70%) para swab conjuntival. Utilizando-se o método kDNA snPCR, foram encontrados 7/30 (23,3%) cães positivos para sangue periférico, 17/30 (57%) para pele, 12/30 (40%) para as amostras de medula e 24/30 (80%) para amostras de swab conjuntival. Através de método LnPCR foram detectados 9/30 (30%) cães positivos para as amostras de sangue periférico, 15/30 (50%) para medula, 13/30 (43,3%) para as amostras de pele e 19/30 (63,3%) para swab conjuntival. As análises pelo método ITS-1 nPCR das amostras de sangue periférico detectaram 19/30 (63,3%) cães positivos, 19/30 (63,33%) para pele, 29/30 (97%) para medula óssea e 29/30 (97%) para swab conjuntival. Quando comparados os métodos com base no somatório das positividades obtidas para todas as amostras clínicas, o método ITS-1 nPCR obteve 96/120 resultados positivos, o kDNA PCR hibridização 62/120, o kDNA snPCR 60/120 e o LnPCR 56/120. Na comparação da amostras com base na positividade obtida para todos os métodos o swab conjuntival apresentou 93/120 resultados positivos, a medula 68/120, a pele 63/120 e o sangue 40/120. Os resultados deste estudo indicam o swab conjuntival associado ao método ITS 1 nPCR como a melhor opção, entre os métodos e amostras testados, para o diagnóstico molecular da leishmaniose visceral canina em animais assintomáticos. Palavras-chave: Leishmaniose Visceral canina; Reação em Cadeia da Polimerase (PCR); Diagnóstico. / Visceral Leishmaniasis (VL) is a serious public health problem in Brazil. In the urban area the dog is the main source of infection and VL control in Brazil involves the elimination of infected dogs. Serological tests are used for routine surveys, but they present problems of specificity and sensitivity. Molecular methods as the PCR are useful in the diagnosis and identification of Leishmania species. PCR is able to detect seronegative animals and is more sensitive and specific, particularly in the diagnosis in asymptomatic dogs. One obstacle on the implementation of molecular assays is the lack of standardization. More than 400 articles on the diagnosis of leishmaniasis had been pubhished since 1989, however a few studies had compared the efficiency of the diverse available techniques. The aim of this work was compare different methods of PCR in different clinical samples for the diagnosis of canine visceral leishmaniasis (CVL) in asymptomatic animals. Bone marrow, peripheral blood, conjunctival swab and skin biopsies had been analyzed by the methods kDNA PCR - Hybridization, kDNA semi nested PCR (kDNA snPCR), Leishmania nested PCR (LnPCR) e Internal Transcribed Spacer 1 nested PCR (ITS-1 nPCR). Thirty positive asymptomatic dogs for serology and parasitology examination had been used. Six not infected dogs had been used as controls. The DNA extration from swabs was performed by Phenol-Chloroform method. Commercial kits had been used for DNA extraction of peripheral blood, bone marrow and skin biopsies. The kDNA PCR - Hybridization detected 5/30 (16.7%) positive dogs for peripheral blood, 17/30 (57%) for skin, 19/30 (63.3%) for bone marrow and 21/30 (70%) for conjunctival swab. Using the method kDNA snPCR had been found 7/30 (23.3%) positive dogs for peripheral blood, 17/30 (57%) for skin, 12/30 (40%) for bone marrow and 24/30 (80%) samples of conjunctival swab. Through LnPCR method 9/30 (30%) positive dogs for the samples of peripheral blood had been detected, 15/30 (50%) for bone marrow, 13/30 (43.3%) for the samples of skin and 19/30 (63.3%) for conjunctival swab. The ITS-1 nPCR analyse showed 19/30 (63.3%) positive dogs for peripheral blood, 19/30 (63.33%) for skin, 29/30 (97%) for bone marrow and 29/30 (97%) for conjunctival swab. The ITS-1 nPCR was superior to other methods based on the positivities obtained using the summatory of all clinical samples. The ITS-1 nPCR obtained 96/120 positive results, kDNA PCR-hibridization 62/120, kDNA snPCR 60/120 and LnPCR 56/120. The conjunctival swab presented the best result considering the summatory of the positivities obtained by all methods. The conjunctival swab obtained 93/120 positive results, medula 73/120, skin biopsies 68/120 and blood 40/120. The results of this study indicated the conjunctival swab associated to ITS-1 nPCR as the best option for the molecular diagnosis of visceral leishmaniasis in asymptomatic dogs, among the methods and samples analysed.

This diploma thesis deals with the issue of vaccination coverage among children. Vaccination in the Czech Republic has a long tradition and represents a very effective protection of children and adults not only against infectious diseases, but also against their consequences. It also prevents the development of infectious diseases. Vaccination is one of the most successful preventive methods that affect the health of individuals and the whole population. Vaccination is also very important for unvaccinated individuals. If the population reaches a high level of vaccination coverage, the spread of infection between vaccinated individuals is interrupted which significantly reduces the risk of transmission of infection to unvaccinated individuals as well. Vaccination thus protects also those who cannot be vaccinated because of illness, decreased immunity or other reasons. Currently, however, there are some opinions which question the usefulness and importance of compulsory vaccination. An increasing number of those who refuse vaccination occur due to the increased accessibility of the Internet and social networks, where we can notice a growing amount of information to the disadvantage of vaccination. The most common reason for refusing vaccination is the belief that some vaccinations are not necessary. The thesis is divided into two main parts - theoretical and practical. The first theoretical chapter contains an introduction to the issue of vaccination. In the following part of my thesis I deal with the system of vaccination in the Czech Republic, its planning, organization and control, and the role of public health protection authorities. The following chapter deals with the importance and division of vaccination and kinds of vaccines. The thesis is also focused on the diseases which are vaccinated against under mandatory vaccination scheme. At present mandatory vaccination in the Czech Republic includes vaccination against diphtheria, tetanus, pertussis, rubella, mumps, measles, transmissible polio, hepatitis B and invasive diseases caused by Haemophilus influenzae type b. Vaccination especially against tick-borne encephalitis, hepatitis A, diseases caused by pneumococci and invasive meningococcal disease is recommended. Last but not least, I also mention contraindications for vaccination and the adverse reactions after the vaccination. In the next chapter of the theoretical part I write about the implementation of vaccination and the control management of vaccination coverage in the Czech Republic. In conclusion of the theoretical part I deal with the issue of vaccination opponents and their reasons for refusing vaccination.

A leishmaniose visceral (LV) no Brasil é causada pela espécie Leishmania chagasi (L. infantum) e os cães são considerados o principal reservatório doméstico desse parasita. Portanto, o diagnóstico correto e seguro é muito importante para evitar a transmissão da doença ou o sacrifício desnecessário de cães. O objetivo deste trabalho foi avaliar o swab conjuntival (SC), um método não invasivo de amostragem, para o diagnóstico da LV canina por PCR-hibridização. Primeiramente, um teste in vitro foi delineado utilizando-se swabs contaminados com 103 até 1,0 célula de L. chagasi. Três métodos de extração de DNA foram testados: fenol-clorofórmio, kit Wizard e fervura. Em seguida, dois grupos de 23 cães soropositivos foram utilizados. Foram feitos esfregaços por SC em ambos os olhos de cada animal. A extração de DNA de SC foi realizada utilizando-se o método fenolclorofórmio no grupo 1 e a técnica de fervura no grupo 2. Além disso, sangue foi coletado de cada cão sendo que 30&#956;L foram aplicados em papel filtro (PF) e 1,0mL foi tratado para obtenção do anel leucocitário (AL). A purificação de DNA para PF e AL foi realizada da mesma forma em ambos os grupos utilizando-se kits comerciais. A análise de todas as amostras foi feita por PCR seguida de hibridização com sondas de DNA marcadas com 32P. O experimento com swabs contaminados com L. chagasi mostrou positividade na PCR para até 25, 10 e 1,0 célula pelos métodos da fervura, kit Wizard e fenol-clorofórmio respectivamente. A hibridização aumentou a sensibilidade para até 10 e 1,0 célula pelos métodos da fervura e kit Wizard respectivamente. As positividades da PCR para os cães do grupo 1 e 2 foram respectivamente: 73,9% e 52,2% (SC), 8,7% e 30,4% (AL), 8,7% e 17,4% (PF). A hibridização aumentou essas positividades para: 91,3% e 65,2% (SC), 21,7% e 34,8% (AL), 30,4% e 43,5% (PF) respectivamente. Os melhores resultados foram obtidos pela associação de SC com o método de fenol-clorofórmio para extração de DNA. O resultado final obtido desse tratamento foi estatisticamente diferente daqueles referentes ao AL e PF no grupo 1 (p<0,01). No grupo 2, o resultado final proveniente do SC associado com a técnica de fervura para o isolamento de DNA foi estatisticamente distinto apenas do resultado referente ao AL (p<0,05). Concluiu-se que a combinação de SC com a extração de DNA por fenol-clorofórmio é uma ferramenta valiosa para o diagnóstico da LV canina e pode ser recomendada para o diagnóstico em cães sintomáticos. / The visceral leishmaniasis (VL) in Brazil is caused by Leishmania chagasi (L. infantum) and dogs are considered to be the main domestic reservoir. Therefore the correct diagnosis is very important in order to avoid the disease transmission or unnecessary culling of dogs. The aim of this study was to evaluate the conjunctival swab (CS) as a noninvasive sampling method for the canine VL diagnosis by the PCR-hybridization procedure. Firstly, an in vitro test was carried out using cotton swabs seeded with 103 to one cell of L. chagasi. Three DNA purification techniques were tested: phenol-chloroform, Wizard kit and boiling. After that, two groups of 23 seropositive dogs were used. CS samples were obtained from both eyes of each animal. The DNA extraction from CS was performed by the phenol chloroform method in group 1 and by boiling in group 2. In addition, blood was collected from each animal so that 30&#956;L were spotted onto filter paper (FP) and 1.0mL was treated to obtain the buffy coat (BC). The DNA extraction from the BC and FP was accomplished by the same way in both groups using commercial kits. The analysis of all samples was made by PCR associated to the hybridization with 32P labeled DNA probes. The in vitro test with seeded parasites showed positivity to until 25, 10 and one cell for boiling, Wizard kit and phenol chloroform methods respectively. The hybridization step increased the sensitivity until 10 and one cell for the boiling and Wizard respectively. The PCR positivities for the dogs in groups 1 and 2 were respectively: 73.9% and 52.2% (CS), 8,7% and 30.4% (BC), 8.7% and 17.4% (FP). The hybridization step increased the positivities for: 91.3% and 65.2% (CS), 21.7% and 34.8% (BC), 30.4% and 43.5% (FP) respectively. The best frequency of positivity was obtained by the association between CS and the DNA extraction by phenol chloroform. The final result obtained from this treatment was statistically different from the BC and FP data in group 1 (p<0,05). In group 2, the result from CS associated with DNA purification by boiling was distinct only from the BC data (p<0,05). We conclude that the CS associated with the DNA extraction by phenol chloroform is a valuable tool for diagnosis of canine LV and can be recommended for diagnosis of symptomatic dogs.

One hundred years after the discovery of antimicrobials and antibiotics, intracellular bacterial pathogens remain a major cause of global morbidity and mortality. This is due to the complex and intricate ability of these pathogens to undergo intracellular replication while evading host cell immune defense. Bacterial agents such as Legionella pneumophila, Francisella tularensis, and Mycobacterium tuberculosis, as the causative agents of Legionnaires' disease, pulmonary tularemia, and tuberculosis (TB), respectively, contribute to this burden. Moreover, these agents are weaponizable pathogens due to their aerosolizability. TB represents a global health problem, although a potentially curative therapy has been available for approximately 50 years; this intracellular disease affects approximately 1 in 3 people worldwide, with over 10 million new cases per year and one death every three minutes. TB can usually be treated with a 6- to 9-month course of combined therapy. The necessity of using a cocktail of anti-TB drugs and the long-term treatment schedules required for conventional therapy, however, result in poor patient compliance; therefore, the risk of treatment failure and relapses is higher. Hence, improved drug delivery strategies for the existing drugs can be exploited to shorten the duration of TB...

BACKGROUND: Drug abuse is a social problem with psychosocial and physical complications. The lifestyle of injection drug users (IUD) increases the risk of infectious as well as of non-infectious diseases. The workers of low-threshold programmes are often the first ones to encounter the physical complications of injection drug users, and the workers are accordingly often the ones who take the initiative in dealing with those complications. Mapping the possible solutions of injection drug users' complications by the workers of low-threshold programmes would respond to the needs for methodological approach widely available to the workers of low-threshold programmes. AIMS: The present thesis aims to describe the possible solutions to physical complications of injection drug users through mapping the solutions in the practice of the low-threshold programmes workers for drug users in Prague. SAMPLE: All the seven low-threshold programmes facilities based in Prague were appealed to participate on the research. Thirty eight respondents participated in the study (39 % outreach programs, 53 % drop-in centre, 8 % combined services) METHODS: The present research was carried out via questionnaire research. The output data was analysed through descriptive statistics. The standardized questions of the...

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Muitos estudos já demonstraram a aplicabilidade da reação em cadeia da polimerase (PCR) para o diagnóstico da leishmaniose visceral canina (LVC), cujo agente etiológico no Brasil é a Leishmania (Leishmania) chagasi. Um dos maiores obstáculos para a implementação desta técnica é a falta de padronização. Centenas de trabalhos foram publicados até o momento sobre o diagnóstico por PCR das leishmanioses, mas poucos foram realizados com a finalidade de comparar a eficiência dos diversos protocolos disponíveis. O objetivo deste trabalho foi comparar a sensibilidade de quatro métodos de PCR para o diagnóstico da LVC. As técnicas foram primeiramente testadas usando DNA purificado de promastigotas cultivados e em seguida em amostras coletadas de cães infectados pelo método do swab conjuntival. Todos os métodos de PCR utilizados neste trabalho apresentam duas etapas: amplificação seguida de hibridização ou de uma nova amplificação (nested ou semi nested). Dois dos métodos (kDNA PCR-Hibridização e kDNA snPCR) utilizam iniciadores endereçados aos minicírculos do cinetoplasto (kDNA) e os outros dois métodos apresentam como alvo a região codificante (LnPCR) e intergênica não codificante (ITS1 nPCR) dos genes do RNA ribossômico (RNAr). Quando foi utilizado DNA purificado de L. (L.) chagasi o kDNA snPCR apresentou a melhor sensibilidade detectando até 10 fg enquanto que os outros métodos detectaram até 100 fg. Estes resultados não se correlacionaram bem com os obtidos de cães infectados através do swab conjuntival. Dois grupos de 23 cães foram usados. No Grupo 1 o DNA foi extraído dos swabs pelo método do fenol-clorofórmio e no Grupo 2 por fervura. Para os cães do grupo 1 os métodos mais eficientes foram os baseados em alvos de kDNA. O kDNA PCR-Hibridização detectou parasitas em 22/23 cães (95,6%) e em 40/46 amostras (86,9%), considerando as conjuntivas direita e esquerda. O kDNA snPCR foi positivo para 21/23 cães (91,3%) e para 40/46 amostras (86,9%). As positividades destes métodos foram significativamente superiores as obtidas pelos métodos com alvos nos genes de RNAr (p<0,05). O método LnPCR obteve resultado positivo em 17/23 cães (73,9%) e em 30/46 amostras (65.2%). Já o ITS1 nPCR conseguiu detectar os parasitas em 16/23 cães (69,6%) e 28/46 (60,9%) das amostras. No grupo 2 o método kDNA PCR-Hibridização também mostrou melhor desempenho detectando parasitas em 18/23 cães (78,3%) e em 31/46 amostras (67,4%), resultado significativamente superior (p<0.05) aos outros três métodos. As positividades dos métodos kDNA snPCR e LnPCR foram abaixo do esperado e estes ensaios parecem ter sofrido algum tipo de inibição relacionada ao processo de extração de DNA. A maior sensibilidade dos métodos baseados em minicírculos de kDNA descrita por outros pesquisadores foi confirmada neste estudo. O kDNA PCR-Hibridização mostrou a melhor sensibilidade entre os métodos avaliados, entretanto a escolha do melhor método vai depender do tipo de informação requerida com o diagnóstico. Como um todo, nossos resultados apóiam a aplicabilidade do método do swab conjuntival para diagnóstico da LVC. / Many studies have demonstrated the applicability of Polymerase chain reaction (PCR) for diagnosis of canine visceral leishmaniasis (CVL). The disease in Brazil is caused by Leishmania (Leishmania) chagasi. A major concern in the development and implementation of PCR for Leishmania ssp. diagnosis is the lack of standardization. Many works on PCR diagnosis of leishmaniasis have been published, but very few studies have compared different protocols. The aim this work was to compare the sensitivities of four PCR methods for CVL diagnosis. The comparison was firstly accomplished using DNA purified from cultured promastigotas and then using samples collected from infect dogs by the conjunctival swab procedure. All PCR methods presented two steps: a first amplification followed by hybrization or a new amplification (nested or semi nested). Two of the methods (kDNA PCR-Hibridization and kDNA snPCR) used primers addressed to kinetoplast minicircles and the other two methods to the coding (LnPCR) and intergenic noncoding regions (ITS1 nPCR) of the ribosomal rRNA genes. The assessment using purified DNA of L. (L.) chagasi demonstrated that the kDNA snPCR showed the best sensitivity detecting up 10 fg while all other methods detected up to 100 fg. These results did not correlate well with those obtained from infected dogs by the conjunctival swab procedure. Two groups of 23 dogs were used. In Group 1 the DNA was extracted from cotton swabs by phenol-chloroform and in Group 2 by boiling. In the Group 1 the most efficient methods were those based on kDNA targets. The kDNA PCR-Hybridization was able detect parasites in 22/23 dogs (95.6%) and in 40/46 samples (86.9%), considering the right and the left conjunctivas. The kDNA snPCR was positive for 21/23 dogs (91.3%) and for 40/46 samples (86.9%). The positivities of kDNA based methods were significantly higher than the positivities obtained by the two methods based on ribosomal rRNA genes (p<0.05). The method LnPCR was able to detect parasites in 17/23 dogs (73.9%) and 30/46 (65.2%) samples. The ITS1 nPCR was positive for 16/23 dogs (69.6%) and 28/46 (60.9%) samples. In Group 2 the kDNA PCR-Hybridization also showed the best performance. It was able to detected parasites in 18/23 dogs (78.3%) and 31/46 samples (67.4%), significantly higher (p<0.05) than the other three methods. The positivities of two methods, kDNA snPCR, and LnPCR, were below than the expected and these assays seem to be undergone some kind of inhibition related to DNA extraction procedure. The higher sensitivity of the minicircle kDNA based assays reported by others was confirmed in this study. The kDNA PCR-Hybridization showed the best sensitivity among the assays evaluated, however the choice of the best method will depend on the kind of information needed with the diagnosis. As a whole, our results support the applicability of the conjuntival swab procedure for CVL diagnosis.