Analysis and prediction of the occurrence of leptospirosis in wild boars (Sus scrofa Linnaeus, 1758) of the Trás-os-Montes Region
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2016-01-13
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A leptospirose é uma zoonose (re) emergente com importância mundial, causada por espiroquetas patogénicas do género Leptospira, mantidas no meio ambiente por vários reservatórios selvagens e domésticos, os quais representam a principal fonte de infeção para os humanos e outros hospedeiros suscetíveis.
O javali (Sus scrofa) é o ungulado de caça maior com maior importância em termos cinegéticos em Portugal. Apresenta uma das distribuições geográficas mais amplas e na Europa as suas densidades populacionais têm aumentado, havendo uma crescente evidência de que o javali pode atuar como reservatório para algumas doenças infeciosas com importância na Saúde Pública e sanidade animal. O aumento da sua densidade populacional no espaço europeu, bem como a sua elevada capacidade de dispersão, levantam interrogações sobre o potencial papel desempenhado na transmissão de leptospiras patogénicas aos agentes envolvidos na caça, nomeadamente caçadores e cães, dada a sua direta exposição aos tecidos, sangue e urina.
A transmissão da infeção ao homem e animais (selvagens e domésticos) ocorre geralmente por contato direto ou indireto com a urina de animais infetados. O rim é o habitat natural das leptospiras patogénicas e estas são eliminadas através da urina para o meio ambiente. Um bom reservatório de Leptospira carateriza-se pela presença do agente no rim por períodos prolongados, muitas vezes durante toda a vida do animal.
Este trabalho teve como objetivo a pesquisa de aglutininas anti-Leptospira interrogans s.l. e a deteção de DNA leptospírico no tecido renal de javalis abatidos em montarias realizadas na região de Trás-os-Montes, durante as épocas venatórias de 2011/2012 e 2012/2013.
Foram analisados 101 soros pela técnica serológica de referência para o diagnóstico da leptospirose, o teste de aglutinação microscópica (TAM), frente a uma bateria de antigénios constituída por 16 estirpes vivas de Leptospira (estirpes de referência e também isolados nacionais). A sero-ocorrência de animais positivos para um “cut-off” de 1:50 foi de 54.5% (55/101) e os serogrupos mais prevalentes foram Tarassovi (41.8%), Autumnalis (14.6%) e Australis (12.7%). Através do método molecular de diagnóstico, a reação em cadeia da polimerase (PCR), foi possível confirmar a presença de DNA leptospírico em 3 animais (3/43).
Para prever a presença do javali (através de um índice de abundância relativo, o WBindex) e a ocorrência de animais positivos à leptospirose (OPL, expresso em percentagem) na região, foi utilizada a metodologia estocástico dinâmica (StDM).
Os resultados obtidos parecem representar uma contribuição útil para capturar diferenças do WBindex e OPL em cenários ambientais complexos e variáveis. Os padrões espaciais obtidos foram holisticamente determinados pela estrutura do habitat, e as simulações permitiram uma melhor percepção das influências da dinâmica da ocupação dos usos solo sobre os padrões espaciais de ocorrência da leptospirose.
Os resultados sugerem que o javali poderá representar um importante reservatório da leptospirose no ecossistema, sendo uma fonte potencial de transmissão da doença ao homem e animais (selvagens e domésticos) na região de Trás-os-Montes, em particular aos agentes envolvidos nas atividades venatórias.
Leptospirosis is a zoonotic disease of global importance that is caused by pathogenic spirochetes of the genus Leptospira, maintained in nature by numerous wild and domestic reservoirs, which constitute a potential source of infection for humans and other susceptible hosts. The wild boar (Sus scrofa) is widely distributed in Europe and represents an important hunting species. The wild boar populations have increased in the last two decades, and there is growing evidence that species can act as a reservoir for some infectious diseases of importance in public and animal health. Increased population density in Europe, as well as its high-dispersion, raise questions about the potential role in the transmission of pathogenic Leptospira to agents involved in hunting, hunters and dogs in particular, due the direct exposure to tissues, blood and urine. The transmission of the infection to humans and animals (wild and domestic) usually occurs by direct or indirect contact with the urine of infected animals. The kidney is the natural habitat of pathogenic leptospires and these are eliminated through the urine to the environment. Pathogenic leptospires hosts carried the agent for long periods in kidneys, and many times throughout their entire life. This study aimed to search anti-Leptospira interrogans sensu lato (s.l.) agglutinins, and detection of leptospiral DNA in the kidney of hunted wild boars in Trás-os-Montes region, during the hunting seasons of 2011/2012 and 2012/2013. The leptospirosis diagnosis was made by microscopic agglutination test (MAT) (serological gold standard test) with 16 live antigens of Leptospira (reference and local isolated strains). Of the 101 serum samples tested by MAT, 54.5% (55/101) showed anti-Leptospira interrogans s.l. antibodies at a titre of 1:50 or higher. Antibodies against Tarassovi (41.8%), Autumnalis (14.6%) and Bratislava (12.7%) were the most frequently detected. The Polymerase Chain Reaction (PCR) method was amplified leptospiral DNA in three kidney samples (3/43). Based on data obtained in the previous laboratorial tests, the Stochastic Dynamic Methodology (StDM) was applied in order to predict the presence of the wild boars (by using a relative abundance index, the WBindex) and the occurrence of positives to leptospirosis (OPL, expressed in percentage) in the region. The obtained simulation results are encouraging since they seem to represent a useful contribution to capture the key changes in the WBindex and in the OPL under very complex and variable environmental scenarios. Since the WBindex and OPL are holistically determined by the habitat structure, the StDM simulations allowed a better perception of the influences of land cover dynamics on the spatial patterns of Leptospira antibodies occurrence. These results reinforce the previously known suspicion that the wild boar is a potential reservoir host for some Leptospira serovars, and they can represent one of the potential sources of leptospirosis for humans and especially for hunters and hunting dog´s during the hunting practice (through direct contact with the tissue, blood or urine).
Leptospirosis is a zoonotic disease of global importance that is caused by pathogenic spirochetes of the genus Leptospira, maintained in nature by numerous wild and domestic reservoirs, which constitute a potential source of infection for humans and other susceptible hosts. The wild boar (Sus scrofa) is widely distributed in Europe and represents an important hunting species. The wild boar populations have increased in the last two decades, and there is growing evidence that species can act as a reservoir for some infectious diseases of importance in public and animal health. Increased population density in Europe, as well as its high-dispersion, raise questions about the potential role in the transmission of pathogenic Leptospira to agents involved in hunting, hunters and dogs in particular, due the direct exposure to tissues, blood and urine. The transmission of the infection to humans and animals (wild and domestic) usually occurs by direct or indirect contact with the urine of infected animals. The kidney is the natural habitat of pathogenic leptospires and these are eliminated through the urine to the environment. Pathogenic leptospires hosts carried the agent for long periods in kidneys, and many times throughout their entire life. This study aimed to search anti-Leptospira interrogans sensu lato (s.l.) agglutinins, and detection of leptospiral DNA in the kidney of hunted wild boars in Trás-os-Montes region, during the hunting seasons of 2011/2012 and 2012/2013. The leptospirosis diagnosis was made by microscopic agglutination test (MAT) (serological gold standard test) with 16 live antigens of Leptospira (reference and local isolated strains). Of the 101 serum samples tested by MAT, 54.5% (55/101) showed anti-Leptospira interrogans s.l. antibodies at a titre of 1:50 or higher. Antibodies against Tarassovi (41.8%), Autumnalis (14.6%) and Bratislava (12.7%) were the most frequently detected. The Polymerase Chain Reaction (PCR) method was amplified leptospiral DNA in three kidney samples (3/43). Based on data obtained in the previous laboratorial tests, the Stochastic Dynamic Methodology (StDM) was applied in order to predict the presence of the wild boars (by using a relative abundance index, the WBindex) and the occurrence of positives to leptospirosis (OPL, expressed in percentage) in the region. The obtained simulation results are encouraging since they seem to represent a useful contribution to capture the key changes in the WBindex and in the OPL under very complex and variable environmental scenarios. Since the WBindex and OPL are holistically determined by the habitat structure, the StDM simulations allowed a better perception of the influences of land cover dynamics on the spatial patterns of Leptospira antibodies occurrence. These results reinforce the previously known suspicion that the wild boar is a potential reservoir host for some Leptospira serovars, and they can represent one of the potential sources of leptospirosis for humans and especially for hunters and hunting dog´s during the hunting practice (through direct contact with the tissue, blood or urine).
Descrição
Dissertação de Mestrado em Biologia Clínica Laboratorial
Palavras-chave
Leptospirose , Javali (Sus scrofa) , Montaria , Teste de aglutinação microscópica (TAM)