Prevalência de anticorpos contra Yersinia pestis em carnívoros domésticos nos focos pestosos, do Estado do Ceará / Prevalence of antibodies against Yersinia pestis in domestic carnivores, in plague foci in the State of Ceará

Analisou-se a prevalência de anticorpos contra Yersinia pestis em carnívoros domésticos (cães e gatos) nas áreas pestígenas do Estado do Ceará, visando estabelecer a importância do monitoramento desses animais na rotina do Programa de Controle da Peste. No decênio 1997-2006, analisaram-se 146.732 amostras de soros (95.883 cães e 50.849 gatos), das quais 2.629 (2.234 cães e 395 gatos) revelaram-se positivas. A prevalência entre os cães (85 por cento) foi superior a dos gatos (15 por cento) em todo o decênio e locais, exceto em Ibiapina, em 1998. O significado desses achados ainda não foi determinado. Os estudos sobre a zoonose no Brasil pautaram-se por paradigmas que não contemplavam todos os elementos envolvidos na zoonose, impossibilitando a devida elucidação do papel desses carnívoros. O monitoramento da atividade pestosa, realizado exclusivamente por inquéritos caninos, pode redundar no desconhecimento progressivo da situação epidemiológica da peste, caso não sejam desenvolvidas pesquisas interinstitucionais suplementares.

The prevalence of antibodies against Yersinia pestis in domestic carnivores (dogs and cats), in plague areas in the State of Ceará, was analyzed to establish the importance of monitoring these animals within the routine practice of the plague control program. Over the decade 1997-2006, 146,732 serum samples were examined (95,883 from dogs and 50,849 from cats), of which 2,629 (2,234 from dogs and 395 from cats) proved to be positive. The prevalence among dogs (85 percent) was higher than among cats (15 percent) throughout the decade and in all places, except in Ibiapina in 1998. The significance of these findings has not yet been determined. Studies on this zoonosis in Brazil have been based on paradigms that did not cover all the elements involved in the zoonosis, thus making it impossible to properly understand the role of these carnivores. Monitoring of plague foci conducted exclusively by means of dog surveys may result in progressive lack of knowledge of the epidemiological situation of plague, if supplementary inter-institutional research is not developed.

[Prevalence of antibodies against Yersinia pestis in domestic carnivores, in plague foci in the State of Ceará]. / Prevalência de anticorpos contra Yersinia pestis em carnívoros domésticos nos focos pestosos, do Estado do Ceará

The prevalence of antibodies against Yersinia pestis in domestic carnivores (dogs and cats), in plague areas in the State of Ceará, was analyzed to establish the importance of monitoring these animals within the routine practice of the plague control program. Over the decade 1997-2006, 146,732 serum samples were examined (95,883 from dogs and 50,849 from cats), of which 2,629 (2,234 from dogs and 395 from cats) proved to be positive. The prevalence among dogs (85%) was higher than among cats (15%) throughout the decade and in all places, except in Ibiapina in 1998. The significance of these findings has not yet been determined. Studies on this zoonosis in Brazil have been based on paradigms that did not cover all the elements involved in the zoonosis, thus making it impossible to properly understand the role of these carnivores. Monitoring of plague foci conducted exclusively by means of dog surveys may result in progressive lack of knowledge of the epidemiological situation of plague, if supplementary inter-institutional research is not developed.

[Contribution towards plague diagnosis]. / Contribuição para o diagnóstico de peste.

Despite the clinical-epidemiological features of plague, numerous suspected cases in Brazilian outbreaks have been discarded because of negative results from the hemagglutination test for antibodies against the Yersinia pestis F1 antigen. The transcendence of plague justifies studying whether such results are due to unresponsiveness to F1, and whether other Y. pestis proteins might be recognized in suspect serum. These would therefore be candidates to be alternative diagnostic targets to the F1 antigen. Thus, strains of Y. pestis and Y. pseudotuberculosis, a recombinant YopH protein and the F1 antigen were used to analyze serum from patients and immune serum from rabbits. F1 and YopH were not recognized by HA-negative human serum and no major protein common to all the human and rabbit serum samples was identified. This allows the conclusion that suspected cases must be subjected to more rigorous clinical-laboratory evaluation, with strengthening of epidemiological investigations in the search of other etiologies.

[Secular plague trend in Ceará State, Brazil]. / Tendência secular da peste no Estado do Ceará, Brasil.

After its introduction into the State of Ceará, Brazil, in 1900, the plague was established in seven ecological complexes: Chapada do Araripe and the Ibiapaba, Baturité, Machado, Matas, Pedra Branca, and Uruburetama mountains. These natural foci were monitored successively from 1935 to 2004 by the National Health Department, National Plague Service, National Department of Rural Endemics, Superintendency of Public Health Campaigns, National Health Foundation, and finally by the National Health Surveillance Secretariat. Data analysis on human cases during these 70 years allowing identifying different plague circulation patterns in the human population, alternating high incidence with silent periods and characterizing a chronological periodicity with unique epidemiological characteristics, besides concluding that plague should still be considered a potential threat, thus justifying the revitalization of surveillance measures by strengthening all levels in the Unified National Health System.

Tendência secular da peste no Estado do Ceará, Brasil / Secular plague trend in Ceará State, Brazil

Após a sua introdução no Ceará, Brasil, em 1900, a peste focalizou-se em sete complexos ecológicos: Chapada do Araripe e Serras da Ibiapaba, do Baturité, do Machado, das Matas, da Pedra Branca e de Uruburetama. As atividades de vigilância nesses focos no período de 1935/2004 foram desenvolvidas sucessivamente pelo Departamento Nacional de Saúde, Serviço Nacional de Peste, Departamento Nacional de Endemias Rurais, Superintendência de Campanhas de Saúde Pública, Fundação Nacional de Saúde e finalmente pela Secretaria de Vigilância em Saúde. A análise dos dados levantados sobre a ocorrência de casos humanos nesses 70 anos permite identificar diferentes padrões de circulação da enfermidade na população humana, caracterizados pela alternância de momentos de elevadas incidências e de silêncio, possibilitando estabelecer uma periodização cronológica com características epidemiológicas próprias. Conclui-se desses resultados que a peste ainda deve ser considerada uma ameaça potencial, o que justifica revitalizar as ações de vigilância epidemiológica, o que só ocorrerá com o fortalecimento de todas as instâncias do Sistema Unico de Saúde.

After its introduction into the State of Ceará, Brazil, in 1900, the plague was established in seven ecological complexes: Chapada do Araripe and the Ibiapaba, Baturité, Machado, Matas, Pedra Branca, and Uruburetama mountains. These natural foci were monitored successively from 1935 to 2004 by the National Health Department, National Plague Service, National Department of Rural Endemics, Superintendency of Public Health Campaigns, National Health Foundation, and finally by the National Health Surveillance Secretariat. Data analysis on human cases during these 70 years allowing identifying different plague circulation patterns in the human population, alternating high incidence with silent periods and characterizing a chronological periodicity with unique epidemiological characteristics, besides concluding that plague should still be considered a potential threat, thus justifying the revitalization of surveillance measures by strengthening all levels in the Unified National Health System.

Contribuição para o diagnóstico de peste / Contribution towards plague diagnosis

Apesar de sua fundamentação clínico-epidemiológica, numerosos casos suspeitos de peste nos focos brasileiros têm sido descartados por serem negativos pelo teste de hemaglutinação para detecção de anticorpos contra o antígeno F1 da Yersinia pestis. A transcendência da peste justifica estudar se tais resultados decorrem da falta de resposta ao F1, e se outras proteínas da Yersinia pestis poderiam ser reconhecidas nos soros suspeitos, sendo desta forma candidatas como alvo diagnóstico alternativo ao F1. Assim sendo, cepas de Yersinia pestis e de Yersinia pseudotuberculosis, uma proteína YopH recombinante e a F1 foram utilizadas para analisar soros de pacientes e soros imunes de coelhos. A F1 e a YopH não foram reconhecidas pelos soros humanos HA- e nenhuma proteína majoritária, comum a todos os soros humanos e coelhos, foi identificada, o que permite concluir que os casos suspeitos devem ser submetidos a uma avaliação clínico-laboratorial mais rigorosa, aprofundando a investigação epidemiológica em busca de outras etiologias.

Despite the clinical-epidemiological features of plague, numerous suspected cases in Brazilian outbreaks have been discarded because of negative results from the hemagglutination test for antibodies against the Yersinia pestis F1 antigen. The transcendence of plague justifies studying whether such results are due to unresponsiveness to F1, and whether other Y. pestis proteins might be recognized in suspect serum. These would therefore be candidates to be alternative diagnostic targets to the F1 antigen. Thus, strains of Y. pestis and Y. pseudotuberculosis, a recombinant YopH protein and the F1 antigen were used to analyze serum from patients and immune serum from rabbits. F1 and YopH were not recognized by HA-negative human serum and no major protein common to all the human and rabbit serum samples was identified. This allows the conclusion that suspected cases must be subjected to more rigorous clinical-laboratory evaluation, with strengthening of epidemiological investigations in the search of other etiologies.

[Surveillance of plague in the State of Ceará: 1990-1999]. / Vigilância da peste no Estado do Ceará: 1990-1999.

Serological surveillance activities regarding the foci of plague in Ceará State have detected a rising number of sentinel animals with antiplague antibodies in 1995, with a peak in 1997 demonstrating an increase in the plague bacteria activities throughout all the foci investigated. From a total of 110,725 serum samples collected from rodents (7,873) and domestic carnivores (102,852) analyzed by the Hemaglutination technique (HA) for antibodies against F1 antigen of Yersinia pestis 905 samples tested positive. In these samples there were 15 rodents (4 Rattus rattus and 11 Galea spp), 720 dogs and 170 cats. Of the 652 human suspected and contact cases investigated by HA, only two were positive. A third case had a positive hemoculture for Y. pestis. The isolate is highly pathogenic for laboratory animals and showed sensitivity to the antimicrobial drugs used for plague treatment.

Vigilância da peste no Estado do Ceará: 1990-1999 / Surveillance of plague in the State of Ceará: 1990-1999

As atividades de vigilância sorológica da peste nos focos do Estado do Ceará detectaram elevaçäo do número de animais indicadores/sentinela com anticorpos antipestosos a partir de 1995, com pico em 1997 evidenciando aumento da circulaçäo do bacilo pestoso em todos os focos investigados. De um total de 110.725 amostras de soro obtidas de roedores (7.873) e carnívoros domésticos (102.852) analisadas pela técnica de hemaglutinaçäo (HA) para detecçäo de anticorpos contra o antígeno F1 da Yersinia pestis, 905 revelaram-se positivas, sendo 15 de roedores (4 Rattus rattus e 11 Galea spp), 720 de cäes e 170 de gatos. Dos 652 casos humanos suspeitos e contatos investigados apenas dois foram positivos pela HA e um terceiro paciente foi positivo por hemocultura. A cepa isolada revelou-se altamente patogênica para animais de laboratório e mostrou sensibilidade aos antimicrobianos usados no tratamento dos doentes