Vigilância da peste no Estado do Ceará: 1990-1999

Aragão, Antônia Ivoneida; Seoane, Antonio; Leal, Tereza Cristina Arcanjo; Leal, Nilma Cintra; Almeida, Alzira Maria Paiva de

doi:10.1590/s0037-86822002000200003

Cited by 14 publications

(7 citation statements)

References 11 publications

(2 reference statements)

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“…However, it is worth pointing out that these LD 50 values are higher than the one obtained at isolation (LD 50 : < 10) (Aragão et al 2002). In spite of its apparent stability (no alteration had been detected though 32 subcultures) and for reasons still not explained, its virulence in mice was decreased.…”

Section: Resultsmentioning

confidence: 77%

Differences in the stability of the plasmids of Yersinia pestis cultures in vitro: impact on virulence

Leal-Balbino¹,

Leal²,

Lopes³

et al. 2004

Mem. Inst. Oswaldo Cruz

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Plasmid and chromosomal genes encode determinants of virulence for (Perry & Fetherston 1997, Parkhill et al. 2001, Deng et al. 2002. A 102-kb, unstable chromosomal area (locus pgm) is essential for Y. pestis virulence (Fetherston et al. 1992, Hinnebusch et al. 1996, Buchrieser et al. 1998.Typical strains of Y. pestis harbour three plasmids: pPst (9.5kb), encoding a plasminogen activator protease (Pla) (Sodeinde & Goguen, 1988; pFra (90kb), encoding a capsular protein Fraction 1 (F1) with antiphagocytic activities (Du et al. 2002) and murine toxin (Ymt), required for survival in the flea (Hinnebusch et al. 2002); pYV (70kb), encoding the Yop virulon which comprises both the Yop effectors proteins and the proteins necessary for injecting them into host cells. The Yop virulon enables the bacteria to survive and multiply in the lymphoid tissues of the host (Cornelis 2002). Several insertion sequences (IS100, IS200, IS285) present in the three plasmids favour recombination events and genetic plasticity (Filippov et al. 1995, Parkhill et al. 2001, Deng et al. 2002.However, atypical strains lacking some plasmids have been found in several foci around the world. On the other hand, strains containing extra DNA bands or additional cryptic plasmids have also been found (Filippov et al. 1990, Chu et al. 1998. In vitro, Y. pestis genome is very plastic and several changes have been described: emergence of additional DNA-bands, increasing of plasmid molecular mass, and integration of plasmids into the bacterial chromosome with or without loss of functions (Zsigray et al. 1985, Protsenko et al. 1991. Furthermore, the typical plasmids may be eliminated spontaneously at a high frequency during storage in the laboratory or through successive subcultures (Protsenko et al. 1991).The study of the plasmid content of Y. pestis isolates from the plague foci of Northeast Brazil, stored in the laboratory for several decades, showed that some of them displayed an atypical plasmid profile characterized by the absence of some plasmids or by the presence of extra DNA bands (Leal et al. 1997a, Leal & Almeida 1999, Cavalcanti et al. 2002. The absence of plasmids and the emergence of extra-DNA bands in the Brazilian isolates could also have been produced during storage or handling in the laboratory.To observe possible alterations in plasmids of the cultures in vitro and the impact of the alterations to their pathogenicity, three low subcultured and highly pathogenic Y. pestis isolates were submitted to serial subcultures. Colonies selected after subcultures were analyzed for their plasmid content and the presence of some characteristic genes of each plasmid. LD 50 in mice of the parental strains and derived cultures displaying different plasmid contents were compared. MATERIALS AND METHODSBacteria and culture conditions -The study involved two Brazilian isolates: one old (P. Exu 340, originating from a finger bone marrow in a fatal human case in 1969), and the most recent Brazilian isolate (P. CE 882, originating from a hemoculture from a plagu...

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Section: Resultsmentioning

confidence: 77%

Differences in the stability of the plasmids of Yersinia pestis cultures in vitro: impact on virulence

Leal-Balbino¹,

Leal²,

Lopes³

et al. 2004

Mem. Inst. Oswaldo Cruz

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“…These foci appear to exist independently of one another in time and space [1] , and overall numbers of human cases varied from 20 to 100 until the 1970s. Since that time, all of the foci entered a period of relative inactivity, with few or no human cases [5] , [6] , [7] , [8] . The last significant outbreak in Brazil was in the late 1980s in Paraíba [9] .…”

Section: Introductionmentioning

confidence: 99%

Ecology and Geography of Plague Transmission Areas in Northeastern Brazil

Giles

Peterson

Almeida³

2011

PLoS Negl Trop Dis

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Plague in Brazil is poorly known and now rarely seen, so studies of its ecology are difficult. We used ecological niche models of historical (1966-present) records of human plague cases across northeastern Brazil to assess hypotheses regarding environmental correlates of plague occurrences across the region. Results indicate that the apparently focal distribution of plague in northeastern Brazil is indeed discontinuous, and that the causes of the discontinuity are not necessarily only related to elevation—rather, a diversity of environmental dimensions correlate to presence of plague foci in the region. Perhaps most interesting is that suitable areas for plague show marked seasonal variation in photosynthetic mass, with peaks in April and May, suggesting links to particular land cover types. Next steps in this line of research will require more detailed and specific examination of reservoir ecology and natural history.

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“…These surveys can be initiated by governmental agencies or also the result of independent research by university scientists. Trapping and testing rodents for plague in a country in order to estimate the levels of infection in wildlife is an example of this scenario [57].…”

mentioning

confidence: 99%

Linkages between animal and human health sentinel data

2009

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Introduction: In order to identify priorities for building integrated surveillance systems that effectively model and predict human risk of zoonotic diseases, there is a need for improved understanding of the practical options for linking surveillance data of animals and humans. We conducted an analysis of the literature and characterized the linkage between animal and human health data. We discuss the findings in relation to zoonotic surveillance and the linkage of human and animal data.

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Vigilância da peste no Estado do Ceará: 1990-1999

Cited by 14 publications

References 11 publications

Differences in the stability of the plasmids of Yersinia pestis cultures in vitro: impact on virulence

Differences in the stability of the plasmids of Yersinia pestis cultures in vitro: impact on virulence

Ecology and Geography of Plague Transmission Areas in Northeastern Brazil

Linkages between animal and human health sentinel data

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