Molecular approaches to malaria and Babesisosis diagnosis

The development of additional methods for detecting and identifuing Babesia and Plasmodium infections may be useful in disease monitoring, management and control efforts. To preliminarily evaluate sunthetic peptide-based serodiagnosis, a hydrophilic sequence (DDESEFDKEK)was selected from published BabR gene of B. bovis. Immunization of rabbits and cattle with the hemocyanin-conjugated peptide elicited antibody responses that specifically detected both P. falciparum and B. bovis antigens by immunofluorescence and Western blots. Using a dot-ELISA with this peptide, antisera from immunized and naturally-infected cattle, and immunized rodents, were specifically detected. Reactivity was weak and correlated with peptide immunization or infection. DNA-based detection using repetitive DNA was species-specific in dot-blot formats for B. bovis DNA, and in both dot-blot and in situ formats for P. falciparum; a streamlined enzymelinked synthetic DNA assay for P. falciparum detected 30 parasites/mm(cúbicos) from patient blood using either colorimetric (2-15 h color development) or chemiluminescent detection (0.5-6-min. exposures). Serodiagnostic and DNA hybridization methods may be complementary in the respective detection of both chronic and acute infections. However, recent improvements in the polymerase chain reaction (PCR) make feasible a more sensitive and uniform approach to the diagnosis of these and other infectious disease complexes, with appropriate primers and processing methods. An analysis of ribosomal DNA genes of Plasmodium and Toxoplasma identified Apicomplexa-conserved sequence regions. Specific and distinctive PCR profiles were obtained for primers spanning the internal transcribed spacer locus for each of several Plasmodium and Babesia species.

Parvovirus B19 infections in state of Rio de Janeiro, Brasil: 526 sera analyzed by IgM-enzyme-linked immunosorbent assay and polymerase chain reaction

In this study were analyzed 526 sera; the patients aged from two days to 65 years old presenting exanthema, which was the most frequent symptom observed, besides fever, adenomegaly, and arthralgia. These sera were negative by enzyme-linked immunosorbent assay (IgM-ELISA) for either rubella (495), toxoplasma (41), cytomegalovirus (12), measles (40), dengue (56), and they were submitted to nested polymerase chain reaction (PCR) for B19 DNA and commercial IgM-ELISA for B19. In 39 abortion cases, IgM or DNA were not detected, therefore they were not took into account for analysis. Specific DNA and IgM were detected respectively in 71 (14.5%) and IgM in 62 (12.7%) sera from 487 sera analyzed. IgM and DNA were simultaneously detected in 43 (8.8%), while agreement among the results by PCR and IgM-ELISA was observed in 440 (90.4%). The sera were collected from January 1999 to December 2000, most of them in 1999 (325), during winter and spring. The major number of clinical cases was observed in the age group from one to ten years old. IgM or DNA were detected in 23 from 51 municipal districts of the state of Rio de Janeiro, where the samples were collected.

Oocyst wall formation and composition in coccidian parasites

The oocyst wall of coccidian parasites is a robust structure that is resistant to a variety of environmental and chemical insults. This resilience allows oocysts to survive for long periods, facilitating transmission from host to host. The wall is bilayered and is formed by the sequential release of the contents of two specialized organelles - wall forming body 1 and wall forming body 2 - found in the macrogametocyte stage of Coccidia. The oocyst wall is over 90% protein but few of these proteins have been studied. One group is cysteine-rich and may be presumed to crosslink via disulphide bridges, though this is yet to be investigated. Another group of wall proteins is rich in tyrosine. These proteins, which range in size from 8-31 kDa, are derived from larger precursors of 56 and 82 kDa found in the wall forming bodies. Proteases may catalyze processing of the precursors into tyrosine-rich peptides, which are then oxidatively crosslinked in a reaction catalyzed by peroxidases. In support of this hypothesis, the oocyst wall has high levels of dityrosine bonds. These dityrosine crosslinked proteins may provide a structural matrix for assembly of the oocyst wall and contribute to its resilience.

Why prevent, diagnose and treat congenital toxoplasmosis?

Evidence that prevention, diagnosis and treatment of toxoplasmosis is beneficial developed as follows: anti-parasitic agents abrogate Toxoplasma gondiitachyzoite growth, preventing destruction of infected, cultured, mammalian cells and cure active infections in experimental animals, including primates. They treat active infections in persons who are immune-compromised, limit destruction of retina by replicating parasites and thereby treat ocular toxoplasmosis and treat active infection in the fetus and infant. Outcomes of untreated congenital toxoplasmosis include adverse ocular and neurologic sequelae described in different countries and decades. Better outcomes are associated with treatment of infected infants throughout their first year of life. Shorter intervals between diagnosis and treatment in utero improve outcomes. A French approach for diagnosis and treatment of congenital toxoplasmosis in the fetus and infant can prevent toxoplasmosis and limit adverse sequelae. In addition, new data demonstrate that this French approach results in favorable outcomes with some early gestation infections. A standardized approach to diagnosis and treatment during gestation has not yet been applied generally in the USA. Nonetheless, a small, similar experience confirms that this French approach is feasible, safe, and results in favorable outcomes in the National Collaborative Chicago-based Congenital Toxoplasmosis Study cohort. Prompt diagnosis, prevention and treatment reduce adverse sequelae of congenital toxoplasmosis.

Contributions to the history of ocular toxoplasmosis in Southern Brazil

The evolution of knowledge regarding ocular toxoplasmosis over the last 30 years is described based on studies and observations performed in Southern Brazil. The isolation ofToxoplasma gondii established the definitive diagnosis of the disease. It was proven that in most cases, the disease was acquired after birth, a concept supported by the description of numerous familial cases and observation of the disease many years after primary infection. Epidemiological studies showed important regional variations in the prevalence of the disease due to different factors, including the types of strains involved, of which type I predominates. The large number of patients also enabled detailed study of the different forms of clinical presentation of the disease and its complications. New parameters have been established for the use of steroids and the management of pregnant women with active lesions. Studies on the epidemiology of toxoplasmic infection in pregnant women and newborns showed a high prevalence of infection. The different factors of exposure to infection have also been studied. Gradually, preventive actions have been developed in the sphere of public health, although they have not been sufficiently effective. Trends for future research over the next few years are also outlined.

Molecular and antigenic characterisation of ribosomal phosphoprotein P0 from Babesia bovis

Babesia bovis is a tick-borne pathogen that remains an important constraint for the development of cattle industries in tropical and subtropical regions of the world. Effective control can be achieved by vaccination with live attenuated phenotypes of the parasite. However, these phenotypes have a number of drawbacks, which justifies the search for new, more efficient immunogens based mainly on recombinant protein technology. In the present paper, ribosomal phosphoprotein P0 from a Brazilian isolate of B. bovis was produced and evaluated with regard to conservation and antigenicity. The protein sequence displayed high conservation between different Brazilian isolates of B. bovis and several Apicomplexa parasites such as Theileria, Neospora and Toxoplasma. IgG from cattle experimentally and naturally infected with B. bovisas well as IgG1 and IgG2 from naturally infected cattle reacted with the recombinant protein. IgG from cattle experimentally infected with Babesia bigemina cross-reacted with B. bovis recombinant P0. These characteristics suggest that P0 is a potential antigen for recombinant vaccine preparations against bovine babesiosis.

Toxoplasmose: soroprevalência em puérperas atendidas pelo Sistema Único de Saúde

OBJETIVO: estabelecer a taxa de soroprevalência para toxoplasmose em puérperas atendidas pelo SUS, em duas maternidades de Cuiabá, buscando relacioná-la à idade, antecedentes de abortamento e ao conhecimento desta doença pelas mulheres. MÉTODOS: trata-se de estudo de corte transversal, sendo a amostra constituída por 205 mulheres, com idade entre 14 e 43 anos, no primeiro ou segundo dias de puerpério, atendidas nestes hospitais durante dois meses. Cada mulher foi entrevistada através de um pequeno questionário e submetida à coleta de amostra de sangue periférico. Estas amostras foram armazenadas a 20°C até serem analisadas. A soroprevalência foi determinada, quantitativamente, pela detecção de imunoglobulina G específica contra toxoplasma, através de um método imunoenzimático indireto. Todas as amostras foram analisadas ao mesmo tempo. RESULTADOS: a média de idade das pacientes foi de 22,4 anos, tendo em média 2,2 gestações, sendo a maioria primigestas. A soropositividade para toxoplasma foi detectada em 165 (70,7%) das 205 puérperas estudadas. Não se identificou associação significante entre soropositividade para toxoplasmose e a idade das mulheres (p = 0,967) ou o abortamento prévio (p = 0,82). A maioria das mulheres incluídas neste estudo desconhecia a existência da toxoplasmose (78%) e não se identificou associação significante entre este aspecto e maior soroprevalência contra a doença (p = 0,49). CONCLUSÕES: esta alta prevalência encontrada é concordante com muitos estudos nacionais e estrangeiros. Permanece, entre o grupo de mulheres incluídas neste estudo, um importante contingente delas (29,3%) sob risco de contaminação. A ausência de associação significante entre soroprevalência e a idade das pacientes, relato de abortamento prévio e conhecimento ou não da doença é concordante com alguns estudos e discordante de outros.

Análise espacial da prevalência de toxoplasmose em gestantes de Aracaju, Sergipe, Brasil

OBJETIVO:Analisar a distribuição espacial da prevalência de anticorpos antitoxoplasma em gestantes residentes em uma cidade do Nordeste do Brasil, e correlacionar a prevalência de anticorpos antitoxoplasma com a faixa etária materna e o local de residência.MÉTODOS:Estudo ecológico, descritivo e analítico, desenvolvido no período de 01 janeiro a 31 de dezembro de 2012. As informações foram obtidas retrospectivamente de um banco de dados, e processadas com o pacote estatístico Epi info (Epi 7, Centers for Disease Control and Prevention, Atlanta, EUA) e também em planilha do pacote Microsoft Office Excel, versão 2010. Para avaliar a associação entre a prevalência de anticorpos para a toxoplasmose e a faixa etária, foi aplicado o teste do X2. A análise espacial da prevalência dessa infecção foi realizada com o programa TerraView, versão 4.2.2, utilizando o estimador de intensidade Kernel, que permite estimar a quantidade de eventos em mapa para identificar áreas de maior concentração de casos no município.RESULTADOS:A soroprevalência encontrada para IgG foi de 68,5% (IC95% 67,2-69,8) e IgM de 0,36% (IC95% 0,23-0,6). Foi encontrado incremento da prevalência de IgG associado ao aumento da idade nos bairros mais antigos da capital. Entre as mulheres mais jovens, a maior prevalência foi nos bairros de periferia. Quanto ao anticorpo IgM, a concentração espacial foi mais elevada em bairros da periferia e não ocorreu associação significativa entre a soroprevalência e a idade.CONCLUSÃO:O geoprocessamento permitiu identificar as áreas de maior prevalência, assim como a faixa etária com maior suscetibilidade, servindo como instrumento de avaliação e implementação de medidas preventivas apropriadas para esse município e outras regiões do Brasil.

Prevalência de toxoplasmose em gestantes atendidas em dois centros de referência em uma cidade do Nordeste, Brasil

OBJETIVO: Determinar a prevalência de toxoplasmose e identificar os principais fatores associados à sororeatividade em gestantes atendidas em dois centros de referência em uma cidade do Nordeste do Brasil.MÉTODOS: Foi realizado um estudo transversal com 561 gestantes atendidas em dois centros de referência para pré-natal de alto risco em uma cidade do Nordeste do Brasil. Todas foram entrevistadas por meio de um questionário epidemiológico e foram coletadas amostras de sangue em que foram realizadas sorologia anti-Toxoplasma gondiipara IgG e IgM (ELISA), teste de avidez da IgG e reação em cadeia da polimerase (PCR). A análise estatística foi realizada com o programa SPSS version 18.0 Windows, usando odds ratio e intervalo de confiança de 95%, considerando-se o nível de significância de 5%.RESULTADOS: Constatou-se sororeatividade para toxoplasmose em 437 (77,0%), susceptibilidade em 124 (22,1%) e 5 (0,9%) gestantes com infecção ativa. Não encontramos associação significativa entre sororeatividade para toxoplasmose e idade, procedência, renda, escolaridade, situação da rede de esgotos, número de gestações e idade gestacional. As variáveis com associação significativa (p≤0,05) para sororeatividade foram: multigestas (p=0,03) e convívio com cães soltos na rua (p=0,001).CONCLUSÕES: O estudo permitiu identificar uma alta sororeatividade para toxoplasmose entre as pacientes atendidas no pré-natal, assim como os fatores associados à sororeatividade, devendo ser reforçadas orientações apropriadas sobre medidas de prevenção primária e monitoramento sorológico trimestral das gestantes nesse município e outras regiões do Nordeste do Brasil.