Risk of Zika virus transmission by blood donations in Brazil

ABSTRACT Background: Zika, a disease caused by Zika virus infections, has recently emerged and caused outbreaks in many parts of the world. The clinical manifestations of Zika are usually mild, mostly presenting as an exanthematic febrile disease, but on some occasions, it might be associated with microcephaly after intrauterine infection, and Guillain-Barré Syndrome. Zika virus is primarily transmitted by mosquito bites, but other means of transmission have been described, and potential risk for blood transmission has been reported in French Polynesia and Brazil. Methods: To investigate the risk of Zika virus infection after a blood transfusion in an area of Brazil where a possible transmission by a platelet concentrate has been described. Using a mini-pool format, 1857 blood donations were evaluated by real-time reverse transcriptase polymerase chain reaction designed to detect Zika virus RNA. Results: After testing samples individually from positive mini-pools, the prevalence of Zika virus RNA was only 0.16%, a result probably associated to the low circulation of this virus in the study area. In addition, it was evident that the implementation of post-surveillance programs is important to detect Zika virus infections in blood donors, as the post-donation surveillance program detected two blood donors with the disease in this study. Conclusion: This study shows that the risk for Zika virus transmission by blood transfusion is real, even in regions with a low circulation of the disease, but the combination of the detection of Zika virus RNA by polymerase chain reaction and post-donation surveillance might reduce the risk of transmission by blood transfusions.

Will Mayaro virus be responsible for the next outbreak of an arthropod-borne virus in Brazil?

Abstract Mayaro virus is an alphavirus from the Togaviridae family and is transmitted mainly by Hemagogus mosquitoes. This virus circulates in high-density tropical forests or rural areas of Central and South America causing a disease characterized by high-grade fever, maculopapular skin rash and marked arthralgia that, in some patients, can persist for long periods after infection and may be misinterpreted as chikungunya. Although only a few outbreaks involving this virus have been reported, in the last years the number of Mayaro virus infections has increased in the central and northern regions of Brazil. In this review, we describe the reported prevalence of this infection over the years and discuss the circumstances that can contribute to the establishment of an urban mayaro virus epidemic in Brazil and the problems encountered with the specific diagnosis, especially the antigenic cross-reactivity of this pathogen with other viruses of the same family.

Sensitivity and detection of chikungunya viral genetic material using several PCR-based approaches

Abstract INTRODUCTION: Chikungunya fever is a condition resulting from infection by chikungunya virus (CHIKV), an Aedes sp.-transmitted virus. This disease has been diagnosed in thousands of cases in the Americas, particularly in Brazil, in recent years, and there is an ongoing epidemic of chikungunya fever in Brazil that began in 2014. Clinical diagnosis is difficult; only a few cases have been confirmed by laboratory tests due to the low number of specific, efficient tests available for virus or antibody detection. Here, we aimed to evaluate different polymerase chain reaction (PCR) approaches for detection of CHIKV genetic material. METHODS: Specific primers and probes within the viral capsid gene region were designed for this work. To evaluate the analytic sensitivity of detection, human sera were spiked with serial dilutions of the viral stock. Several PCR protocols were performed to investigate the sensitivity of CHIKV RNA detection in serum dilutions ranging from 106 to 1 PFU equivalents. RESULTS: The technique showing the greatest sensitivity was a real-time PCR assay using specific probes that could detect the genetic material of the virus at all dilutions, followed by conventional PCR. Digital PCR showed low sensitivity and was much more expensive than other technologies. Digital PCR should be used for specific purposes other than clinical diagnosis. CONCLUSIONS: Although quantitative PCR using probes was more expensive than the use of intercalating dyes or conventional PCR, it had the highest sensitivity out of all tested PCR approaches.

First complete Genome Sequence of Zika Virus (Flaviviridae, Flavivirus) from an Autochthonous Transmission in Brazil

We report here the genome sequence of Zika virus, strain ZikaSPH2015, containing all structural and nonstructural proteins flanked by the 5' and 3' untranslated region. It was isolated in São Paulo state, Brazil, in 2015, from a patient who received a blood transfusion from an asymptomatic donor at the time of donation.

Dengue vaccines: what we know, what has been done, but what does the future hold? / Vacinas contra a dengue: o que sabemos, o que tem sido feito, mas o que nos reserva o futuro?

Dengue, a disease caused by any of the four serotypes of dengue viruses, is the most important arthropod-borne viral disease in the world in terms of both morbidity and mortality. The infection by these viruses induces a plethora of clinical manifestations ranging from asymptomatic infections to severe diseases with involvement of several organs. Severe forms of the disease are more frequent in secondary infections by distinct serotypes and, consequently, a dengue vaccine must be tetravalent. Although several approaches have been used on the vaccine development, no vaccine is available against these viruses, especially because of problems on the development of a tetravalent vaccine. Here, we describe briefly the vaccine candidates available and their ability to elicit a protective immune response. We also discuss the problems and possibilities of any of the vaccines in final development stage reaching the market for human use.

Dengue, doença causada por qualquer um dos quatro sorotipos dos vírus dengue, é atualmente a mais importante doença viral transmitida por artrópodos em todo o mundo, tanto em termos de morbidade como de mortalidade. A infecção por estes vírus causa grande variedade de manifestações clínicas, desde infecções assintomáticas até doenças graves com envolvimento de diversos órgãos. As formas graves da dengue são mais frequentes em infecções secundárias por sorotipos diferentes e, por esta razão, a vacina contra a dengue deve ser tetravalente. Embora várias estratégias tenham sido usadas no desenvolvimento de vacinas contra a dengue, não há ainda nenhuma vacina disponível, particularmente por problemas no desenvolvimento de uma vacina tetravalente. Aqui, descreve-se brevemente os candidatos vacinais disponíveis e a capacidade de eles induzirem resposta imune protetora contra novas infecções. Ainda, discutimos os problemas e as possibilidades de liberação, para uso em seres humanos, de qualquer uma das vacinas em fase final de desenvolvimento