We discuss the complex eco-social factors involved in the puzzle of the unexpected rapid viral spread in the ongoing Brazilian yellow fever (YF) outbreak, which has increased the reurbanisation risk of a disease without urban cases in Brazil since 1942. Indeed, this rapid spatial viral dissemination to the Southeast and South regions, now circulating in the Atlantic Forest fragments close to peri-urban areas of the main Brazilian megalopolises (São Paulo and Rio de Janeiro) has led to an exponential increase in the number of yellow fever cases. In less than 18 months, 1,833 confirmed cases and 578 deaths were recorded most of them reported in the Southeast region (99,9%). Large epizooties in monkeys and other non-human primates (NHPs) were communicated in the country with 732 YF virus (YFV) laboratory confirmed events only in the 2017/2018 monitoring period. We also discuss the peculiarities and similarities of the current outbreak when compared with previous great epidemics, examining several hypotheses to explain the recent unexpected acceleration of epizootic waves in the sylvatic cycle of the YFV together with the role of human, NHPs and mosquito mobility with respect to viral spread. We conclude that the most feasible hypothesis to explain this rapidity would be related to human behavior combined with ecological changes that promoted a significant increase in mosquito and NHP densities and their contacts with humans. We emphasize the urgent need for an adequate response to this outbreak such as extending immunisation coverage to the whole Brazilian population and developing novel strategies for immunisation of NHPs confined in selected reserve areas and zoos. Finally, we stress the urgent need to improve the quality of response in order to prevent future outbreaks and a catastrophic reurbanisation of the disease in Brazil and other South American countries. Continuous monitoring of YFV receptivity and vulnerability conditions with effective control of the urban vector Aedes aegypti and significant investments in YF vaccine production capacity and research and development for reduction of adverse effects are of the highest priority.

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This article discusses the peculiar conditions that favoured the unexpected introduction of Zika virus into the poorest northeastern region of Brazil in 2015, its speed of transmission to other Brazilian states, other Latin American countries and other regions, and the severity of related neurological disorders in newborns and adults. Contrasting with evidence that Zika had so far caused only mild cases in humans in the last six decades, the epidemiological scenario of this outbreak in Brazil indicates dramatic health effects: in 2015, an increase of 20-fold in notified cases of microcephaly and/or central nervous system (CNS) alterations suggestive of Zika congenital infection, followed by an exponential increase in 2016, with 2366 cumulative cases confirmed in the country by the end of December 2016. A significant increase in Guillain-Barré syndrome in adults has also been reported. Factors involved in viral dissemination, neural pathogenesis and routes of transmission in Brazil are examined, such as the role of social and environmental factors and the controversies involved in the hypothesis of antibody-dependent enhancement, to explain the incidence of congenital Zika syndrome in Brazil. Responses to the Zika outbreak and the development of new products are also discussed.

OBJECTIVES:Zika virus, which was first discovered in 1947, has become a global threat to human health as it is rapidly spreading through Latin America, the Caribbean, the US and Asia, after causing a large outbreak in the Northeast region of Brazil in 2015. There is ample evidence to support that Zika virus is associated with neurological complications such as microcephaly. The review aims to provide an overview on the complex issues involved in the emergence of Zika virus’s neurological disorders and to discuss possible explanations of Zika virus introduction and dissemination in Brazil. We also suggest national and global strategies to adequately respond to the Zika virus emergence.METHODS:We provide an analytical evaluation of the main issues related to the Zika outbreak in Brazil, based on available scientific literature, including government documents, and on epidemiological information from national surveillance databases.RESULTS:The studies on the clinical manifestations of the Zika virus infection coupled with the epidemiological surveillance information in Brazil have provided significant evidence that the Zika virus is associated with neurological disorders such as microcephaly and Guillain-Barré syndrome. Based on phylogenetic and molecular analysis, the hypothesis regarding the introduction of Zika virus in the country is that it took place following international events in 2013 and 2014, when many foreign visitors could have brought Zika virus into Brazil. The immunologically naïve status of populations in the Americas, previous infection with dengue virus, and the increased activity of Aedes aegypti might be the contributing factors for such an outbreak in Brazil. The Zika virus emergence emphasized the importance of cross-disciplinary perspective. Besides the scientific-based vector control strategies, it is important to understand the nature of the evolutionary processes involved in the viral evolution in complex ecosystems and to have social and anthropological knowledge on the conditions related to the spread of the disease in order to properly respond to the spread of the Zika virus.CONCLUSIONS:The experiences of Brazil have demonstrated the significance of multi-disciplinary approach in response to new and resurgent arboviral diseases and provided important lessons that could be applied to other developing countries.

The quest for a cure for HIV remains a timely and key challenge for the HIV research community. Despite significant scientific advances, current HIV therapy regimens do not completely eliminate the negative impact of HIV on the immune system; and the economic impact of treating all people infected with HIV globally, for the duration of their lifetimes, presents significant challenges. This article discusses, from a multi-disciplinary approach, critical social, behavioral, ethical, and economic issues permeating the HIV cure research agenda. As part of a search for an HIV cure, both the perspective of patients/participants and clinical researchers should be taken into account. In addition, continued efforts should be made to involve and educate the broader community.

There is a decreasing trend of HIV vertical transmission in São Paulo with levels approaching elimination, which seems to be associated with antiretroviral policy and interruption of breastfeeding. Although there are serious operational issues, conditions exist to respond effectively. São Paulo state demonstrates that it is possible to achieve advanced levels of control for this mode of HIV transmission.

The emergence and re-emergence of infectious diseases and their rapid dissemination worldwide are challenging national health systems, particularly in developing countries affected by extreme poverty and environmental degradation. The expectations that new vaccines and drugs and global surveillance would help reverse these trends have been frustrated thus far by the complexity of the epidemiological transition, despite promising prospects for the near future in biomolecular research and genetic engineering. This impasse raises crucial issues concerning conceptual frameworks supporting priority-setting, risk anticipation, and the transfer of science and technology's results to society. This article discusses these issues and the limitations of social and economic sciences on the one hand and ecology on the other as the main theoretical references of the health sciences in confronting the complexity of these issues on their own. The tension between these historically dissociated paradigms is discussed and a transdisciplinary approach is proposed, that of social ecosystem health, incorporating these distinct perspectives into a comprehensive framework.

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