Zika virus emergency in Brazil: scientific challenges and early developments

In the last decades, Brazil has faced different arbovirus epidemics. However, none of them had the complexity of Zika virus and associated diseases. In April 2015, the first cases of the virus were reported in the country¹. Initially, the occurrence was considered to be of no greater threat than dengue or chikungunya. Nonetheless, by the end of October, the number of microcephaly cases started to rise sharply, which triggered a thorough investigation and subsequently the declaration of a National Public Health Emergency^2,3. On December 5, the President of Brazil launched the National Microcephaly Response Plan, involving 19 institutions and structured on three pillars: 1) vector control, 2) health care, and 3) research & education².

The research agenda focused on four main areas: 1) virological, clinical and epidemiological studies, 2) alternative vector control strategies, 3) development and evaluation of diagnostic tests, and 4) development and evaluation of vaccines. After almost one year since the reporting of the first cases of microcephaly associated with Zika in the country, many developments in the agenda were achieved and other challenges emerged:

1) Virological, clinical, and epidemiological studies – Researchers in Brazil were able to characterize transplacental Zika transmission and its influence in halting neurological development^4,5. These findings supported campaigns to increase awareness and protection of pregnant women against mosquitoes. Although Zika seems to be the main culprit of microcephaly increase, other cofactors are under investigation, what may lead to new policies to tackle other risk factors⁶. Recent studies also suggest that the consequences of Zika infection go beyond microcephaly, pointing out the need to further characterize syndromes and related diseases as well as to revise diagnostic and management protocols⁷.

2) Alternative vector control strategies – After the Zika emergency was declared, a range of new vector control strategies were proposed, which target different phases of the mosquito life cycle and different settings. The Brazilian Ministry of Health has been promoting effectiveness evaluations of promising strategies, including Wolbachia-infected mosquitoes and mosquito-driven dissemination of pyriproxyfen^8,9. These studies will provide invaluable information to improve Aedes control policies in Brazil. Entomological studies have also been investigating if Aedes Aegypti is the only Zika virus vector in Brazil¹⁰. This is a crucial point because other mosquito species have different breeding and feeding habits; in which case, the results of these studies may have an important impact on vector control measures.

3) Development and evaluation of diagnostic tests – Since the first cases of Zika have been identified there has been an ongoing effort to improve molecular tests and to develop highly sensitive and specific serological tests, with limited cross-reaction with other arbovirus, allowing point-of-care utilization¹¹. Candidates have arisen from private and public initiatives, which are being validated and evaluated with support from the Brazilian Ministry of Health. The inclusion of such tests in the public health system will require training of health professionals and modifying follow-up protocols. As the spectrum of Zika consequences widens, so does the need for detection and treatment.

4) Development and evaluation of vaccines – The development of an effective and secure vaccine against Zika has been one of the main goals worldwide. Different research groups are working on that, including groups in Brazil. Nonetheless, only one vaccine candidate has received FDA approval to initiate a phase I clinical trial¹². Brazilian governmental bodies, such as the National Research Ethics Council, the National Clinical Trials Registry and the National Health Surveillance Agency, developed task-forces to timely evaluate research projects, clinical trials, and products related to Zika virus and associated diseases.

It has also been a race against the clock to quickly translate the results of R&D initiatives into public policies. For this purpose, the Brazilian Ministry of Health set up the Zika and Related Diseases Specialists Network, fostering greater collaboration between researchers and decision makers¹³. The joint effort between the Ministries of Health; Science, Technology, Innovation and Communication; and Education also made possible the launching of an open call for strategic research projects to tackle this emergency.

International research collaborations were established with partners such as the Center for Diseases Control, the World Health Organization, the US National Institutes of Health and the British Council. Since WHO declared a Public Health Emergency of International Concern, new communication channels have also been built between Ministries of Health from different countries¹⁴. As the world becomes more interconnected and urbanized, it is likely that many other epidemics will follow. Therefore, it is paramount that lessons learned from Zika lead to fast and effective responses to future global threats.