9

Closing Remarks

Each of the workshop’s two days ended with a brief session summarizing that day’s remarks. The summaries offered a chance to look back on the high points of the workshop.

DAY 1: CURRENT LANDSCAPE AND RISK ASSESSMENT OF ARBOVIRAL THREATS

Peter Daszak of EcoHealth Alliance summarized the first day’s proceedings.

In his introductory remarks, Thomas W. Scott focused on the complexity of arbovirus life cycles and the drivers of disease risk, which create challenges for surveillance, control, and mitigation techniques. However, Daszak noted, “complexity drives innovation,” which should eventually lead to answers.

Next, Eve Lackritz spoke about the Zika roadmap. Her talk, Daszak said, was “a reminder of where we are and what we don’t have yet despite decades of research.” For Zika, that means no vaccines, no diagnostics, and no antenatal tests. “It is a disgrace,” he said, “that such a devastating disease leaves us 10 years on with this situation.”

The first panel, with speakers Duane Gubler, Sylvain Aldighieri, Laura Kramer, and Raman Velayudhan, described the current situation with arboviruses. A major message there, Daszak said, is that complacency is a problem. New arbovirus outbreaks will continue occurring, yet not enough is being done to prepare for them. The session also covered the underlying drivers of arboviral disease, such as population growth, urbanization,

global travel, and global climate change. Various comments indicated the seriousness of the arboviral threat, including how the West Nile virus expanded in the United States and the fact that there is local transmission of dengue in places like Arizona, California, Texas, and Florida as well as France, Italy, and Portugal.

The second session, with speakers Diana Rojas, Nuno Faria, Lee Ching Ng, and Debi Boeras (speaking for Rosanna Peeling), described several positive developments in epidemiological surveillance, genomic surveillance, risk assessment, and diagnostics. For instance, genomics and hotspot mapping can be used to better target surveillance to the places that most need it. Ng’s case study of Singapore shows what is possible with an integrated combination of various techniques, including rapid testing and community alerts and a carrot-and-stick approach to individual compliance.

The third session focused on different ways to combat arboviral threats, including vaccines, vector control, surveillance, and modeling. The speakers were Gabriela Paz-Bailey, Thomas W. Scott, Thais dos Santos, and Oliver Brady. One clear message, Daszak said, is that the complexity of arboviral diseases is a challenge to finding effective responses. Particularly striking, he said, is how slow progress is on vaccines. Although there have been some developments in chikungunya, yellow fever, and dengue, vaccines are still a work in progress for Zika and West Nile, he added Among the challenges are how sporadic the outbreaks are, the complexity of the life cycles, and the uncertainty of the market. Some good news is that targeted residential spraying led to a 90 percent reduction in dengue cases in Australia. “These interventions work,” Daszak said, but what is lacking is the implementation science, such as trials of single and multiple interventions. “That is happening now, and it’s really quite an exciting time.” The experience of the Pan American Health Organization (PAHO) with virtual collaborative spaces shows how hard it is to work with different countries and share data in a rapid way. Although the idea of virtual collaborative might seem obvious to some, Daszak noted the large amount of work that has been invested to gain trust from countries to allow rapid information sharing for diseases of public health relevance.

The day’s final session had Erin Staples and Peter Hotez speaking on lessons learned from previous outbreaks. Daszak found two phrases particularly memorable: Staples’s reference to having “an arbovirologist in every state,” and Hotez’s phrase of “arbovirus tsunami” as the sort of language that people in the room should be using to get better funding and more recognition for these diseases.

DAY 2: INNOVATION FOR FUTURE ARBOVIRUS MITIGATION

Thomas W. Scott, Distinguished Professor at University of California, Davis, offered a summary of the second day. He began with Session five,

whose speakers were Jamie Lloyd-Smith, Nikos Vasilakis, Segaran Pillai, and Valerie Paz-Soldán. One of the topics was analytical tools, which can be used, for example, to understand animal-to-human transmission. Such transmission requires a series of critical steps for a virus to spread, and these can be used to identify viruses of greatest concern and to tease apart the elements of spillover, which might lead to targets for intervention. Vasilakis spoke about mechanisms to assimilate, interpret, and implement data with the goal of identifying the drivers behind virus emergence and spread to better understand how to interfere with outbreaks. Pillai discussed how to rank different viruses according to their risk. This makes it possible to stratify viruses by the degree of health concern. Then Paz-Soldán spoke about implementation and the behavioral and social sciences and argued that when one is assessing the public health value of a tool, it is critical to look at the details associated with the real-world implementation of that tool. Scott said that this brings up the crucial difference between the efficacy and effectiveness of an intervention. Efficacy is how well the intervention works in perfectly controlled circumstances and can be judged best through randomized controlled trials (RCTs). Effectiveness, on the other hand, is what happens in the real world. This is a critical point, Scott said, because one can have amazing RCT results that indicate an intervention is very promising, but “if we don’t know how to implement it and we don’t do it correctly, we’re not going to get the outcome that we want.” He suggested that effective use has been a problem with many of the tools that have been developed over the past 50–70 years.

Session six, with speakers Steven Lindsay, Graham Alabaster, Eng Eong Ooi, and Anne Wilson, was devoted to the urban environment and how best to manage it. Lindsay described the concept of “building Aedes out,” which suggests that new urban development and construction should be carried out in a way that minimizes the transmission of viruses by mosquitoes. Scott described this as “a city-led, locally adapted new paradigm for proactive urban viral disease prevention.” Lindsay also spoke about linking arboviral disease prevention with networks like Resilient Cities or Healthy Cities, Healthy People. There are people already moving forward with these networks, Scott said, but arboviruses are not on their radar. “So, it’s really up to us to engage with them and get them to start thinking about how they could benefit if they included this in what they’re doing.”

Alabaster spoke about how urban expansion is an opportunity for local public health improvement, such as can be accomplished by things like solid waste removal, which would improve the quality of people’s lives but also reduce the breeding sites for Aedes aegypti. That in turn can mobilize local support for more of such efforts and their long-term maintenance. The two-pronged approach that Alabaster described can be a very powerful tool. To get political support for a project, Scott said, one cannot have a program

that goes beyond election cycles and takes 10 to 20 years to show results. A better approach, he continued, is to do a short-term project on a limited scale, and apply the best tools, and then use the positive results from the program to build support for a larger, longer-term program.

Of all the techniques available right now, Scott said, one of the most promising is targeted indoor residual spraying along with larval control. At the same time, there should be an effort to push new construction in a direction that will make it easier to disrupt the transmission of arboviruses, he continued. Vector control will always be necessary, he said, but if new development and construction is done in a way that accounts for virus transmission, future efforts may rely less on direct vector control and more on the built environment. Singapore, as discussed by Ooi, offers a case study of how reshaping the built environment in innovative ways can have a major effect on arboviral transmission as well as on the standard of living in an area. Wilson made the case that, with the appearance of Anopheles stephensi mosquitoes, there is an opportunity for synergy between malaria control efforts and arboviral control efforts.

Finally, Scott reviewed the workshop’s final session, which captured the most important aspects identified in the workshop for strengthening preparedness for arboviral diseases. The speakers/discussants in that session were Lee Ching Ng, Linda S. Lloyd, Audrey Lenhart, and Kariuki Njenga.

One question that arose in the session was whether RCTs are necessary. They can have a real benefit, Scott said, pointing to the remarkable RCT result against dengue for the vector-control method using Wolbachia replacements. On the other hand, he said, there are clearly issues with effectiveness versus efficacy, and it can be very difficult to carry out RCTs with multiple different implementation arms. A key message from the session was the importance of community engagement if a program is to be sustainable, including having the right leaders in place in the community. As such, the chosen location to do a pilot study can make all the difference.

Scott shared that four other major themes that emerged were the value of context-driven, socially adapted interventions; the importance of funding effectiveness trials; the opportunity offered by projects that address arboviruses at the same time as they address other disease; and the need to strengthen the evidence base. The experience in Singapore shows that a very effective vector-control program can result in lower herd immunity of a population to the point that an outbreak is possible even when there are very few mosquitoes. Thus, Scott said, “Vector control unto itself is not sustainable for the long-term. It can have an effect for a period of time, but a long-term sustainable intervention should combine different strategies, he said.

Speaking of points of interest from the workshop, Scott named the work done by Lloyd-Smith on modeling zoonotic spillover, noting the

importance of taking a systematic approach to understanding the processes that are involved to prevent disease. He also highlighted Pillai’s systematic ranking of risks as a way of targeting interventions and Njenga’s discussion of how getting a multivalent vaccine for domestic animals could almost eliminate epidemic Rift Valley fever transmission. He also noted Steven Lindsay’s comments on the importance of the built environment and demonstrating benefits of environmental management to city leaders to gain buy-in and enact sustainable change.

Scott highlighted one take-home message for workshop attendees: if the status quo of inaction prevails, the situation will only become worse. The workshop has provided insight on ways to move forward with innovative and integrated arbovirus control, and action must be taken to apply these strategies to make meaningful progress.

This page intentionally left blank.