Ebola and Zika: what one can teach us about the other

Just two years ago, Ebola ripped through West Africa, resulting in 11,000 deaths and orphaning more than 16,000 children. My colleagues and I at The Boston Consulting Group responded to a call from the UN to assist in getting the epidemic under control. Working closely with the World Health Organization, we supported the development of a 30-60-90 day plan to reverse the trajectory of the outbreak. Sadly, we knew the outbreak would get much worse before it got better—but the health care providers and affected communities ultimately prevailed.

Now we are faced with Zika, a mosquito-borne infection that is being linked to microcephaly, a birth defect in which children have undersized heads and abnormal brain development. With Zika outbreaks in 69 countries, more than 32,000 confirmed cases in the US and US territories, and evidence that the virus is becoming endemic in many parts of the world, people are asking: how can we take the lessons from Ebola to change the trajectory of Zika?

We need to be careful about importing lessons directly from Ebola to Zika, because the analogy breaks down quickly. To be sure, the two viruses share certain similarities: for both, there is no vaccine; we can treat the symptoms, but not the virus; and we know relatively little about either disease. But there are also substantial differences.

First, there’s the issue of transmission. Ebola was rapidly transmitted from human to human and the disease was perpetuated by local traditional burial practices. Substantial changes in behavior, and infrastructure, were needed to reverse the epidemic. Zika is mosquito-borne and the best way to control the disease is by preventing mosquito bites. Further, the Zika epidemic has a seasonal component: mosquito transmission will drop off in the colder months and flare up again as the weather warms.

Second, while both can have devastating effects, the impact of Ebola was very different than Zika. Ebola had an immediate effect, most often resulting in death within a few days. Zika can have mild or no symptoms—infected individuals may not even know they have it. The most severe consequences of Zika are second order, in pregnancy. This can take up to 9-12 months to manifest, but results in a lifetime of disability for the child born with microcephaly.

With colder weather on the way in some parts of the world, and early control efforts beginning to have impact, we may get a short reprieve from Zika—the WHO recently announced that Zika is no longer considered a global public health emergency. But Zika will rebound—and we need to have a robust strategy in place when it does.

Balancing a People-Centric Approach with a Virus-Centric Approach

Perhaps one of the most important lessons we learned from the Ebola crisis was this: the response to the Ebola crisis was too virus-centric for too long. By virus-centric, I mean the global health community mobilized as many resources, equipment, personnel, and technical solutions as it could possibly muster to fight the virus. But this approach can only get us so far. It wasn’t until the response became “people-focused”—where emergency response teams listened to the community, understood the influences of culture, beliefs, and practices, adapted their strategies accordingly, and the communities themselves began to change their behaviors—that Ebola began to be brought under control.

With Zika, the virus poses a unique people-centric challenge: how can we make a compelling case for widespread behavior change when the most severe consequences are limited to a small population (families who are pregnant or interested in becoming pregnant) and the effects may take months to manifest? Individuals in affected communities can deter mosquito bites by applying strong insect repellent, wearing clothing that covers their arms and legs, using screens on windows, or sleeping under bed nets. In addition, they can further prevention efforts by removing standing water outside the home. These are simple behavioral changes that could markedly reduce Zika cases. We know this kind of widespread behavior change can occur. Just think of seatbelts and sunscreen. Thirty years ago, these were rarely used. Now, children in many countries are required to use car seats and they are also typically slathered head to toe in SPF 50 sunscreen.

But given the difficulty in ensuring behavior change, we do also need virus-centric approaches to manage Zika. In an effort to keep the mosquito population under control, some cities have used aerial spraying, standing water treatment, and other similar prevention techniques in high-risk areas. These are important, and they offer short-term benefits, but we also need to be thinking about the more sustainable, longer-term solutions.

Making an investment in research and development must also be a priority. The Coalition for Epidemic Preparedness Innovations (CEPI), for example, is a public-private alliance that aims to finance and coordinate the development of new vaccines for infectious diseases, and they could play an important role in this regard. Since market-based incentives are not necessarily sufficient to encourage continued R&D investment in Ebola, Zika, and other emerging diseases, CEPI could fill a critical gap.

We also need more innovation in the area of vector control. Two South American cities—Rio de Janeiro, Brazil and Medellin, Colombia—recently announced that they will deploy Wolbachia-infected mosquitoes to combat viral infections. The Wolbachia bacteria hinders the insects' ability to transmit Zika, dengue, and a host of other viruses. This entirely novel form of vector control represents the kind of out-of-the-box approach that could dramatically improve protection from Zika.

The Path Forward

Zika’s trajectory and its long-term global impact is still unclear, but we know that early funding for emergency preparedness offers a high return on investment. The US Congress approved $1.1 billion in funding to help fight the spread and effects of the Zika virus. The funding includes $394 million for mosquito control, $397 million to help develop a vaccine and better diagnostic testing, and $66 million to help people affected by Zika in Puerto Rico and other U.S. territories. This is an extremely important first step and should be applauded.

But the battle against infectious disease requires many warriors and continued commitment. We must enlist the people within the affected communities to join the cause. By listening to their needs, and engaging them in tailoring interventions and finding novel ways to encourage behavior change, we'll be much closer to effective, global solutions.