March 14, 2016

The Zika virus has reached Philadelphia, after the virus already struck two people in Pennsylvania and one in Delaware, all who acquired the infection during travel to affected areas.

It is one of the latest extensions of the mosquito-borne virus that has spread through parts of Africa, southeast Asia, South America and the Caribbean since 2007. Now, the United States is experiencing cases of the virus, which can result in symptoms including fever, joint pains, rashes and, sometimes, conjunctivitis (pink eye). Most significantly, Zika is dangerous for pregnant women, as it causes microcephaly (small head) and other complications in fetuses.

As cases of the virus crop up in different parts of the country, the question could be asked: Were we ready for a disease like this?

Esther Chernak, MD, associate research professor of Environmental and Occupational Health in the Dornsife School of Public Health and director of the Center for Public Health Readiness and Communication, took some time to explain what could make the virus spread further, how to stop it and how it differs from the last news-grabbing epidemic, Ebola.

Can the United States handle this new outbreak?

In the immediate future, the control of Zika virus in the United States will depend on our ability to control the Aedes mosquitos that spread the virus. The state of mosquito control across the country varies and most agencies have fewer resources than they did 10 years ago for the surveillance, tracking and spraying that is necessary.

This is an immediate concern in Puerto Rico, the U.S. Virgin Islands and American Samoa, where the virus is already spreading locally and is likely to surge in coming months. Poor communities are extremely vulnerable, where few people have window screens or air conditioning to protect them from mosquitoes.

In the continental United States, there are communities along the Gulf coast of Texas and southern Florida — where Aedes mosquitoes are present — that have already experienced local transmission of Dengue virus, a mosquito-borne virus related to Zika. These locations are at the highest risk for local spread of Zika virus.

Will there be a vaccine for Zika? And how quickly can we expect it?

Development of a protective vaccine is the definitive control measure and will be critical in locations where effective mosquito control and personal protection will be hard to achieve. Prior work on vaccines against other flaviviruses, like Dengue, provides researchers with a platform for Zika vaccine development and may accelerate the arrival of a Zika vaccine.

Researchers at the National Institutes of Health suggest that early ‘pre-clinical’ trials (e.g., to determine safety and the ability of the vaccine to elicit an immune response) may only be months away. However, testing a new vaccine on pregnant women, the highest risk population for Zika Virus infection, generally poses additional challenges, which may delay the timeframe.

In addition, researchers are working to understand the extent to which existing antibodies to Zika or related viruses may cause additional infectious complications. This possibility will be important in the study of any new vaccine. Thus, a full vaccine testing process may take years.

It can be a Catch-22: Because rare disease epidemics are unpredictable and infrequent, it may not be cost-effective to vaccinate large populations in advance of outbreaks; but rapid deployment of vaccine once an outbreak has begun may not occur quickly enough to control disease spread. Investments in vaccine research and in new medications to treat viruses like this one clearly pay off when infections like Zika emerge.

Have we learned anything from the Ebola outbreak that we can apply to the current situation with Zika?

The Zika virus is very different from the Ebola virus, which is primarily spread from person to person and causes severe and often fatal illness.

For the most part, Zika causes only mild illness but appears to have catastrophic consequences for a developing fetus when pregnant women are infected, much like rubella virus epidemics (German Measles) in the early 1960s.

The Ebola outbreak placed unprecedented pressures on healthcare systems to prepare and respond in ways that provided optimal care for critically ill patients without jeopardizing the health of healthcare professionals and others. This outbreak of Zika virus will place enormous pressure on public health and environmental protection agencies in places where the virus is circulating, all at a time when resources for public health are lower than they were a decade ago.

Investments in public health pay dividends. The routine functions of disease surveillance, laboratory testing, controlling the spread of diseases and disseminating information are often not apparent to the general public. They require professionals trained in epidemiology, public health planning, risk communication, laboratory science and environmental health.

What lessons do you think can be learned from this Zika outbreak?

This reinforces the lesson that public health is global. Our health security is as strong as the health security of nations around the world, and many countries have weak health care and public health systems.

And Zika, like all emerging infections, also reminds us to expect the unexpected. The community that prepares for such diseases understands this all too well. The public and the officials who allocate resources for the important lines of defense need to remember this too.