With Zika virus dominating headlines, we reached out to Dr. Jeff Duchin, Health Officer at Public Health – Seattle & King County and Professor in the Division of Infectious Diseases at the University of Washington to discuss some of the unique challenges in the U.S. arising from the sudden emergence of this virus.
It seems like every year or so, there’s a new global infectious disease outbreak, like Ebola or MERS, and now Zika. Why is this, and what should we be prepared to do about it?
Part of this is due to the increased encroachment of humans on new habitats coupled with increased ease of regional and global travel, creating more opportunities for disease to spread. Humans and disease-carrying organisms are coming into more contact through urbanization and deforestation. Climate change has facilitated the movement of vectors like mosquitoes to broader habitats. And microorganisms have been adapting to be resistant to some of the treatments that have worked in the past.
To be effective in our response to infectious diseases, we must invest in a stronger public health system at the federal, state and local levels. State and local public health departments are on the front lines in our communities. We do surveillance to track and monitor diseases, update and coordinate our partners in hospitals and healthcare, provide public information and education, and operationalize federal guidance and plans on the local level.
Ongoing cuts in federal funding for the CDC and state and local public health have reduced our ability to respond. Across the nation, the cuts at state and local health departments have compromised critical health emergency preparedness capacity and shrunk the public health workforce.
We appreciate the strong support the Big Cities Health Coalition and NACCHO have shown for the White House’s emergency funding for Zika virus readiness and response capacity. Without this funding, the federal public health system would be seriously hampered in developing the diagnostic tests and vaccine needed for Zika virus and in researching the link between Zika virus infections, birth defects, and other health risks. At the state and local levels, this investment will shore up mosquito control programs and develop the infrastructure needed for testing and surveillance of the disease.
Yet, while intermittent supplemental funding during health emergencies is critical, it does not provide the stability needed to ensure that an adequate level of public health resources, personnel and systems are available to address the many infectious, non-infectious and chronic disease health challenges facing our communities every day. And when emergency funds displace resources for other public health work, the net benefit is diminished. Because Zika is assuredly the latest, but not the last global infectious disease threat to emerge, long-term solutions to the lack of stable public health funding can’t come too soon.
Just how much of a threat is Zika virus to the American public?
In the US, the risk is mainly to travelers. Zika is a primarily a concern for pregnant women that are in or have traveled to areas with Zika virus transmission. Current information about Zika infections in pregnant women suggests a link to a serious problem in newborns called microcephaly, an abnormally small brain and skull, and other poor pregnancy outcomes. Zika can also spread through sex with a man who has been in a Zika-affected area because the virus can survive in semen for an extended period. A link between Zika and a type of paralysis that can last weeks to months called Guillain Barré syndrome is also being investigated.
Based on experience with dengue and chikungunya (viruses that are transmitted by the same Aedes mosquitoes) Zika is unlikely to cause large outbreaks in the US. In areas within the US where these mosquitos exist, limited transmission of Zika could occur. For those who are infected, only about one in five will experience symptoms, and symptoms are typically mild: fever, rash, joint pain, or conjunctivitis (red eyes).
Some political candidates have called for quarantine of travelers from countries that have ongoing Zika transmission. Do you think that will help in the response?
It’s not a good idea. Quarantine of travelers exposed to Zika virus is neither appropriate nor feasible, and would likely have no meaningful impact on the spread on the disease–but would result in significant negative unintended consequences on travel, commerce, individuals and families. Quarantine of returning travelers would be costly and complicated to carry out for no real benefit. Although Zika poses a real threat of continued global spread, measures to protect travelers, reduce the mosquito vectors and control outbreaks where they are occurring are more appropriate responses.
What are more practical steps for protecting against Zika?
Right now, since Zika is not spreading locally in the US, avoiding travel to Zika-affected areas, particularly if you are pregnant, is the best prevention measure. Keep up with travel alert updates from the CDC. Take precautions to protect against mosquito bites if you do travel, such as wearing mosquito repellent, covering up with long sleeves and pants, and sleeping in a screened-in or air-conditioned room.
There have been two reports of Zika transmission through sexual intercourse, but there’s still much that’s unknown about the risk of sexual transmission. Until we know more, CDC recommends that men who have lived in or traveled to an area with Zika virus should abstain from sex or use condoms if their partner is pregnant, and it’s a good idea to take those precautions with female partners that are not pregnant as well.
It may be a matter of time before we see local transmission in the US in parts of the country where the Aedes species of mosquitoes lives. Local and state health departments are working with the CDC to monitor for disease, equip diagnostic laboratories, and support mosquito control programs. We are also educating our communities about Zika virus, especially healthcare providers and the pregnant women they serve. Although it will require some time for development and safety testing, a Zika virus vaccine may eventually offer the best protection.
In the coming months, there are large-scale events happening in countries with ongoing Zika transmission, like Carnival in much of Latin America and the Caribbean, and the Olympics in Brazil. What are some of the challenges presented by these events?
International travelers can unknowingly carry infectious diseases to their travel destinations. Whether the disease then spreads or takes hold locally depends on a variety of factors. Density of population is one factor that facilitates spread of infection, while pre-existing population immunity would prevent it. For diseases like Zika, dengue, and chikungunya, the specific mosquitoes that can carry the virus must be present for transmission to occur. Factors that reduce opportunities for mosquitos to bite an infected person and then bite a susceptible person would reduce the risk of spread. The more that susceptible people are crowded together, the more opportunity a disease would have theoretically to move from person to person.