The month of October has finally arrived, bringing to a close what has been one of the hottest summers on record on the East Coast. As Halloween and Thanksgiving draw nearer, so too does cooler fall weather, bringing with it a decline in U.S. mosquito populations. These mosquitoes, particularly those of the Aedes aegypti species, have caused widespread concern throughout the U.S. and abroad, as Zika virus infections have emerged in numerous countries. The continental United States saw its first locally transmitted Zika case in Florida in late July, and additional locally-acquired cases have been occurring since then.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), has been at the forefront of the U.S. fight against this disease. Last month, I had the pleasure of attending a colloquium at Georgetown University’s O’Neill Institute for National and Global Health Law led by Dr. Fauci, which also featured other experts in policy and infectious diseases including Dr. Stephen Morrison from the Center for Strategic and International Studies, and Dr. Daniel Lucey from the O’Neill Institute. While a wide variety of topics were addressed, there were two themes that continually emerged during their discussion.
1. Funding. Public health practitioners cannot effectively fight a disease that has been declared a public health emergency of international concern by the World Health Organization with an empty bank account. While awaiting funding from Congress, NIAID had to shift money earmarked for other deadly diseases such as malaria and Ebola, and the National Institutes of Health had to pull money from other areas to fund Zika activities and research, including vaccines, treatment and vector control.
On September 28, nearly eight months after President Obama’s initial request for $1.9 billion dollars in emergency supplemental appropriations to fight Zika, Congress finally passed a funding bill. While the funding bill, at $1.1 billion dollars, is 800 million dollars short of President Obama’s initial funding target, it is a move in the right direction. Now, it is critical that these funds are distributed promptly to aid in vector control, to invest in research to better understand the effects of the virus on fetuses and children, and to aid in diagnostic technologies and vaccine research.
The idea of a public health contingency fund was brought up multiple times by the panelists, and could potentially alleviate the need to grapple for funding as an epidemic is unfolding. This would greatly enhance preparedness for infectious disease threats, allowing medical countermeasure research to commence quicker and provide resources for public health departments who are in the throes of responding to an emergency.
2. Preparedness. Zika virus is not the first emerging infectious disease to challenge our national and global health security, nor will it be the last. Rapid urbanization, high-speed global travel, climate change and deforestation are just four of the many factors that are driving the emergence or reemergence of severe infectious diseases. Given this reality, we should not be surprised when they occur, and have robust plans and programs in place to mitigate their worst effects. This more proactive response prioritizes disease surveillance, rapid microbiological characterization, medical countermeasure development, and support to the local health sector. As Dr. Fauci stressed, infectious diseases know no borders, and epidemics outside of the U.S. should be just as concerning as ones within our own borders.
As cooler temperatures approach, it is likely that the number of Zika virus cases will decline. It is important, however, that the lessons learned from the Zika virus outbreak are applied to future infectious disease outbreaks, and we’re able to shift to a more proactive response when the next disease inevitably emerges.
Status Report: Zika Virus in the United States
As of early October, there have been 105 locally-acquired cases and 3,712 travel-associated cases in the United States, and thirteen cases of Guillain-Barre Syndrome (GBS). In the U.S. territories, there have been 24,118 locally acquired cases, and 83 travel-associated cases reported, with an unknown number transmitted through sexual contact. Additionally, there have been 39 cases of GBS in U.S. territories. Florida is the only state thus far to have reported locally acquired cases, and along with New York, also makes up the greatest percentage of travel-associated cases. Puerto Rico, unfortunately, accounts for nearly all of both travel-associated and locally acquired cases in the U.S. territories, and is easily bearing the greatest burden from the Zika outbreak.
The National Institute for Allergy and Infectious Diseases NIAID is currently developing multiple vaccine candidates for Zika prevention. The candidates include a DNA-based vaccine, a live-attenuated vaccine, an investigational vaccine using genetically engineered vesicular stomatitis virus, and a whole-particle inactivated vaccine. In late September, the candidate DNA vaccine entered phase 1 clinical trials, which will determine its safety in human subjects. DNA vaccines are a relatively new immunization technology where a sequence that encodes an antigen of interest is introduced and expressed, hopefully leading to an immune response. The early progress of this and other Zika vaccine candidates is encouraging, however it will likely be years before a vaccine is available to the public.
Prevention has largely included efforts to control the mosquitoes that vector Zika, including aerial spraying of insecticides and getting rid of standing water. Individuals are also encouraged to protect themselves from mosquito bites by using insect repellent and wearing long-sleeve shirts. Since Zika is now known to spread through sexual contact, safe sex practices such as condom use are also being promoted.
Finally, in a recent publication in JAMA, Dr. Tom Frieden, the director of the CDC, provides a more in-depth update on the Zika outbreak, which he calls an “unprecedented emergency” due to its ability to cause birth defects via a mosquito bite.
The future of Zika virus is uncertain. While impending colder temperatures will almost certainly decrease transmission in most of the continental US, it remains a possibility that Zika will persist in over-wintering Aedes mosquitoes. As a result, continued research in medical countermeasure development should remain a priority. The U.S. public health and healthcare sectors should also continue to prepare to support the children and families who have been, and will continue to be, impacted by this virus.