Calling All Southern States: Zika is on Your Doorstep

From its initial discovery in Ugandan forests nearly 70 years ago, Zika virus is beginning to emerge as a worldwide public health crisis. According to the Journal of the American Medical Association, there is active transmission in more than 40 countries in the Americas and Caribbean. With Florida health officials confirming local Zika transmission, and reported occurrences of the Aedes aegypti mosquito, which spreads Zika, in the continental United States, there’s reason to be concerned. The map below represents the number of years where at least one Aedes aegypti mosquito was reported by county between January 1995 and March 2016 in the United States.

These findings, along with the release of the 2016 National Health Security Preparedness Index, indicate the southern states could be at risk. According to the 2016 Index, Oklahoma, Arkansas, Louisiana, Alabama, Mississippi and Georgia scored below the index national average of 6.7 out of 10 for preparedness against public health emergencies. Glen Mays, Professor of Health Policy at the University of Kentucky’s College of Public Health, who leads the team that oversees the 2016 Index, says: “There’s a lot we don’t know about Zika, but states need to have the capability to respond in case of a larger-scale outbreak.”

The CDC recommends that communities be ready for Zika virus by preparing action plans for controlling mosquito populations in their state. The CDC suggests that states and local governments consider an Integrated Vector Management (IVM) strategy when developing their mosquito control action plans. IVM includes mosquito control planning that targets both larval and adult mosquitoes using chemical and nonchemical control methods.

Since the basis of IVM is mosquito monitoring and control at various points of the mosquito lifecycle, below are a few methods the CDC recommends for both larval and adult mosquito control:

• Get Them Early by Managing Larva
One of the keys to larval mosquito control is to manage larva populations before they become adults.

• Reduce the source
Draining and disposing of containers that hold rainwater can go a long way to reducing habitats that produce mosquitoes. Ensuring communities have access to trash containers and services for debris removal is also critical to successful source reduction.

• Apply larvicide
EPA-registered pesticides for larval control may be applied where they are found or added to containers that could serve as breeding sites. Pesticide application can be done using handheld devices, truck-mounted sprayers, aircraft, or a combination of these methods.


Source reduction and larvicide treatment alone won’t keep adult populations low enough to limit the spread of the virus. The objective of the adult mosquito control component of an IVM program is to complement larval control by reducing the number of adult, actively biting mosquitoes, thereby reducing the number of eggs laid in breeding sites. This becomes even more critical if a Zika outbreak occurs. Here are some methods to control the adult Aedes mosquito:

• Targeted outdoor spraying
This method involves spraying outdoor surfaces that may house adult mosquitoes. A handheld device is used to apply the pesticide in a 150-yard radius around the target. This approach is ideal in situations where long-lasting control is desired and requires aggressive attention and quick action to reduce the virus from spreading.

• Targeted indoor spraying
This method should only be considered for locations where the Aedes aegypti can establish itself in homes that do not have sufficient screening or air conditioning. Two chemicals approved for indoor use by the EPA, deltamethrin and bifenthrin, may be sprayed indoors where mosquitoes live. These areas include: back of closets, under and behind furniture, and in corners. It’s important to note that there are no residual insecticides registered in the U.S. for widespread spraying of indoor areas to control adult mosquitoes.

• Widespread outdoor application
A more widespread approach to outdoor spraying is ideal where adult Aedes mosquito populations are high or more widespread local transmission of Zika is found. This type of spraying is called space spraying and offers a rapid method of control in emergency or epidemic situations as it provides rapid knockdown and mortality with little or no residual effects. As in larvicide applications, pesticides for adult mosquitoes approved by the EPA can be applied to wider areas using handheld devices, truck-mounted sprayers, aircraft, or a combination of these methods.

In addition to these Zika control recommendations, state and local health officials should develop a communications network to make sure information is shared in a timely manner. This information should not only include ways to reduce mosquito breeding sites, but also educating the public on personal protection.

As of the date of this publication, officials have reported several locally acquired mosquito-borne cases were reported in Florida. However, all states and local health departments should know that if additional cases are identified, they would need to take aggressive measures to help control the spread of Zika.

The information contained in this publication is intended for general information purposes only and is based on information available as of the initial date of publication. No representation is made that the information or references are complete or remain current. This publication is not a substitute for review of the current applicable government regulations and standards specific to your location and business activity, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the applicable standards or consult with an attorney.