The Zika virus is coming to the United States, and it has prompted a very high level of concern on the part of public health officials at all levels. Media attention on Zika is white hot, and articles and reports are appearing on a daily basis. And it seems that each new finding about the effects of this mosquito-borne disease ratchets up fears to an even higher level.
So, what does Zika virus disease mean to parks and recreation? Are our employees and the public we serve on the front line of exposure? Do we need to take action, and if so, what kind? As the threat of locally originated cases of Zika grows, how can park and recreation agencies be best prepared to deal with this emerging public health threat?
What Is It?
Zika virus diseasae is a mosquito-borne disease having much in common with dengue fever, Chikungunya and West Nile virus. Zika affects the myelin sheath of nerves, resulting in neurological damage. While first thought relatively benign, Zika has now been identified by the World Health Organization (WHO) as the cause of microcephaly in infants and Gullian-Barré Syndrome in adults, two especially damaging neurological conditions.
Zika was first discovered in 1947 in Africa near the Zika forest in Uganda, thus its name. While known medically since 1948, it wasn’t until 2007 that a widespread infection of up to 80 percent of the human population of the Island of Yap in Micronesia was discovered. However, even then, the disease still did not prompt a high level of concern because the effects on most people were mild — a slight rash, itching, fever, muscle aches and other symptoms — and where it breaks out, many people didn’t even know they contracted Zika virus.
However, early in 2015, the disease began to explosively spread through the Americas beginning in Brazil. What was once seen as an ailment without serious impacts suddenly became a major public health issue. In Brazil alone, more than 4,000 cases of microcephaly, a birth defect causing an abnormally small head and incomplete brain development, were reported in 2015. In addition, a number of instances of Gullian-Barré, a condition in which the body’s immune system attacks part of the peripheral nerve system, were reported in adults. Recent scientific research is now linking Zika to other possible neurological damage, and the level of public health concern has grown even higher with the recent determination by WHO and the Centers for Disease Control and Prevention (CDC) that Zika is a causal factor in these conditions.
How Is It Transmitted?
There are more than 3,000 species of mosquitoes world-wide, and about 175 mosquito species have been found in the United States. Only two mosquito species in the United States are considered to be potential carriers of the Zika virus. These are the Aedes aegypti mosquito, which is sometimes called the Yellow Fever mosquito and more recently the “urban mosquito,” and Aedes albopictus, which is commonly called the Asian tiger mosquito. Because of its habits and its closer association with humans, Aedes aegypti is considered to be the primary vector species for Zika in the United States.
Aedes aegypti has been around a long time in the United States, in fact, some attribute an outbreak of Yellow Fever in 1793 in Philadelphia to this mosquito species. The species is common in Florida, parts of the Southeast and along the Gulf Coast states. Although it is considered a tropical and sub-tropical mosquito, it has moved rapidly northward into temperate climates. A breeding population of A. aegypti has been verified in Washington, D.C. Some researchers believe that the range of this species is expanding northward because of climate change conditions. A. albopictus, the Asian tiger mosquito, only appeared in the United States in 1980, but since then, it has a much broader range northward in the country.
The Zika virus is generally transmitted by the bite of an infected mosquito. If transmitted by a mosquito, it will only be through the saliva of the female mosquito when she re-bites a human to obtain blood, which contains needed proteins for her eggs. New evidence is emerging that Zika may also be transmitted by sexual contact. Much is still unknown, but the recent declaration by the WHO, now confirmed by CDC, that the Zika virus causes microcephaly in infants and Gullian-Barré in adults, makes concerns much more serious. Dr. Thomas Friedan, head of CDC, said, “There is no longer any doubt that Zika causes microcephaly.”
The greatest threat has been to women of child-bearing age who are pregnant or who are planning to become pregnant, but new evidence of potential sexual transmission of Zika means that there is a much wider pool of those who may transmit the disease. Public health officials have previously used language such as “has been associated with…” or “is linked to…” but now are expected to be much more direct about the potential threat.
All cases of Zika virus in the United States so far have been “travel” cases, that is, they have come from persons who have traveled to countries where the disease is endemic. There have been no Zika cases that have yet been reported from local transmission.
John-Paul Mutebi, a research entomologist for CDC and a member of the agency’s Zika Action Team, agrees with the description of A. aegypti as the “urban mosquito.” He says this species is most often associated with cities because of its preference for warmer temperatures, darker places and higher levels of moisture. “Where humans go, this mosquito follows,” he says. Mutebi also noted that wherever A. aegypti is found, it is expanding its range northward and remaining there, depending on how mild winters are. Range estimates are now northward to New York City in the east, Kansas City in the Midwest and San Francisco in the west. Populations are generally estimated to be higher along coastal areas because of warmer temperatures.
Aedes aegypti is a highly successful mosquito of the Cuclicidae family. It breeds most often in artificial containers wherever standing water can accumulate. Eggs can remain dormant and dry for more than 30 days, perhaps much longer, and only need as much as a bottle cap of water for them to hatch and pupate. If water is not removed, within 10 days to two weeks adults emerge, and the female will seek a blood meal to start the cycle again.
A. aegypti feeds efficiently on humans. It generally bites the back of legs or arms avoiding detection. It lands lightly and bites gently compared to other mosquitoes. It bites at any time during the day, not just dawn or dusk, and it doesn’t alert you with a high pitched whine as some other species do. If there was ever a mosquito well-adapted to biting humans and getting away with it, it is Aedes aegypti.
What Can Be Done?
President Obama has proposed major funding at the federal level to address Zika and states and cities are beginning to acknowledge the potential threat. Dr. David Persse, public health director and incident command director for Zika in the city of Houston, says, “We are definitely preparing.” He continues, “This is the pre-season. We have a plan and we know we will have to manage adaptively, but we are definitely getting ready.” The scenario for which they have begun to plan is that once mosquitoes start breeding in large numbers, local A. aegypti mosquitoes will bite an infected traveler and then transmit the disease to humans locally. He says, “We must all take responsibility to ensure that no child is born with microcephaly.”
When asked if parks and recreation can be part of the response to the threat of Zika, Persse says, “Oh yeah!” Persse described how Houston has established an Incident Command Structure, a multi-agency quick-response action approach that is initiated in times of public safety emergencies. Houston’s task force is composed of public works, fire, housing, finance and parks and recreation, as well as other agencies that are participating in the response along with Harris County, which overlies much of the city.
What Does Zika Mean for Parks and Recreation?
Even though the range of Aedes mosquitoes has rapidly expanded northward, most park and recreation agencies have not yet taken the threat of Zika seriously. However, a number of agencies in the south and along the Gulf Coast are already well along in planning and activating their role in Zika response.
Joe Maguire, natural areas manager for Miami-Dade Parks, Recreation and Open Spaces, says his agency is fully engaged in addressing the threat posed by the Zika virus. “We are the agency that meets with a lot of the public,” says Maguire, “and we take this responsibility seriously.”
Miami-Dade has instructed staff to aggressively work to clean up any sources of standing water in parks by locating and draining small containers that could hold water. They promote a “fill and cover” message to staff and public and are looking at everything from storm drains to rooftops. They are also covering trash receptacles and working with their county solid waste management division to encourage faster, more efficient disposal of trash that can hold water, such as abandoned tires. The parks and recreation department has trained park staff on best methods of personal protection and has developed public-facing messages as well. They now distribute trilingual handouts at park entrance gates, the zoo and after school to parents.
The Recreation Commission of East Baton Rouge (BREC) says it does not post public safety messages for Zika, but it does discuss possible hazards and provide insect repellents for program participants at the beginning of conservation education programs in its nature parks. Carolyn McKnight, superintendent of BREC, says her agency is in the initial stages of understanding and managing Zika and the more information it receives the better its response can be.
Other agencies queried in the known habitat areas of A. aegypti mosquitoes had varying degrees of knowledge and readiness for the potential threat of Zika. One clear need that park and recreation agencies expressed was that they did not know if these mosquitoes are present in their jurisdiction and in their parks. Mutebi says this is a critical piece of knowledge. “Are these mosquitoes in your parks or not?” He says it is important to do surveillance, and that park and recreation agencies should be working with their local mosquito control units and request that parks be included in the areas where traps are placed.
What Should Park and Recreation Agencies on the Front Line Do?
Public education is one of the most important roles that park and recreation agencies can play in Zika response. “Park and recreation agencies have the ability to educate the public,” says Persse. “People touch parks everywhere, especially younger people who like to be outdoors.”
Houston has adopted the “3D Zika Defense — Dress properly, Drain containers and use DEET.” Miami-Dade is placing doorknob hang-tags in parks and in facilities that promote a message of “Drain and Cover.” In addition, both agencies are instructing program participants in how to utilize personal protection for biting mosquitoes — repellents, defensive clothing, including loose long-sleeved shirts and long pants, and effective screens in place at dwelling places.
While DEET is considered one of the most effective mosquito repellents, a number of people have concerns about using products with DEET. CDC recommends five repellents, four of which are alternatives to DEET. These are repellents that contain Picaridin, IR 3535, oil of lemon eucalyptus and para-menthane-diol. The so-called “botanicals” are not generally considered as effective as 20-25 percent concentrations of DEET, with the exception of oil of lemon eucalyptus. Picaridin repellents also rank highly.
Joe Turner, director of Houston Parks and Recreation Department (HPARD), says his agency is very concerned about staff members having the best information and being well-equipped to prevent exposure. “We want to know what the staff needs to do. Nearly 70 percent of our staff works outdoors.”
With regard to insect control in parks, unfortunately, many park and recreation agencies don’t know if Aedes aegypti mosquitoes are present, and they don’t know exactly what is being sprayed by city or county mosquito control units, often in another department or branch of government, in and around their parks. Mutebi says this is important information, and park and rec agencies should insist on knowing what insecticides are being used in and around their parks. Although there is not good evidence to make generalized comparisons, it appears that many local parks are not sprayed regularly, if at all, unless it is specifically requested by the park agency.
Aerial spraying is generally not considered the most effective control measure for A. aegypti mosquitoes because of their secretive habits and breeding locations. In stagnant standing water that cannot be drained, larvacides that are applied in small cakes to standing pools of water can be effective.
The presence of A. aegypti can only be determined by monitoring and trapping, Persse says, and he notes that Houston’s trap strategy is evolving. Their mosquito control unit is presently using three types of traps and expanding trap locations. It doesn’t matter whether your mosquito control unit performs surveillance or you hire a private contractor, says Mutebi, you must know if you have these mosquito species in your parks. Then you can make appropriate plans to take action.
Jed Aplaca, natural resources manager for HPARD, says natural controls are important as well. In public programs, HPARD staff members encourages the public to conserve all insect predators, especially those that eat mosquitoes. “We look to preserve habitat for bats, for example, in the parks, and we encourage people to put up bat boxes, purple martin houses and to look for other ways to promote insect predators.”
Cooperation Is Key to Successful Response
Public education is paramount, and as this public health crisis threatens to expand, the more people know, the better the response can be. NRPA continues to promote better collaboration between park and recreation agencies and local public health agencies. The spread of Zika virus disease is a compelling reason to seek more and better cooperation with public health counterparts. Park and recreation agencies can be an excellent way to get the best, up-to-date, accurate information about the threat of Zika to the public.
“We don’t know what the future will bring,” Maguire says, “but we are working with the mayor’s office, mosquito control and other agencies to ensure we have the most effective response.” Persse adds, “At the end of the day, local government can only do so much. But, it is hugely important that we do everything we can. And, we need everyone else to do all they can.”
Zarnaaz Bashir, NRPA’s Vice President of Strategic Health Initiatives, contributed to this article.
[Ed. Note: A significant new development regarding transmission of the Zika virus has occurred since this article went to press. In a finding reported by the Pan American Health Organization, the Zika virus has been detected in the Asian tiger mosquito, Aedes albopictus, in Mexico. Public health experts speculate that the Zika virus could now potentially expand to a much wider range in the United States including New England and the lower Great Lakes region, areas not expected to be affected by Zika virus disease.]
Richard J. Dolesh is NRPA’s Vice President of Conservation and Parks.
CDC recommendations for Zika prevention
Relative effectiveness of insect repellents for mosquitoes