What are you people going to do about this?
![Picture](/uploads/3/9/0/6/39066599/3461628.jpg?386)
The most thorough response to any new disease outbreak, especially a new vector-borne disease, must involve the integration of multiple levels of disease control. The disease can be managed at the following levels:
While an ideal management protocol would involve all of these areas concurrently, such a plan is unfeasible with real-world considerations (e.g. budget constraints, personnel limitations, etc.). In addition, a more focused method of control allows for more precision and hopefully, effectiveness. Vaccines take a long time to develop (College of Physicians of Philadelphia, accessed 11-25-2014), and while antiviral agents show some effect for certain illnesses (e.g. influenza), they are not a panacea (CDC, accessed 11-25-2014). Therefore, an initial focus on fighting Arterivirus potestas in humans in vivo would be amount to a wasted effort. Similarly, supportive treatments in the afflicted patients are proving to be minimally effective. Though supportive measures are the first line of treatment in other zoonotic viral diseases (e.g. ebola) and other vector-borne viral diseases (e.g. West Nile Virus), Orlando Fever is less responsive to such measures, and should therefore be combatted through other means.
Murine rodents may seem like a tempting prospect for disease control, but are in reality fairly difficult to control (Richer et al. 2014). Though reservoir vaccination has shown some promising results in controlling Borrelia burgdorferi, the bacterial agent causing Lyme disease, the efforts necessary to effectively eliminate such a vector-borne agent are enormous and long-ranging. In addition, there is no reason to assume that those measures which inhibit the spread of bacteria will be similarly effective against viruses; while a broad-spectrum antibiotic is effective against a bacterial infection (e.g. anaplasmosis), it has no effect whatsoever on viral infections (e.g. Dengue). Many more years worth of research would be needed to reach a point where Arterivirus potestas could be controlled by reservoir vaccination, given that no such vaccine exists or is even in development. While rodent vaccination holds great promise for controlling established diseases (e.g. Lyme disease), it is a slow-moving process and will not present any short-term benefit in controlling this outbreak of Orlando Fever (Richer et al. 2014). In addition, the fact that mice and rats are fast-reproducing, r-selected animals of a very small size makes them significantly more difficult to track and monitor than a larger, K-selected animal like the white-tailed deer or the gray wolf. Finally, murine behavioral dynamics can have large impacts on disease burden and transmissibility, and those behaviors tend to be complicated and require a great deal of work to understand (Ferreri et al. 2014). Thus, a reservoir approach is not a good choice for this outbreak.
Given the limitations on these other control methods, we have decided to focus our efforts on the vector and its environment. There are a number of effective acaricides (tick poisons) available. Acaricides are a prudent first step because they are easily obtained, inexpensive, easy to apply, consistently effective, and require only infrequent and relatively small-scale treatments to be effective (Stafford 2004). Synthetic pyrethroids in particular are the ideal chemical for the job because they are highly effective against ticks, minimally toxic to birds and mammals, and stable in the environment (Stafford 2004). Though it is impractical to aim to completely eradicate a tick population, a temporary reduction in Amblyomma maculatum abundance such that Arterivirus potestas disappears from local rodent populations will be sufficient to effectively control the disease spread (Peter et al. 2005). In following a guide to tick management by Stafford (2004), we can minimize effort and cost while maximizing effect.
Our first step in control entails environmental treatment as follows:
- the disease agent in humans (e.g. broad-spectrum antiviral agents, an eventual vaccine)
- the patients themselves (e.g. supportive treatments to control symptoms)
- the disease reservoir (e.g. controlling parasite loads, preventing contact with humans, culling populations)
- the tick vector (e.g. extermination)
- the environment (e.g. preventing the vector and reservoir from interacting with humans on a physical level by closing parks or removing suitable habitats)
While an ideal management protocol would involve all of these areas concurrently, such a plan is unfeasible with real-world considerations (e.g. budget constraints, personnel limitations, etc.). In addition, a more focused method of control allows for more precision and hopefully, effectiveness. Vaccines take a long time to develop (College of Physicians of Philadelphia, accessed 11-25-2014), and while antiviral agents show some effect for certain illnesses (e.g. influenza), they are not a panacea (CDC, accessed 11-25-2014). Therefore, an initial focus on fighting Arterivirus potestas in humans in vivo would be amount to a wasted effort. Similarly, supportive treatments in the afflicted patients are proving to be minimally effective. Though supportive measures are the first line of treatment in other zoonotic viral diseases (e.g. ebola) and other vector-borne viral diseases (e.g. West Nile Virus), Orlando Fever is less responsive to such measures, and should therefore be combatted through other means.
Murine rodents may seem like a tempting prospect for disease control, but are in reality fairly difficult to control (Richer et al. 2014). Though reservoir vaccination has shown some promising results in controlling Borrelia burgdorferi, the bacterial agent causing Lyme disease, the efforts necessary to effectively eliminate such a vector-borne agent are enormous and long-ranging. In addition, there is no reason to assume that those measures which inhibit the spread of bacteria will be similarly effective against viruses; while a broad-spectrum antibiotic is effective against a bacterial infection (e.g. anaplasmosis), it has no effect whatsoever on viral infections (e.g. Dengue). Many more years worth of research would be needed to reach a point where Arterivirus potestas could be controlled by reservoir vaccination, given that no such vaccine exists or is even in development. While rodent vaccination holds great promise for controlling established diseases (e.g. Lyme disease), it is a slow-moving process and will not present any short-term benefit in controlling this outbreak of Orlando Fever (Richer et al. 2014). In addition, the fact that mice and rats are fast-reproducing, r-selected animals of a very small size makes them significantly more difficult to track and monitor than a larger, K-selected animal like the white-tailed deer or the gray wolf. Finally, murine behavioral dynamics can have large impacts on disease burden and transmissibility, and those behaviors tend to be complicated and require a great deal of work to understand (Ferreri et al. 2014). Thus, a reservoir approach is not a good choice for this outbreak.
Given the limitations on these other control methods, we have decided to focus our efforts on the vector and its environment. There are a number of effective acaricides (tick poisons) available. Acaricides are a prudent first step because they are easily obtained, inexpensive, easy to apply, consistently effective, and require only infrequent and relatively small-scale treatments to be effective (Stafford 2004). Synthetic pyrethroids in particular are the ideal chemical for the job because they are highly effective against ticks, minimally toxic to birds and mammals, and stable in the environment (Stafford 2004). Though it is impractical to aim to completely eradicate a tick population, a temporary reduction in Amblyomma maculatum abundance such that Arterivirus potestas disappears from local rodent populations will be sufficient to effectively control the disease spread (Peter et al. 2005). In following a guide to tick management by Stafford (2004), we can minimize effort and cost while maximizing effect.
Our first step in control entails environmental treatment as follows:
- judicious spraying with pyrethroids in areas of high tick abundance AND high likelihood of human contact, to include brush habitats favored by the Gulf Coast Tick, particularly those around hiking trails and park entrances
- closing of high incidence parks and recreation areas for the duration of spraying and one week following
- posting of signs and fliers advising people why the parks have been closed, as well as steps people can take for tick prevention such as wearing long pants and socks, light-colored clothing, and permethrin-treated garments
As pyrethroids are highly toxic to aquatic animals, no spraying will occur within 25 feet of bodies of water. Spraying will also not occur on athletic fields as acaricides will not be useful in such habitat, or on ornamental plants intended to attract butterflies as the acaricides may also negatively affect charismatic pollinators (Stafford 2004).
A signage and education campaign will occur concurrently with acaricide spraying. As mentioned previously, signs will be posted outside the park advising people to stay on trails, carefully check themselves and their pets for ticks, and to wear appropriate clothing, as outlined below. Light-colored clothing facilitates easy identification and removal of ticks on the body. Closed-toed shoes with thick soles restrict access to potential biting sites, long socks and long pants tucked into socks prevent ticks from gaining access to exposed legs, and long-sleeve shirts tucked into pants prevent ticks from easily crawling beneath waistbands or up shirts (Nicholson et al. 2009). Permethrin-impregnated socks are widely available and highly effective in preventing tick bites (Banks et al 2014). Other clothing may be treated with permethrin (away from household pets and preferably outside), and any exposed skin should be treated with other insect repellent, such as DEET (Nicholson et al. 2009).
Monitoring has been identified as an important element of tick-borne disease prevention (Semenza and Zeller 2014). As such, tick and rodent populations will continue to be monitored, along with human incidence for the course of acaricide spraying. Monitoring will entail the continued reporting by local hospitals of patients suspected to have been infected with the disease in the affected parks, combined with weekly trapping and ELISA tests on rodents in the affected parks until a month has passed with no new incidence of infection.
It is predicted that this protocol will reduce the number of ticks in the natural parks in Florida where humans have come into contact with the pathogen. Reducing the population of the vector will reduce the chances of a human coming into contact with the vector and by extension, the pathogen as well.
Parks to be targeted in the Orlando area include:
A signage and education campaign will occur concurrently with acaricide spraying. As mentioned previously, signs will be posted outside the park advising people to stay on trails, carefully check themselves and their pets for ticks, and to wear appropriate clothing, as outlined below. Light-colored clothing facilitates easy identification and removal of ticks on the body. Closed-toed shoes with thick soles restrict access to potential biting sites, long socks and long pants tucked into socks prevent ticks from gaining access to exposed legs, and long-sleeve shirts tucked into pants prevent ticks from easily crawling beneath waistbands or up shirts (Nicholson et al. 2009). Permethrin-impregnated socks are widely available and highly effective in preventing tick bites (Banks et al 2014). Other clothing may be treated with permethrin (away from household pets and preferably outside), and any exposed skin should be treated with other insect repellent, such as DEET (Nicholson et al. 2009).
Monitoring has been identified as an important element of tick-borne disease prevention (Semenza and Zeller 2014). As such, tick and rodent populations will continue to be monitored, along with human incidence for the course of acaricide spraying. Monitoring will entail the continued reporting by local hospitals of patients suspected to have been infected with the disease in the affected parks, combined with weekly trapping and ELISA tests on rodents in the affected parks until a month has passed with no new incidence of infection.
It is predicted that this protocol will reduce the number of ticks in the natural parks in Florida where humans have come into contact with the pathogen. Reducing the population of the vector will reduce the chances of a human coming into contact with the vector and by extension, the pathogen as well.
Parks to be targeted in the Orlando area include:
- Bear Creek Nature Trail
- Florida Trail, Mills Creek
- Hal Scott Preserve
- Lake Jesup
- Tibet-Butler Preserve
- Twin Oaks
- Lake Lotus Park
- Historic Babb Landing
Literature Cited
Banks, S.D., N. Murray, A. Wilder-Smith, and J.G. Logan. 2014. Insecticide-treated clothes for the control of vector-borne diseases: a review on effectiveness and safety. Med Vet Entomol 28:14-25.
(CDC). 2014. Use of antivirals. http://www.cdc.gov/flu/professionals/antivirals/antiviral-use-influenza.htm
(College of Physicians of Philadelphia). 2014. Vaccine development, testing, and regulation. http://www.historyofvaccines.org/content/articles/vaccine-development-testing-and-regulation
Ferreri, L., M. Giacobini, P. Bajardi, L. Bertolotti, L. Bolzoni, V. Tagliapietra, A. Rizzoli, and R. Rosà. 2014. Pattern of tick aggregation on mice: larger than expected distribution tail enhances the spread of tick-borne pathogens. PLoS Comp Biol 10.
Nicholson, W.L., D.E. Sonenshine, R.S. Lane, and G. Uilenberg. 2009. Ticks (Ixodida), pp. 493-542. In: G.R. Mullen and L.A. Durden (eds.), Medical and veterinary entomology, 2nd ed. Academic Press, Burlington, MA.
Peter, R.J., P. Van den Bossche, B.L. Penzhorn, and B. Sharp. 2005. Tick, fly, and mosquito control--Lessons from the past, solutions for the future. Vet Parasitol 132: 205-215.
Richer, L.M., D. Brisson, R. Melo, R.S. Ostfeld, N. Zeidner, and M. Gomes-Solecki. 2014. Reservoir targeted vaccine against Borrelia burgdorferi: a new strategy to prevent Lyme disease transmission. J Infect Dis 209:1972-1980.
Semenza, J.C., and H. Zeller. 2014. Integrated surveillance for prevention and control of emerging vector-borne diseases in Europe. Euro Surveill 19.
Stafford, K.C. III. 2004. Tick management handbook: a integrated guide for homeowners, pest control operators, and public health officials for the prevention of tick-associated disease. The Connecticut Agricultural Experiment Station, New Haven, CT.
(CDC). 2014. Use of antivirals. http://www.cdc.gov/flu/professionals/antivirals/antiviral-use-influenza.htm
(College of Physicians of Philadelphia). 2014. Vaccine development, testing, and regulation. http://www.historyofvaccines.org/content/articles/vaccine-development-testing-and-regulation
Ferreri, L., M. Giacobini, P. Bajardi, L. Bertolotti, L. Bolzoni, V. Tagliapietra, A. Rizzoli, and R. Rosà. 2014. Pattern of tick aggregation on mice: larger than expected distribution tail enhances the spread of tick-borne pathogens. PLoS Comp Biol 10.
Nicholson, W.L., D.E. Sonenshine, R.S. Lane, and G. Uilenberg. 2009. Ticks (Ixodida), pp. 493-542. In: G.R. Mullen and L.A. Durden (eds.), Medical and veterinary entomology, 2nd ed. Academic Press, Burlington, MA.
Peter, R.J., P. Van den Bossche, B.L. Penzhorn, and B. Sharp. 2005. Tick, fly, and mosquito control--Lessons from the past, solutions for the future. Vet Parasitol 132: 205-215.
Richer, L.M., D. Brisson, R. Melo, R.S. Ostfeld, N. Zeidner, and M. Gomes-Solecki. 2014. Reservoir targeted vaccine against Borrelia burgdorferi: a new strategy to prevent Lyme disease transmission. J Infect Dis 209:1972-1980.
Semenza, J.C., and H. Zeller. 2014. Integrated surveillance for prevention and control of emerging vector-borne diseases in Europe. Euro Surveill 19.
Stafford, K.C. III. 2004. Tick management handbook: a integrated guide for homeowners, pest control operators, and public health officials for the prevention of tick-associated disease. The Connecticut Agricultural Experiment Station, New Haven, CT.