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Public Health and Lyme Disease


According to the American Public Health Association, public health aims to “promote and protect the health of people and the communities where they live, learn, work, and play” (APHA 2016). They accomplish this by encouraging healthy lifestyles, conducting research on disease and injury prevention, and detecting and controlling infectious diseases. Examples of careers involved in public health include first responders, health educators, researchers, epidemiologists, and public policymakers. Many public health professionals are currently trying to figure out how to control, prevent, diagnose, and treat Lyme disease around the world. This blog will focus on some key ways in which public health plays a role in addressing Lyme disease and how potential wildlife control management strategies may help with this challenging endeavor.


Prevention is one major way in which public health professionals try to protect the public from Lyme disease. This involves warning people of the risks of tick bites, educating them on how to detect and properly remove ticks, and providing ways in which to reduce their overall contact with potentially infected ticks. Warning signs may come in the form of actual road signs posted along wooded areas or as a public message that may be broadcasted on the radio, television, etc. The CDC’s website has an extensive webpage on how to best prevent tick bites. They include measures such as knowing where to expect ticks, using a repellent with DEET (on skin or clothing) or permethrin (on clothing and gear only), creating tick-safe zones in your yard, and performing daily tick checks (CDC 2016). They also alert you of signs and symptoms to be aware of if you do have a tick attach to you, such as a fever or rash. All of these preventive measures can significantly reduce your chances of contracting Lyme disease.

Vaccination is another important public health component. There is currently no approved vaccine for Lyme disease. LYMErix was a Lyme disease vaccine that was discontinued in 2002. Many people that did receive this vaccine reported several adverse effects, with the most common ones being arthralgia, myalgia, pain, asthenia, headaches, fever, and rash (Shen et al. 2011). According to the Vaccine Adverse Event Reporting System (VAERS), 7.4% of the reported adverse events were classified as serious, which is defined as “one which resulted in life-threatening illness, hospitalization, prolongation of hospitalization, persistent or significant disability/incapacity, or death” (Braun and Ellenberg, 1997; Lathrop et al. 2002). A new Lyme disease vaccine, the novel multivalent OspA vaccine, is currently being developed (Wressnigg et al. 2013). Although this vaccine looks promising for the prevention of Lyme disease, more studies are needed to confirm its effectiveness and safety.

Another way in which public health tackles Lyme disease is via improving methods used for diagnosing and treating Lyme disease. As mentioned in a previous blog posting, Diagnosing and Treating Lyme Disease, diagnosing Lyme disease can be very tricky. Most of the commonly used diagnostic tests are not perfect, allowing for a great number of both false negatives and false positives every year (Borchers et al. 2015). Improved diagnostic tests can then help public health authorities to develop and monitor medical guidelines designed to reduce the prevalence of Lyme disease and enhance outcomes through earlier diagnosis and treatment of the disease. Treating Lyme disease, however, is not that simple. Although most doctors agree that antibiotics should be prescribed to treat Lyme disease, the type of antibiotic used and the duration of treatment depends on both the patient and Borrelia strain involved. Borrelia burgdorferi can also hide itself from antibiotics, allowing it to persist after the patient completes his/her treatment. Public health officials are constantly researching new ways to both diagnose and treat Lyme disease more effectively in order to reduce the occurrence of under-diagnosis, over-diagnosis, and chronic stages of Lyme disease.



Since Borrelia burgdorferi relies on both ticks and wildlife reservoirs/hosts, could wildlife control management be used to further prevent/control Lyme disease among the human population? Pesticides against Ixodes ticks are commonly used and can be helpful in reducing the risk of contracting Lyme disease. However, there is always the chance of these ticks becoming pesticide-resistant as mentioned in Diagnosing and Treating Lyme Disease. Another method mentioned in a previous blog entry, Reservoir host of Lyme Disease, is the use of “tick tubes.” These easy-to-make tubes are hollow pipes stuffed with pesticide-treated cotton balls, which burrowing animals, such as the white-footed mouse, use in their burrows. By exposing ticks feeding on these rodents to pesticides, we may be able to stop these infected ticks from spreading the disease. Another way to expose white-footed mice and other rodents to these pesticides is by luring them into small boxes that brush them with tick-killing chemicals. Dolan et al (2004) found that bait boxes are an effective delivery method of acaricides onto white-footed mice, as both nymphal and larval tick infestations on white-footed mice reduced by 68 and 84%, respectively. An alternative to the chemical control of ticks on mice/rodents is the use of microscopic roundworms that infect and kill ticks, especially adult female ticks. Symbiotic bacteria living within the guts of these nematodes (genus Xenorhabdus) are released within the tick once the worms get inside the tick, which then liquefy the tick’s tissues (Suszkiw 1998). This is beneficial for the microscopic nematode as these worms then feed on the tick’s liquefied tissues, followed by mating and the generation of thousands of offspring. However, more research is needed to verify both the effectiveness and safety of this control method.


Another way in which wildlife control management could help prevent the spread of Lyme disease to the human population is via the control of our deer populations. White-tailed deer are an important host for Ixodes scapularis, primarily the adult ticks. Researchers found that managing deer for tick control and Lyme disease can be quite effective. One control strategy is via deer exclusion/restriction using deer fencing. Stafford III (1993) found that high tensile electric deer fencing significantly reduced both nymphal and adult I. scapularis numbers. Similarly, Daniels and Fish (1993) found 84% fewer nymphs inside fenced areas in New York. The main limiting factor of this strategy, however, is that fencing can only be used to keep deer out of small areas (ex. around homes) due to installation and maintenance costs. Another seemingly effective strategy is to treat the deer themselves with acaricides to kill ticks on the deer. Results from a long-term study on the effectiveness of this strategy found that blacklegged ticks were reduced by about 60-70% over 5 years of use (Garnett et al. 2011). They also found that this reduction in ticks had a significant impact on the incidence of Lyme disease in the surrounding communities. A similar study done in Maryland found a 96-97% reduction in nymphal blacklegged ticks when exposing deer to acaricides (Solberg et al. 2003). There are several potential downfalls associated with this strategy. The “4-poster” feeding devices commonly used are not approved in all states. Most states require permits from state wildlife authorities before these devices can be installed. This strategy is also costly and requires a great deal of time and expertise from personnel. A third strategy is deer reduction. This is accomplished via regulated traditional hunting, controlled hunts, or sharpshooters. It seems that reducing deer densities to less than 20 deer/mile2 can significantly reduce tick bite risk, while densities around 8 deer/mile2 can interrupt the enzootic cycle of Lyme disease and the transmission of B. burgdorferi to both wildlife and humans (Rand et al. 2003; Kilpatrick et al. 2014; Stafford III and Williams, 2014). Problems with this strategy include community acceptance of lethal deer management strategies (Kilpatrick and LaBonte 2003; Kilpatrick et al. 2007). This strategy is also more difficult to perform in areas that are densely populated by people.


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References

APHA: American Public Health Association. 2016. What is Public Health? Accessed October 27, 2016. Available at: https://www.apha.org/what-is-public-health.

Braun, M.M., Ellenberg, S.S. 1997. Descriptive epidemiology of adverse events after immunization: reports to the vaccine adverse event reporting system (VAERS), 1991-1994. The Journal of Pediatrics 131: 529-535.

CDC: Centers for Disease Control and Prevention. 2016. Prevent Lyme Disease. Accessed October 27, 2016. Available at: http://www.cdc.gov/features/lymedisease/.

Daniels, T.J., Fish, D. 1993. Effect of deer exclusion on the abundance of immature Ixodes scapularis (Acari: Ixodidae) in southern New York State. Journal of Medical Entomology 32: 5-11.

Dolan, M.C., Maupin, G.O., Schneider, B.S., Denatale, C., Hamon, N., Cole, C., Zeidner, N.S., Stafford III, K.C. 2004. Control of immature Ixodes scapularis (Acari: Ixodidae) on rodent reservoirs of Borrelia burgdorferi in a residential community of southeastern Connecticut. Journal of Medial Entomology 41: 1043-1054.

Garnett, J.M., Connally, N.P., Stafford III, K.C., Cartter, M.L. 2011. Evaluations of deer targeted interventions on Lyme disease incidence in Connecticut. Public Health Reports 126: 446-454.

Kilpatrick, H.J., LaBonte, A.M. 2003. Deer hunting in a residential community: the community’s perspective. Wildlife Society Bulletin 31: 340-348.

Kilpatrick, H.J., LaBonte, A.M., Barclay, J.S. 2007. Acceptance of deer management strategies by suburban homeowners and bowhunters. Journal of Wildlife Management 71: 2095-2101.

Kilpatrick, H.J., LaBonte, A.M., Stafford III, K.C. 2014. The relationship between deer density, tick abundance, and human cases of Lyme disease in a residential community. Journal of Medical Entomology 51: 777-784.

Lathrop, S.L., Ball, R., Haber, P., Mootrey, G.T., Braun, M.M., Shadomy, S.V., Ellenberg, S.S., Chen, R.T., Hayes, E.B. 2002. Adverse event reports following vaccination for Lyme disease: December 1998 – July 2000. Vaccine 20: 1603-1608.

Rand, P.W., Lubelczyk, C., Lavigne, G.R., Elias, S., Holman, M.S., LaCombe, E.H., Smith III, R.P. 2003. Deer density and the abundance of Ixodes scapularis (Acari: Ixodidae). Journal of Medical Entomology 40: 179-184.

Shen, A.K., Mead, P.S., Beard, C.B. 2011. The Lyme disease vaccine – a public health perspective. Clinical Infectious Diseases 52: s247-s252.

Solberg, V.B., Miller, J.A., Hadfield, T., Burge, R., Schech, J.M., Pound, J.M. 2003. Control of Ixodes scapularis (Acari: Ixodidae) with topical self-application of permethrin by white-tailed deer inhabiting NASA, Beltsville, Maryland. Journal of Vector Ecology 28: 117-134.

Stafford III, K.C. 1993. Reduced abundance of Ixodes scapularis (Acari: Ixodidae) with exclusion of deer by electric fencing. Journal of Medical Entomology 30: 986-996.

Stafford III, K.C., Williams, S.C. 2014. Deer, ticks, and Lyme disease: deer management as a strategy for the reduction of Lyme disease. The Connecticut Agricultural Experiment Station. Accessed October 28, 2016. Available at: http://www.ct.gov/caes/lib/caes/documents/publications/fact_sheets/entomology/deer_&_ticks_fact_sheet.pdf.

Suszkiw, J. 1998. Tackling ticks that spread Lyme disease. Agricultural Research 46.3: 22-24.

Wressnigg, N., Pollabauer, E.M., Aichinger, G., Portsmouth, D., Low-Baselli, A., Fritsch, S., Livey, I., Crowe, B.A., Schwendinger, M., Bruhl, P., Pilz, A., Dvorak, T., Singer, J., Firth, C., Luft, B., Schmitt, B., Zeitlinger, M., Muller, M., Kollaritsch, H., Paulke-Korinek, M., Esen, M., Kremsner, P.G., Ehrlich, H.J., Barrett, P.N. 2013. Safety and immunogenicity of a novel multivalent OspA vaccine against Lyme borreliosis in healthy adults: a double-blind, randomized, dose-escalation phase 1/2 trial. The Lancet 13: 680-689.