Lyme disease is an infectious zoonotic disease transmitted by arthropods. This disease can be caused by three or more species of the genus Borrelia. Nevertheless, Borrelia burgdorferi sensu stricto happens to be the most prevalent in the U.S. In Europe, the major species causing Lyme disease are Borrelia garinii and Borrelia afzelii (Halperin, 2011).
Among the various zoonotic diseases, Lyme disease is considered as having the highest prevalence. This is because there is a high prevalence of the host Ixodes scapularis. Peromyscus leucopus is a white-footed mouse believed to be the B. burgdorferi wildlife host (Halperin, 2011). This white-footed mouse is also believed to be the principal host for the tick vector immature stages and in central and eastern endemic zones. There is an assumption that mice propagate the B. burgdorferi-infected ticks’ prevalence and hence increase the risk for Lyme disease. Scientists, therefore, focus on interrupting mice-ticks B. burgdorferi transmission in an effort to reduce the exposure of the disease to human beings. However, scientists discovered that B. burgdorferi infects a range of vertebrate species which transmit the bacteria to ticks, thus increasing infected ticks density which subsequently leads to an increased Lyme disease risk (Brisson, Dykhuizen & Ostfeld, 2008).
The interventions focusing on mice-ticks B. burgdorferi transmission have had weak effects due to the existence of other host species which maintain the host-tick transmission cycle. For the transmission cycle to be maintained, the numbers of ticks feeding on the hosts as well as the species-specific reservoir competence come into play. Immature ticks heavily parasitize white-footed mice where approximately 85 percent of ticks get B. burgdorferi. This clearly shows that the reservoir potential of mice is high and hence an assertion that mice are the major hosts of B. burgdorferi and immature ticks. Other B. burgdorferi host species have a lower reservoir potential compared to mice. However, a study by Brisson, Dykhuizen and Ostfeld (2007) shows that a white-footed mouse is not the primary host for B. burgdorferi and tick vector. Even though mice are conspicuous and common vertebrates in Midwestern and northeastern USA, results from ecological and molecular data show that mice in the northeastern fields provide blood meal to just 10% of larvae. Out of all these larvae, it is only 85 percent that becomes infected which leads to an 8.5 percent of infected larvae. In the field sites, it is approximately 35 percent of host-seeking nymphs are infected. This shows that mice can only infect 25 percent of the total nymph ticks infected by B. burgdorferi. This is a good proportion but it cannot be used to indicate that mice are B. burgdorferi primary reservoirs (Brisson, Dykhuizen & Ostfeld, 2008).
Black-legged ticks are commonly found in places that are wooded and bushy. People working in these areas have high exposure to infected ticks and hence they are exposed to the risk of Lyme disease. Lyme disease is widely distributed in the northern hemisphere. In the USA the disease is prevalent in the northeast states, North-central states (Minnesota and Wisconsin) and West Coast (Northern California). The disease has also been traced in Pennsylvania.
Lyme disease can be prevented by clearing bushes and tall grass around living or working places. Using acaricides to control ticks can also be used as a way of controlling Lyme disease transmission. There is a relationship between deer and deer ticks in the eastern parts of the USA. Reduction of deer population can therefore reduce the abundance of ticks which subsequently leads to reduced risk of Lyme disease (Halperin, 2011).
References
Brisson, D., Dykhuizen, D. E. and Ostfeld, R.S. (2008). Conspicuous impacts of inconspicuous hosts on the Lyme disease epidemic. Proceedings of the Royal Society of Biological Sciences, 275: 227-235.
Halperin J. J. (2011). Lyme disease: An evidence-based approach. London, UK: CAB International.