Digital WPI Major Qualifying Projects ( All Years ) Major Qualifying Projects March 2017 Lyme Disease & Indicators of Biodiversity

Incidences of Lyme disease have increased steadily in Massachusetts since 2012. The University of Massachusetts has used a self-submission based tick testing database to document the number of ticks submitted and the number of infected ticks tested positive for tick-borne diseases. This project’s goal was to determine which potential surrogates of biodiversity best explain the incidence of Lyme disease in Massachusetts. Loss of biodiversity across landscapes may play an important role in the increased spread of infectious diseases. Based on the dilution effect high levels of biodiversity can reduce the spread of diseases. Using correlation and AICc analyses, we examined the influences of forest cover, number of people, deer density, seasonal temperature, and seasonal precipitation have on tick submissions and infection of ticks. Our results demonstrated that the number of people best explained the percent of infected ticks and was negatively correlated. The dilution effect was not supported by these analyses. However, based on our findings that number of people influences percent infected ticks, awareness efforts can be implemented to curb pathogen transmission. Introduction Lyme disease is a vector-borne disease transmitted by an Ixodidae scapularis tick that is infected with the pathogenic bacterium Borrelia burgdorferi (Estrada-Peña, 2015). During a blood meal, B. burgdorferi is passed from the tick to a competent reservoir host such as the Peromyscus leucopus (white-footed mice) or Odocoileus virginianus (white-tailed deer). These species allow maintenance of the parasitic bacterium to thus increase transmission of the disease (Fiset et al, 2015). Although ticks may encounter an incompetent host, a host that cannot support 21 the B. burgdorferi pathogen, these species facilitate tick survival throughout their larvae, nymph, and adult life stages by providing a blood meal (Estrada-Peña, 2015). Biodiversity, or abundance of different species present in a designated area, can influence the transmission and maintenance of pathogens (Ostfeld, 2011; Li et al, 2012). A proposed hypothesis, called the dilution effect, suggests that a decrease in host species diversity will result in an increase in the prevalence of Lyme disease (Ostfeld, 2011; Li et al, 2012). In addition to the host species diversity present, the hypothesis states that three other conditions have an effect on the infection rate. The three conditions include that (1) host species differ in reservoir competence of the disease, (2) a low number of competent hosts disrupt the distribution of the pathogen, and (3) competent hosts are not susceptible to species loss (Ostfeld, 2011). Well known competent hosts for maintaining and transmitting Lyme disease include the white-footed mouse and the white-tailed deer. Humans are affected by Lyme disease as low competence hosts (LoGuidice et al, 2003; Ostfeld, 2011). Overall, the dilution effect suggests that a general loss in biodiversity would increase the risk of pathogen transmission (LoGuidice et al, 2003; Ostfeld, 2011). Alternative research using simulation data challenges that the dilution effect is not plausible (Zolnik et al, 2015). Climate, soil moisture, and land cover can have an effect on the species diversity that is present in a habitat, which in turn may affect pathogen transmission (Costanza et al, 2007; Greenfield, 2011; Wang et al, 2009). Areas with high temperatures and high precipitation have been known to have the greatest amount of biodiversity because of the diverse species richness in the environment (Costanza et al, 2007; Wang et al, 2009). Soil moisture influences tick behavior that may lead to an increase in the number of ticks that can infect a competent host (Greenfield, 2011; Gilbert, 2014). Moreover, areas of land that are well developed may lead to a 22 decrease in biodiversity present (McKinney, 2002). This paper will examine the role of these biodiversity indicators and their influence on the prevalence of Lyme disease in areas across