Lyme disease: self-regulation and pathogen invasion

Area of Science:

• Ecology
• Epidemiology
• Mathematical Biology

Background:

• Lyme disease is transmitted through a complex cycle involving spirochetes, ticks, and vertebrate hosts.
• Understanding the ecological factors driving Lyme disease epidemics is crucial for public health.

Purpose of the Study:

• To develop a mathematical model simulating Lyme disease transmission dynamics.
• To identify ecological conditions that favor the invasion and persistence of the Lyme disease spirochete.

Main Methods:

• A compartmental model was developed to track tick and mouse populations and infection status.
• Equilibrium abundances were calculated for a homogeneous-mixing scenario.
• Local stability analysis was performed to determine conditions for spirochete extinction or invasion.

Main Results:

• A stable condition for spirochete extinction was identified.
• Reversing the extinction condition indicated stable spirochete invasion.
• Spirochete invasion is favored by high mouse density, low mouse mortality, high host and tick susceptibility, high tick attack rates on mice, and abundant larval ticks.

Conclusions:

• Ecological factors significantly influence Lyme disease transmission.
• Specific host-pathogen-vector parameters can predict the establishment of the spirochete in an ecosystem.
• The model provides insights into managing Lyme disease by targeting key ecological drivers.