Module 1 Lecture 9

Module Overview

• Focus on ecosystem health and infectious diseases.

• Specific cases: Lyme disease and hantavirus.

• General structure: shorter lectures than Module 1.

Ecosystem Health and Biodiversity

• Key Question: Do lower biodiversity ecosystems function differently than higher biodiversity ecosystems?

• Hypothesis: Biodiversity contributes to beneficial ecosystem services that may justify conservation efforts.

• Importance of translating significance of biodiversity to various stakeholders (e.g., grant providers, community members).

• Focus on protecting human health through wildlife and biodiversity preservation.

Lyme Disease

• Understanding Lyme disease: chronic and diverse symptoms that mimic other diseases.

• Rising prevalence in the developed world due to habitat loss and human encroachment.

• Diagnostic challenges due to symptoms overlapping with other ailments.

  • Characteristic erythema migrans rash is diagnostic but not present in all cases.

• Early signs include fever and joint aches; treatment with antibiotics may be effective in early stages but remains debated.

Transmission and Pathogen Details

• Caused by Borrelia burgdorferi; vector-borne, primarily through Ixodes ticks.

• Life cycle of ticks: larval, nymph, and adult stages; nymphs primarily feed on humans and pets.

• The longer a tick feeds, the higher the risk of transmitting the bacterium. CDC suggests a window of 24-48 hours for significant risk.

• Ticks are non-infectious when they emerge as larvae; need a blood meal to become infected.

Biodiversity and Disease Dynamics

• High biodiversity correlates to lower incidence of Lyme disease transmission.

  • Increased white-footed mice populations boost infection rates since they are preferred hosts for larval ticks.

  • Ideal ecological conditions are necessary for a variety of host species to maintain ecosystem balance.

• Other less favorable hosts (like opossums) may help decrease Lyme disease transmission.

• Direct implications of biodiversity loss: Increased Lyme disease cases tied to encroachment and degradation of natural habitats.

  • More deer suggest higher tick populations, contributing to increased Lyme disease transmission.

Hantavirus

• RNA virus with rodents as primary reservoirs; transmitted through contact with rodent excretions.

• Associated with hantavirus pulmonary syndrome; high fatality rate (~40%).

• Infection risk increases with rodent population density and direct human contact.

• Similar patterns to Lyme disease: increased rodent host diversity correlates to lower human disease rates.

Environmental Influences

• Climate and weather conditions can significantly affect disease outbreaks (e.g., El Niño effects).

  • Example: 1993 hantavirus outbreak linked with drought and subsequent weather changes leading to rodent population increases.

Conservation Implications

• Conclusion: High biodiversity is protective against disease outbreaks, which benefits human health.

• Importance of understanding ecological relationships in disease transmission and prevention efforts.

• Encouragement of further research into reservoir species dynamics and the impact of environmental changes on disease transmission.

Research Directions

• Opportunities for research in understanding how species become generalists in disease transmission.

• Need for studies on biodiversity's role in emerging infectious diseases, beneficial both for immediate health impacts and long-term ecological maintenance.

Next Steps

• Upcoming activities: Watch a video on Lyme disease and biodiversity; read an article on biodiversity's impact on emerging infectious diseases.