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Module 1 Lecture 9

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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.