Vector-Borne Disease

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Headshot of Anne Grossman, MD, FACP · Assistant Professor, Medical Education and Clinical Sciences
Anne Grossman
MD, FACP · Assistant Professor, Medical Education and Clinical Sciences
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Clinical connection: Hunting for a Diagnosis

This short video (~9 min.) from the New England Journal of Medicine (NEJM) highlights the effects of climate change on health through an illustrative patient case.

Source: Leslie Chang, M.D., Debra Malina, Ph.D., Lisa Rosenbaum, M.D., Caren Solomon, M.D., M.P.H., and Timothy Vining. Hunting for a Diagnosis. N Engl J Med 2023;388: e16. Published February 15, 2023.

Additional exploration

Lyme Disease

planetary-health-vector-borne-lyme-disease

  • Caused by the spirochete bacteria: Borrelia burgdorferi.
  • Transmitted by Ixodes scapularis (East) and Ixodes pacificus (West).
  • Early Signs and Symptoms (3–30 days post-tick bite):
    • Fever.
    • Chills.
    • Fatigue.
    • Erythema.
    • Migrans rash in 70–80% patients.
  • Later signs and symptoms (days to months post-tick bite):
    • Multiple EM rashes.
    • Meningitis.
    • Bell’s Palsy.
    • Carditis.
    • Arthritis.

planetary-health-vector-borne-lyme-disease-statistics

  • In the U.S., the incidence of lyme disease has doubled since 1991, from about four cases per 100,000 people to eight per 100,000 people (300K cases per year)
    • Peaks in May through July when ticks are most active.
    • >90% of Lyme cases in the Northeast, Upper Midwest, and mid-Atlantic; however, the number of counties that are now deemed high-risk for lyme has increased >320% since the late 1990s.
  • Climate is one reason (along with deer population surges, land use change, and human behavior) is why lyme disease is increasing.
    • Tick distribution is affected by temperature, rainfall, and humidity.
    • Tick abundance is greatest in moist, humid environments and declines during hot, dry periods.
    • Warmer temperatures can also increase the developmental rate of ticks.
  • With global warming, tick populations can move farther north, expanding their range and increasing the length of tick season.
  • Tick numbers may also be affected by abundance of animal hosts, such as rodents (acorns!) and deer (hunting limits), which are also affected by climate.