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Arthropod Diseases Affecting Outdoor Activities: Lyme Disease Dr. Richard M. Houseman Department of Entomology University of Missouri Lyme Disease Background • Bacterial disease first identified in Conneticut (1977) – Inflammation of joints (arthritis) – Rarely, if ever fatal • 92% of all cases occur in nine states – CT, RI, NY, PA, DE, NJ, MD, MA, WI. • Leading cause of vector-borne infectious disease in U.S. (15,000 cases annually) – Borrelia burgdorferi – Similar bacteria in Europe, Asia Lyme Disease Transmission • Transmitted by the bite of infected tick Ixodes scapularis – Rodents, deer, birds, dogs are primary hosts – Human infections after tick feeds for >36 hours • In temperate areas (24º-66º latitude) virus transmission is seasonal – Most in late spring to mid summer (nymphs) – Few in fall and early spring (adults) adults + eggs SPRING nymphs adults nymphs FALL adults nymphs WINTER adults YEAR 1 SUMMER (dormant) (dormant) YEAR 2 larvae Lyme Disease Risks • Risk of exposure is greatest in woods and fringe areas of properties – Ticks may also be transported to lawn/garden • Highest attack rates – Children 0-14 and 30+ years of age • Outdoor recreation, outdoor work, new homes in wooded areas • Blood transfusions, infected blood, urine are NOT documented risks Lyme Disease Symptoms • Within 7-14 days 80% of people develop red, expanding bulls eye – Tired, fever, headache, muscle aches, joint pain • If untreated some patients develop arthritis within a few weeks to months – Also swelling, meningitis, facial palsy, encephalitis • Antibiotic treatment for 3-4 weeks – Doxycycline, amoxicillin, erythromycin – NO immunity Lyme Disease in Missouri • 90 to 100 cases per year on average – Low risk overall – Relatively high compared to neighboring states – Reported cases have decreased dramatically in recent years • Lyme-like condition present (STARI) – Southern Tick Associated Rash Illness Average Number of Lyme Disease Cases Reported Each Year by State Health Departments (1990-1999) 120 MO AR OK KS NE IA IL KY TN Average Cases per Year 100 80 60 40 20 0 MO AR OK KS NE State IA IL KY TN Lyme Disease Cases Reported to CDC by Missouri State Health Department (1990-1999) 250 Cases Reported 200 150 100 50 0 1988 1990 1992 1994 Year 1996 1998 2000 STARI • Southern Tick Associated Rash Illness – ER indistinguishable from Lyme Disease • Transmitted by bite of Amblyomma americanum – Tick is abundant in southern states – Similar life cycle and ecology • Borrelia lonestari – Serologically different from Lyme bacteria Preventing Lyme Disease • Minimize and Avoid tick habitats – Leaf litter, brush, wood piles, tall grass – Spring/summer when nymphs are prevalent • Use personal protective measures – Clothing • Long sleeved shirts, light colors, tuck pants into socks • Permethrin – Repellents • DEET on clothing or skin – Tick check and removal