Arthropod Diseases Affecting Arthropod Diseases Affecting Outdoor Activities: Lyme DiseaseOutdoor Activities: Lyme Disease

Dr. Richard M. HousemanDr. Richard M. Houseman

Department of EntomologyDepartment of EntomologyUniversity of MissouriUniversity of Missouri

Lyme Disease BackgroundLyme Disease Background

• Bacterial disease first identified in Bacterial disease first identified in Conneticut (1977)Conneticut (1977)– Inflammation of joints (arthritis)Inflammation of joints (arthritis)– Rarely, if ever fatalRarely, if ever fatal

• 92% of all cases occur in nine states92% of all cases occur in nine states– CT, RI, NY, PA, DE, NJ, MD, MA, WI.CT, RI, NY, PA, DE, NJ, MD, MA, WI.

• Leading cause of vector-borne infectious Leading cause of vector-borne infectious disease in U.S. (15,000 cases annually)disease in U.S. (15,000 cases annually)– Borrelia burgdorferiBorrelia burgdorferi– Similar bacteria in Europe, AsiaSimilar bacteria in Europe, Asia

Lyme Disease TransmissionLyme Disease Transmission

• Transmitted by the bite of infected tick Transmitted by the bite of infected tick Ixodes scapularisIxodes scapularis– Rodents, deer, birds, dogs are primary hostsRodents, deer, birds, dogs are primary hosts– Human infections after tick feeds for >36 hoursHuman infections after tick feeds for >36 hours

• In temperate areas (24In temperate areas (24ºº-66-66ºº latitude) latitude) virus transmission is seasonalvirus transmission is seasonal– Most in late spring to mid summer (nymphs)Most in late spring to mid summer (nymphs)– Few in fall and early spring (adults)Few in fall and early spring (adults)

YE

AR

1Y

EA

R 2

adults + eggs

larvae

nymphs

nymphs(dormant)

nymphs

adults

adults

adults(dormant)

SPRING

SUMMER

FALL

WINTER

Lyme Disease RisksLyme Disease Risks

• Risk of exposure is greatest in woods Risk of exposure is greatest in woods and fringe areas of propertiesand fringe areas of properties– Ticks may also be transported to lawn/gardenTicks may also be transported to lawn/garden

• Highest attack ratesHighest attack rates– Children 0-14 and 30+ years of ageChildren 0-14 and 30+ years of age

• Outdoor recreation, outdoor work, new Outdoor recreation, outdoor work, new homes in wooded areashomes in wooded areas

• Blood transfusions, infected blood, urine Blood transfusions, infected blood, urine are NOT documented risksare NOT documented risks

Lyme Disease SymptomsLyme Disease Symptoms

• Within 7-14 days 80% of people Within 7-14 days 80% of people develop red, expanding bulls eyedevelop red, expanding bulls eye– Tired, fever, headache, muscle aches, joint painTired, fever, headache, muscle aches, joint pain

• If untreated some patients develop If untreated some patients develop arthritis within a few weeks to monthsarthritis within a few weeks to months– Also swelling, meningitis, facial palsy, encephalitisAlso swelling, meningitis, facial palsy, encephalitis

• Antibiotic treatment for 3-4 weeksAntibiotic treatment for 3-4 weeks– Doxycycline, amoxicillin, erythromycinDoxycycline, amoxicillin, erythromycin– NO immunityNO immunity

Lyme Disease in MissouriLyme Disease in Missouri

• 90 to 100 cases per year on average90 to 100 cases per year on average– Low risk overallLow risk overall– Relatively high compared to neighboring Relatively high compared to neighboring

statesstates– Reported cases have decreased Reported cases have decreased

dramatically in recent yearsdramatically in recent years

• Lyme-like condition present (STARI)Lyme-like condition present (STARI)– Southern Tick Associated Rash IllnessSouthern Tick Associated Rash Illness

Average Number of Lyme Disease Cases Reported Each Year by State Health Departments (1990-1999)

State

MO AR OK KS NE IA IL KY TN

Ave

rag

e C

ases

per

Yea

r

0

20

40

60

80

100

120

MOAROKKSNEIAILKYTN

Lyme Disease Cases Reported to CDC by MissouriState Health Department (1990-1999)

Year

1988 1990 1992 1994 1996 1998 2000

Cas

es R

epo

rted

0

50

100

150

200

250

STARISTARI

• Southern Tick Associated Rash IllnessSouthern Tick Associated Rash Illness– ER indistinguishable from Lyme DiseaseER indistinguishable from Lyme Disease

• Transmitted by bite of Transmitted by bite of Amblyomma Amblyomma americanumamericanum– Tick is abundant in southern statesTick is abundant in southern states– Similar life cycle and ecologySimilar life cycle and ecology

• Borrelia lonestariBorrelia lonestari– Serologically different from Lyme bacteriaSerologically different from Lyme bacteria

Preventing Lyme DiseasePreventing Lyme Disease

• Minimize and Avoid tick habitatsMinimize and Avoid tick habitats– Leaf litter, brush, wood piles, tall grassLeaf litter, brush, wood piles, tall grass– Spring/summer when nymphs are prevalentSpring/summer when nymphs are prevalent

• Use personal protective measuresUse personal protective measures– ClothingClothing

• Long sleeved shirts, light colors, tuck pants into socksLong sleeved shirts, light colors, tuck pants into socks• PermethrinPermethrin

– RepellentsRepellents• DEET on clothing or skinDEET on clothing or skin

– Tick check and removalTick check and removal