Lyme Disease (Borrelia burgdorferi)

Rancho Murieta Association Board Meeting August 19, 2014

Kent Fowler, D.V.M. Chief, Animal Health Branch

California Department of Food and Agriculture

Panel Members

•  California Department of Food and Agriculture (CDFA) –  Kent Fowler, DVM – Branch Chief, Animal Health Branch (AHB)

•  California Department of Public Health (CDPH) –  Anne Kjemtrup, DVM, MPVM, PhD – Epidemiologist in Vector-Borne

Diseases –  Bryan Jackson, PhD - Associate Public Health Biologist

•  California Department of Fish and Wildlife (CDFW) –  Ben Gonzales, DVM, MPVM – Senior Wildlife Veterinarian –  Helayna Pera - Environmental Scientist (Wildlife) –  Brian Patrick - Wildlife Officer CDFW

Discussion Issues

•  Lyme Disease – Background –  Humans –  Horses –  Dogs

•  Cause •  Transmission •  Symptoms •  Diagnosis •  Prevention •  Vaccination •  Treatment •  Rancho Murieta Deer Population Health •  Deer Population Interaction with RMA residents

A Brief Overview of

Lyme Disease In California

California Tick Species 47 species of ticks in California Only 8 species bite humans

–  Ixodid (“hard”) ticks •  Ixodes pacificus (western black-legged tick) •  Dermacentor variabilis (American dog tick) •  Dermacentor occidentalis (Pacific Coast tick) •  Dermacentor andersoni (wood tick) •  Rhipicephalus sanguineus (brown dog tick)

–  Argasid (“soft”) ticks •  Ornithodoros hermsi •  Ornithodoros parkeri •  Ornithodoros coriaceus (Pajahuello tick )

Lyme Disease

•  Borrelia burgdorferi •  Cause of Lyme disease in U.S.*

•  Spirochete bacteria

•  Lyme disease is the most common vector-borne disease in the U.S.

•  In California, western blacklegged tick (Ixodes pacificus) only tick species that transmits LD to people **

* Steere, 2006. Wien Klin Wochenschr. (118): 625-633 **Lane et al. 2004 J. Med Entomol. (41): 239-248

Early Symptoms of Lyme Disease

•  Non-specific “flu-like” symptoms •  Erythema migrans (EM) rash

–  EM rash is slowly expanding rash that sometimes has central clearing

–  Rash typically develops 7-10 days following tick bite (range 1-30 days)

–  Rash is rarely pruritic (Wormser, N Engl J Med 2006;354:2794-801) –  Reported in about 60% of CA cases

•  Rash should not be confused with tick-bite lesions (or allergic response)

EM Rash. Source: Ross Ritter

Other Signs of Lyme disease

•  Neurologic –  Idiopathic facial palsy (Bell’s palsy) – Radiculoneuropathy

•  Arthritic – Arthritis in one or more joints

•  Cardiac – Atrioventricular conduction

disturbances, myocarditis, pericarditis

Transmission of B. burgdorferi to humans in California

Ixodes pacificus

Life cycle

adult female

female lays eggs

larva

nymph Larvae or nymphal Ixodes pacificua ticks acquire the bacteria by feeding on infected mammal hosts. People are accidentally infected through the bite of an infected nymph or adult female western black-legged tick.

Ixodes pacificus--Adult habitat

Along trail sides, waiting on vegetation, often on the uphill side of a trail

Deciduous hardwood forests

Ixodes pacificus: nymphal habitat

Photos courtesy Dr. Robert Lane, UC Berkeley

Leafy under-story in deciduous hardwood forests On fallen logs in

hardwood forests

Adult ticks are found on wild grasses and low plants

Ticks do not fall from trees, jump or fly

Ticks “quest” or wait on the ends of grasses for a host to come by and brush

against the grass

Ticks grasp a

host with their

forelimbs

California: Ixodes pacificus Infection Prevalence with B. burgdorferi

•  Adult I. pacificus: 1-5%

•  Nymphal I. pacificus: 0-20% –  In northern CA where studied, (Mendocino,

Placer, Yolo Counties), prevalence is often higher in nymphal than adult ticks*

•  I. pacificus larvae: 0% –  Larvae rarely bite people

From left to right: Adult female, larva (lower), nymph (above), adult male Ixodes pacificus ticks. Source:CADPH

* Clover and Lane 1995. J. Trop Med Hyg. 53: 237-240; Wright et al 1998. J. Med Ent 35: 1044-1049

California: Lizards and Lyme Disease

•  Larval and nymphal I. pacificus ticks feed on lizards. •  A borreliacidal protein in lizard blood kills Lyme disease

spirochetes in the gut of infected I. pacificus nymphs. •  As a result, in some areas in California, the proportion of

infected adult I. pacificus ticks is lower than in the nymphal I. pacificus ticks because the blood meal from the lizard “cleaned” the tick.

Western fence lizard

Lane and Quistad 1997. J. Parasitol. 84: 29-34; Salkeld and Lane, 2010 Ecology 91 (1): 293-298

About 100 reported cases of Lyme disease per year in California

Trinity 5.9

Humboldt 4.3 > 5.0

Mendocino 4.0

Sierra 3.1

Nevada 2.4 3.0 – 4.9

Mono 2.0

Santa Cruz 1.7

Mariposa 1.7

Amador 1.6 1.0 – 2.9

Sonoma 1.4

Marin 1.0

Others 0.1 – 0.9

No cases reported

Reported cases per 100,000 person-years, 2004 – 2013*

Figure 2. Incidence of Lyme disease, by county, California, 2004 - 2013

*Though Lyme disease cases have been reported in nearly every county, cases are reported based on the county of residence, not necessarily the county of infection.

Interactive Lyme Disease Map: www.cdph.ca.gov

www.cdph.ca.gov

Erythema migrans

Ixodes scapularis tick

Ixodes pacificus tick

larva

nymph

male

female

Lyme Disease in Horses

•  Low grade fever •  Chronic weight loss •  Sporadic lameness •  Muscle tenderness •  Chronically poor performance •  Arthritis •  Diverse orthopedic problems •  Extreme skin hypersensitivity •  Neurologic signs •  Uveitis

Lyme Disease in Horses/Dogs

•  Diagnosis –  Antibody based serologic tests difficult to interpret

•  ELISA, Western Blot, IFA •  PCR

•  Treatment –  Doxycycline –  Oxytetracycline

•  Vaccination –  No licensed vaccines for horses –  Three (3) vaccines available for dogs

–  Human vaccine on the market for 4 years (1998-2002) •  LYMErix by SmithKline Beecham

Lameness/Health Issues in RM Deer

•  Vesicular Stomatitis* •  Foot and Mouth Disease* •  Adenovirus Hemorrhagic Disease* •  Bluetongue* •  EHD (Epizootic Hemorrhagic Disease)* •  Malignant Catarrhal Fever* •  Foot Rot •  Lyme Disease •  Injury •  Copper Deficiency

Issues to Address Concerning Lyme Disease/RM Deer Health

•  Prevalence of lyme disease? – Deer ticks – species? – prevalence + for Lyme

•  Health of deer population? – Risk to other livestock/human

•  Possibility to answer these questions with complete workup and necropsy of several deer (4-6) – select by lameness/poor health

If we really want to get something done, we’ll find a way. If we don’t, we’ll find an

excuse.

Thank You!

Kent Fowler, D.V.M. Kent.fowler@cdfa.ca.gov

(916) 900-5040 Chief, Animal Health Branch

California Department of Food and Agriculture