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Lyme Disease in NH: 2011 Update. Jodie Dionne-Odom, MD Deputy State Epidemiologist Division of Public Health Services, DHHS Section of Infectious Disease Dartmouth Medical School. Outline. History Tick Biology and Ecology Surveillance National and Local Epidemiology
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Lyme Disease in NH: 2011 Update Jodie Dionne-Odom, MD Deputy State Epidemiologist Division of Public Health Services, DHHS Section of Infectious Disease Dartmouth Medical School
Outline History Tick Biology and Ecology Surveillance National and Local Epidemiology Clinical Manifestations Management Prevention
Lyme Disease • First recognized US 1975 • Many juvenile rheumatoid arthritis cases around Lyme, CT • In Europe, similar skin rashes and meningopolyneuritis described for 100 years. • In 1983, both syndromes linked after recovery of the spirochete in a patient.
Biology of Lyme Disease This bacteria is difficult to culture. Extracellular pathogen B. burgdorferi is carried by ticks. Vector = Ixodes Lyme disease is now the most common vector-borne disease in the US and Europe.
Geography • Worldwide in temperate zones: • North America • Northeast: Maine to Maryland • Mid West: Wisconsin and Minnesota • West Coast: California and Oregon • Europe (forested areas) – B. garinii • Northern Asia
Dog Ticks (aka Wood Ticks) American dog tickPhoto credit: U of MN Entomology Dept.
The Life Story of Ixodesscapularis Larval, nymph and adult stages. • Adults peak in spring and fall – preferred host is white-tailed deer. Mating occurs. • Nymphs peak May-July – aggressive - frequently bite humans • Larvae peak August-September (from eggs on the ground)
Reservoir Hosts • Deer, wild rodents, and other animals • White-footed mice are preferential hosts for larval and nymphs (Mice maintain spirochetemia)
Case Classification 2011 Confirmed: a) case of EM with a known exposure b) case of EM with laboratory evidence of infection c) a case with at least one late manifestation with lab evidence of infection. Probable: case of physician-diagnosed Lyme disease with lab evidence of infection Suspected: a) a case of EM with no known exposure or lab evidence of infection b) a case with lab evidence of infection but no clinical information.
Surveillance Case definition 2011 Laboratory criteria for diagnosis • Positive Culture for B. burgdorferi • Two-tier testing interpreted using established criteria: • ELISA, then Western Blot (IgM and IgG) • Single-tier IgG immunoblot seropositivity using established criteria. • CSF antibody positive for B. burgdorferi
Lyme Disease Surveillance in NH • Reportable in NH since 1990 • 1991-1999: 15-47 cases per year • Increasing incidence began in 2000 • 124 cases in 2000 • 1,621 cases in 2008 (peak) • 2nd most common reportable infectious disease
Reporting Process • In 2006, all reported cases were assigned to a public health nurse for investigation • Called provided to collect symptom, treatment, and exposure information • >100% increase in 2006 • 271 cases in 2005 vs. 617 cases in 2006 • In 2007, a letter system implemented to reduce burden to public health staff • Collected surveillance data via form mailed to all providers ordering a Lyme disease test with a positive result
2010 Lyme Disease Investigations • A total of 2,002 Lyme disease reports received • 826 (41%) Confirmed • 509 (25%) Probable • 175 (9%) Suspect (missing information) • 492 (25%) did not meet case definition
Active Surveillance for Borrelia in New Hampshire Deer Ticks • Fall 2007, Fall 2008, and Fall 2009 deer ticks were collected from all ten NH counties • Ticks were tested for presence of Borrelia burgdorferi by PCR • Fewer than 20 ticks were collected from 4 counties and data could not be analyzed • Overall state proportion of ticks infected was 60% (686 of 1,140 ticks collected) • Babesia and Anaplasma also detected at lower rates (<10%) though testing not complete
