440 likes | 1.1k Views
Canine Tick Infestation is a Sentinel for Environmental Tick Activity and Human Tick-Related Health Events 7th International Society for Disease Surveillance Conference Raleigh, NC Sarah Rhea, DVM 1 Larry Glickman, VMD, DrPH 1 Seth Glickman, MD, MBA 1 Anna Waller, ScD 1 Amy Ising, MSIS 1
E N D
Canine Tick Infestation is a Sentinel for EnvironmentalTick Activity andHuman Tick-Related Health Events 7th International Society for Disease Surveillance ConferenceRaleigh, NC Sarah Rhea, DVM1 Larry Glickman, VMD, DrPH1 Seth Glickman, MD, MBA1 Anna Waller, ScD1 Amy Ising, MSIS1 Jean-Marie Maillard, MD, MSc2 Jeff Engel, MD2 • Department of Emergency Medicine, UNC Chapel Hill • North Carolina Division of Public Health
Outline • Basic tick biology • Approaches to tick surveillance • Hypotheses and study methods • Results • Conclusions • Future studies • Potential uses and advantages of a novel tick surveillance system
Ticks Indigenous to North Carolina* • Hard ticks: hard shell (scutum) covering body • Deer tick or blacklegged tick (Ixodes scapularis) • American dog tick (Dermacentor variabilis) • Lone star tick (Amblyomma americanum) *Apperson, Engber, Waldvogel, Ticks and Tick-Borne Diseases in North Carolina, 2003
Importance of Tick Surveillance in North Carolina • Tick-borne diseases are significant cause of morbidity & mortality in NC • Rocky Mountain Spotted Fever (Rickettsia rickettsii) • Ehrlichiosis, Anaplasmosis (Ehrlichia spp) • Lyme disease (Borrelia burgdorferi) CDC
Traditional Methods of Tick Surveillance • Environment • Field dragging • Small mammal trapping • People • Reportable tick-borne diseases • Calls to health departments or poison control centers
Limitations to TraditionalSurveillance Methods • Environment • Samples small geographic areas only • Labor intensive • People • Reported tick-borne diseases are a gross underestimation • Paired titers infrequently available to support a diagnosis (3-5%)
A Study to Evaluate Potential Sources of Human and Veterinary Medical Data for Tick Surveillance: Canine tick activity is a sentinel for environmental tick activity and human tick-related health events
Dog Tick Infestation & Human Lyme Disease in the US by Month, 2002-2004 Glickman et al, Vector-borne & Zoonotic Diseases, 2006
Hypotheses • Canine tick infestation in NC is seasonal • Affected by topography and climate of NC • Precedes onset of human tick-related health events in NC • NC emergency department surveillance data is useful in monitoring human tick-borne infections in a community in a timely manner. • Doxycycline prescription rates and hospital inpatient data correlate well with ED chief complaints of tick exposure and ED diagnoses of tick-borne diseases
Study Methods:Source of Canine Tick Data (2005-2007) • BanfieldR primary care veterinary hospital electronic medical records • >700 BanfieldR hospitals in 44 states • 33 NC hospitals • 2007: >240,000 dog visits & >1700 tick-infested dogs
Sources of Human Tick-related Health Data (2005-2007) • ED surveillance data from NC DETECT (North Carolina Disease Event Tracking and Epidemiologic Collection Tool) • Chief complaint &/or Triage notes with keyword: “tick”* • Tick-related ICD-9-CM diagnosis code(s) • NC Division of Public Health notifiable tick-borne disease reports* • Doxycycline prescription data from the IMS Health informatics corporation • NC Hospital inpatient data from HCUP (Healthcare Cost and Utilization Project) *Preliminary results presented today
NC DETECT ED Data • Statewide early event detection • 110/112 EDs reporting • 2007: >3.7 million ED visits & nearly 1600 keyword “tick” ED visits
Risk of Tick-Related Exposureby NC region • Number of dogs w/ tick infestation per 1,000 dog visits • Number of NC DPH reported human tick-borne disease per 1,000,000 people • Number of ED visits with tick-related chief complaints &/or triage notes per 10,000 ED visits
2005 Sources: NC DPH reportable disease records, Banfield medical records
2005 Sources: NC DPH reportable disease records, Banfield medical records
Conclusions • Canine and human tick activity in NC is seasonal • Patterns are slightly different among the 3 regions • Canine tick data and ED chief complaint surveillance data provide similar information. • Both canine tick data and ED chief complaint surveillance data may provide earlier warnings of tick activity than reportable disease data.
Study Limitations • Currently, small number of Banfield pet hospitals in coastal and mountain regions of NC • Reliance on text documentation and ICD-9 coding for NC DETECT ED data • Doxycycline is indicated for conditions other than tick-borne disease (eg. STIs, acne, respiratory disease) • ED surveillance data cannot be linked to HCUP inpatient data
Planned Studies • Complete the evaluation of human data • NC DETECT ED ICD-9-CM codes • Doxycycline prescriptions • HCUP inpatient data • Determination of the specificity of ED chief complaints and doxycycline prescribing for symptoms & diagnosis of tick-borne disease • Tick collection, identification, & PCR for tick-borne pathogens from pet dogs across NC • Develop statistical models for yearly prediction of the start of tick season
Potential Uses & Advantages • Education and increased awareness of tick-borne disease • Physicians: Consider in differential diagnosis • Veterinarians: Alert pet owners to potential risk for tick exposure in environment, provide topical tick preventatives for pets • Public health practitioners: Alert the public and provide information about tick prevention • Readily available human and dog data • NC DETECT ED data • Banfield veterinary records
Acknowledgements UNC-CH Dept of Emergency Medicine Nita Glickman Charles Cairns NC Division of Public Health Carl Williams UNC-CH Depts of Medicine & Pediatrics David Weber
Brown dog tick (Rhipicephalus sanguineous) • Rarely takes blood meals from humans, feeds almost exclusively on dogs • Typically lives indoors & is active all year • does not likely experience the seasonal changes in activity seen with other NC ticks
RMSF & ErlichiosisCase Classification • Confirmed: A clinically compatible case (meets clinical evidence criteria) that is laboratory confirmed. • Probable: A clinically compatible case that has supportive laboratory results. • Suspect: A case with laboratory evidence of past or present infection but no clinical information available. CDC 2008
Lyme DiseaseCase Classification • Confirmed: a) EM with a known exposure, or b) EM with lab evidence of infection & without a known exposure, or c) a case with at least one late manifestation & lab evidence. • Probable: any other case of physician-diagnosed Lyme disease that has lab evidence. • Suspected: a) EM with no known exposure and no lab evidence, or b) a case with lab evidence but no clinical information available. CDC 2008
Location of 110 EDs in North Carolina Participating in NC DETECT
Dog Tick Infestation and NC DPH Reportable Human Tick-borne Disease, 2005 NC Piedmont Region NC Coastal Region
Dog Tick Infestation and NC DPH Reportable Human Tick-borne Disease, 2006 NC Piedmont Region NC Coastal Region
Coastal Dog & DPH reports, 2007 Piedmont Mountain
Animals as Sentinels for Human Disease • Early coal miners used canaries to detect deadly methane gas in coal mines • Veterinary pathologists discovered WNV as cause for area bird deaths immediately prior to human WNV outbreak, NYC, 1999 • Bioterrorism events
Events for Surveillance • Tick density and biological activity in nature • Tick-related infections & diseases in people • Reportable • Not-reportable • Tick infestation of dogs • Tick-related infections & diseases in dogs
Importance of Tick Surveillance in North Carolina • Tick-borne diseases are significant cause of morbidity & mortality in NC • Rocky Mountain Spotted Fever (Rickettsia rickettsii) • Ehrlichiosis, Anaplasmosis (Ehrlichia spp) • Lyme disease (Borrelia burgdorferi) CDC
Study Methods:Source of Canine Tick Data (2005-2007) • BanfieldR primary care veterinary hospital electronic medical records • >700 BanfieldR hospitals in 44 states • 33 NC hospitals • 2007: >240,000 dog visits & >1700 tick-infested dogs