MEDICAL ADVISORY: Heightened Surveillance for Lyme Disease (LD)

Issued by:  M. Mustafa Hirji, MD MPH FRCPC, Medical Officer of Health & Commissioner (Acting) 

Background

• Niagara Region Public Health (NRPH) has received 7 confirmed reports of Lyme disease (LD) in July
• Infected ticks can be found almost anywhere in Ontario and have been found in a dozen different locations in Niagara now. Wooded areas of areas with tall grasses and bushes, including city gardens and parks are ideal habitats for blacklegged ticks.
• Please be on heightened surveillance for any additional cases of LD

Clinical Presentation

• Average incubation period is 3 to 30 days after initial blacklegged tick bite
• Symptoms for LD may appear in overlapping stages
• Symptoms of early localized LD can include
  • Fever
  • Myalgias
  • Arthralgias
  • Headache
  • Presence of erythema migrans (EM) – typically within seven days of initial bite. Variations of EM are highly indicative of LD and can appear in various forms. Only 70% of individuals with early localized LD present with EM. Therefore, diagnosis should not be based solely on the presence of EM.

Diagnosis and Management

The management of Tick Bites and Investigation of Localized Lyme Disease Clinical Guidance Algorithm provides clinical guidance for diagnosis and management of LD.

For further information, please review the following:

• Lyme disease: Public Health Agency of Canada Lab Diagnostics
• Infectious Diseases Society of America (IDSA), Clinical Practice Guidelines
• Public Health Ontario, Lyme disease Testing

Post-Exposure Prophylaxis (PEP)

PEP is generally recommended for asymptomatic patients if all of the following criteria are met:

• The blacklegged tick was attached for at least 24 hours
• The blacklegged tick was removed within 72 hours
• The blacklegged tick was acquired in an area where the tick infectivity rate is greater than or equal to 20%
• Doxycycline is not contraindicated for the patient

The infectivity rate of ticks in Niagara Region with the bacteria that causes LD is most recently estimated to be 18.8%, though surveillance has been limited this year.

Reporting

LD is reportable to the Medical Officer of Health under the Health Protection and Promotion Act. If you have a probable case of LD, report it to Public Health in one of the following ways

• Report Lyme disease online
• Print / fax the completed Lyme disease surveillance form to 905-682-6470

More Information

For further information, please contact NRPH, Infectious Disease program at 1-888-505-6074 or 905-688-8248 ext. 7554/7543 Monday to Friday 8:30 a.m. to 4:30 p.m. or visit our Ticks and Lyme Disease website.