Rocky Mountain Spotted Fever Exposures at Long Point, ON
To: Ottawa Physicians and Nurse Practitioners
Date: September 22, 2025
From: Dr. Emil Prikryl, Associate Medical Officer of Health
Subject: Rocky Mountain Spotted Fever Exposures at Long Point, ON
Dear Colleagues,
Please see linked below a memo from Ontario’s Office of the Chief Medical Officer of Health regarding Rocky Mountain Spotted Fever (RMSF) exposures at Long Point, Ontario.
This memo highlights the emergence of RMSF in Ontario, with two confirmed human cases and multiple canine cases associated with travel to the Long Point area, a peninsula on the north shore of Lake Erie. It also confirms the presence of Rickettsia rickettsii in American dog ticks collected from that region.
While the risk remains very low for the Ottawa region, health care providers are encouraged to maintain a high index of suspicion for RMSF in patients presenting with compatible signs and symptoms and a history of travel to Long Point or surrounding areas. In such cases, please order diagnostic tests but do not delay treatment with doxycycline while awaiting test results.
RMSF can be difficult to diagnose due to non-specific signs and symptoms in early stages of illness that usually appear 2 to 14 days after a tick bite and may include fever, headache, rash, nausea, vomiting, muscle pain, and abdominal pain. The rash typically starts as a maculopapular rash on the wrists, forearms and ankles, then spreads to the trunk and becomes petechial over time. The characteristic rash may be absent or delayed, and the illness can progress rapidly.
RMSF lab testing involves serology and PCR, but both have low sensitivity early in illness; negative results do not rule out infection, although pairing with a second serum sample 2-3 weeks after development of illness improves accuracy. For information on testing, please visit the Public Health Ontario Laboratory’s testing information page: Rickettsia (Spotted Fever Group and Typhus Group) | Public Health Ontario
English:
Rocky Mountain Spotted Fever Exposures at Long Point, ON
French:
Expositions à la fièvre pourprée des montagnes Rocheuses à Long Point (Ontario)
To report tick-borne diseases to Ottawa Public Health: Call 613-580-2424, extension 24224 and leave a detailed, confidential message including your contact information; or fax 613-580-9640.