Health professionals are encouraged to further their knowledge of Lyme disease and other tick-borne illnesses
Lyme disease is an illness caused by the bacterium Borrelia burgdorferi. The bacterium is a spirochete transmitted by certain species of Ixodes ticks. In eastern Canada it is spread through the bite of infected blacklegged ticks (Ixodes scapularis). Blacklegged ticks can also transmit pathogens that may cause other illnesses, such as anaplamosis, babesiosis and Powassan disease.
Following exposure to B. burgdorferi, patients may have no or minimal symptoms but most cases present with one of three stages, which may overlap:
Early localized disease (usually less than 30 days) usually presents with an acute illness characterized by systemic manifestations - fever, arthralgias, headache and skin manifestations. A single, localized skin lesion known as erythema migrans (EM) is often present. Most patients will present with EM within 7 days of the initial tick bite; however, the incubation period can vary between 3 and 30 days. The skin lesion is present in approximately 80% of patients. EM is a characteristically annular erythematous lesion greater than 5 cm in diameter that slowly increases in size. The lesion sometimes develops a central clearing but can be homogenously erythematous. It is usually painless and non-pruritic.
Co-infection should be considered in patients who present with initial symptoms which are more severe than commonly observed with Lyme disease. Consideration should be given when a high grade fever is present for more than 48 hours despite effective antibiotic therapy, or when thrombocytopenia, leukopenia or anemia are present with flu-like symptoms despite resolution of EM.
Early disseminated disease (usually less than 3 months) can develop if Lyme disease is untreated, as the bacterium disseminates via the bloodstream to other body sites and provokes damage to body tissues at certain sites. Systemic manifestations include fever, arthralgias, headache, and lymphadenopathy. Skin manifestations include multiple EM lesions. Heart manifestations may include atrioventricular block, tachyarrhythmias, myopericarditis, and myocardial dysfunction. Central nervous system manifestations may include aseptic meningitis, cranial neuropathy (most commonly facial nerve palsy), and motor or sensory radiculoneuropathy. Other manifestations including conjunctivitis and uveitis can also occur.
Late disseminated disease (usually more than 3 months) can last months or even years if Lyme disease remains untreated. Musculoskeletal manifestations include oligoarticular arthritis. Central nervous system manifestations include encephalopathy, axonal polyradiculoneuropathy, and chronic encephalomyelitis. Occular manifestations include retinitis.
Post-treatment Lyme disease syndrome. Some people treated for Lyme disease continue to have symptoms months to years after treatment. This condition is known as post-treatment Lyme disease syndrome (PTLDS). The exact cause of PTLDS is not fully understood. The lingering symptoms are generally held to be due to damaged tissues that are the result of the preceding infection and associated immune-mediated inflammation. Studies are ongoing to help understand the pathophysiology of PTLDS. If an individual has been treated for Lyme disease and still feels unwell, they should see their doctor to discuss how to relieve suffering and help cope with the symptoms using the best tools available. Foundational approaches include maintaining a healthy diet, getting plenty of rest, and exercising regularly. Support from family, friends and others who can help find ways of managing stress and dealing with ongoing symptoms is important. Patients with PTLDS almost always get better with time; however, it can take months to feel completely well.
If a patient presents with a tick that is still attached, appropriate removal involves the use of blunt, medium-tipped, angled forceps. The bite area should be inspected carefully for any retained mouthparts, which may be gently excised if possible.
A skin lesion present while a tick is still attached or which has developed within 48 hours of detachment is most likely a tick bite hypersensitivity reaction. Hypersensitivity reactions are usually < 5 cm in largest diameter, sometimes have an urticarial appearance, and typically begin to disappear within 24–48 hours.
Prophylaxis can be started if the patient meets all of the following 4 criteria.
Patients with asymptomatic tick bites of concern should be monitored closely for manifestations of early localized disease, for up to 30 days.
Early localized Lyme disease with erythema migrans (EM) does not require diagnostic testing, beyond clinical assessment, before initiating treatment. A diagnosis of Lyme disease can be made on the basis of the clinical presentation with EM, seasonal occurrence and a history of exposure to infected black legged ticks. Diagnostic testing is insensitive at this stage and not recommended in a patient who has links to an endemic area.
Diagnostic testing with serology is appropriate for persons with symptoms of early localized Lyme disease (EM) that occurs out of season or with no known history of exposure to infected blacklegged ticks. Diagnostic testing is also appropriate for persons with characteristic neurological, cardiac or joint involvement.
The two-tiered serological testing algorithm is an appropriate methodology and includes an enzyme immunoassay (EIA) screening test followed by a confirmatory Western blot test if the EIA is positive or equivocal.
In the setting of EM (acute phase) without an exposure in an endemic area, testing with the two-tiered serological method is recommended and treatment may be provided at the physician’s discretion. If symptoms persist and Lyme disease remains in the differential diagnosis, serological testing should be repeated in three to six weeks if the initial serology was negative.
Canadian laboratory diagnostic guidelines for Lyme disease are consistent with those followed by public health authorities in the United States and Europe and meet international standards. Public health professionals in these countries have ongoing concerns regarding American for-profit laboratories that may not be using properly validated tests or criteria for interpreting test results. By using unvalidated methods, patients who do not have Lyme disease may appear to test positive and they may receive potentially harmful treatments unnecessarily.
Re-infection is the recurrence of symptoms as a result of a new exposure to an infected tick, which has led to a new infection. Re-infection can occur in as many as 2%-21% of patients living in endemic areas who have had Lyme disease. On examination, re-infection typically presents with an erythema migrans (EM) lesion at a different site than the original lesion more than 1-2.5 years after the original infection and not within 11 months of the first infection.
Laboratory diagnosis of re-infection becomes a challenge, given that serology, including lgM, can remain positive for many years. Diagnosis is reliant on the clinical presentation of a new EM lesion at a different site.
Five tick-borne illnesses are known to be transmitted by Ixodes scapularis ticks in the northeastern United States: Lyme disease (Borrelia burgdorferi), babesiosis (Babesia microti), human granulocytic anaplasmosis (Anaplasma phagocytophilum), deer tick virus encephalitis/Powassan disease (Powassan virus), as well as illness due to Borrelia miyamotoi. When Lyme disease is diagnosed, co-infection should be considered if there is a more severe clinical presentation, if symptoms persist, or if there is a poor response to recommended therapies. Consultation with an infectious disease specialist for all complex tick-borne diseases including co-infections should be considered.
Babesiosis is caused by the protozoan parasite Babesia microti (rarely other Babesia species). Its distribution in North America largely coincides with the distribution of Lyme disease but lower incidence.. The incubation period is variable, though is usually one to six weeks, but may be up to six months following blood transfusion. Common manifestations include gradual onset of fatigue, accompanied by intermittent fever and other non-specific flu-like symptoms (i.e., headache, chills and muscle aches) but not erythema migrans (EM). It is a more severe infection than Lyme disease, particularly in splenectomised patients. Hemolytic anemia and thrombocytopenia are also common. Babesia parasites can be detected by light-microscopic examination of blood smears, although multiple smears may need to be examined. Serological testing, in the setting of babesiosis, will reveal elevated titres and 4-fold rise in antibody titre between acute infection and convalescence. PCR testing can also be used to detect Babesia.
Human granulocytic anaplasmosis (HGA) is caused by a rickettsia bacterium Anaplasma phagocytophilum. Distribution in North America largely coincides with Lyme disease distribution, though at a much lower incidence. The incubation period is usually 1-2 weeks. Clinical symptoms include fever and flu-like symptoms (i.e., fatigue, headache, chills, and muscle aches) that are typically more severe than in early Lyme disease. Thrombocytopenia, leukopenia, and increased liver enzymes also occur. Serological testing, in the setting of anaplasmosis, will show a 4-fold rise in antibody titre between acute infection and convalescent phase.
Powassan virus is a member of the deer tick virus complex and in North America has two lineages; one carried by I. scapularis ticks and one carried by I. cookei and I. marxi ticks. It is a rare infection in humans. The initial symptoms are nonspecific but present as a more severe infection than Lyme diseae with frequent progression to life threatening neurological complications.
Borrelia miyamotoi has only recently been found to infect humans. Patients with this infection generally have fever, chills, and headache. Other common symptoms include body and joint pain and fatigue.
Obtaining a complete blood cell count, comprehensive metabolic panel, and examination of peripheral blood smear are essential when considering a diagnosis of tick-borne diseases.
Laboratory confirmed and suspect clinical cases of Lyme disease and other tick borne diseases are reportable to Public Health as per regulation (in writing within seven days).
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