Early Symptoms and Testing
The early stage of Lyme disease can be difficult to diagnose as symptoms are often vague and resemble those of other illnesses. Within days to weeks of being bitten by an infected tick, many people develop flu-like symptoms including fatigue, chills, fever, headache, joint and muscle pain, and swollen lymph nodes. A circular rash known as erythema migrans or EM rash often appears at the site of the tick bite, although it is not present in all cases. This distinctive rash is considered a hallmark of Lyme disease in the early stages. Blood tests may be negative at this point and other diagnostic tools are needed.
If the characteristic bulls-eye rash is evident, physicians will often prescribe antibiotics without additional testing. But without the rash, more specific diagnostic methods are necessary to determine if symptoms are indeed caused by Lyme disease. Various blood tests are available but have limitations in the earliest stages. Culture testing of infected tissue from the rash or blood is more definitive but not routinely available. Diagnosis through symptoms and medical history remains challenging without clear test confirmation. Making the correct diagnosis early allows treatment before complications arise.
Later Stage Symptoms Complicate Diagnosis
If left untreated, the Borrelia bacteria that causes Lyme disease can spread to other parts of the body weeks to months after the initial infection. A variety of symptoms may emerge involving the joints, heart and nervous system. Common joint symptoms include severe pain, swelling and stiffness. Heart related issues can involve abnormalities in rhythm or conduction. Neurologic problems such as facial palsy, numbness, nerve pain and issues with memory, concentration and mood are also potential indicators of disseminated Lyme disease.
Diagnosing later stage or disseminated Lyme disease based on symptoms alone can be difficult due to variability between individuals and similarities to other illnesses. Blood tests become more accurate over time but do not provide information on organ involvement. Where the infection has spread determines what diagnostic testing is most applicable. Cerebrospinal fluid analysis helps evaluate nervous system abnormalities while echocardiograms assess heart function. MRI and lumbar puncture may be used on a case-by-case basis depending on symptom presentation. Making the correct diagnosis with certainty at this stage remains challenging.
Limitations of Current Diagnostic Tools
No single laboratory test can definitively determine if a patient’s symptoms are due to acute or disseminated Lyme disease. Available blood tests, which detect antibodies the body produces against Borrelia burgdorferi, are imperfect. Serological testing in the first few weeks of infection may show negative results due to the time needed for antibodies to develop. Even later on, up to 30% of patients with confirmed Lyme disease will never generate a positive test result.
Co-infections with other tick-borne diseases further complicate the diagnostic picture. A large percentage of patients infected with Lyme disease also have co-infections, yet blood tests only check for antibodies to Borrelia burgdorferi and cannot determine if other pathogens are involved. Diagnosis based on clinical presentation alone poses challenges due to the varied array of symptoms Lyme disease can produce and the potential for multiple tick-borne infections to occur simultaneously in individuals. None of the currently available diagnostic methods can provide a definitive positive or negative result in every patient.
Improving Diagnostic Accuracy and Testing
Given the limitations of existing testing options, research continues into more accurate diagnostic tools for Lyme disease. Recent studies have focused on identifying distinctive biomarkers in cerebrospinal fluid, blood plasma and urine that correspond to different stages of infection. Identification of Borrelia burgdorferi DNA fragments or unique proteins shed by the bacteria also show promise. Culturing the Borrelia bacteria from infected patients remains the gold standard but larger trials are still needed to improve sensitivity and standardization.
As testing options progress, determining the best diagnostic approach on an individual basis will likely remain a process of considering symptoms, exposure history, test results and clinical judgment. Utilizing multiple tests over the course of infection may provide a more definitive assessment when analyzed together. However, the complex nature of Lyme disease poses ongoing challenges to diagnosis. Improving awareness of the disorder among healthcare providers and at-risk patient groups helps ensure appropriate consideration of this difficult to detect infection. With further refinements in laboratory techniques and data collection on diagnostic accuracy, chances for earlier and more definitive diagnosis of Lyme disease may continue to rise.