What tickborne illnesses should I look for in the Northeast?

Tickborne Illnesses to Look for in the Northeast

In the Northeast United States, clinicians should primarily screen for Lyme disease, anaplasmosis, babesiosis, and ehrlichiosis when evaluating patients with suspected tickborne illness, as these represent the most common and clinically significant infections in this region. 1

Primary Tickborne Diseases in the Northeast

Lyme Disease

• Caused by Borrelia burgdorferi and transmitted by the blacklegged tick (Ixodes scapularis) 1
• Highest incidence occurs in northeastern and upper midwestern states 1
• Presents with erythema migrans rash in 70-80% of patients, often accompanied by fever, headache, fatigue, and muscle/joint pain 2
• Can progress to neurologic, cardiac, and arthritic manifestations if untreated 1

Anaplasmosis

• Caused by Anaplasma phagocytophilum and transmitted by Ixodes scapularis 1
• Highest incidence reported in Rhode Island, Minnesota, Connecticut, New York, and Maryland 1
• Typically presents with fever, headache, and myalgia; rash is rare 1
• Laboratory findings include thrombocytopenia, leukopenia, elevated hepatic transaminases, and mild anemia 1
• Blood smear examination may reveal morulae within granulocytes in up to 60% of cases 1

Babesiosis

• Caused primarily by Babesia microti and transmitted by Ixodes scapularis 1, 3
• Endemic in the same northeastern regions as Lyme disease 3
• Presents with fever, fatigue, headache, chills, and hemolytic anemia 4
• Can be severe in asplenic, elderly, or immunocompromised patients 5

Ehrlichiosis

• Primarily Human Monocytic Ehrlichiosis (HME) caused by Ehrlichia chaffeensis 1
• Also includes emerging infections with Ehrlichia muris-like agent (EML) in Minnesota and Wisconsin 1
• Presents with fever, headache, myalgia, and sometimes rash 1
• Laboratory findings include leukopenia, thrombocytopenia, and elevated liver enzymes 1

Emerging Tickborne Pathogens in the Northeast

• Borrelia miyamotoi - causes relapsing fever and is transmitted by Ixodes scapularis 1, 4
• Powassan virus (deer tick virus) - can cause encephalitis and is transmitted by Ixodes scapularis 1, 5
• Borrelia mayonii - recently identified cause of Lyme-like illness 4

Co-infections

• Co-infections are more common than expected by chance alone, particularly Babesia microti with Borrelia burgdorferi (83% more co-infection than predicted) 3
• Co-infections can increase disease severity and complicate diagnosis and treatment 3
• When treating suspected Lyme disease with beta-lactam antibiotics, be alert for persistent symptoms that may indicate unrecognized co-infection with Anaplasma phagocytophilum 1
• Leukopenia or thrombocytopenia in a patient with Lyme disease should raise suspicion for co-infection with A. phagocytophilum 1

Diagnostic Approach

• Consider seasonal timing - most infections occur during spring and summer months when nymphal ticks are active 1, 2
• Evaluate for specific clinical presentations:
  • Erythema migrans rash (Lyme disease) 2
  • Fever with leukopenia and thrombocytopenia (anaplasmosis or ehrlichiosis) 1
  • Hemolytic anemia (babesiosis) 5
• Early empiric treatment is often necessary before laboratory confirmation 2
• Use appropriate testing modalities:
  • Serology (paired acute and convalescent samples) 4
  • PCR for acute infections 4
  • Blood smear examination for babesiosis and sometimes anaplasmosis 1

Common Pitfalls and Caveats

• Relying solely on presence of rash - not all tickborne diseases present with rash, and rash is rare in anaplasmosis 1
• Failing to consider co-infections, which occur more frequently than expected 3
• Delaying treatment while awaiting laboratory confirmation can lead to increased morbidity and mortality 2
• Testing patient-retrieved ticks for infections is not recommended for clinical decision-making 2
• Amoxicillin can be used to treat early Lyme disease but is not effective for anaplasmosis, requiring doxycycline if co-infection is suspected 1