In a 2017 study, non-human primates whose symptoms, disease progression, and treatment response mimic humans were infected via tick bite with Borrelia burgdorferi, the causative agent of Lyme Disease, and monitored for 1.2 years. Four months after infection a portion of the primates were treated with doxycycline, a CDC recommended and commonly prescribed antibiotic for the treatment of Lyme, for 28 days. 

Despite infection with the same strain, affected tissues varied between animals. Inflammation was found around the spinal cord, in the heart, skeletal muscle, and joints. B. burgdorferi-specific DNA was found in a variety of tissues from treated and untreated primates, including the skeletal muscles, heart, bladder, peripheral nerves, and the central nervous system. 

At 12 months post infection, ticks were allowed to feed on the primates. Active Borrelia spirochetes were cultured from the guts of ticks who fed on 4 of 5 untreated animals and 3 of 5 treated animals. The authors interpreted this as an indication that doxycycline “may reduce the spirochetes to a small, dormant population, but does not rid the primates of viable B. burgdorferi.”

As the infection became chronic, antibody response waned in some primates but not others, regardless of whether they had been treated. This shows that persistence and chronic infection may not be reflected in antibody production, meaning antibody tests can yield false negatives in persistent and chronic infections. One primate who developed an erythema migrans rash, a telltale symptom of Lyme, even had no antibody response despite persistent spirochetes found in his tissues and the ticks that fed on him.

Key takeaways:

  • Despite infection with the same strain, affected tissues varied between animals.
  • CDC recommended antibiotic treatment failed to clear Lyme.
  • Due to waning antibody levels over time, antibody tests may yield false negatives in persistent (resistant to treatment) and chronic infections.