Researchers have transferred DNA from the Lyme parasite onto ticks in an attempt to study Lyme disease in humans, and the results are showing promise.
The small experiment aimed to determine if xenodiagnosis, or diagnosis with another animal, could be effective, safe, and appropriate for humans. It has only been used once before, to detect Chagas disease, another parasitic infection, in humans.
There were 36 participants in this study, which was published in the journal Clinical Infectious Diseases. Of the 36, 26 had either persistent symptoms of Lyme disease even after treatment, or retained the red, itchy lesion at the site of the original bite, or had unusually high levels of antibodies against the infection even though treatment seemed to have been successful. The other 10 participants were healthy and never had Lyme disease.
The researchers then placed between 25 and 30 uninfected ticks on the arm of each participant, allowed the ticks to feed for a few days under a special dressing, and then collected the ticks, which were then incubated for up to two weeks.
The incubation was done to allow any Lyme bacteria to develop in the ticks that could have been transmitted from the infected participants. After the incubation period, the researchers examined the ticks and found that the ticks from the healthy volunteers had no evidence of the Lyme bacteria. They were able to harvest usable ticks from 23 participants infected with Lyme disease, and 21 had no ticks test positive for signs of bacteria.
"This is a very initial study, our main objective was to develop the technique in humans," said lead author Dr. Adriana Marques of the National Institutes of Health in Bethesda, Maryland. "It is very hard to find evidence of the bacteria itself, not just antibodies, in infected people once the skin rash is gone."
The major complaint from some of the participants consist only of mild itching, so this new study has found that xenodiagnosis as a technique is safe for humans.
Lyme disease is transmitted through a bite from an infected tick. Initial symptoms can include headaches, musculoskeletal pain, coughing, sore throat, conjunctivitis, minor neurological impairment, and a skin lesion called erythema chronicum migrans. The symptoms, though, can vary from person to person.
Individuals who contract Lyme disease are often cleared of the infection after two weeks of antibiotics, and are declared completely clear if their blood shows no infection after another four weeks. However, 10 to 20 percent of those who get the disease continue to suffer from the symptoms, such as pain and fatigue, for over six months, even if tests show that the infection is gone. This is called Post-Treatment Lyme Disease Syndrome (PTLDS).
The disease can also infect the heart, a condition known as Lyme carditis. The Centers for Disease Control and Prevention has stated that there have been three deaths due to Lyme carditis in 2012 and 2013. Between the years 1985 and 2008, there were only four deaths reported.