Non-infected ticks could help detect Lyme disease in people still experiencing symptoms after treatment.
The process, dubbed "xenodiagnoses" uses the disease-carrier to find evidence of the microbe that causes the conditions, a National Institute of Allergy And Infectious Disease (NIAID) news release reported.
Lyme disease is caused by the Borrelia burgdorferi bacteria which are transmitted to humans from ticks in the Ixodes genus, such as deer ticks.
"Most cases of Lyme disease are cured by antibiotics, but some patients continue to experience symptoms despite the absence of detectable Lyme bacteria," NIAID Director Anthony S. Fauci, M.D. "This poses a mystery that requires continued research into new or improved ways to diagnose Lyme disease and determine the cause of unresolved symptoms."
"Xenodiagnosis using ticks to detect B. burgdorferi has been used previously in animal studies, but this is the first time it has been tried in people," Adriana Marques, M.D., of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and Linden Hu, M.D., of Tufts Medical Center said in the news release. "Our primary goals in this initial trial were to develop procedures for tick xenodiagnosis and to determine its safety in humans."
The researchers looked at 36 adult volunteers; 10 of the volunteers had post-treatment Lyme disease syndrome (PTLDS); 10 had high levels of the antibodies that fight B. burgdorferi after being treated with antibiotics; five who had erythema migrans (a bull's-eye rash) and had been treated with antibiotics in the past; one person who had erythema migrans and had been treated with antibiotics at the time of tick placement; and a control group of 10 healthy volunteers.
The participants allowed up to 30 larval ticks (that were disease free and had been bred in the lab) placed on them, especially near problem areas such as aching joints or rashes; after four to six days the tick were removed and tested for symptoms of lyme.
"The most common adverse event experienced by volunteers was mild itching at the site of tick attachment,"Dr. Marques said.
Not all the participants ended up with enough "blood-engorged" ticks to perform xenodiagnoses. Twenty-three of the patients had at least one tick tested; 19 people tested negative and two had indeterminate results, but B. burgdorferi DNA was found in the patient who was in therapy for erythema migrans and one PTLDS patient.
"Future studies are necessary to determine the incidence of positive xenodiagnostic results for B. burgdorferi after antibiotic treatment, if these results represent viable organisms or remnants of infection, and whether these results can be related to ongoing symptoms in patients after therapy for Lyme disease," the researchers wrote according to the news release.
