Lyme disease (LD) is caused by bacteria of the Borrelia burgdorferi sensu lato complex and transmitted by the bite of ticks of the Ixodes ricinus complex. To date, no autochthonous cases have been reported in Argentina. Its diagnosis involves serological tests included in a two-step algorithm. The study proposes to report the results of laboratory tests, describe the clinical-epidemiological characteristics of consultations received due to suspected LD, and critically evaluate the scientific evidence on alleged autochthonous cases of Lyme in Argentina.

From 09/2014-05/2022, a study was carried out that included 53 individuals who consulted due to suspected LD at a reference laboratory. Serum samples were obtained and referred to the Centers for Disease Control and Prevention (CDC) for determination of IgM and IgG antibodies. The samples met one or both inclusion criteria: -Travel to an area where the transmitting vector circulates; -Positive diagnostic tests reported by national and international laboratories.

According to the data collected from the epidemiological form, it was evident: 36% of the patients presented non-specific neurological symptoms and 64% reported rheumatological symptoms; 57% of the patients did not report traveling to the area of circulation of the transmitting vector; 46% reported having suffered multiple bites. According to the aforementioned selection criteria, 43% (n = 23) of the patients met both criteria, which would suggest 23 possible imported cases of LD. The remaining 57% only showed positive results in at least one diagnostic technique for EL, which represented 30 “autochthonous” cases. Only 5 cases (9%), with positive results issued by national and international laboratories, were confirmed as positive by the CDC. These individuals had an epidemiological history of traveling to the tick vector circulation area. The remainder of the cases were reported as negative by the CDC and were ruled out as possible indigenous Lyme cases. The comparison of the results sent by private laboratories and those obtained by the CDC showed 91% (n = 48) false positives.

The diagnosis of LD should only be considered based on the presence of typical symptoms of infection in patients with a history of exposure to the vector. Always use FDA-approved assays and recommended interpretation criteria.

Argentina, Lyme, Diagnostico.

There was no conflicts of interest.

Declarations of interest: None.