IMPROVED SERODIAGNOSIS OF LYME-DISEASE

Aims-To determine whether enzyme linked immunosorbent assay (ELISA) re sults for Borrelia burgdorferi require confirmation by immunoblotting and how immunoblotting may best be used in the diagnosis of Lyme disea se. Methods-Over one year, all referrals for Lyme disease to a distric t general hospital with a large tick population in its catchment area were tested by ELISA. Positive, low positive and negative serum sample s were subjected to immunoblotting and the reactive bands analysed. Re sults-In total, 633 samples were received; 38 were ELISA positive and 97 low positive. More serum samples were from rural (n = 356) than fro m urban (n = 277) areas but a higher percentage of serum samples from urban areas were ELISA positive. The ELISA results were confirmed by i mmunoblotting in 15/38 positive samples but in only four of 37 with a low positive titre. An IgM positive blot required a 41 kDa band plus g reater than or equal to 1 specific band; for IgG a 41 kDa band plus gr eater than or equal to 2 specific bands were necessary. Five serum sam ples were IgM positive with a 41 kDa plus one or more other specific b ands. For IgG blots, the best discrimination was seen with the 21, 31, 46, and 92 kDa bands. Nonspecific, weakly reacting bands at 55, 60 an d 67 kDa were frequently seen. Infection was confirmed in four of six patients with arthritis, but in only one of 10 patients with erythema chronicum migrans. Conclusions-ELISA alone is insufficient for diagnos is. All positive and low positive or negative serum samples with a goo d clinical history should be examined by immunoblotting. A higher perc entage of modified ELISA positive than low positive results were confi rmed. There are significant differences between European and American immunoblotting patterns. Local results show similarity to American res ults, highlighting the need for a local Borrelia isolate.