Dogs as sentinels for human Lyme borreliosis in The Netherlands.

Serum samples from hunters (n = 440), their hunting dogs (n = 448), and hunters without dog ownership (n = 53) were collected in The Netherlands at hunting dog trials and were tested for antibodies against Borrelia burgdorferi by a whole-cell enzyme-linked immunosorbent assay. Additionally, 75 healthy pet dogs were tested. The results of this study indicate that the seroprevalence among hunting dogs (18%) was of the same order as the seroprevalence among pet dogs (17%) and hunters (15%). The seropositivity of a hunting dog was not a significant indicator of increased risk of Lyme borreliosis for its owner. No significant rise in seroprevalence was found in dogs older than 24 months. This indicated that seropositivity after an infection with B. burgdorferi in dogs is rather short, approximately 1 year. In humans this is considerably longer but is also not lifelong. Therefore, the incidence of B. burgdorferi infections among dogs was greater than that among hunters, despite a similar prevalence of seropositivity among hunters and their hunting dogs. Because no positive correlation was observed between the seropositivity of a hunter and the seropositivity of the hunter's dog, direct transfer of ticks between dog and hunter does not seem important and owning a dog should not be considered a risk factor for Lyme borreliosis.

Serodiagnosis of Lyme borreliosis using detection of different immunoglobulin (sub)classes by enzyme-linked immunosorbent assay and Western blotting.

To improve the performance of enzyme-linked immunosorbent assays for the serodiagnosis of Lyme borreliosis, the prevalence of several immunoglobulin classes and subclasses against various antigens of Borrelia burgdorferi was investigated by Western blotting. The sera of 40 early Lyme borreliosis patients (ELB), 27 late Lyme borreliosis patients (LLB), 62 healthy controls and 140 non-Lyme borreliosis patients were used. Detection of IgG1 versus total IgG was found to be more sensitive in detecting Borrelia burgdorferi antigens, especially flagellin (41 kD) protein, but did not improve the performance of Western blotting. The use of IgG1 detection showed an increase in sensitivity and specificity for the early Lyme borreliosis patient group compared to the standard IgG and IgM detection method by enzyme immunoassays using purified Borrelia burgdorferi flagellum. However, in an enzyme immunoassay using a total sonicate, sensitivity in detecting early Lyme borreliosis and late Lyme borreliosis with IgG1 remained lower compared to the detection of early Lyme borreliosis by IgM antibodies and late Lyme borreliosis by total IgG antibodies.

Evaluation of fifteen commercially available serological tests for diagnosis of Lyme borreliosis.

The performance of 11 commercially available enzyme immunoassays (EIA) and four Western blot (WB) tests for the detection of IgM and IgG antibodies against Borrelia burgdorferi were compared. A total of 229 serum specimens were used: 26 from patients with early Lyme borreliosis, 13 from patients with late Lyme borreliosis, 62 from healthy controls and 128 from patients with disorders clinically mimicking Lyme borreliosis and/or known to cause cross-reactivity in Lyme borreliosis serological tests (patient control group). In specimens from patients with early Lyme borreliosis, the sensitivity of the individual tests ranged from 35 to 81% for detection of IgM. In late Lyme borreliosis, sensitivity of the tests ranged from 46 to 92%. In healthy controls the specificity of the tests ranged from 89 to 100% and from 82 to 97% for IgM and IgG tests, respectively. In the patient control group, specificity of the tests ranged from 75 to 90% for IgM and from 84 to 100% for IgG tests. The Behring (Germany) and Genzyme Virotech (Germany) IgM EIA tests showed the best performance in detecting early Lyme borreliosis. For the detection of late Lyme borreliosis, the Dako (Denmark) IgG test was the best despite its low sensitivity. The maximum sensitivity of Western blotting for detecting IgM in patients with early Lyme borreliosis and IgG in patients with late Lyme borreliosis was 50 and 46%, respectively. The use of an EIA-WB two-test protocol improved the specificity and positive predictive values of the EIA results but caused a significant loss in sensitivity. Patients with Epstein-Barr virus or cytomegalovirus infection who had a positive reaction in the IgM EIA could not be discriminated from patients with early Lyme borreliosis with the help of Western blotting. Hence, positive and negative predictive values in combination with sensitivity and specificity values indicated that the exclusion of these infections was more relevant than the confirmation of a positive IgM EIA with Western blot.

Evaluation of nine serological tests for diagnosis of Lyme borreliosis.

Two hundred serum specimens including 13 sera from patients with early Lyme borreliosis, 21 patients with late Lyme borreliosis, 15 rheumatoid factor positive sera, 31 sera from patients with syphilis and 84 sera from healthy controls were used to evaluate the following assays for the detection of antibodies to Borrelia burgdorferi: two in-house enzyme immunoassays (EIAs), two in-house immunofluorescent antibody assays (IFAs), a commercial haemagglutination assay (HA) (Diagast) and four commercial EIAs (Diagast, Dako, Diamedix, Whittaker Bioproducts). In early and late Lyme borreliosis sera sensitivity ranged from 8% to 62% and from 62% to 86% respectively. With the exception of the Dako EIA, which was signifcantly more sensitive in early Lyme borreliosis (62%) than the Diagast HA (8%) (p = 0.05), differences in sensitivity were not significant. In healthy controls the specificity was > or = 95% for all tests. Taking into account sensitivity, specificity, intra-test and inter-test precision, ease of performance and cost, the Dako EIA and Diamedix EIA were shown to be good alternatives to the in-house EIA and in-house IFA. Because of its low sensitivity in diagnosis of both early and late Lyme borreliosis, use of the Diagast HA should be discouraged.

The woodmouse (Apodemus sylvaticus) as a reservoir of tick-transmitted spirochetes (Borrelia burgdorferi) in The Netherlands.

In three widely separated locations in the Netherlands, woodmice (Apodemus sylvaticus) were trapped, examined for ticks and subjected to xenodiagnosis for the detection of tick-transmitted spirochetes (Borrelia burgdorferi). During the spring and summer, an average of 2.4 Ixodes larvae/mouse (n = 170) was observed, but the true numbers were probably greater. The numbers of nymphs could be determined more accurately and amounted to 0.46 nymphs/mouse. The percentage of mice that were infected with tick-transmitted spirochetes was 47% (n = 45), 29% (n = 58) and 0% (n = 64) for the three locations respectively. The absence of spirochete-infected mice in location 3 is puzzling because spirochete-infected I. ricinus nymphs were collected (infection rate up to 11%) in the same location during the subsequent spring. Sexually active mice were more frequently infected with spirochetes than juveniles and non-sexually active ones. On location 1, the island of Texel, a sample of mice was also caught during the subsequent winter and subjected to xenodiagnosis. The results indicate that B. burgdorferi survives the winter in the vector tick rather than in the reservoir rodents.

Lyme borreliosis: a very infrequent cause of arthritis of undetermined aetiology in the southern part of The Netherlands.

Seventy-three patients with undiagnosed arthritis of undetermined aetiology, 94 patients with classified arthritis (rheumatoid arthritis, ankylosing spondylitis, etc.) and 70 controls were studied for clinical and serological manifestations of Lyme borreliosis. The patients were recruited from the three rheumatology units in the most southern part of The Netherlands. A clinical diagnosis of possible Lyme borreliosis was made in seven of 73 patients with arthritis of undetermined aetiology, in four of 94 patients with classified arthritis and in one of the controls. A definite diagnosis of Lyme borreliosis could be made in only one patient who belonged to the arthritis of undetermined aetiology group. This patient had erythema migrans, arthritis of the knee joint and showed positive antibodies to B. burgdorferi. In the southern part of The Netherlands, Lyme arthritis does not seem to be a frequent cause of arthritis of undetermined aetiology.

[Prevalence of Lyme borreliosis in The Netherlands]. / Prevalentie van Lyme-borreliose in Nederland.

In the autumn of 1989 a seroepidemiological study was carried out among 440 owners of hunting dogs and 1052 blood donors from different regions in the Netherlands. To detect IgG antibodies to Borrelia burgdorferi an enzyme-linked immunosorbent assay was performed. The prevalence of antibodies to B. burgdorferi in owners of hunting dogs was 15%, which was significantly higher than in blood donors (9%). In both groups the prevalence of seropositivity increased with age. There was no difference between men and women. The prevalence of antibodies to B. burgdorferi in blood donors from different regions varied significantly, ranging from 2% to 17%. Only 3% of the owners of hunting dogs could recall having had symptoms most likely to be due to Lyme borreliosis. Of the 68 seropositive hunters 64 (94%) were asymptomatic. The results of this study indicate that in the Netherlands asymptomatic infections with B. burgdorferi are common in individuals highly exposed to ticks and that there is considerable variation in the prevalence of seropositivity in the general population. Hence caution is called for in the clinical interpretation of IgG test results.

[Occurrence of Borrelia burgdorferi in Ixodes ricinus in The Netherlands]. / Voorkomen van Borrelia burgdorferi in Ixodes ricinus in Nederland.

In a 1989 surveillance to study the infection rate of Ixodes ricinus ticks with Borrelia burgdorferi, a total of 1838 nymphal and adult Ixodes ricinus ticks were collected from 20 locations in The Netherlands. By means of a culture method using modified Barbour-Kelly-Stoenner medium nymphs were examined in pools of 4 and adults were examined individually. With 63 out of 75 isolates propagation and serological identification were possible. All of these 63 isolates were identified as Borrelia burgdorferi by means of an indirect immunofluorescence assay. In nymphs the minimal infection rate was 2.4%. The rate of infection for adults was shown to be 14.3%. These results are in agreement with the percentages found by other investigators in West-Europe. In all locations examined Ixodes ricinus were found to be infected with Borrelia burgdorferi, although the infection rate varied. The results indicate that the infection is widespread among ticks in The Netherlands and the potential risk of acquiring Lyme borreliosis after a tick bite is serious.