Strain Variation of Lyme Disease Spirochetes Isolated from Ixodes ricinus Ticks and Rodents Collected in Two Endemic Areas in Switzerland

Abstract

The relationship among Lyme borreliosis, Borrelia genospecies, rodent reservoirs, and Ixodes ricinus L. ticks was studied in two endemic areas in Switzerland. Ear punch biopsies and sampling of internal organs were used to isolate Borrelia hurgdorferi (Johnson, Schmid, Hyde, Steigerwalt and Brenner) from small mammals, Apodemus sylvaticus L., A. flavicollis Melchior, Clethrionomys glareolus Schreber. Spirochetes were isolated from ear tissue and spleen of the rodents. Isolates were homogeneous and belonged to typing group II identified as B. afzelii (Canica, Nato, du Merle, Mazie, Baranton and Postic). Our data show that a specific association exists between B. afzelii and rodent reservoirs in European foci. Borreliae were also isolated from field-collected I. ricinus ticks from the same study areas. Proteinic and antigenic analysis indicated that more than one genospecies were present in the tick population. This suggests that other vertebrate hosts may serve as reservoirs of other Borrelia genospecies implicated with Lyme disease.

Infection of Ixodes ricinus (Acari: Ixodidae) by Borrelia burgdorferi sensu lato in North Africa

“…burgdorferi sensu stricto, B. garinii, and B. afzelii. These genospecies have been isolated from patients, rodents, birds, and I. ricinus from various areas in Europe (Humair et al 1995, Olsen et al 1995, Picken et al 1996, Zhioua et al 1996. Two additional genospecies have been observed in I. ricinus and identiÞed as B. valaisiana and B. lusitaniae (formerly the genospecies VS116 and PotiB2, respectively) (Postic et al 1994Pé ter et al 1995;Rijpkema et al 1995;Le Flè che et al 1997;Wang et al 1997).…”

Sex-Biased Genetic Structure in the Vector of Lyme Disease, Ixodes Ricinus

“…Such a pattern could have major epidemiological consequences in terms of pathogen transmission. In Europe, human Lyme disease is caused by different genospecies of Borrelia (B. burgdorferi sensu stricto, B. afzelii, and B. garinii, Humair et al 1995) that are found in specific associations with vertebrate reservoirs (rodents, other mammals, birds; Humair and Gern 1998;Kurtenbach et al 1998a). It has been shown that the serum-complement of some animals is specifically lethal for some species of Borrelia (Kurtenbach et al 1998b).…”

Vector Competence of Ixodes scapularis and Ixodes ricinus (Acari: Ixodidae) for Three Genospecies of Borrelia burgdorferi

“…In the northeastern United States, the white-footed mouse, Peromyscus leucopus, is the primary reservoir of B. burgdorferi sensu stricto (Mather et al 1989); in the Rocky Mountains, the Mexican woodrat, Neotoma mexicana, is the primary reservoir (Maupin et al 1994), and the dusky-footed woodrat, Neotoma fuscipes, and the California kangaroo rat, Dipodomys heermanni, serve as primary reservoirs in the Pacific Northwest (Brown and Lane 1992). In Europe (Humair et al 1995) and in Japan (Nakao and Miyamoto 1995) Borrelia isolates from rodents appear to be principally B. afzelii. Humair et al (1995) reported a specific association exists between B. afzelii and rodent reservoirs in Europe.…”

“…In Europe (Humair et al 1995) and in Japan (Nakao and Miyamoto 1995) Borrelia isolates from rodents appear to be principally B. afzelii. Humair et al (1995) reported a specific association exists between B. afzelii and rodent reservoirs in Europe.…”

“…Strle et al (1995) reported isolating B. afzelii only from rodents in 3 of 6 sites studied in Slovenia. Moreover, Humair et al (1995) reported isolating only 1 genospecies, B. afzelii, from rodent ears in 2 Lyme disease-endemic areas of Switzerland, despite isolating all 3 genospecies from the ticks in the same 2 areas. Their findings of heterogeneity of tick isolates and homogeneity of rodent isolates suggests that an affinity exists between B. afzelii and rodents, and indicates other genospecies may be associated with other vertebrate hosts.…”