J Wildl Dis. 1997 Jan;33(1):40-6.
Role of the eastern chipmunk (Tamias striatus) in the epizootiology of Lyme borreliosis in northwestern Illinois, USA.
The role of the eastern chipmunk (Tamias striatus) in the epizootiology of Lyme borreliosis was evaluated in Castle RockState Park, Illinois (USA), an enzootic region, from June to August 1993. Prevalence, intensity, and molting rate of immature Ixodes scapularis were determined for chipmunks, white footed mice (Peromyscus leucopus), and raccoons (Procyon lotor). Chipmunks were the primary host for I. scapularis nymphs and an important secondary host for I. scapularis larvae. Based upon ear punch biopsy analysis, B. burgdorferi prevalence in chipmunks was similar to that of mice in August and greater than that of mice in June and July. Thus we propose that chipmunks are the primary source of B. burgdorferi infection for I. scapularis nymphs and an important secondary source of infection for larvae.
PMID: 9027689 [PubMed - indexed for MEDLINE]
J Parasitol. 1991 Dec;77(6):945-9.
Spatial and temporal dispersion of immature Ixodes dammini on Peromyscus leucopus in northwestern Illinois.
Infestation by immature Ixodes dammini and infection by Borrelia burgdorferi of the white-footed mouse Peromyscus leucopus were studied in Castle Rock State Park in northwestern Illinois during June-October 1990. Prevalence and intensity of infestation of larvae on mice were highest in August with a smaller peak in early June.
The distribution of larvae on mice was highly aggregated during each of the sampling periods. Aggregation appears to be the result of a series of nonrandom successful attachments by single larvae, rather than of simultaneous attachment by clumps of larvae.
Infection rate of mice by B. burgdorferi averaged 21.4% with a peak of 28.6% in August. A comparison of the numbers of attached immature ticks collected from mice and of questing ticks collected through dragging indicated that the larvae-to-nymph ratio was higher on mice than on drags. Given the low total numbers of nymphs collected from mice, this suggests a potential role for other hosts of I. dammini nymphs in northwestern Illinois.
PMID: 1779300 [PubMed - indexed for MEDLINE]
J Med Entomol. 1991 Jan;28(1):101-4.
Spatial and temporal distribution of Ixodes dammini (Acari: Ixodidae) in a northwestern Illinois state park.
Five km of hiking trails in Castle Rock State Park in Ogle Co., Ill., were drag-sampled for Ixodes dammini Spielman, Clifford, Piesman & Corwin between 15 May and 19 October 1989.
Densities of nymphs peaked on 22 June, larval densities peaked on 9 August, and adult densities had two peaks, 15 May and 19 October. The terrain crossed by the trails consisted of woods and meadow.
There were no discernible habitat preferences for adult females, but nymphs and larvae were most numerous in the woods.
Peak nymph density averaged one nymph per 28.5 m in woods, one nymph per 67 m in mixed habitat, and one nymph per 194 m in meadow. The results of this study are consistent with previously published data from the east coast of the United States.
Recoveries of nymphs using a modified tick drag, consisting of one dozen 0.5-m strips, and the standard 1-m design were compared.
PMID: 2033600 [PubMed - indexed for MEDLINE]
J Med Entomol. 1990 Jul;27(4):556-60.
Status of Ixodes dammini (Acari: Ixodidae) in Illinois.
- 1Center for Economic Entomology, Illinois Natural History Survey, Champaign 61820.
Ixodes dammini Spielman, Clifford, Piesman & Corwin was found for the first time in Illinois in November 1987, when two adult females were collected from two deer in Jo Daviess County in the northwestern corner of the state.
In 1988, in a study of six state parks in northern Illinois, questing adults and nymphs were encountered in one park in Ogle County. During the firearm deer hunt in November 1988, adult female and male ticks were found in several counties, with a high rate of infestation (greater than 25%) in two counties (Ogle and Rock Island) along the Rock River, which flows from Wisconsin into the Mississippi River.
Several cases in humans with no history of travel outside of the state have been reported, primarily from northern Illinois. We suspect that infiltration of infected ticks and wildlife from Wisconsin is resulting in the emergence of Lyme disease in Illinois.
Because all the components necessary for the completion of the tick life cycle and for the transmission of Borrelia burgdorferi are available throughout much of the state, I. dammini and Lyme disease can spread and become established in large portions of Illinois.
PMID: 2388231 [PubMed - indexed for MEDLINE]