A case-control study of an outbreak of Eastern Equine Encephalomyelitis in Michigan (USA) equine herds in 1991

Ross, Whitney A.; Kaneene, John B.

doi:10.1016/0167-5877(95)00479-g

Cited by 10 publications

(9 citation statements)

References 13 publications

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“…The tree density may also provide suitable sheltering locations for various mosquito species. The location of crop and pasturelands next to the tree plantations also might provide an edge effect, allowing for a greater concentration of both vector and avian populations within the horse habitats [36]. A concurrent explanation is that the tree plantation habitats often rest on poorly drained soil.…”

Section: Discussionmentioning

confidence: 99%

Spatial epidemiology of eastern equine encephalitis in Florida

et al. 2012

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BackgroundEastern Equine Encephalitis virus (EEEV) is an alphavirus with high pathogenicity in both humans and horses. Florida continues to have the highest occurrence of human cases in the USA, with four fatalities recorded in 2010. Unlike other states, Florida supports year-round EEEV transmission. This research uses GIS to examine spatial patterns of documented horse cases during 2005–2010 in order to understand the relationships between habitat and transmission intensity of EEEV in Florida.MethodsCumulative incidence rates of EEE in horses were calculated for each county. Two cluster analyses were performed using density-based spatial clustering of applications with noise (DBSCAN). The first analysis was based on regional clustering while the second focused on local clustering. Ecological associations of EEEV were examined using compositional analysis and Euclidean distance analysis to determine if the proportion or proximity of certain habitats played a role in transmission.ResultsThe DBSCAN algorithm identified five distinct regional spatial clusters that contained 360 of the 438 horse cases. The local clustering resulted in 18 separate clusters containing 105 of the 438 cases. Both the compositional analysis and Euclidean distance analysis indicated that the top five habitats positively associated with horse cases were rural residential areas, crop and pastureland, upland hardwood forests, vegetated non-forested wetlands, and tree plantations.ConclusionsThis study demonstrates that in Florida tree plantations are a focus for epizootic transmission of EEEV. It appears both the abundance and proximity of tree plantations are factors associated with increased risk of EEE in horses and therefore humans. This association helps to explain why there is are spatially distinct differences in the amount of EEE horse cases across Florida.

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Section: Discussionmentioning

confidence: 99%

Spatial epidemiology of eastern equine encephalitis in Florida

et al. 2012

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“…The greater number of deer cases might simply reflect a greater risk of exposure resulting from their greater use of wetland habitats. If vector activity is actually responsible, models developed to predict outbreaks of EEE in horses based on precipitation (Ross and Kaneene, 1996) also might be useful in predicting EEE occurrence in deer, affording wildlife agencies the opportunity to expedite surveillance and public education efforts in advance. This case series highlights several issues of significance to wildlife managers.…”

Section: Discussionmentioning

confidence: 99%

“…The first human case of EEE was reported in 1980 (Centers for Disease Control, 1980), and since that time, status as a reportable disease has facilitated annual surveillance in humans (Centers for Disease Control, 1992) and horses (Centers for Disease Control, 1993Control, , 1995, as well as captiveraised ring-necked pheasants (Phasianus colchicus) (Centers for Disease Control, 1995). The epidemiology and natural history of EEE have been well-described previously (Scott and Weaver, 1989), and epidemiological analyses of recent equine outbreaks (Ross andKaneene, 1995, 1996) and vector species identification (Shaw, 1976) also have been carried out in Michigan. Limited efforts have been made to identify free-ranging bird and rodent hosts to assess the risk they might pose as reservoirs (McLean et al, 1985).…”

Section: Introductionmentioning

confidence: 99%

An Outbreak of Eastern Equine Encephalitis Virus in Free-Ranging White-Tailed Deer in Michigan

Schmitt

Cooley

Fitzgerald

et al. 2007

Journal of Wildlife Diseases

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Eastern equine encephalitis (EEE) virus has been recognized as affecting horses and humans in the eastern United States for 70 yr. Evidence of exposure with EEE virus has been reported in a variety of free-ranging wild birds and mammals but cases of clinical disease are much less commonly reported. In Michigan, reports of outbreaks of EEE virus in equine species extend back more than a half century. We report diagnosis of EEE virus infection of multiple free-ranging white-tailed deer (Odocoileus virginianus) from three Michigan counties during late summer of 2005. Infection was confirmed in seven of 30 deer collected based on reported neurologic signs and results from immunohistochemistry, polymerase chain reaction, and/or virus isolation. One of the deer also was infected with West Nile virus and an eighth deer had microscopic lesions in the cerebrum consistent with those reported for EEE. To our knowledge, this is the first report of multiple cases of EEE in free-ranging white-tailed deer, and highlights several issues of significance to wildlife managers and public health officials.

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“…8 Affected equids demonstrated rapidly progressive neurologic disease for < 3 days. Among 21 equids with detailed clinical histories, 17 died or were euthanized after illnesses of <24 hr.…”

Section: Methodsmentioning

confidence: 99%

Immunohistochemical Diagnosis of Eastern Equine Encephalomyelitis

et al. 1996

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Abstract. An immunohistochemical (IHC) assay was developed for the detection of eastern equine encephalomyelitis (EEE) virus antigen in formalin-fixed, paraffin-embedded tissues. All cases of EEE diagnosed at the Michigan State University Animal Health Diagnostic Laboratory from 1991 through 1994 were evaluated. The diagnosis was based on histopathologic examination of the brain and confirmatory virus isolation. Sections of cerebrum from 26 equids and 5 birds were assessed by IHC. Histologically normal brain tissues from 2 horses and 1 pheasant and brain tissues from 2 cases of equine neurologic disease with diagnoses other than EEE served as negative controls. The IHC assay was based on standard streptavidin-biotin technology, using a commercially available kit and a monospecific polyclonal primary antibody preparation derived from murine ascitic fluid. Nineteen of 20 equids and all 5 birds positive by histopathology and virus isolation were positive for EEE virus antigen by IHC. Three equids with histologic lesions compatible with a diagnosis of EEE but negative by virus isolation also were negative for virus antigen by IHC. In 3 other equids, histopathology and IHC were positive for EEE, but virus isolation was not attempted because of contamination of the brain specimen. The IHC assay of formalin-fixed, paraffin-embedded brain tissues for EEE virus antigen is a rapid, effective test for confirming a histopathologic diagnosis of EEE, and assay results correlate well with virus isolation results.

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A case-control study of an outbreak of Eastern Equine Encephalomyelitis in Michigan (USA) equine herds in 1991

Cited by 10 publications

References 13 publications

Spatial epidemiology of eastern equine encephalitis in Florida

Spatial epidemiology of eastern equine encephalitis in Florida

An Outbreak of Eastern Equine Encephalitis Virus in Free-Ranging White-Tailed Deer in Michigan

Immunohistochemical Diagnosis of Eastern Equine Encephalomyelitis

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