Patients with laboratory evidence of West Nile virus disease without reported fever.

In 2013, the national surveillance case definition for West Nile virus (WNV) disease was revised to remove fever as a criterion for neuroinvasive disease and require at most subjective fever for non-neuroinvasive disease. The aims of this project were to determine how often afebrile WNV disease occurs and assess differences among patients with and without fever. We included cases with laboratory evidence of WNV disease reported from four states in 2014. We compared demographics, clinical symptoms and laboratory evidence for patients with and without fever and stratified the analysis by neuroinvasive and non-neuroinvasive presentations. Among 956 included patients, 39 (4%) had no fever; this proportion was similar among patients with and without neuroinvasive disease symptoms. For neuroinvasive and non-neuroinvasive patients, there were no differences in age, sex, or laboratory evidence between febrile and afebrile patients, but hospitalisations were more common among patients with fever (P < 0.01). The only significant difference in symptoms was for ataxia, which was more common in neuroinvasive patients without fever (P = 0.04). Only 5% of non-neuroinvasive patients did not meet the WNV case definition due to lack of fever. The evidence presented here supports the changes made to the national case definition in 2013.

Underreporting of Lyme and Other Tick-Borne Diseases in Residents of a High-Incidence County, Minnesota, 2009.

Lyme disease (LD), anaplasmosis, babesiosis and other tick-borne diseases (TBDs) attributed to Ixodes ticks are thought to be widely underreported in the United States. To identify TBD cases diagnosed in 2009, but not reported to the Minnesota Department of Health (MDH), diagnostic and procedural billing codes suggestive of tick-borne diseases were used to select medical charts for retrospective review in medical facilities serving residents of a highly endemic county in Minnesota. Of 444 illness events, 352 (79%) were not reported. Of these, 102 (29%) met confirmed or probable surveillance case criteria, including 91 (26%) confirmed LD cases with physician-diagnosed erythema migrans (EM). For each confirmed and probable LD, probable anaplasmosis and confirmed babesiosis case reported to MDH in 2009, 2.8, 1.3, 1.2 and 1.0 cases were likely diagnosed, respectively. These revised estimates provide a more accurate assessment and better understanding of the burden of these diseases in a highly endemic county.

Validation of Random Sampling as an Estimation Procedure for Lyme Disease Surveillance in Massachusetts and Minnesota.

Many disease surveillance programs, including the Massachusetts Department of Public Health and the Minnesota Department of Health, are challenged by marked increases in Lyme disease (LD) reports. The purpose of this study was to retrospectively analyse LD reports from 2005 through 2012 to determine whether key epidemiologic characteristics were statistically indistinguishable when an estimation procedure based on sampling was utilized. Estimates of the number of LD cases were produced by taking random 20% and 50% samples of laboratory-only reports, multiplying by 5 or 2, respectively, and adding the number of provider-reported confirmed cases. Estimated LD case counts were compared to observed, confirmed cases each year. In addition, the proportions of cases that were male, were ≤12 years of age, had erythema migrans (EM), had any late manifestation of LD, had a specific late manifestation of LD (arthritis, cranial neuritis or carditis) or lived in a specific region were compared to the proportions of cases identified using standard surveillance to determine whether estimated proportions were representative of observed proportions. Results indicate that the estimated counts of confirmed LD cases were consistently similar to observed, confirmed LD cases and accurately conveyed temporal trends. Most of the key demographic and disease manifestation characteristics were not significantly different (P < 0.05), although estimates for the 20% random sample demonstrated greater deviation than the 50% random sample. Applying this estimation procedure in endemic states could conserve limited resources by reducing follow-up effort while maintaining the ability to track disease trends.

Hospital-based enhanced surveillance for West Nile virus neuroinvasive disease.

Accurate data on the incidence of West Nile virus (WNV) disease are important for directing public health education and control activities. The objective of this project was to assess the underdiagnosis of WNV neuroinvasive disease through laboratory testing of patients with suspected viral meningitis or encephalitis at selected hospitals serving WNV-endemic regions in three states. Of the 279 patients with cerebrospinal fluid (CSF) specimens tested for WNV immunoglobulin M (IgM) antibodies, 258 (92%) were negative, 19 (7%) were positive, and two (1%) had equivocal results. Overall, 63% (12/19) of patients with WNV IgM-positive CSF had WNV IgM testing ordered by their attending physician. Seven (37%) cases would not have been identified as probable WNV infections without the further testing conducted through this project. These findings indicate that over a third of WNV infections in patients with clinically compatible neurological illness might be undiagnosed due to either lack of testing or inappropriate testing, leading to substantial underestimates of WNV neuroinvasive disease burden. Efforts should be made to educate healthcare providers and laboratorians about the local epidemiology of arboviral diseases and the optimal tests to be used in different clinical situations.

Mosquitoes in Moose Country: A Mosquito Survey of Northern Minnesota.

An adult mosquito survey was conducted at 12 sites using carbon dioxide traps in northern Minnesota throughout the summer of 2012. Specimens were counted, identified to species, sorted into pools, and tested for eastern equine encephalitis (EEEV) and West Nile virus (WNV). Our findings extend the known range of Culiseta melanura, Anopheles barberi, and An. quadrimaculatus and document the presence and abundance of 27 other mosquito taxa in the region. None of the pools tested positive for EEEV or WNV.

Habitat Suitability Model for the Distribution of Ixodes scapularis (Acari: Ixodidae) in Minnesota.

Ixodes scapularis Say, the black-legged tick, is the primary vector in the eastern United States of several pathogens causing human diseases including Lyme disease, anaplasmosis, and babesiosis. Over the past two decades, I. scapularis-borne diseases have increased in incidence as well as geographic distribution. Lyme disease exists in two major foci in the United States, one encompassing northeastern states and the other in the Upper Midwest. Minnesota represents a state with an appreciable increase in counties reporting I. scapularis-borne illnesses, suggesting geographic expansion of vector populations in recent years. Recent tick distribution records support this assumption. Here, we used those records to create a fine resolution, subcounty-level distribution model for I. scapularis using variable response curves in addition to tests of variable importance. The model identified 19% of Minnesota as potentially suitable for establishment of the tick and indicated with high accuracy (AUC = 0.863) that the distribution is driven by land cover type, summer precipitation, maximum summer temperatures, and annual temperature variation. We provide updated records of established populations near the northwestern species range limit and present a model that increases our understanding of the potential distribution of I. scapularis in Minnesota.

The nucleotide sequence of Saccharomyces cerevisiae chromosome XII.

The yeast Saccharomyces cerevisiae is the pre-eminent organism for the study of basic functions of eukaryotic cells. All of the genes of this simple eukaryotic cell have recently been revealed by an international collaborative effort to determine the complete DNA sequence of its nuclear genome. Here we describe some of the features of chromosome XII.

The nucleotide sequence of Saccharomyces cerevisiae chromosome XIV and its evolutionary implications.

In 1992 we started assembling an ordered library of cosmid clones from chromosome XIV of the yeast Saccharomyces cerevisiae. At that time, only 49 genes were known to be located on this chromosome and we estimated that 80% to 90% of its genes were yet to be discovered. In 1993, a team of 20 European laboratories began the systematic sequence analysis of chromosome XIV. The completed and intensively checked final sequence of 784,328 base pairs was released in April, 1996. Substantial parts had been published before or had previously been made available on request. The sequence contained 419 known or presumptive protein-coding genes, including two pseudogenes and three retrotransposons, 14 tRNA genes, and three small nuclear RNA genes. For 116 (30%) protein-coding sequences, one or more structural homologues were identified elsewhere in the yeast genome. Half of them belong to duplicated groups of 6-14 loosely linked genes, in most cases with conserved gene order and orientation (relaxed interchromosomal synteny). We have considered the possible evolutionary origins of this unexpected feature of yeast genome organization.

Natural infection of small mammal species in Minnesota with the agent of human granulocytic ehrlichiosis.

The natural reservoirs for the agent of human granulocytic ehrlichiosis (HGE) are suspected to be the small mammals that host immature stages of Ixodes scapularis ticks. To determine if such small mammals are naturally infected, we collected blood and serum samples from small mammal species in rural and suburban areas of Minneapolis and St. Paul, Minn. Samples were collected from white-footed mice (Peromyscus leucopus), eastern chipmunks (Tamias striatus), southern red-backed voles (Clethrionomys gapperi), and insectivorous shrews (Blarina brevicauda and Sorex cinereus). Blood samples were tested by PCR for active infection with the HGE agent, and sera from P. leucopus mice were tested for serologic evidence of infection by indirect immunofluorescence. PCR analyses revealed the presence of HGE agent DNA in 20 of the 190 samples (10.5%) tested. Of the 119 P. leucopus mouse serum samples that were analyzed, 12 (10.1%) contained Ehrlichia equi antibodies. In 3 of 119 (2.5%) P. leucopus mice from which both blood and serum were collected. HGE agent DNA and antibodies against E. equi were present. Animals with evidence of infection with the HGE agent are widely distributed around the Minneapolis-St. Paul area in regions with known I. scapularis tick activity. Small mammals that are frequent hosts for larval I. scapularis ticks and that are found in areas where HGE occurs are likely to be a major reservoir from which infected ticks that bite humans are derived.

Nucleotide sequence of human adenovirus type 12 DNA: comparative functional analysis.

A fresh inoculum of human adenovirus type 12 (Ad12) was obtained from the American Type Culture Collection and passaged once on human embryonic kidney cells, and Ad12 DNA was prepared from the first-passage yield to avoid higher passages which might have generated host-virus DNA recombinants. The 18 PstI fragments of Ad12 DNA were cloned into the pBluescript KS vector, and the entire nucleotide sequence of both strands from all 18 fragments was determined by using successive oligodeoxyribonucleotide primers. Ad12 DNA extends over 34,125 nucleotide pairs, and its molecular weight is calculated to be about 22 x 10(6). The nucleotide sequence of Ad12 DNA was subjected to computer analyses that determined possible open reading of frames on the two strands, the leader sequences, the position of the virus-associated RNA coding region, possible TATA, and polyadenylation signals. The distribution of the Ad12 open reading frames was similar to that in the previously sequenced Ad2 DNA, but there were also distinct differences. Ad12 DNA has an inverted terminal redundancy of 161 nucleotides, compared with 102 nucleotides in Ad2 DNA. There were stretches of sequence identity between Ad2 and Ad12 DNAs at both termini; the overall sequence similarity between the two viral genomes ranged between 59% (polypeptide IX) and 77% (in the E2 region), with high homology also in the sequences for the adenovirus DNA polymerase.

Serologic analysis of white-tailed deer sera for antibodies to Borrelia burgdorferi by enzyme-linked immunosorbent assay and western immunoblotting.

White-tailed deer serum samples were collected in the Minneapolis-St. Paul, Minn., metropolitan area during the fall and winter months from 1989 to 1992 and analyzed for antibodies to Borrelia burgdorferi, the etiologic agent of Lyme borreliosis. Ninety-eight percent of the serum samples were collected from regions where currently the vector tick, Ixodes dammini, is nonexistent. Antibodies to B. burgdorferi were detected in 2.2% of 508 samples by enzyme-linked immunosorbent assay, and their presence was confirmed by Western immunoblot analysis. Western immunoblotting yielded mean numbers of reactive bands of 0.1 and 6.0 for samples that were negative and positive for antibodies by enzyme-linked immunosorbent assay, respectively. The molecular weights of the antigens in many of the reactive bands from positive samples were similar to the molecular weights of antigens reactive with samples from humans with Lyme borreliosis. An antibody response to the major outer surface proteins A and B was not detected. Serologic analysis of deer sera may provide a valuable method for surveillance programs designed to monitor the spread of B. burgdorferi in nature.

Serological evidence of California group and Cache Valley virus infection in Minnesota white-tailed deer.

Blood samples were obtained from 138 white-tailed deer (Odocoileus virginianus) harvested at three sites surrounding the greater Minneapolis-St. Paul, Minnesota, metropolitan area (USA) and tested for neutralizing antibody to Cache Valley virus and three California serogroup (Jamestown Canyon, La Crosse, trivittatus) viruses (Bunyaviridae). Deer at each site had neutralizing antibody to one or more California serogroup viruses and/or Cache Valley virus. The majority of adult deer (85%) had antibody to both a California serogroup virus and Cache Valley virus. Antibody prevalence varied significantly with age of the deer. Fawns had a significantly lower prevalence of antibody to either a California serogroup (17%) or Cache Valley virus (39%) than did older (greater than 1-yr-old) deer (89% for a California serogroup virus and 91% for Cache Valley virus). The geometric mean titers of antibody in fawns to California serogroup (1:6) and Cache Valley viruses (1:17) were also less than that seen in older animals (1:11 and 1:28 for California serogroup and Cache Valley viruses, respectively). Of 76 older deer with antibody to the California serogroup, 91% had antibody specific for Jamestown Canyon virus. Jamestown Canyon is the primary California serogroup virus circulating in the suburban/rural Minneapolis-St. Paul area. Transmission occurs in an enzootic pattern similar to that documented in Indiana and Michigan. Cache Valley virus also appears to be enzootically transmitted in this area. However, the impact on domestic or wild animal populations is unknown.