Culex flavivirus isolates from mosquitoes in Guatemala.

A new strain of Culex flavivirus (family Flaviviridae, genus Flavivirus, CxFV), an insect virus first described in Japan, was isolated from adult Culex quinquefasciatus Say (Diptera: Culicidae) collected in 2006 from Izabal Department on the Caribbean coast of Guatemala. Mosquito pools were assayed for flavivirus RNA by using flavivirus group-specific primers that amplified a 720-bp region of the nonstructural (NS) 5 gene by standard reverse transcriptase-polymerase chain reaction. From 210 pools (1,699 mosquitoes), eight tested positive, and six of these mosquito pools produced virus isolates in Aedes albopictus Skuse C6/36 cells. Nucleotide sequence comparison of the eight flavivirus RNA-positive pools showed that there was 100% identity among them, and phylogenetic analysis of the NS5 and envelope gene regions indicated that they represent a strain of the recently described CxFV from Japan. This is the first report of an insect flavivirus from Central America.

First isolation of La Crosse virus from naturally infected Aedes albopictus.

La Crosse (LAC) virus, a California serogroup bunyavirus, is the leading cause of pediatric arboviral encephalitis in the United States and an emerging disease in Tennessee, West Virginia, and North Carolina. Human cases of LAC encephalitis in Tennessee and North Carolina have increased above endemic levels during 1997 to 1999 and may represent an expansion of a new southeastern endemic focus. This report describes the isolation of LAC virus from the exotic mosquito Aedes albopictus. The discovery of LAC virus in wild populations of Ae. albopictus coupled with its expanding distribution in the southeastern United States, suggests that this mosquito may become an important accessory vector, potentially increasing the number of human cases in endemic foci or expanding the range of the disease.

Serologic evidence for West Nile virus infection in birds in the New York City vicinity during an outbreak in 1999.

As part of an investigation of an encephalitis outbreak in New York City, we sampled 430 birds, representing 18 species in four orders, during September 13-23, 1999, in Queens and surrounding counties. Overall, 33% were positive for West Nile (WN) virus-neutralizing antibodies, and 0.5% were positive for St. Louis encephalitis virus-neutralizing antibodies. By county, Queens had the most seropositive birds for WN virus (50%); species with the greatest seropositivity for WN virus (sample sizes were at least six) were Domestic Goose, Domestic Chicken, House Sparrow, Canada Goose, and Rock Dove. One sampled bird, a captive adult Domestic Goose, showed signs of illness; WN virus infection was confirmed. Our results support the concept that chickens and House Sparrows are good arbovirus sentinels. This study also implicates the House Sparrow as an important vertebrate reservoir host.

Exposure of domestic mammals to West Nile virus during an outbreak of human encephalitis, New York City, 1999.

We evaluated West Nile (WN) virus seroprevalence in healthy horses, dogs, and cats in New York City after an outbreak of human WN virus encephalitis in 1999. Two (3%) of 73 horses, 10 (5%) of 189 dogs, and none of 12 cats tested positive for WN virus-neutralizing antibodies. Domestic mammals should be evaluated as sentinels for local WN virus activity and predictors of the infection in humans.

Comparative West Nile virus detection in organs of naturally infected American Crows (Corvus brachyrhynchos).

Widespread deaths of American Crows (Corvus brachyrhynchos)were associated with the 1999 outbreak of West Nile (WN) virus in the New York City region. We compared six organs from 20 crow carcasses as targets for WN virus detection. Half the carcasses had at least one positive test result for WN virus infection. The brain was the most sensitive test organ; it was the only positive organ for three of the positive crows. The sensitivity of crow organs as targets for WN virus detection makes crow death useful for WN virus surveillance.

Arbovirus infection increases with group size.

Buggy Creek (BCR) virus is an arthropod-borne alphavirus that is naturally transmitted to its vertebrate host the cliff swallow (Petrochelidon pyrrhonota) by an invertebrate vector, namely the cimicid swallow bug (Oeciacus vicarius). We examined how the prevalence of the virus varied with the group size of both its vector and host. The study was conducted in southwestern Nebraska where cliff swallows breed in colonies ranging from one to 3700 nests and the bug populations at a site vary directly with the cliff swallow colony size. The percentage of cliff swallow nests containing bugs infected with BCR virus increased significantly with colony size at a site in the current year and at the site in the previous year. This result could not be explained by differences in the bug sampling methods, date of sampling, sample size of the bugs, age structure of the bugs or the presence of an alternate host, the house sparrow (Passer domesticus). Colony sites that were reused by cliff swallows showed a positive autocorrelation in the percentage of nests with infected bugs between year t and year t+1, but the spatial autocorrelation broke down for year t+2. The increased prevalence of BCR virus at larger cliff swallow colonies probably reflects the larger bug populations there, which are less likely to decline in size and lead to virus extinction. To the authors' knowledge this is the first demonstration of arbovirus infection increasing with group size and one of the few known predictive ecological relationships between an arbovirus and its vectors/hosts. The results have implications for both understanding the fitness consequences of coloniality for cliff swallows and understanding the temporal and spatial variation in arboviral epidemics.

Serologic evidence for West Nile virus infection in birds in Staten Island, New York, after an outbreak in 2000.

After an outbreak of West Nile virus (WNV) infections in people, horses, and wildlife in Staten Island, NY, during the summer of 2000, we surveyed the bird population of the island for evidence of infection. Neutralizing antibodies were detected in 59 of 257 (23.0%) resident birds and none of 96 transient (migrating) birds sampled in early October. Species with the greatest seroprevalence were northern cardinal (Cardinalis cardinalis) (69.2%) and rock dove (Columba livia) (54.5%). House sparrows (Passer domesticus) and chickens (Gallus gallus) had lower than expected seroprevalences, 8.6% and 5.5%, respectively. The geographic distribution of seropositivity suggested focal transmission at several locations on the island. The concentration of seropositive birds among resident bird populations on Staten Island supports the concept that many birds survive WNV infection and that some of these play an important role in the WNV-bird-mosquito transmission cycle.

Rapid detection of west nile virus from human clinical specimens, field-collected mosquitoes, and avian samples by a TaqMan reverse transcriptase-PCR assay.

The authors report on the development and application of a rapid TaqMan assay for the detection of West Nile (WN) virus in a variety of human clinical specimens and field-collected specimens. Oligonucleotide primers and FAM- and TAMRA-labeled WN virus-specific probes were designed by using the nucleotide sequence of the New York 1999 WN virus isolate. The TaqMan assay was compared to a traditional reverse transcriptase (RT)-PCR assay and to virus isolation in Vero cells with a large number ( approximately 500) of specimens obtained from humans (serum, cerebrospinal fluid, and brain tissue), field-collected mosquitoes, and avian tissue samples. The TaqMan assay was specific for WN virus and demonstrated a greater sensitivity than the traditional RT-PCR method and correctly identified WN virus in 100% of the culture-positive mosquito pools and 98% of the culture-positive avian tissue samples. The assay should be of utility in the diagnostic laboratory to complement existing human diagnostic testing and as a tool to conduct WN virus surveillance in the United States.

La Crosse encephalitis virus habitat associations in Nicholas County, West Virginia.

Aedes triseriatus (Say) population density patterns and La Crosse encephalitis virus infection rates were evaluated in relation to a variety of habitat parameters over a 14-wk period. Ovitraps and landing collections were used in a La Crosse virus-enzootic area in Nicholas County, WV. Study sites were divided into categories by habitat type and by proximity to the residences of known La Crosse encephalitis cases. Results demonstrated that Ae. triseriatus population densities were higher in sugar maple/red maple habitats than in hemlock/mixed hardwood habitats or in a site characterized by a large number of small red maple trees. Sites containing artificial containers had higher population densities than those without. La Crosse virus minimum infection rates in mosquitoes collected as eggs ranged from 0.4/1,000 to 7.5/1,000 in the 12 study sites, but did not differ significantly among sites regardless of habitat type or proximity to human case residences. La Crosse virus infection rates in landing Ae. triseriatus mosquitoes ranged from 0.0/1,000 to 27.0/1,000. La Crosse virus was also isolated from host-seeking Ae. canadensis (Theobald) in two study sites, at rates similar to those found in the Ae. triseriatus populations. The Ae. triseriatus oviposition patterns and La Crosse virus infection rates suggest that this mosquito species disperses readily in the large woodlands of central West Virginia. The La Crosse enzootic habitats in Nicholas County, WV, are contrasted with those studied in other geographic regions where La Crosse virus is found.

Pathology of fatal West Nile virus infections in native and exotic birds during the 1999 outbreak in New York City, New York.

West Nile fever caused fatal disease in humans, horses, and birds in the northeastern United States during 1999. We studied birds from two wildlife facilities in New York City, New York, that died or were euthanatized and were suspected to have West Nile virus infections. Using standard histologic and ultrastructural methods, virus isolation, immunohistochemistry, in situ hybridization and reverse-transcriptase polymerase chain reaction, we identified West Nile virus as the cause of clinical disease, severe pathologic changes, and death in 27 birds representing eight orders and 14 species. Virus was detected in 23/26 brains (88%), 24/ 25 hearts (96%), 15/18 spleens (83%), 14/20 livers (70%), 20/20 kidneys (100%), 10/13 adrenals (77%), 13/ 14 intestines (93%), 10/12 pancreata (83%), 5/12 lungs (42%), and 4/8 ovaries (50%) by one or more methods. Cellular targets included neurons and glial cells in the brain, spinal cord, and peripheral ganglia; myocardial fibers; macrophages and blood monocytes; renal tubular epithelium; adrenal cortical cells; pancreatic acinar cells and islet cells; intestinal crypt epithelium; oocytes; and fibroblasts and smooth muscle cells. Purkinje cells were especially targeted, except in crows and magpies. Gross hemorrhage of the brain, splenomegaly, meningoencephalitis, and myocarditis were the most prominent lesions. Immunohistochemistry was an efficient and reliable method for identifying infected cases, but the polyclonal antibody cross-reacted with St. Louis encephalitis virus and other flaviviruses. In contrast, the in situ hybridization probe pWNV-E (WN-USAMRIID99) reacted only with West Nile virus. These methods should aid diagnosticians faced with the emergence of West Nile virus in the United States.

Borrelia burgdorferi-pulsed dendritic cells induce a protective immune response against tick-transmitted spirochetes.

Borrelia burgdorferi-pulsed dendritic cells and epidermal cells were able to initiate the production of anti-outer surface protein A (OspA) antibody in vitro with normal T and B cells from either BALB/c or C3H/HeJ mice. Inhibition of anti-B. burgdorferi antibody production was observed after 3 days, but not after 2 days, of exposure of the antigen-presenting cells to tumor necrosis factor alpha +/- granulocyte-macrophage colony-stimulating factor. Furthermore, splenic dendritic cells pulsed in vitro with live B. burgdorferi spirochetes and then adoptively transferred into naive syngeneic mice mediated a protective immune response against tick-transmitted spirochetes. This protection appeared not to be due to killing of spirochetes in the feeding ticks, since ticks fed to repletion on B. burgdorferi-pulsed dendritic cell-sensitized mice still harbored live spirochetes. Western blot analysis of the sera collected from dendritic cell-sensitized mice demonstrated that the mice responded to a limited set of B. burgdorferi antigens, including OspA, -B, and -C compared to control groups that either had received unpulsed dendritic cells or were not treated. Finally, mice in the early stage of B. burgdorferi infection were able to develop anti-OspA antibody following injection with B. burgdorferi-pulsed dendritic cells. Our results demonstrate for the first time that adoptive transfer of B. burgdorferi-pulsed dendritic cells induces a protective immune response against tick-transmitted B. burgdorferi and stimulates the production of antibodies specific for a limited set of B. burgdorferi antigens in vivo.

Susceptibility of immature Ixodes scapularis (Acari:Ixodidae) to plant-derived acaricides.

Plant-derived acaricides, extracted from various botanical species, and commercially available phytochemicals were evaluated for biological activity against immature Ixodes scapularis (Say) using the disposable pipet method. In addition, residual activity of the plant extracts was determined. Of the 13 plant extracts tested, 9 exhibited biological activity with Alaska yellow cedar, Chamaecyparis nootkatensis (D. Don) Spach., being the most effective against the nymphal ticks (LC50 = 0.151% wt:vol) and eastern red cedar, Juniperus virginiana L., showing the greatest activity against larval ticks (LC50 = .001% wt:vol). The commercially available products were significantly less active than the plant extracts we prepared, but some commercial compounds did exhibit limited activity. Only the Alaska yellow cedar exhibited any residual activity that lasted 21 d after treatment.

Vector competence of Ixodes scapularis, I. spinipalpis, and Dermacentor andersoni (Acari:Ixodidae) in transmitting Borrelia burgdorferi, the etiologic agent of Lyme disease.

This report describes the vector competence of 3 ixodid tick species, Ixodes scapularis (Say), I. spinipalpis (Nuttall), and Dermacentor andersoni (Stiles), for Borrelia burgdorferi in Colorado. The study was based on preliminary field work performed in 6 Colorado counties, where rodents and ticks were collected and assayed for the presence of B. burgdorferi. Four of the 6 counties produced 52 rodent and 39 I. spinipalpis isolates of B. burgdorferi. Two B. burgdorferi isolates were tested under laboratory conditions and found to be infective to Imperial Cancer Research Fund (ICRF) outbred mice. The 1st, a low-passage strain originating from New York (B-31, passage 6) was used as a control, and the 2nd was isolated from ear tissue of a Neotoma mexicana (Baird) (Mexican wood rat) that was trapped in Colorado. Larvae of I. scapularis, I. spinipalpis. and D. andersoni were fed on infected mice and cultured in Barbour-Stoner-Kelly media to assay for infection at 1, 2, 3, and 4 wk after repletion. The infection rates in replete larvae. were 75, 69, and 8.5%, respectively, whereas transstadial nymphal infection rates were 80, 75, and 0%, respectively. Both I. scapularis and I. spinipalpis were shown to be competent vectors that acquired the infection from the host reservoir mice and subsequently transmitted it to naive mice. Given that I. scapularis are not found in Colorado, I. spinipalpis are restricted to the nests and burrows of rodents, and because of the semiarid environment in Colorado, the risk of human contact with B. burgdorferi appears to be low.

Flea (Siphonaptera:Ceratophyllidae, hystrichopsyllidae) and tick (Acarina:Ixodidae) control on wood rats using host-targeted liquid permethrin in bait tubes.

The efficacy of a liquid permethrin-treated bait tube controlling fleas and ticks on Mexican wood rats, Neotoma mexicana Baird, was evaluated during a 1-yr study in north-central Colorado. Results indicated that the bait tubes were effective for reducing flea and tick infestations on wood rats. The effects of treatment persisted throughout the study, despite the fact that bait tubes were replenished with bait and permethrin only during the first 4 mo (4 replenishments). Our results suggest that these bait tubes provide an effective, economical, and environmentally acceptable means of controlling vectors of flea or tick-borne diseases, although slight modifications of the basic bait tube design might be required to maintain the effectiveness of the tube under different ecological conditions.

The patients' library movement: an overview of early efforts in the United States to establish organized libraries for hospital patients.

The patients' library movement in the United States, a dynamic, cohesive drive begun and sustained by librarians and physicians, strove to promote placement of organized libraries for patients in hospitals. It took shape in the early years of this century, evolving from its proponents' deeply held conviction that books and reading foster the rehabilitation of sick people. The American Library Association's World War I service to hospitalized military personnel dramatically reinforced the conviction; the post-World War I institution of public library extension services to general hospitals explicitly reflected it. Enormous energy was infused into the patients' library movement. Throughout the first half of this century, there were sustained efforts not only to establish organized libraries for hospitalized people but also to expand and systematically study bibliotherapy and to shape patients' librarianship as a professional specialty. The movement's achievements include the establishment of patients' library committees within national and international associations; impetus for development of academic programs to train patients' librarians; and publication, from 1944 through 1970, of successive sets of standards for hospital patients' libraries. The first of these remain the first standards written and issued by a professional library association for a hospital library.