Contaminants in organic and conventional foodstuffs in France.

The aim was to compare the levels of contamination in organic and conventional raw materials. To this end, the level of contamination by heavy metals (lead, cadmium, arsenic, mercury), nitrates and nitrites, and some mycotoxins were monitored. Fifteen products were tested in their organic and conventional forms, including meat, milk, eggs, vegetables and cereals. The median levels of contamination were calculated and compared with the recommended or regulated maximum levels. The maximum levels were exceeded for lead in organic carrots and buckwheat, and in conventional wheat; for cadmium, in both organic and conventional buckwheat; for nitrates, in organic spinach; and for patulin in organic apples. Moreover, contamination of both conventional and organic wheat by deoxynivalenol was observed with a higher level in organic products. However, the health risk for consumers might be real only for the contamination by mycotoxins as the contaminated foods (apples, wheat) are the main contributors to total exposure.

Characterization of modulation of western equine encephalomyelitis virus by Culex tarsalis (Diptera: Culicidae) maintained at 32 degrees C following parenteral infection.

Two lines of Culex tarsalis Coquillett genetically selected for low or high western equine encephalomyelitis (WEE) virus production (low viral producer [LVP] or high viral producer [HVP], respectively) modulated WEE (i.e., decreased the concentration of virus to < 10(4) plaque-forming units after intrathoracic inoculation). The LVP line modulated WEE more than HVP, and modulation was most pronounced at 32 degrees C. At 15 degrees C, viral replication to high titers occurred in both lines. When infected LVP were transferred to 15 degrees C after 4 d extrinsic incubation at 32 degrees C, replication of WEE to high titers did not occur. Mosquitoes transferred from 15 degrees C after replication to high titers occurred; to 32 degrees C did significantly modulate WEE titer. Incubation at 32 degrees C prior to infection had no effect on the degree or timing of WEE modulation in both LVP and HVP lines. Most LVP infected following feeding on a high dose of WEE had salivary gland infection barriers. Viral modulation by Cx. tarsalis was an alphavirus phenomenon, and was not restricted to WEE.

Adsorptive endocytosis of California encephalitis virus into mosquito and mammalian cells: a role for G1.

The G1 glycoprotein of California encephalitis (CE) virus plays a critical role in the infection of mosquito and mammalian cells. We found that CE virus enters baby hamster kidney (BHK-21) and Aedes albopictus (C6/36) cells by the endocytic pathway. Ammonium chloride, a lysosomotropic amine that prevents release of virus from endosomes, inhibited infection of both cell types when added within 10 min after viral adsorption. In addition, infected cells formed polykaryons when the extracellular pH was lowered to 6.3; optimal fusion occurred at pH 5.8 and 6.0 (C6/36 and BHK-21 cells, respectively). Two neutralizing G1 MAba, 6D5.5 and 7D4.5, inhibited low pH-induced syncytia formation without affecting viral attachment, suggesting a role for G1 in viral entry. Since viral fusion proteins have been demonstrated to undergo conformational changes at low pH, acid-induced changes in G1 and G2 were assessed. While both G1 and G2 demonstrated low pH-induced alterations in detergent binding, only G1 displayed an altered protease cleavage pattern at the fusion pH. These results indicate that the G1 protein of CE virus undergoes conformational changes necessary for low pH-mediated entry into both mosquito and mammalian cells.

Genotypic and phenotypic variation of selected Saint Louis encephalitis viral strains isolated in California.

The mechanism for long-term maintenance of St. Louis encephalitis (SLE) virus in California is unknown. Two possibilities are 1) that the virus is maintained locally in discrete enzootic foci by one or more reservoir mechanisms, and/or 2) that the foci are ephemeral in nature and virus is reintroduced periodically from other enzootic areas by migratory birds or movement of vectors. We have investigated these epidemiologic alternatives by studies of genetic variation within a 277 nucleotide portion of the envelope-encoding region among 17 strains of SLE virus isolated since 1952 from different geographic locations in California. Three lineages of virus were detected. One lineage, Group A, consisted of four SLE virus strains isolated in California since 1972 from the Coachella, Sacramento, and San Joaquin Valleys. The group A strains were closely related to strain MSI-7 of SLE virus isolated in Mississippi in 1975. The 13 other strains formed the second and third lineages (Groups B1 and B2) that had geographically overlapping distributions. Group A (BFN 4585) and Group B2 (BFN 4820) appeared to be sympatric in the Sacramento Valley in 1972. Strains from the San Joaquin Valley isolated prior to 1989 (Groups B1 and B2) differed markedly from a 1989 isolate from the same location, Kern 373 (Group A). These results suggest that virus introduction(s) led to changes in genotype, or alternatively that the enzootic virus was subjected to selective pressure leading to rapid emergence of a new genotype. Nucleotide sequences of the envelope and 5' untranslated region of the viral genome of these virus strains did not correlate with virulence as measured by mortality in weanling mice, nor viremia levels and duration in chickens.

Mouse and baby chicken virulence of enzootic strains of western equine encephalomyelitis virus from California.

Eight enzootic strains of western equine encephalomyelitis (WEE) virus isolated from Culex tarsalis or Aedes melanimon collected in several geographic areas of California were evaluated for their virulence in suckling mice, adult mice, and one-day-old baby chickens. The epidemic Fleming strain and the cloned B628(Cl 15) variant were used as virulent and avirulent control viruses, respectively, in adult mice. Enzootic strains of WEE virus were grouped into three phenotypes on the basis of their neurovirulent and neuroinvasive properties in adult mice. Three strains possessed high neurovirulence and were neuroinvasive; three strains had intermediate neurovirulence and lacked neuroinvasiveness; and two strains had low to nil neurovirulence and were non-neuroinvasive. In fact, five of the eight enzootic strains lacked neuroinvasiveness. Interestingly, highly virulent enzootic strains of WEE virus were isolated from Cx. tarsalis collected in the Sacramento Valley during 1994 and 1995 in the absence of identified human disease. The Fleming strain, the B628(Cl 15) variant, and four enzootic strains from the Sacramento Valley were virulent for baby chickens following subcutaneous inoculation. Thus, inoculation into baby chicks cannot discriminate between WEE viruses that are virulent and avirulent for adult mice.

Landscape ecology of arboviruses in southeastern California: temporal and spatial patterns of enzootic activity in Imperial Valley, 1991-1994.

Western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses were detected in the Imperial Valley during the summers of 1991-1994 by isolation from the primary vector, Culex tarsalis Coquillett, and by the seroconversion of sentinel chickens. Enzootic transmission consistently was not detected first each year at sampling sites near specific landscape features such as a heron rookery and other riparian habitats along the New River, sites along the Mexican border, or saline and freshwater marshes along the southern shore of the Salton Sea. Despite mild winter temperatures and the elevated vernal abundance of Cx. tarsalis, WEE and SLE activity was not detected until June or July, indicating considerable amplification may be necessary before detection by testing mosquito pools for virus infection or sentinel chicken sera for antibodies. Results did not permit the spatial focusing of early season control efforts or research on mechanisms of virus interseasonal persistence.

Effects of water quality on the vector competence of Culex tarsalis (Diptera: Culicidae) for western equine encephalomyelitis (Togaviridae) and St. Louis encephalitis (Flaviviridae) viruses.

The effects of water quality during immature development on the vector competence of adult female Culex tarsalis Coquillett for western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses was evaluated during 6 field and 4 laboratory experiments. Immatures of the Bakersfield Field Station laboratory strain and the F1 progeny of field-collected females were reared in the field or laboratory and then infected by feeding on pledgets, after which remnants (head, thorax, abdomen), legs, and salivary secretions were tested for WEE or SLE virus to estimate infection, dissemination, and transmission rates, respectively. Although the salt content of the 6 larval habitats varied markedly (range, alkalinity 160-1,310 ppm CaCO3, conductivity 460-7,600 microns hos/cm, chlorides 22-1,560 ppm) and significantly altered immature survival, development time, and female body size (wing length), consistent changes in infection, dissemination, or transmission rates were not observed. Susceptibility (ID50) to WEE virus in field strains decreased as a linear function of developmental time, with populations from a dry alkali lake bed (Goose Lake) least susceptible. Three subsequent laboratory experiments that tested the effects of rearing immatures in dilution series of water from Goose Lake failed to produce consistent within or among experiment patterns in vector competence. A 4th laboratory experiment tested changes in NaCl concentration with negative results. Changes in female size was not related to vector competence. These and previous temperature studies indicated that temporal changes in vector competence observed within and among field populations probably were related to intrinsic genetic factors and were not related directly to extrinsic factors in the immature aquatic environment.

The current status of nursing informatics in undergraduate nursing programs: comparative case studies between Sweden and Australia.

During the last ten years, the inclusion of education in health information systems has assumed an important role in graduate programs for health professionals. More recently, attention has focused on undergraduate programs. Throughout the world schools of nursing, organisations and associations are addressing the issue of educational offerings in nursing informatics. This paper reports on the status of nursing informatics at undergraduate level. Nurse academics from Gävle and Lund in Sweden, and from Melbourne and Sydney in Australia, took part in a survey of the respective nursing courses. The purpose of the study was to identify and describe examples of types of nursing informatics courses in Australia and Sweden. A convenient sample of academics were approached and interviewed. The results of the survey illustrate, in the schools surveyed, the slow emergence of nursing informatics into nursing curricula.

Ecology of mosquitoes and lack of arbovirus activity at Morro Bay, San Luis Obispo County, California.

During 1994-95, totals of 17,656 adult females and 111,104 adults reared from field-collected immatures comprising 19 species in 4 genera of mosquitoes were collected from Morro Bay estuary and surrounding environs in San Luis Obispo County, California. Aedes dorsalis was the dominant summer mosquito, whereas Aedes squamiger and Ae. washinoi were abundant during winter and early spring. Host-seeking Culex tarsalis were collected infrequently, even though immatures were collected frequently from freshwater surface pools. Overall, 13,561 adults (386 pools) and 91,547 adults reared from field-collected immatures (3,027 pools) were tested for arboviruses by plaque assay in Vero cell culture. Morro Bay virus, a member of the California serogroup, was isolated from 4 pools of Ae. squamiger reared from field-collected immatures (minimum field infection rate-1.07 per 1,000), verifying the maintenance of this virus by vertical transmission. All remaining pools were negative. Three flocks of 10 sentinel chickens and one group of 5 sentinel rabbits were bled biweekly and tested for arbovirus antibodies with negative results. Neither horizontal nor vertical transmission of western equine encephalomyelitis virus was detected.

Prevalence of antibodies to mosquito-borne encephalitis viruses in residents of the Coachella Valley, California.

Sera from 19 (2.6%) and 118 (16.4%) of 719 outpatients attending clinics in the southeastern Coachella Valley, California during 1993 and 1994 exhibited IgG antibodies to western equine encephalomyelitis and St. Louis encephalitis (SLE) viruses, respectively, using enzyme immunoassays. However, only seven (1.0%) and 36 (5.0%) outpatients were positive by plaque-reduction neutralization tests (PRNTs), and seven (1.0%) and 84 (11.7%) outpatients were positive by sera hemagglutination inhibition assays, respectively. None were positive for IgM antibodies indicative of recent infection or were diagnosed clinically with central nervous system disease. Prevalence of PRNT antibody to SLE increased as a function of patient age, but did not vary significantly in relation to years of residence, sex, race, postal zip code, occupation, or month of collection.

Ecology of Jamestown Canyon virus (Bunyaviridae: California serogroup) in coastal California.

This paper reports the first isolation of Jamestown Canyon (JC) virus from coastal California and the results of tests for antibody to JC virus in mammals living in coastal California. The virus isolation was made from a pool of 50 Aedes dorsalis females collected as adults from Morro Bay, San Luis Obispo County, California. The virus isolate was identified by two-way plaque reduction-serum dilution neutralization tests done in Vero cell cultures. Sera from the mammals were tested for antibody to JC virus by a plaque-reduction serum dilution neutralization method. A high prevalence of JC virus-specific antibody was found in horses and cattle sampled from Morro Bay. This finding is additional evidence for the presence of a virus antigenically identical or closely related to JC virus in Morro Bay and indicates that the vectors of the virus in Morro Bay feed on large mammals. A high prevalence of virus-specific antibody was also found in horses sampled from Marin and San Diego counties. This finding suggests that viruses antigenically identical or closely related to JC virus are geographically widespread in coastal California.

Geographic distribution and serologic and genomic characterization of Morro Bay virus, a newly recognized bunyavirus.

More than 75,000 immature mosquitoes in three genera were collected from coastal California, reared to the adult stage, and tested for virus by plaque assay in Vero cell cultures. Twenty-six strains of Morro Bay (MB) virus, a newly recognized member of the California (CAL) serogroup, were isolated from Aedes squamiger, a pestiferous salt marsh mosquito species restricted to intertidal salt marshes in coastal California and Baja California. The geographic distribution of the isolates was 10 from San Luis Obispo County, one each from Santa Barbara and Orange Counties, and 14 from San Diego County. No virus isolations were made from 23,157 Ae. squamiger collected north of San Luis Obispo County (midpoint in the geographic range of this species in California). Thus, MB virus infection in Ae. squamiger appears to be restricted to the southern range of this species in California. Serum dilution neutralization tests indicated that MB virus represents a novel subtype of the California encephalitis (CE) serotype within the CAL serogroup. Comparative analyses of genomic sequence data from four geographically distinct MB virus isolates indicated that the isolates are genetically similar to each other and distinct from other CE serotype bunyaviruses. Phylogenetic analysis of nucleocapsid protein gene sequence data indicated that MB virus represents a distinct lineage within the CE serotype and thus supports the serologic classification of MB virus as a distinct CAL serogroup virus.

Seasonal variation in the vector competence of Culex tarsalis (Diptera:Culicidae) from the Coachella Valley of California for western equine encephalomyelitis and St. Louis encephalitis viruses.

The vector competence of Culex tarsalis Coquillett from the Coachella Valley of California for western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses was monitored monthly from February to November 1993. The concentration of WEE virus required to infect 50% of the females increased during summer coincidentally with ambient temperature and was highest during July. Transmission rates of WEE virus were high during March, low during May-June, and high again during July-September. Females expressed both mesenteronal escape and salivary gland barriers limiting WEE virus dissemination and transmission rates, respectively. SLE virus infection and dissemination rates did not vary among months, but transmission rates, were highest during July-September. Although infection rates with SLE virus were moderate, most infected females developed disseminated infections. Salivary gland infection or escape barriers prevented SLE virus transmission in 16-100% of infected females.

Landscape ecology of arboviruses in southern California: temporal and spatial patterns of vector and virus activity in Coachella Valley, 1990-1992.

Consistent temporal and spatial patterns in the activity of Culex tarsalis Coquillett and western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses were delineated that were useful in developing a stratified surveillance program. Vernal increases in Cx. tarsalis abundance typically were associated with flooding of saline marshes along the north shore of the Salton Sea and were followed 6-8 wk later by the onset of WEE and SLE virus activity. Viruses then spread to managed marsh (duck club) and agricultural habitats in the Whitewater Channel flood plain and, depending upon the intensity of amplification, to agricultural and residential areas in the more elevated northwestern portion of the valley. Mean annual Cx. tarsalis abundance was correlated inversely with elevation and distance from the Salton Sea. Abundance was greatest at managed marsh habitats. Although spatially correlated with vector abundance among sites, virus transmission rates to sentinel chickens were asynchronous temporally with vector abundance. Seroconversion rates were related to flock location but not flock size (10 versus 20 chickens). Human cases were not detected during the study period, despite elevated transmission rates of both WEE and SLE viruses to sentinel chickens positioned in peridomestic habitats.

Landscape ecology of arboviruses in southern California: patterns in the epizootic dissemination of western equine encephalomyelitis and St. Louis encephalitis viruses in Coachella Valley, 1991-1992.

Temporal and spatial patterns in the initiation and dissemination of western equine encephalomyelitis and St. Louis encephalitis virus activity in Coachella Valley during 1991 and 1992 were detected by testing pools of host-seeking Culex tarsalis Coquillett for virus infection and sentinel chickens for seroconversions. Both viruses repeatedly were detected first at a salt marsh adjacent to the Salton Sea in the southeastern corner of the study area and then disseminated to the northwest to freshwater marsh, agricultural, and residential habitats. Virus dissemination was relatively slow (< 1 km/d) and may have been accomplished by dispersive host-seeking mosquitoes. Repeated early-season recovery of virus activity indicated that both viruses may persist interseasonally in salt marsh habitat.

Bionomics of Culex tarsalis (Diptera: Culicidae) in relation to arbovirus transmission in southeastern California.

Population dynamics and bionomics of host-seeking Culex tarsalis Coquillett were studied in the Imperial and Coachella valleys of California during periods in 1991 and 1992 when western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses were transmitted to sentinel chickens. Female abundance was greatest during the spring and fall, before and after most virus transmission occurred and was not correlated with temperature, humidity, or rainfall. Parity rates were highest during late summer when virus activity peaked and were lowest during December when females may enter a short-term reproductive diapause. Although most likely underestimated, the proportion of older multiparous females were collected at a consistent, but low level throughout the year. Changes in the parity rate seemed to be influenced primarily by the proportions of 1-parous females. Survivorship estimated from the parity rate (adjusted to account for autogeny) was highest in winter; however, the proportion of females surviving to potentially transmit either WEE or SLE virus was highest in summer and early fall. Wing length decreased in summer as an inverse correlate of temperature and increased as a function of female age, implying that larger females lived longest. However, autogenous females were larger than anautogenous females at emergence and only parous autogenous females were collected host seeking, thereby confounding the relationship between size and age. The proportion of females testing positive for fructose was greatest during winter and lowest during summer, perhaps affecting survivorship and blood-feeding avidity. The vector competence (infection, dissemination and transmission rates, and ID50) of females collected host seeking or emerging from field-collected pupae for WEE or SLE viruses remained similar over time, even though the wing length of females used in these experiments differed among samples. We conclude that in nature virus transmission progressed efficiently during midsummer because elevated temperatures shortened the extrinsic incubation period without markedly decreasing survivorship resulting in an increased proportion of females surviving extrinsic incubation to become infective.

Determination and comparative analysis of the small RNA genomic sequences of California encephalitis, Jamestown Canyon, Jerry Slough, Melao, Keystone and Trivittatus viruses (Bunyaviridae, genus Bunyavirus, California serogroup).

The nucleotide sequences of the small (S) genomic RNAs of six California (CAL) serogroup bunyaviruses (Bunyaviridae: genus Bunyavirus) were determined. The S RNAs of two California encephalitis virus strains, two Jamestown Canyon virus strains, Jerry Slough virus, Melao virus, Keystone virus and Trivittatus virus contained the overlapping nucleocapsid (N) and non-structural (NSs) protein open reading frames (ORFs) as described previously for the S RNAs of other CAL serogroup viruses. All N protein ORFs were 708 nucleotides in length and encoded a putative 235 amino acid gene product. The NSs ORFs were found to be of two lengths, 279 and 294 nucleotides, which potentially encode 92 and 97 amino acid proteins, respectively. The complementary termini and a purine-rich sequence in the 3' non-coding region (genome-complementary sense) were highly conserved amongst CAL serogroup bunyavirus S RNAs. Phylogenetic analyses of N ORF sequences indicate that the CAL serogroup bunyaviruses can be divided into three monophyletic lineages corresponding to three of the complexes previously derived by serological classification. The truncated version of the NSs protein, which is found in five CAL serogroup bunyaviruses, appears to have arisen twice during virus evolution.

Requirement for the G1 protein of California encephalitis virus in infection in vitro and in vivo.

A role for the large glycoprotein (G1) of California encephalitis (CE) virus was examined in the infection of baby hamster kidney (BHK-21) and Aedes albopictus (C6/36) cell lines and the mosquito Ae. dorsalis using G1 monoclonal antibodies (MAbs) and selective protein cleavage. Five MAbs neutralized CE viral infectivity in both cell lines. One MAb, 7D4.5, efficiently neutralized the peroral infection of Ae. dorsalis females fed CE virus in artificial bloodmeals. To determine if MAbs to G1 neutralized CE virus by sterically hindering the small glycoprotein (G2), portions of G1 were trypsinized, and viral infectivity was assayed in vivo and in vitro. Cleavage of G1 resulted in a complete loss of infectivity both in mosquitoes and in culture, even though a significant amount of G2 remained intact. The loss of infectivity by both neutralization with G1 MAbs and trypsinization indicates that the G1 protein of CE virus is required for infection of mosquito and mammalian cells in vitro and of mosquitoes by the peroral route.

Assessment of the level of the actual and desirable levels of computer literacy, usage and expected knowledge of undergraduate students of nursing.

The aim of the study was to determine the perceptions of students entering nursing at the bachelors level, of their actual and desirable knowledge about computers and their applications relevant to nursing and health care. Within the health care system the use of computerized systems is increasing rapidly. In Australia, the NSW Health Department's Information Management Resource Consortium pilot project--to introduce the First Data Hospital Information System into NSW public hospitals--is a significant example of this trend. While the importance of computerized systems is fairly well recognized for the areas of management and research, they are becoming increasingly significant in the delivery of clinical care and quality assurance. It is important that nurses during their undergraduate education develop the computer literacy and awareness that will allow them access to the both the information and its management. To achieve this effectively it is essential to determine both the entry knowledge of students and what skills and knowledge are essential and desirable for their future roles as nurses. The research undertaken replicated an American study [2] and used their validated questionnaire. Both pre-registration(n=20) and post-registration (n=24) undergraduate students responded to a 21 item questionnaire. The issues addressed related to computer literacy, usage, and knowledge of clinical applications. Both groups desired more "hands on" experience and knowledge in the nurse's role in developing applications and using computers to help care for patients. These results were consistent with the Parks et. al. study. The significance of comparing actual and desirable levels of computer knowledge and awareness is in assisting educators to shape curriculum and course content to more effectively meet the educational needs of these groups in terms of Health Informatics.

Viremia and serological responses in adult chickens infected with western equine encephalomyelitis and St. Louis encephalitis viruses.

Adult hens, similar to those used for arbovirus surveillance, were experimentally infected with western equine encephalomyelitis (WEE) and St. Louis encephalitis (SLE) viruses to describe the viremia response, to compare serological testing methods, and to evaluate a new method of collecting whole blood onto filter paper strips from lancet pricks of the chicken comb. Young (19 weeks), but not old (38 weeks), hens developed a low-titer, transient viremia for a 1-day period. Immunoglobulin G (IgG) was detected by days 10 and 14 after infection with WEE and SLE viruses, respectively, by indirect fluorescent antibody tests, hemagglutination inhibition tests, and plaque reduction neutralization tests on sera and in direct enzyme immunoassays (EIA) on both sera and eluates from filter paper samples. Immunoglobulin M (IgM) was first detected in sera 2 and 3 days before IgG, respectively, but IgM could not be detected reliably in eluates from dried blood. Sera and dried blood samples collected from naturally infected sentinel chickens gave comparable results when tested by an EIA for IgG.