Pathogenesis of Vesicular Stomatitis New Jersey Virus Infection in Deer Mice ( Peromyscus maniculatus) Transmitted by Black Flies ( Simulium vittatum).

The natural transmission of vesicular stomatitis New Jersey virus (VSNJV), an arthropod-borne virus, is not completely understood. Rodents may have a role as reservoir or amplifying hosts. In this study, juvenile and nestling deer mice ( Peromyscus maniculatus) were exposed to VSNJV-infected black fly ( Simulium vittatum) bites followed by a second exposure to naive black flies on the nestling mice. Severe neurological signs were observed in some juvenile mice by 6 to 8 days postinoculation (DPI); viremia was not detected in 25 juvenile deer mice following exposure to VSNJV-infected fly bites. Both juvenile and nestling mice had lesions and viral antigen in the central nervous system (CNS); in juveniles, their distribution suggested that the sensory pathway was the most likely route to the CNS. In contrast, a hematogenous route was probably involved in nestling mice, since all of these mice developed viremia and had widespread antigen distribution in the CNS and other tissues on 2 DPI. VSNJV was recovered from naive flies that fed on viremic nestling mice. This is the first report of viremia in a potential natural host following infection with VSNJV via insect bite and conversely of an insect becoming infected with VSNJV by feeding on a viremic host. These results, along with histopathology and immunohistochemistry, show that nestling mice have widespread dissemination of VSNJV following VSNJV-infected black fly bite and are a potential reservoir or amplifying host for VSNJV.

Domestic cattle as a non-conventional amplifying host of vesicular stomatitis New Jersey virus.

The role of vertebrates as amplifying and maintenance hosts for vesicular stomatitis New Jersey virus (VSNJV) remains unclear. Livestock have been considered dead-end hosts because detectable viraemia is absent in VSNJV-infected animals. This study demonstrated two situations in which cattle can represent a source of VSNJV to Simulium vittatum Zetterstedt (Diptera: Simuliidae) by serving: (a) as a substrate for horizontal transmission among co-feeding black flies, and (b) as a source of infection to uninfected black flies feeding on sites where VSNJV-infected black flies have previously fed. Observed co-feeding transmission rates ranged from 0% to 67%. Uninfected flies physically separated from infected flies by a distance of up to 11 cm were able to acquire virus during feeding although the rate of transmission decreased as the distance between infected and uninfected flies increased. Acquisition of VSNJV by uninfected flies feeding on initial inoculation sites at 24 h, 48 h and 72 h post-infection, in both the presence and absence of vesicular lesions, was detected.

Black fly salivary gland extract inhibits proliferation and induces apoptosis in murine splenocytes.

Black flies are known to be vectors of pathogens including Onchocerca volvulus, which causes human onchocerciasis, and Vesicular Stomatitis Virus. Their salivary secretion has been shown to contain a complex cocktail of anti-haemostatic factors and immunomodulatory activities, which may contribute to efficient transmission of the pathogens. Black fly salivary gland extract (SGE) inhibits mitogen-stimulated mouse splenocyte proliferation, including proliferation of both CD4(+) and CD8(+) T cells. The factor responsible for the inhibition was determined to be a protein (or protein complex) of a size larger than 50 kDa. Moreover, exposure to SGE results in activation of caspase 3 and characteristic morphological changes in CD4(+) and CD8(+) T cells, suggesting that induction of apoptosis could, at least in part, be responsible for this inhibition.

Experimental transmission of vesicular stomatitis New Jersey virus from Simulium vittatum to cattle: clinical outcome is influenced by site of insect feeding.

Vesicular stomatitis New Jersey virus (VSNJV) is an insect-transmitted Rhabdovirus causing vesicular disease in domestic livestock including cattle, horses, and pigs. Natural transmission during epidemics remains poorly understood, particularly in cattle, one of the most affected species during outbreaks. This study reports the first successful transmission of VSNJV to cattle by insect bite resulting in clinical disease. When infected black flies (Simulium vittatum Zetterstedt) fed at sites where VS lesions are usually observed (mouth, nostrils, and foot coronary band), infection occurred, characterized by local viral replication, vesicular lesions, and high neutralizing antibody titers (> 1: 256). Viral RNA was detected up to 9 d postinfection in tissues collected during necropsy from lesion sites and lymph nodes draining those sites. Interestingly, when flies were allowed to feed on flank or neck skin, viral replication was poor, lesions were not observed, and low levels of neutralizing antibodies (range, 1:8-1:32) developed. Viremia was never observed in any of the animals and infectious virus was not recovered from tissues on necropsies performed between 8 and 27 d postinfection. Demonstration that VSNJV transmission to cattle by infected black flies can result in clinical disease contributes to a better understanding of the epidemiology and potential prevention and control methods for this important disease.

Experimental cryptosporidiosis in germfree lambs.

Contaminating bacteria were removed from an isolate of calf Cryptosporidium by 3 sequential passages of the parasite in gnotobiotic lambs, together with antibiotic treatment of the lambs. This preparation, which contained no detectable bacteria or viruses, was given by mouth to 8 2-day-old gnotobiotic lambs, 3 of which were dosed at the same time with bacterial flora from a healthy calf. Lambs were killed at intervals from 12 to 288 h post-inoculation and the sequential development of the parasite, of enteric lesions, and of clinical illness was observed. Lesions were characterized by severe villus stunting and fusion. Clinically the most consistent sign was anorexia, with some lambs developing also a severe watery diarrhoea. Lesions and clinical signs were similar in lambs with and without intestinal bacteria. This demonstration of the enteropathogenicity of Cryptosporidium in germfree lambs suggests that it is a pathogen of significance.

A rotavirus in lambs with diarrhoea.

A reovirus-like agent was identified from an outbreak of enteritis in young lambs. From its morphology and immunological relationship with calf rotavirus, it was concluded that it was a rotavirus which infects lambs.

Diarrhea in lambs experimentally infected with Cryptosporidium isolated from calves.

Two to 5 days after oral inoculation with Cryptosporidium obtained from infected calves, 7 newborn specific-pathogen-free lambs became depressed and anorectic and developed diarrhea. Four moribund lambs were killed within 3 days after onset of illness, and the 3 other lambs died after protracted intermittent diarrhea and reduced milk intake, which lasted up to 14 days. The small and large intestines were heavily infected with Cryptosporidium, with the terminal portion of the ileum being the most severely affected. Histologic examination revealed villous atrophy, with considerable fusion and epithelial cross-bridging between villi. Lambs infected at 5 to 20 days of age had less severe clinical signs of disease, with intermittent diarrhea, reduced milk intake, and growth retardation. Lambs infected at 30 days of age became infected with the organism, but did not develop clinical signs of disease or growth retardation.

The Morgan Recharger: a new horn fly (Diptera: Muscidae) control device for beef cattle.

A 20% diazinon formulation was evaluated for control efficacy against the horn fly, Haematobia irritans (L.), in the Morgan Recharger (Morgan International Products, College Grove, Tenn.). The Morgan Recharger releases insecticide with a wicking system from an insecticide reservoir and can be attached to an animal's ear or tail. This device was most effective against the horn fly when used as an ear tag with two per head; horn fly counts did not exceed five flies per side through 8 wk. The diazinon formulation tested was released from the Morgan Recharger at a decreasing rate. The problems and potential of the Morgan Recharger as an effective horn fly control device are discussed.

Ultrastructural Studies of Orf Virus Infection and Replication in Fetal Lamb Fibrocytes.

Résumé- Le cycle de réplication du virus de l'ecthyma contagieux a été identifié dans des études in vitro et un modèle hypothétique a été développé. Pendant la premiére phase, qui dure à peu près 5 heures, le virus pénètre la cellule par le biais d'un processus de phagocytose, et perd ses enveloppes. La phase d'éclipse, pendant laquelle le virus est apparemment intégréà l'ADN de l'hôte, dure environ 8 à 10 heures. Pendant la phase finale, les virions se développent dans des zones biens définies du viroplasme à partir desquelles les viriojns matures vont migrer jusqu'aux bords de la cellule. Là, ils sortent soit par exocytose, soit à l'intérieur de projections microvilleuses qui sont pincées à leur base, soit encore par désintégration de la cellule hôte. [Onwuka, S.K., Jenkinson, D. Mc, Inglis, L., Pow, I., GRAY, E.W., Reid, H.W. Ultrastructural studies of orf virus infection and replication in fetal lamb fibrocytes (Etudes ultrasturcturales de l'infection par le virus de l'ecthyma contagieux et de sa réplication dans les fibrocytes de foetus d'agneau). Resumen- Se identificó el ciclo de replicación del virus del ectima contagioso en estudios temporales in vitro y se desarroló un posible modelo experimental. Durante la primera fase, que dura unas 5 h, el virus penetra en la células por fagocitosis y se libera de la cubierta. La fase de "eclipse", con el virus presentándose como hebras de DNA, dura aproximadamente de 8 a 10 h. En la fase final los viriones se desarrollan dentro de zonas bien definidas en el viroplasma desde las cuales los viriones maduros migran hasta los limites celulares. A partir de alii parecen salir por exocitosis o en proyecciones de microvellosidades "pinzadas" hacia el exterior; también pueden ser liberados como consecuencia de la desintegración de la célula huésped. [Onwuka, S.K., Jenkinson, D. Mc, Inglis, L., Pow, I., GRAY, E.W., Reid, H.W. Ultrastructural studies of orf virus infection and replication in fetal lamb fibrocytes (Estudios ultraestructurales de la infección por el virus del ectima contagioso y replicación en fibrocitos fetales de carnero). Abstract- The cycle of replication of orf virus was identified in temporal in vitro studies and a putative model was developed. During the first phase, which lasts about 5 h, the virus enters the cells by a phagocytic process and uncoats. The "eclipse" phase, with the virus apparently present as strands of DNA, lasts for approximately the next 8-10 h. In the final phase virions develop within well-defined zones of viroplasm from which mature virions migrate to the margins of the cell. There they apparently exit either by exocytosis or within microvillous projections which are "pinched off"; they can also be released by disintegration of the host cell.

Isolation of a parapoxvirus from a grey seal (Halichoerus grypus).

A grey seal (Halichoerus grypus) developed cutaneous pocks which progressed to involve the skin extensively, necessitating euthanasia. Macroscopically and histologically the lesions resembled previous descriptions of parapoxvirus infections of seals and virus particles were observed in preparations of a scab and a skin lesion. Suspensions of the scab and skin lesion were prepared and inoculated on to monolayer cultures of grey seal kidney cells. After 25 days in culture and three passages, cytopathic effects were observed and parapoxvirus particles were detected by electron microscopy in the supernatant fluid. Both isolates were adapted to cultures of fetal lamb muscle cells and shown to be antigenically related to orf virus.

Virus infections in cattle and sheep in Scotland 1975-1978.

Over the four-year period 1975-78 attempts were made to identify virus in samples from 1231 outbreaks of disease in cattle, and 682 outbreaks of disease in sheep. A virus identification was possible in 26 per cent of these disease outbreaks. The nature and significance of these virus infections is discussed.

Economic impact of black flies (Diptera:Simuliidae) in South Carolina and development of a localized suppression program.

The membership of a private golf club in South Carolina's Piedmont Physiographic Region was surveyed to determine perceptions regarding local black fly populations and the effects of these populations on golfing habits. The economic impact of black fly annoyance at this club was estimated to be $27,202. Adult monitoring indicated that the pest species were members of the Simulium jenningsi group; larval monitoring identified the Enoree River, Laurens County, as the primary source of the pest species. A localized suppression program was initiated during the late summer of 1994 and continued through the fall of 1995. Four larvicide applications were conducted in 1994 and 11 in 1995, using the biological insecticide Vectobac. Larval mortalities of 94.5 and 97% were produced during 1994 and 1995, respectively. Adult black fly populations were reduced 92 and 88% during 1994 and 1995, respectively, from pre-program populations. Improvements for future suppression programs are proposed.

Development of the first black fly (Diptera: Simuliidae) management program in Argentina and comparison with other programs.

In response to increasing pest populations of black flies, the government of Argentina initiated a pilot program to evaluate the effectiveness of larval control in the irrigation system of the Negro River Valley, an 18,240-km2 area in Patagonia. The extensive system of irrigation canals, drainage ditches, and natural waterways not only provides water for agriculture and general habitation but also affords habitat for immature black flies. Three species (Simulium bonaerense, Simulium wolffhuegeli, and Simulium nigristrigatum) are primary pests of humans and animals in this area. Trials were conducted using Vectobac AS in representative irrigation canals, a drainage ditch, and a medium-sized river. Most trials resulted in effective larval mortality and insecticide carry. Based on a comparison with 11 black fly suppression programs throughout the world, a suppression program for the Negro River Valley has a projected cost of approximately $1,623,360/year. This study represents the initial steps in development of the 1st areawide black fly suppression program in Argentina.

Radioactivity in cathode ray tubes.

While surveying used computer equipment out of a zone posted as a Contamination Area, 100% of the computer monitors surveyed had levels of radioactivity that were significantly above background. The radioactivity was primarily on the front face of the cathode ray tube and was not amenable to decontamination. Hot spots were found also along the edges and seals of the cathode ray tube. Similar surveys of computer monitors that were never in Contamination Areas confirmed that radioactivity was incorporated into the monitor. Surveys were made of recently manufactured television sets with similar results. Gamma spectroscopy indicates that the radioactivity is due to naturally occurring radioactive materials. Since most surveys of cathode ray tubes in the literature were made while the units were energized and indicated low-energy x-rays, the use of naturally occurring radioactive materials in the manufacture of cathode ray tubes has not been widely recognized. This paper presents the results of these surveys, the results of gamma spectroscopy, and a method for releasing existing computer equipment having naturally occurring radioactive materials.

Ticks of South Carolina (Acari: Ixodoidea).

County and host records are reported for 19 species of ticks from South Carolina: Amblyomma americanum, Amblyomma maculatum, Amblyomma tuberculatum, Aponomma latum, Boophilus annulatus, Boophilus microplus, Dermacentor albipictus, Dermacentor variablis, Haemaphysalis leporispalustris, Ixodes affinis, Ixodes brunneus, Ixodes cookei, Ixodes marxi, Ixodes minor, Ixodes scapularis, Ixodes texanus, Ixodes woodi, Rhipicephalus sanguineus, and Ornithodoros capensis. Ixodes woodi is recorded from South Carolina for the first time. Boophilus annulatus and Boophilus microplus probably no longer exist in South Carolina, and Aponomma latum is an exotic species that is not established in South Carolina. Brief notes follow each species.

Underinsured and uninsured patients. Basic health care: the Washington State experiment.

During the early 1980s in the state of Washington, a change in access to health care became apparent. This was due to a change in the basic method of financing. Within the state, a shift to a service-dominated economy resulted in minimum wage earning with no fringe benefit for health, and a severe recession resulted in unemployment and under-employment. This article describes the approach taken by the people of Washington in order to solve this problem and documents the results of their work, as of December 1988. The story is not over, but it does illustrate what can be done when members of a society decide to work together to solve a problem.