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Virus Transmission (virus + transmission)
Selected AbstractsEvidence for the effectiveness of sterile injecting equipment provision in preventing hepatitis C and human immunodeficiency virus transmission among injecting drug users: a review of reviewsADDICTION, Issue 5 2010Norah Palmateer ABSTRACT Aims To review the evidence on the effectiveness of harm reduction interventions involving the provision of sterile injecting equipment in the prevention of hepatitis C virus (HCV) and human immunodeficiency virus (HIV) transmission among injecting drug users (IDUs). The interventions assessed were needle and syringe programmes (NSP), alternative modes of needle/syringe provision (pharmacies, vending machines and outreach) and the provision of injecting equipment other than needles/syringes. Methods Systematic searches of the English language literature to March 2007 were undertaken to identify systematic, narrative or meta-analytical reviews (also known as a review of reviews) of the impact of interventions on HCV transmission, HIV transmission or injecting risk behaviour (IRB). Critical appraisal criteria classified the reviews as either high quality (,core') or supplementary: a framework based on the quality of reviews, the reviewers' conclusions and the designs/findings of the primary studies was used to derive evidence statements. Results Three core and two supplementary reviews of injecting equipment interventions were identified. According to the proposed framework, this study found (a) insufficient evidence to conclude that any of the interventions are effective in preventing HCV transmission; (b) tentative evidence to support the effectiveness of NSP in preventing HIV transmission; (c) sufficient evidence to support the effectiveness of NSP (and tentative evidence of an additional impact of pharmacy NSP) in reducing self-reported IRB; and (d) little to no evidence on vending machines, outreach or providing other injecting equipment in relation to any of the outcomes. Conclusions The evidence is weaker than given credit for in the literature. The lack of evidence for effectiveness of NSP vis-à-vis biological outcomes (HCV and HIV incidence/prevalence) reflects the limitations of studies that have been undertaken to investigate these associations. Particularly for HCV, low levels of IRB may be insufficient to reduce high levels of transmission. New studies are required to identify the intervention coverage necessary to achieve sustained changes in blood-borne virus transmission. [source] Tospoviruses infecting vegetable crops in IsraelEPPO BULLETIN, Issue 2 2000A. Gera Symptoms of vein clearing, stem necrosis, curling, necrotic spots and rings on the leaves associated with infection by tomato spotted wilt tospovirus (TSWV) were documented among vegetable crops growing in commercial glasshouses and open fields in Israel. Plants exhibiting symptoms were collected, from 1994-01 to 1998-12. Among cultivated vegetable crops analysed for TSWV by ELISA, the following plants were found to be infected: tomato, capsicum, aubergine, lettuce, cabbage and cucumber. These incidences of the virus were all correlated with the occurrence in high population of Frankliniella occidentalis. Transmission of the virus from infected Datura stramonium to Petunia leaf discs, by F. occidentalis, was up to 26%. TSWV antigens were readily detected by ELISA in seeds harvested from naturally infected vegetable crops. However, we failed to show virus transmission to the progeny plants. Iris yellow spot tospovirus (IYSV) was detected in onion. High incidence of the disease was associated with large populations of Thrips tabaci. [source] Knowledge of disease and adherence in adult patients with haemophiliaHAEMOPHILIA, Issue 4 2010K. LINDVALL Summary., Patients with moderate and severe haemophilia are evaluated on a regular basis at their haemophilia centres but patients with mild haemophilia are seen less often because of fewer problems related to their disease. The needs of patients with milder forms of haemophilia, however, are often underestimated, both by the patient and staff at healthcare facilities. This study evaluated the knowledge of disease and adherence to treatment among patients with severe, moderate and mild haemophilia. This was a prospective multicentre study performed in Haemophilia Centres in Scandinavia. A total of 413 (67%) of 612 patients aged >25 years with mild, moderate and severe haemophilia completed a self-administered questionnaire. The mean age of the respondents was 49.7 years (range 25,87 years). Of the 413 respondents, 150 had a mild, 86 had a moderate and 177 had a severe form of haemophilia. A total of 22 (5%) patients did not know the severity of their disease, and 230 (56%) patients knew the effect of factor concentrate in the blood. Of the 413 respondents, 53 (13%) of the cohort never treated a haemorrhage. Patients with mild haemophilia, P , 0.001, were the least likely to treat a haemorrhage. The relative number of patients who were afraid of virus transmission by factor concentrate was about similar in the three groups, 27% of those with severe haemophilia, 26% with moderate and 24% with mild haemophilia. This study shows that the amount of knowledge among haemophilia patients about their disease and treatment is somewhat limited, and demonstrates the importance of continually providing information about haemophilia and treatment, especially to patients with a mild form of the disease. [source] Forum on: the role of recombinant factor VIII in children with severe haemophilia AHAEMOPHILIA, Issue 2 2009M. FRANCHINI Summary., The development of recombinant FVIII (rFVIII) products, fuelled by the need for improved safety of treatment arising from the dramatic widespread blood-borne virus transmission in the 1970,1980s revolutionized the care of children with haemophilia A over the last two decades. The larger availability of perceived safer replacement therapy associated with the introduction of rFVIII products reassured the haemophilia community and there was a strong push in some Western countries to treat haemophilic children only with rFVIII. Moreover, this significantly contributed in the 1990s to the diffusion outside Northern Europe of prophylactic regimens implemented at an early age to prevent bleeding and the resultant joint damage (i.e. primary prophylaxis), together with the possibility of home treatment. These changes led to a substantial improvement of the quality of life of haemophilic children and of their families. The general agreement that primary prophylaxis represents the first-choice treatment for haemophilic children has been recently supported by two randomized controlled trials carried out with rFVIII products, providing evidence on the efficacy of early prophylaxis over on-demand treatment in preserving joint health in haemophilic children. However, the intensity and optimal modalities of implementation of prophylaxis in children, in particular with respect to the issue of the venous access, are still debated. A number of studies also supports the role of secondary prophylaxis in children, frequently used in countries in which primary prophylaxis was introduced more recently. With viral safety now less than an issue and with the more widespread use of prophylaxis able to prevent arthropathy, the most challenging complication of replacement therapy for children with haemophilia remains the risk of inhibitor development. Despite conflicting data, there is no evidence that the type of FVIII concentrate significantly influences the complex multifactorial process leading to anti-FVIII alloantibodies, whereas other treatment-related factors are likely to increase (early intensive treatments due to surgery or severe bleeds) or reduce (prophylaxis) the risk. Although the optimal regimen is still uncertain, eradication of anti-FVIII antibodies by immune tolerance induction (ITI), usually with the same product administered at inhibitor detection, should be the first-choice treatment for all patients with recent onset inhibitors. This issue applies particularly to children, as most patients undergo ITI at an early age, when inhibitors usually appear. The availability of a stable and long-lasting venous access represents a leading problem also in this setting. These and other topics concerning rFVIII treatment of haemophilic children were discussed in a meeting held in Rome on 27 February 2008 and are summarized in this report. [source] Modelling hantavirus in fluctuating populations of bank voles: the role of indirect transmission on virus persistenceJOURNAL OF ANIMAL ECOLOGY, Issue 1 2003Frank Sauvage Summary 1Using field data published in the literature, we investigated pathogen dynamics and conditions of persistence in a mathematical model of the bank vole (Clethrionomys glareolus),Puumala hantavirus system. The host population is assumed to have a 3-year periodic cycle. The duration of very low host density is critical for virus transmission and survival. 2Field epidemiological data strongly suggested a transmission of the hantavirus by the contaminated environment. We thus studied whether this ,indirect' transmission affected the virus persistence in the host population. 3The model assumptions were derived from the following conditions found in the literature: (1) there is no additional mortality nor fecundity loss due to the virus in infected hosts, thus the cyclic demographical pattern is not due to the virus; (2) no remission has been observed, thus we did not consider the existence of recovered individuals; (3) adult females are territorial and juveniles disperse to find a new territory and reach sexual maturity. A fragmented landscape was assumed to occur: individuals can live in favourable or unfavourable patches. 4The model was a compartmental model; the population was structured into susceptible or infectious individuals. We considered two age classes, juveniles and adults, and two sites (populations) connected by juvenile dispersal. 5Model dynamics accurately predicted the cyclic trend in disease prevalence as observed in epidemiological studies. They also showed that indirect transmission significantly increased the probability for the virus to persist during the low-density period of the host population. More precisely, even a low survival rate of the virus outside the host was sufficient to decrease extinction risk of the infection by stochastic events. 6Elasticity analysis showed a high robustness of the model to changes in the parameters of indirect transmission but a high sensitivity to changes in adult density. [source] Midgut infection by tomato spotted wilt virus and vector incompetence of Frankliniella triticiJOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2005F. M. de Assis Filho Abstract:, The mechanism leading to vector competence of thrips species to transmit tomato spotted wilt virus (TSWV) is not well characterized. We investigated the interaction of TSWV and the non-vector species Frankliniella tritici. A monoclonal antibody to the non-structural protein (NSs) of the TSWV was used to detect TSWV replication within the thrips by immunofluorescence microscopy and enzyme-linked immonosorbent assay (ELISA). TSWV was acquired by F. tritici, replicated and moved within the alimentary canal of F. tritici similar to a known vector of TSWV, Frankliniellaoccidentalis. However, virus was not found in the salivary glands of F. tritici, which is a prerequisite to virus transmission. Thus, movement to the salivary glands may determine vector incompetence of F. tritici. [source] Biology of the European large raspberry aphid (Amphorophora idaei): its role in virus transmission and resistance breakdown in red raspberryAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2009Lindsay S. McMenemy Abstract 1,The European large raspberry aphid Amphorophora idaei Börner is the most important vector of viral diseases afflicting commercially grown red raspberry (Rubus idaeus L.) in Northern Europe, with European raspberry production amounting to 416 000 tonnes per annum. This review synthesizes existing knowledge on its biology and interactions with other organisms, including its host plant and the viral pathogens it vectors. 2,Information about trophic interactions with other insect herbivores and natural enemies is reviewed. Vine weevils Otiorhynchus sulcatus compromise aphid resistance in some raspberry cultivars, increasing A. idaei abundance by 80%. Parasitoids show mixed success in parasitizing A. idaei, although Aphidius ervi attack rates more than doubled when A. idaei fed on a partially susceptible raspberry cultivar, compared with a resistant variety. These findings are discussed in the context of potential biological control as part of an integrated pest and disease management framework. 3,Amphorophora idaei transmits four known viruses: Black raspberry necrosis virus, Raspberry leaf mottle virus, Raspberry leaf spot virus and Rubus yellow net virus, with A. idaei taking as little as 2 min to transmit some viruses. 4,Existing control strategies, including resistant cultivars, insecticides and eradication of disease from parent plants, are described. In particular, strong selection pressures have resulted in A. idaei overcoming genetic resistance in many raspberry cultivars and most insecticides are now ineffective. 5,Future directions for the sustained control of A. idaei are suggested, taking into consideration the possible effects of climate change and also changes in agronomic practices in U.K. agriculture. [source] Passive immunization against oral AIDS virus transmission: An approach to prevent mother-to-infant HIV-1 transmission?JOURNAL OF MEDICAL PRIMATOLOGY, Issue 4 2001Regina Hofmann-Lehmann To develop immunoprophylaxis regimens against mother-to-child human immunodeficiency virus type 1 (HIV-1) transmission, we established a simian,human immunodeficiency virus (SHIV) model in neonatal macaques that mimics intrapartum mucosal virus exposure (T.W. Baba, J. Koch, E.S. Mittler et al.: AIDS Res Hum Retroviruses 10:351,357, 1994). We protected four neonates from oral SHIV-vpu+ challenge by ante- and postpartum treatment with a synergistic triple combination of immunoglobulin (Ig) G1 human anti-HIV-1 neutralizing monoclonal antibodies (mAbs) (T.W. Baba, V. Liska, R. Hofmann-Lehmann et al.: Nature Med 6:200,206, 2000), which recognize the CD4-binding site of Env, a glycosylation-dependent gp120, or a linear gp41 epitope. Two neonates that received only postpartum mAbs were also protected from oral SHIV-vpu+ challenge, indicating that postpartum treatment alone is sufficient. Next, we evaluated a similar mAb combination against SHIV89.6P, which encodes env of primary HIV89.6. One of four mAb-treated neonates was protected from infection and two maintained normal CD4+ T-cell counts. We conclude that the epitopes recognized by the three mAbs are important determinants for achieving protection. Combination immunoprophylaxis with synergistic mAbs seems promising to prevent maternal HIV-1 transmission in humans. [source] Absence of transmission of potentially xenotic viruses in a prospective pig to primate islet xenotransplantation study,JOURNAL OF MEDICAL VIROLOGY, Issue 11 2008Olga Garkavenko Abstract Shortage of human donor organs for transplantation has prompted usage of animals as an alternative donor source. Pigs are the most acceptable candidate animals but issues of xenozoonoses remain. Despite careful monitoring of designated pathogen free pigs there is still a risk that their tissues may carry infectious agents. Thus xenotransplantation requires extensive pre-clinical study on safety of the graft especially for those viruses that are either potentially oncogenic and/or immunosuppressive, or can establish persistent infection. A prospective pig-to-primate islet xenotransplantation study was performed which includes monitoring for potentially xenotic viruses namely porcine endogenous retrovirus (PERV), porcine cytomegalovirus (PCMV), porcine lymphotropic herpesvirus (PLHV), and porcine circovirus (PCV) using both molecular diagnostic,PCR and RT-PCR and serology methods. There was no evidence of pig virus transmission into primate recipients. This preclinical study underlines the information concerning viral safety of islet cell xenograft in pig-to-primate xenotransplantation. J. Med. Virol. 80:2046,2052, 2008. © 2008 Wiley-Liss, Inc. [source] Review article: vaccination and viral hepatitis , current status and future prospectsALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 10 2007R. S. KOFF Summary Background, Viral hepatitis is the most common cause of liver disease in the world. In the past 25 years, vaccines have become available for two of the five hepatitis viruses, and, where implemented, vaccination has become a key component of hepatitis prevention. Aims, To provide an update on recent advances in the use of current hepatitis vaccines and to examine progress in the development of vaccines for the remaining hepatitis viruses. Methods A Medline search was undertaken to identify the recent relevant literature. Search terms included hepatitis vaccines, hepatitis vaccination and hepatitis A,E vaccines. Results, Dramatic vaccine-induced declines in the incidence of both hepatitis A and B have occurred in the USA. Strategies to integrate hepatitis A vaccine into universal childhood immunization are being adopted. Similarly, strategies with the goal of eliminating transmission of hepatitis B have been promulgated. A vaccine for hepatitis E has been reported to be effective and safe, but progress in the development of vaccines for hepatitis C and D has been limited. Conclusion, During the next few decades, the goals of eliminating hepatitis A and B virus transmission may be reached in the USA and elsewhere. [source] An effective system for detecting Iris yellow spot virus transmission by Thrips tabaciPLANT PATHOLOGY, Issue 3 2010T. Inoue A simple, effective and convenient laboratory leaf system was developed to detect transmission of Iris yellow spot virus (IYSV) by thrips. It was shown that IYSV was transmitted highly efficiently by adults and also by larvae of five thelytokous populations of Thripstabaci from distinct areas in Japan: over all these populations, transmission efficiency of adults ranged from 20·4% (19/93) to 41·1% (76/185) and that of larvae from 17·3% (14/81) to 44·1% (67/152). Finally, it was demonstrated that IYSV infection was not detrimental to the development and fecundity of thrips until early adulthood. Larval mortalities of virus-exposed thrips were higher than in their unexposed counterparts in all three populations, but the differences were not significant. The results demonstrated that T. tabaci populations have considerable potential to cause outbreaks of IYSV and spread the disease because of their efficient transmission of the virus. [source] Comparative whitefly transmission of Tomato chlorosis virus and Tomato infectious chlorosis virus from single or mixed infectionsPLANT PATHOLOGY, Issue 2 2009A. Dalmon Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV) are two criniviruses that are emerging worldwide, and induce similar yellowing diseases in tomato crops. While TICV is transmitted only by Trialeurodes vaporariorum, ToCV is transmitted by three whitefly species in two genera Trialeurodes vaporariorum, T. abutilonea and Bemisia tabaci. The efficiency of transmission by T. vaporariorum from plants infected by one virus or by both was compared, and the probability of virus transmission by a single whitefly was derived from group testing experiments. The estimated transmission probabilities ranged from 0·01 to 0·13, and were not significantly different between ToCV and TICV, or between single and mixed infections. Experiments using B. tabaci as a vector and source plants infected by TICV and ToCV did not reveal any functional trans-complementation for transmission of TICV by ToCV, suggesting that if this phenomenon occurs in nature, it is at a very low frequency. Possible reasons why TICV did not establish in southern France while ToCV is now endemic are discussed. [source] Synergism between plant viruses: a mathematical analysis of the epidemiological implicationsPLANT PATHOLOGY, Issue 6 2001X.-S. Zhang Many virus diseases of plants are caused by a synergistic interaction between viruses within the host plant. Such synergism can induce symptoms more severe than would be caused by additive effects. In a synergistic interaction, the virus titre of both, one, or neither virus may be enhanced and, as a consequence, the rate of disease spread may be affected. An epidemiological model was developed in which transmission and loss rates were attributed to the different virus infection possibilities. Sharing the same host population implies competition, and this imposes an increased constraint on the survival of both viruses. It was shown that, in order to ensure virus survival in a mixed infection, the basic reproductive number should exceed a critical value which is larger than unity (R0 > Rc > 1). Here R0 is used in the same sense as in the absence of superinfection. Increased virulence (equivalent to disease severity) in dually infected plants decreases the opportunities for both viruses to coexist, while increased virus transmission from dually infected plants increases such opportunities. The net effect of increased virulence and increased virus transmission on virus persistence was neutral if synergism caused the same proportional effect on both. Total host abundance was, however, reduced. The opportunity for virus persistence was increased if the enhancement of transmission exceeded that of virulence. Indeed, by this mechanism a virus which was nonviable alone could invade and persist in a chronic epidemic of another virus. Where the effect on virulence is greater than that on transmission, the viruses are likely to exclude each other, especially when the transmission rates of both viruses have intermediate values. In such cases, the final outcome is determined by both the parameter values and the initial state. [source] Immobilized HIV-1 Tat protein promotes gene transfer via a transactivation-independent mechanism which requires binding of Tat to viral particlesTHE JOURNAL OF GENE MEDICINE, Issue 11 2009Filomena Nappi Abstract Background Retroviral transduction of cells is improved upon virus adsorption onto immobilized fibronectin (FN) fragments. Because HIV-1 Tat possesses the same functional domains that lead to increased transduction efficiency in FN by colocalization of bound virus and cells, we hypothesized that Tat could enhance gene transfer by a similar mechanism. Methods Single-cycle replication retro- or lentivirus carrying green fluorescent protein or cloramphenicol acetyltransferase as reporter genes were added to wells coated with Tat or Tat peptides. Wells were extensively washed to remove unbound virus and levels of transduction were detected by measuring reporter gene expression. Virus adsorption to immobilized Tat was measured using a p24 antigen capture assay. Results Immobilized Tat efficiently binds retro- and lentiviral particles and mediates virus transmission at virus input doses that were otherwise unable to transduce susceptible cells. Virus adsorption to Tat is not mediated by envelope glycoprotein (Env) because immobilized Tat binds and retains vesicular stomatitis virus G (VSV-G) pseudotypes as well as envelope-free particles. HIV-1 Env or VSV-G are required for Tat-assisted transduction, which is abrogated by an antibody blocking the HIV-1 Env,CD4 interaction. Tat-assisted transduction is mediated by the cysteine-rich region of Tat, which is known to be essential for Tat transactivation activity. However, Tat transactivation is not required for Tat-assisted transduction, as indicated by the enhancement of transduction by transactivation-silent Tat mutants. Conclusions Immobilized Tat promotes virus transduction by a transactiva- tion-independent mechanism, which requires binding of virus to Tat. Recombinant Tat or Tat fragments provide a new method to increase efficiency of retro- and lentiviral based gene transfer and gene therapy. Copyright © 2009 John Wiley & Sons, Ltd. [source] Sexually transmitted infections: impact on male fertilityANDROLOGIA, Issue 2 2008F. R. Ochsendorf Summary The impact of sexually transmitted diseases (STD) on male fertility is strongly dependent on the local prevalence of the STDs. In Western countries STD-infections are of minor relevance. In other regions, i.e. Africa or South East Asia, the situation appears to be different. Acute urethritis could not be associated with male infertility. Chronic infections (gonorrhoea) can cause urethral strictures and epididymo-orchitis. Chlamydia trachomatis and Neisseria gonorrhoea can be transmitted to the female partner and cause pelvic inflammatory disease with tubal obstruction. Ureaplasma urealyticum may impair spermatozoa (motility, DNA condensation). Trichomonas vaginalis has, if any, only minor influence on male fertility. The relevance of viral infections (HPV, HSV) for male infertility is not resolved. Any STD increases the chances of transmission of the human immunodeficiency virus (HIV). The HIV infection is associated with infectious semen and the risk of virus transmission. Semen quality deteriorates with the progression of immunodeficiency. Special counselling of serodiscordant couples is needed. STDs should be treated early and adequately to prevent late sequelae for both men and women. [source] Asymmetrical transmission of human herpesvirus 8 among spouses of patients with Kaposi sarcomaBRITISH JOURNAL OF DERMATOLOGY, Issue 3 2009A. Dupuy Summary Background, Among heterosexuals, the sexual transmission of human herpesvirus 8 (HHV8) has not been established. Objectives, To assess HHV8 seroprevalence in spouses of patients with classic and endemic Kaposi sarcoma (KS) and to suggest possible routes of transmission. Methods, A case,control study was carried out in a teaching hospital among spouses of human immunodeficiency virus-negative patients with KS (cases , exposed subjects) and controls who did not have KS nor were related to patients with KS (nonexposed subjects). HHV8 seroprevalence in spouses of patients with KS was compared with HHV8 seroprevalence in controls matched for age, gender and place of birth. Other serology tests were compared between cases and controls. Among heterosexual couples, HHV8-seropositive and HHV8-seronegative spouses were compared for possible risk factors for virus transmission. Results, HHV8 seroprevalence was significantly higher among spouses of patients with KS (13 of 22; 59%) than among matched controls (19 of 58; 33%; P = 0·043). Among heterosexual couples, five of five (100%) male spouses were HHV8 positive vs. six of 15 (40%) female spouses (P = 0·04). There was no significant difference between HHV8-seropositive and HHV8-seronegative spouses for all other factors screened for among heterosexual couples. Conclusions, Being a spouse of a patient with KS is a risk factor for HHV8 seropositivity. Our results suggest that female-to-male HHV8 transmission could be more efficient than male-to-female transmission among couples including a patient with KS. Transmission could involve distinctive behaviours, or currently unknown biological properties of HHV8. [source] | |||||||||||||