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Influence of the infectious dose of SIV on the acute infection in cynomolgus monkeys and on the effect of treatment ... Influence of the infectious dose of SIV on the acute infection in cynomolgus monkeys and on the effect of treatment with 3'-fluorothymidine. Objective: To study whether the infectious dose of simian immunodeficiency virus (SIVsm) influences the acute infection and the response to antiviral treatment of 3'-fluorothymidine (FLT). When 500-2500 monkey infectious doses (MID50) was inoculated no marked influence of treatment on viral antigen was seen as compared to the controls whereas a virus inoculum of 10-50 MID50 significantly delayed the appearance of viral antigen. www.aegis.com /aidsline/1992/aug/M9280934.html   (470 words)

Infectious Dose   (Site not responding. Last check: 2007-10-26) The infectious dose for man varies and is dependent on the type of agent, the route of exposure, and the health status of the host in addition to dose. This interrelationship is important because it helps to explain why not all laboratory workers who handle infectious agents become ill. Viruses pose a greater hazard than the other agents because the infectious dose for man is lower than that for other agents. The large doses of bacterial agents required to produce disease via ingestion help to explain why all microbiologists do not become clinically ill from their cultures. www.lbl.gov /ehs/biosafety/html/infectious_dose.htm   (208 words)

CDC - Airborne Infection with Bacillus anthracis—from Mills to Mail Since the infectious dose of inhaled virulent anthrax spores cannot ethically be determined experimentally in humans, we estimated the 50% infectious dose (ID) based on data from the 8-hour inhaled dose measured in Manchester in 1957. The inhalation dose for workers in the area where four of the five cases of inhalation anthrax had occurred was estimated to be 140–690 spores <5 µm in size (and 620–2,200 total spores), based on air sampling data (8). On the basis of studies of 1,236 monkeys, Glassman estimated the median lethal dose to be 4,130 spores, and using the probit model he suggested that the LD was associated with a 10-fold decrease in dose (16). www.cdc.gov /ncidod/EID/vol10no6/02-0738.htm   (4035 words)

Prions: dose experiments The prion infectious dose in naturally acquired TSE disease is unknown. The infective dose of the greatest dilution that caused the animal to die (often after years of incubation), was defined as infective unit (IU) if the animal receiving the inoculum was the same species as that of the animal that was donating it. The infectious dose between species is usually higher than between animals of the same species (possibly a million fold), but it is may be the same (e.g. www1.umn.edu /eoh/hazards/hazardssite/prions/priondose.html   (1801 words)

Epidemiology Concepts for Disease in Animal Groups   (Site not responding. Last check: 2007-10-26) Many infectious agents have several mechanisms to exchange genetic material with unrelated species and to change the genetics of their progeny, have very short generation times compared to livestock and are rapidly and constantly changing as a result. For most outbreaks of infectious disease, the highest number of clinical cases usually occurs early in the natural course of the disease through the group and then declines as the animals respond to the infection and the pool of susceptibles declines. Until the transmission of the infectious agent is reduced, the infectious dose lowered, the resistance of the remaining unaffected animals is increased or the pool of susceptibles is exhausted the outbreak expands in a vicious spiral. www.vetmed.wsu.edu /courses-jmgay/EpiMod2.htm   (6709 words)

6. DOSE-RESPONSE MODELLING Therefore, the question of whether a minimal infectious dose truly exists or merely results from the limitations of the data tends to be academic. This concept, however, is distinct from a threshold for administered dose, because of the possibility, however small, that a single ingested organism may survive the multiple barriers in the gut to become established and reproduce. Since, in such a context, each dose group may contain a mixture of responses, analysis of the heterogeneity in the response (segregation of uncertainty and variation) is not possible. www.fao.org /docrep/006/y4666e/y4666e0b.htm   (5611 words)

Cryptosporidium in Immunocompromised Hosts, Exposure Research, US EPA The initial studies determined the dose that causes infection in 50 percent of the mice. The infectious dose for 50% (ID50) of the immunocompetent mice was 61 oocysts, and the calculated ID50 for the immunosuppressed mice was 102 oocysts. If there is a true difference between the infectious doses required for immunosuppressed versus immunocompetent mice, substantially more trials will be required in order to distinguish this difference from the experimental error. www.epa.gov /nerl/research/2001/g2-4.html   (956 words)

Defra, UK - Animal health and welfare - BSE - Science & research - Pathogenesis Pathogenesis refers to the study of the disease process; the sequence in which the tissue of the body became infected and the progression of clinical signs both in experimentally and naturally infected animals. In actuality, this dose is probably 10 -100 times greater than most cattle will have been exposed to via feed. Although any infectious tissues should give results in fewer than three years, to reliably confirm a result as negative can potentially take the full lifespan of the mice. www.defra.gov.uk /animalh/bse/science-research/pathog.html   (1390 words)

Determination of the Infectious Dose of Helicobacter pylori during Primary and Secondary Infection in Rhesus Monkeys ... Determination of the Infectious Dose of Helicobacter pylori during Primary and Secondary Infection in Rhesus Monkeys (Macaca mulatta) -- Solnick et al. Determination of the Infectious Dose of Helicobacter pylori during Primary and Secondary Infection in Rhesus Monkeys (Macaca mulatta) We sought to determine the infectious dose of Helicobacter pylori during primary and secondary infection in the rhesus monkey iai.asm.org /cgi/content/full/69/11/6887   (3039 words)

Sanitation in the control of infectious diseases in livestock   (Site not responding. Last check: 2007-10-26) Enteric infectious disease is a complex, multifactorial condition with numerous factors including pathogen exposure, strain variation, environmental conditions, management conditions, nutritional state and immune status all interacting to cause loss. With the rare exception, it is likely that most infectious enteric agents of cattle co-evolved with their bovine hosts long before their domestication thousands of years ago (25, 26). Because of their envelope, these viruses retain infectiousness better at lower rather than higher relative humidity (13) and are considerably more sensitive to soaps and common disinfectants than are non-enveloped viruses. www.vetmed.wsu.edu /courses-jmgay/FDIUSanitation.htm   (3574 words)

Biohazards and Potentially Infectious Materials Infectious agents may be classified into risk groups based on their relative hazard. Because of the possibility of exposure to potentially infectious agents (i.e., Rabies virus, Cercopithecine herpesvirus 1, Coxiella burnetti), ULAR and the School of Veterinary Medicine have developed policies to protect personnel and students who have animal contact. Typically, the infectious nature of clinical material is unknown, and specimens are often submitted with a broad request for microbiological examination for multiple agents (e.g., sputa submitted for "routine," acid-fast, and fungal cultures). www.ehrs.upenn.edu /programs/bio/bsm/biohazards.html   (2904 words)

Report Notes Difficulties In Eliminating E. Coli O157:H7 From Food Supply Infectious doses associated with this pathogen in outbreaks have been consistently low?a characteristic associated with the organism's acid tolerance, according to Buchanan and Doyle. "[E. coli O157:H7's] low infectious dose in combination with the disease severity means that successful prevention strategies must focus on reducing or eliminating the presence of the microorganism, rather than on preventing pathogen growth as is done in more traditional approaches," Buchanan and Doyle wrote. A low infectious dose of two to 2,000 cells has been associated with outbreaks. www.eurekalert.org /pub_releases/1997-09/IoFT-RNDI-250997.php   (1151 words)

David Rasnick: protease inhibitor/AZT cocktails - part 2 Prior to therapy-when his "viral load" was 643,000-he had 1,000 infectious doses of HIV (per ml of plasma). If infectious doses equaled infectious HIV particles, then the difference between patient 105’s infectious doses and his "viral load" must represent non-infectious HIV particles. In one case a viral load of 643,000 corresponded with 1,000 infectious HIV particles, and in another case a viral load of over 500,000 corresponded to zero infectious HIV partic les. www.healtoronto.com /rasnick2.html   (743 words)

Risk Assessment   (Site not responding. Last check: 2007-10-26) Epidemiologic studies are insufficient to predict infectious dose because of the 3-4 week lag time between exposure and disease outcome. The objective of this project was to determine the minimum infectious oral dose of L. The purpose of this study was to establish the pregnant rhesus monkey as an animal surrogate for human exposure and develop dose information to be used in a risk assessment for Listeria monocytogenes. www.griffin.peachnet.edu /cfs/research/RiskAssessmentResearch.html   (687 words)

[No title]   (Site not responding. Last check: 2007-10-26) The infectious agents may be viruses (HIV, HBV), bacteria, fungi, parasites, etc. The infectious dose is that number of pathogens needed to initiate an infectious process. Since there is a complex host-bacteria interaction involving the immune system and other factors, the infectious dose needed to start periodontal infections will vary between patients. When an infection becomes acutely active, inflammation may be detected in a dental office or by patients in the form of gingivitis, periodontal abscess or loose teeth in severe cases. www.pitt.edu /AFShome/s/u/super1/public/html/lecture/lec1381/007.htm   (150 words)

FDA/CFSAN - Draft Risk Assessment on the Public Health Impact of Vibrio parahaemolyticus in Raw Molluscan Shellfish Similar doses of a Kanagawa negative crab isolate were negative for bacteremia, liver or spleen invasion in all 12 animals challenged (20). Dose-response, using all the doses from the three studies, was characterized by fitting several dose-response models chosen to span the range of extremes of model extrapolated risks at projected levels of population exposure. For each of the models considered, the risk of illness at a specific dose was considered to have a distribution determined by the bootstrap distribution of parameter estimates. vm.cfsan.fda.gov /~dms/vprisk5.html   (4635 words)

Establishment and Maintenance of Gammaherpesvirus Latency Are Independent of Infective Dose and Route of Infection -- ...   (Site not responding. Last check: 2007-10-26) latency is independent of the infectious dose and route of infection. The frequency of ex vivo reactivation from latency is independent of the infectious dose. infectious event is sufficient to result in maximal latency. jvi.asm.org /cgi/content/full/77/13/7696   (4215 words)

Influence of Long Terminal Repeat and Env on the Virulence Phenotype of Equine Infectious Anemia Virus -- Payne et al. ...   (Site not responding. Last check: 2007-10-26) Maturation of the cellular and humoral immune responses to persistent infection in horses by equine infectious anemia virus is a complex and lengthy process. Equine infectious anemia virus envelope evolution in vivo during persistent infection progressively increases resistance to in vitro serum antibody neutralization as a dominant phenotype. Novel and dynamic evolution of equine infectious anemia virus genomic quasispecies associated with sequential disease cycles in an experimentally infected pony. jvi.asm.org /cgi/content/full/78/5/2478   (4999 words)

Comparison of mucosal vs. intravenous infectious dose of a cell associated SIV32H challenge stock in rhesus macaques. Comparison of mucosal vs. intravenous infectious dose of a cell associated SIV32H challenge stock in rhesus macaques. A rhesus macaque infected with 10 monkey infectious doses (MID50) of the 11-88 stock of SIV32H served as a single source of peripheral blood mononuclear cells (PBMCs) and plasma taken at a single time point to establish a cell associated virus stock for homologous or heterologous vaccine challenge. The characteristics of this challenge stock and the minimum infectious dose via mucosal or i.v. www.aegis.com /aidsline/1992/aug/M9280909.html   (455 words)

HIV & AIDS - Non-Infectious HIV is Pathogenic Somebody in the front row challenged Ho’s criteria for what constitutes an assay of infectious virus, a challenge that has profound implications for the basic tool of contemporary HIV science: the viral load test. I noted that there is not one example in the literature of a human infected with viable, infectious HIV that possesses an inhibitor-resistant mutant protease. Assuming that "viral load" testing accurately counted HIV, and that infectious dose testing accurately counted infectious HIV, I offered my 99.8% figure from the Ho/Markowitz paper as the fraction of circulating HIV that was non-infectious. www.virusmyth.net /aids/data/drconf.htm   (3419 words)

Index to Material Safety Data Sheets (MSDS) for Infectious Substances - Public Health Agency of Canada However because many laboratory workers, whether in research, public health, teaching, etc., are exposed to not only chemicals but infectious substances as well, there was a large gap in the readily available safety literature for employees. These MSDS are produced for personnel working in the life sciences as quick safety reference material relating to infectious micro-organisms. The MSDS are organized to contain health hazard information such as infectious dose, viability (including decontamination), medical information, laboratory hazard, recommended precautions, handling information and spill procedures. www.phac-aspc.gc.ca /msds-ftss   (426 words)

Transmission and Infectious Dose of Escherichia coli O157:H7 in Swine -- Cornick and Helgerson 70 (9): 5331 -- Applied ...   (Site not responding. Last check: 2007-10-26) Transmission and Infectious Dose of Escherichia coli O157:H7 in Swine -- Cornick and Helgerson 70 (9): 5331 -- Applied and Environmental Microbiology Transmission and Infectious Dose of Escherichia coli O157:H7 in Swine In addition, the infectious dose must be of such a magnitude aem.asm.org /cgi/content/full/70/9/5331   (3186 words)

eMedicine - Cholera : Article by Sajeev Handa, MBBCh, BAO Pathophysiology: The infectious dose of bacteria required to cause clinical disease varies with the mode of administration. Owing to the relatively large infectious dose, transmission occurs almost exclusively via contaminated water or food. Woodruff AW: A Synopsis of Infectious and Tropical Diseases. www.emedicine.com /med/topic351.htm   (3550 words)

eMedicine - Campylobacter Infections : Article by Mahmud Javid, MD Photosensitivity may occur with prolonged exposure to sunlight or tanning equipment; reduce dose in renal impairment; consider drug serum level determinations in prolonged therapy; tetracycline use during tooth development (last half of pregnancy through age 8 y) can cause permanent discoloration of teeth; Fanconilike syndrome may occur with outdated tetracyclines. Dosing regimens are numerous; adjust dose based on CrCl and changes in volume of distribution. Base initial dose on severity of infection, and administer in equally divided doses; dose may range from 250-500 mg q6h IV for a maximum of 3-4 g/d; alternatively, 500-750 mg q12h IM or intra-abdominally www.emedicine.com /MED/topic263.htm   (3964 words)

Distinct Characteristics of Resistance to Borrelia burgdorferi-Induced Arthritis in C57BL/6N Mice -- Ma et al. 66 (1): ... At all infectious doses, the levels of spirochetes in ankle The effect of increasing infectious dose was also tested in C57BL/6N mice, which have been reported to develop mild arthritis Effects of infectious dose on ankle swelling in C57BL/6N and C3H/HeN mice. iai.asm.org /cgi/content/full/66/1/161   (6505 words)

December 2004 Page 9 At the same time, regulators are taking into consideration new data on the infectious dose for BSE. McChesney noted that the 1997 feed ban was based on the assumption that 1 g of infectious material was required to cause the disease in cattle; research Aban has shown that a much lower dose can be infectious. Current research points to 1 mg as Aban infectious dose – a thousand-fold reduction from the 1 g level. www.alabamapoultry.org /magazine/dec2004/page9.html   (622 words)

Correlation of T Cell Independence of Antibody Responses with Antigen Dose Reaching Secondary Lymphoid Organs: ... crucially on 1) the infectious dose and 2) the route of infection C, Model of the requirements (Ag dose vs amounts in the spleen, described as areas) to induce TI-1, TI-2, or TD Ab responses. Two or three animals were analyzed per infectious dose and time point. www.jimmunol.org /cgi/content/full/164/12/6296   (4777 words)

Clinical Trial: Norwalk Virus Inocula The overall objective of this study is to develop a challenge pool/inoculum of Norwalk Virus (NV). Initially, 20 subjects will be challenged with a dose of NV (Lot 42399) that approximates the dose used in previous challenge studies. Subsequently, smaller groups of subjects will be challenged with lower dosages to determine the Human Infectious Dose 50%. www.clinicaltrials.gov /ct/gui/show/NCT00138476   (1473 words)

The rate of progression to AIDS is independent of virus dose in simian immunodeficiency virus-infected macaques -- ... The rate of progression to AIDS is independent of virus dose in simian immunodeficiency virus-infected macaques -- Holterman et al. The rate of progression to AIDS is independent of virus dose in simian immunodeficiency virus-infected macaques dose and the 2 week peak of primary viraemia or the subsequent vir.sgmjournals.org /cgi/content/full/81/7/1719   (3723 words)

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