Regression models for time to seroconversion following experimental bovine leukaemia virus infection

Lassauzet, Marie‐Liesse G.; Johnson, Wesley O.; Thurmond, Mark

doi:10.1002/sim.4780080610

Cited by 13 publications

(6 citation statements)

References 21 publications

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“…Time of sero-conversion depends on several factors such as transmission route (natural versus experimental infection), the effective infective dose administered, the sampling period and the sensitivity of the method used for detection of specific antibodies (Evermann et al, 1986;Monti and Frankena, 2005). The sero-conversion time observed (about 30 DPI, except for animal F086) for both groups is similar to previous observations for experimentally infected animals (Klintevall et al, 1997;Lassauzet et al, 1989;Nagy et al, 2007), but is shorter than the median seroconversion time estimated by Monti et al (48 DPI) (Monti and Frankena, 2005). This discrepancy is probably due to the characteristics of their analysis that involved a greater number of animals, several experimental designs and the use of different serological tests.…”

Section: Discussionsupporting

confidence: 84%

Co-infection with Mycobacterium bovis does not alter the response to bovine leukemia virus in BoLA DRB3*0902, genetically resistant cattle

Lützelschwab

Forletti

Cepeda

et al. 2016

Research in Veterinary Science

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Section: Discussionsupporting

confidence: 84%

Co-infection with Mycobacterium bovis does not alter the response to bovine leukemia virus in BoLA DRB3*0902, genetically resistant cattle

Lützelschwab

Forletti

Cepeda

et al. 2016

Research in Veterinary Science

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“…This scenario is ideally suited to the technique of probabilistic modeling, in which probability distributions are fitted to observed data. 5,9,28 The desired probability estimates can then be calculated using these distributions. The objective of this study was to predict the duration of detectable viremia in BTV-infected cattle using a statistical analysis of existing data.…”

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confidence: 99%

Maximal Predicted Duration of Viremia in Bluetongue Virus—Infected Cattle

2001

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Abstract. Central to the development of rational trade policies pertaining to bluetongue virus (BTV) infection is determination of the risk posed by ruminants previously exposed to the virus. Precise determination of the maximal duration of infectious viremia is essential to the development of an appropriate quarantine period prior to movement of animals from BTV-endemic to BTV-free regions. The objective of this study was to predict the duration of detectable viremia in BTV-infected cattle using a probabilistic modeling analysis of existing data. Data on the duration of detectable viremia in cattle were obtained from previously published studies. Data sets were created from a large field study of naturally infected cattle in Australia and from experimental infections of cattle with Australian and US serotypes of BTV. Probability distributions were fitted to the pooled empirical data, and the 3 probability distributions that provided the best fit to the data were the gamma, Weibull, and lognormal probability distributions. These asymmetric probability distributions are often well suited for decay processes, such as the time to termination of detectable viremia. The analyses indicated a Ͼ 99% probability of detectable BTV viremia ceasing after Յ 9 weeks of infection in adult cattle and after a slightly longer interval in BTV-infected, colostrum-deprived newborn calves.Bluetongue is an insect-transmitted, noncontagious viral disease of domestic and wild ruminants that is caused by bluetongue virus (BTV). 11,16,26 It is 1 of only 16 diseases included in List A by the Office International des Epizooties (OIE). Diseases included in OIE List A are defined as communicable diseases that have the potential for very serious and rapid spread, irrespective of national borders, that are of serious socioeconomic or public health consequence, and that are of major importance to the international trade of livestock and livestock products. 1 The major adverse economic impact of BTV infection in many regions of the world is its effect on international trade and movement of ruminant livestock and germplasm and not direct losses from bluetongue disease. 16,22,25 Central to the development of rational trade policies pertaining to BTV infection is determination of the risk posed by ruminants previously exposed to the virus. BTV infection of cattle is characterized by prolonged but not persistent viremia. 11 Virus is highly cell associated during viremia, and intimate association of BTV with erythrocytes is responsible for both prolonged viremia as well as infection of the hematophagous vector insects that transmit the virus. 4 Duration of viremia in BTV-infected cattle is related to the lifespan of the bovine erythrocyte, and precise determi-

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“…The hazard function h(t) is given by If the distribution f (t) is a mixed distribution of fi(t) and f2(t) with weight w and 1-w, i.e., f (t) = wf1(t)+ (1-w)f2 (t), then where which leads to Equation (4) . then which leads to Equation (5) .…”

Section: Appendixmentioning

confidence: 96%

Estimating a Hazard Function for Each of Four Items of Adverse Event Induced by the Anti-cancer Drug TS-1

Fukushima

Kashiwagi

Sano

et al. 2006

Japanese Journal of Pharmacoepidemiology/Yakuzai ekigaku

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Background : The safety of newly approved drugs must be assessed using postmarketing surveillance data. One of the difficulties in assessing the hazard rates of adverse events induced by the anti-cancer drug TS-1 was that the time to event was not exactly identified due to the interval censoring. Most patients were outpatients who underwent clinical laboratory tests almost periodically at 1-or 2-week intervals and therefore, the occurrence of an adverse event was confirmed at the time of testing days after the event occurrence. Objective : The purpose of this study was to propose a new model of hazard functions for each of 4 items of adverse event induced by TS-1 using post-marketing surveillance data considering the interval censoring. Methods : The data obtained from 3,294 patients with gastric cancer who received an initial 4-week course of therapy with TS-1 administered orally twice a day, followed by a 4-week second course with a 2-week no-treatment period after the initial course, were used to estimate hazard functions. Four items of adverse event-hemoglobin level (HB) , white blood cell (WBC) , neutrophil (NEUT) and platelet counts (PLT)-were graded, respectively, using the criteria established by the Japan Society of Clinical Oncology. Slip-mixed log-logistic and slip-mixed Weibull models were proposed as candidate models for estimating hazard functions. The goodness of fit of the two candidate models was evaluated by applying them to the above-mentioned data. The hazard functions for each of 4 items were assessed using the model with the better fit. Results : The initial occurrence of adverse event was shown to follow the slip-mixed log-logistic model for each of 4 items. Although most events occurred early on in the initial course of therapy, a small peak in HB was also observed in the second course, while no such peak appeared for the other items.

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Regression models for time to seroconversion following experimental bovine leukaemia virus infection

Cited by 13 publications

References 21 publications

Co-infection with Mycobacterium bovis does not alter the response to bovine leukemia virus in BoLA DRB3*0902, genetically resistant cattle

Co-infection with Mycobacterium bovis does not alter the response to bovine leukemia virus in BoLA DRB3*0902, genetically resistant cattle

Maximal Predicted Duration of Viremia in Bluetongue Virus—Infected Cattle

Estimating a Hazard Function for Each of Four Items of Adverse Event Induced by the Anti-cancer Drug TS-1

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