oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
The SIR Epidemiology Model in Predicting Herd Immunity
Joanna Nicho
Undergraduate Journal of Mathematical Modeling : One + Two , 2010, DOI: 10.5038/2326-3652.2.2.8
Abstract: The Simple Epidemic Model uses three states to describe the spread of an infection: the susceptible (S), the infected (I), and the recovered (R). This model follows the trend of an infection over time and can predict whether an infection will spread. Using this model, epidemiologists may calculate the percentage of the population that needs to be vaccinated in order to provide a population immunity from a disease. This study will compare the vaccination percentage required for herd immunity to measles, mumps, and rubella against the current percentage of vaccinated individuals.
Positive Network Assortativity of Influenza Vaccination at a High School: Implications for Outbreak Risk and Herd Immunity  [PDF]
Victoria C. Barclay, Timo Smieszek, Jianping He, Guohong Cao, Jeanette J. Rainey, Hongjiang Gao, Amra Uzicanin, Marcel Salathé
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0087042
Abstract: Schools are known to play a significant role in the spread of influenza. High vaccination coverage can reduce infectious disease spread within schools and the wider community through vaccine-induced immunity in vaccinated individuals and through the indirect effects afforded by herd immunity. In general, herd immunity is greatest when vaccination coverage is highest, but clusters of unvaccinated individuals can reduce herd immunity. Here, we empirically assess the extent of such clustering by measuring whether vaccinated individuals are randomly distributed or demonstrate positive assortativity across a United States high school contact network. Using computational models based on these empirical measurements, we further assess the impact of assortativity on influenza disease dynamics. We found that the contact network was positively assortative with respect to influenza vaccination: unvaccinated individuals tended to be in contact more often with other unvaccinated individuals than with vaccinated individuals, and these effects were most pronounced when we analyzed contact data collected over multiple days. Of note, unvaccinated males contributed substantially more than unvaccinated females towards the measured positive vaccination assortativity. Influenza simulation models using a positively assortative network resulted in larger average outbreak size, and outbreaks were more likely, compared to an otherwise identical network where vaccinated individuals were not clustered. These findings highlight the importance of understanding and addressing heterogeneities in seasonal influenza vaccine uptake for prevention of large, protracted school-based outbreaks of influenza, in addition to continued efforts to increase overall vaccine coverage.
Pandemic Dynamics and the Breakdown of Herd Immunity  [PDF]
Guy Katriel,Lewi Stone
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009565
Abstract: In this note we discuss the issues involved in attempting to model pandemic dynamics. More specifically, we show how it may be possible to make projections for the ongoing H1N1 pandemic as extrapolated from knowledge of seasonal influenza. We derive first-approximation parameter estimates for the SIR model to describe seasonal influenza, and then explore the implications of the existing classical epidemiological theory for the case of a pandemic virus. In particular, we note the dramatic nonlinear increase in attack rate as a function of the percentage of susceptibles initially present in the population. This has severe consequences for the pandemic, given the general lack of immunity in the global population.
An outbreak of acute bovine mastitis caused by Klebsiella pneumoniae in a dairy herd
Silva, N.;Costa, G.M.;
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2001, DOI: 10.1590/S0102-09352001000400001
Abstract: an outbreak of coliform mastitis is described in a dairy herd from the state of rio de janeiro, brazil. during a four-month period 14 fatal cases of klebsiella pneumoniae-related mastitis were observed in a herd of 104 lactating cows. the symptoms included peracute enterotoxemia in which the cows died 6 to 12 h after the detection of mastitis by cmt. staphylococcus aureus andstreptococcus agalactiae streptococcus agalactiae were also isolated although could not be associated with cases of acute fatal mastitis. milking practices were also evaluated. the milking machine was being used correctly and adequate precautions for hygiene and pre-milking and post-milking teat dipping were used. the organism was sensitive to gentamicin. therapy for acute toxic mastitis required early action for the treatment of infections, involving corticosteroids and fluid therapy. the use of a klebsiella vaccine produced from the microorganisms isolated from the herd, associated with hygiene measures, resulted in the control of the outbreak.
An outbreak of acute bovine mastitis caused by Klebsiella pneumoniae in a dairy herd  [cached]
Silva N.,Costa G.M.
Arquivo Brasileiro de Medicina Veterinária e Zootecnia , 2001,
Abstract: An outbreak of coliform mastitis is described in a dairy herd from the State of Rio de Janeiro, Brazil. During a four-month period 14 fatal cases of Klebsiella pneumoniae-related mastitis were observed in a herd of 104 lactating cows. The symptoms included peracute enterotoxemia in which the cows died 6 to 12 h after the detection of mastitis by CMT. Staphylococcus aureus and Streptococcus agalactiae Streptococcus agalactiae were also isolated although could not be associated with cases of acute fatal mastitis. Milking practices were also evaluated. The milking machine was being used correctly and adequate precautions for hygiene and pre-milking and post-milking teat dipping were used. The organism was sensitive to gentamicin. Therapy for acute toxic mastitis required early action for the treatment of infections, involving corticosteroids and fluid therapy. The use of a Klebsiella vaccine produced from the microorganisms isolated from the herd, associated with hygiene measures, resulted in the control of the outbreak.
Outbreak of botulism in a dairy herd in Turkey
S Senturk, H Cihan
Irish Veterinary Journal , 2007, DOI: 10.1186/2046-0481-60-8-481
Abstract: Botulism is caused by a neurotoxin produced by Clostridium botulinum, a gram-positive, spore-forming anaerobe. Botulinum toxin is an exotoxin produced during the growth and autolysis phase of the organism under anaerobic conditions [12,14]. Eight known botulinum toxins, A, B, Ca, Cb, D, E, F and G, have been identified. Disease in cattle is produced primarily by types C and D. Clostridium botulinum types C and D produce potent toxins in carrion, feed contaminated with dead rodents, birds or reptiles, or any rotting material [12,14,1]. This study is the first confirmation, by direct toxin isolation, of Clostridium botulinum type C and Clostridium botulinum type D in cattle, in Turkey.The study was conducted on a Holstein Friesian breeding farm near the town of Bandirma in Balikesir. The herd consisted of 105 cattle. Clinically, 26 cattle including milking cows were found to be suffering from different degrees of suspected botulism. They ranged in age from four to eight years and had been ill for between two and eight days. A routine clinical examination of the animals, including body temperature, pulse, respiratory rates and ruminal movements, was performed. The neurological examination included an assessment of each affected animal's mental status, gait, pupillary light reflexes, anal reflexes, tongue reflexes, swallowing reflexes, tail tone and sensitivity to pricking with a needle. In the detailed history, the owner reported that the milking cows' feed, in addition to grain, haylage and silage, included ensiled poultry litter. It was reported that dry cows, heifers and calves were unaffected. These animals were fed different rations, without poultry litter. Routine haematological values, including haematocrit, haemoglobin, erythrocyte, total white cell and platelet counts, were determined by a haemocell counter (Cell Dyn 3500; Abbott Inc., USA). The concentrations of serum urea, creatinine, aspartate aminotransferase (AST), creatinine kinase (CK) and, potassium (K
AN OUTBREAK OF FOOT AND MOUTH DISEASE IN A HERD OF CROSSBRED CATTLE  [cached]
Rashid Ahmad, Javaid Iqbal and Ghu1am Akbar1
Pakistan Veterinary Journal , 2002,
Abstract: During the months of December 200 I and January 2002, an outbreak of Foot and Mouth disease (Foot and Mouth Disease type-A virus) was recorded in a crossbred dairy herd at Livestock Experiment Station, Qadirabad. The sick animals showed only the oral lesions except one, which developed foot lesions after 10 days. The overall morbidity rate was 52.13% while the same was recorded as 7.95, 14.06, 97.36, 80.14, 62.68, 62.68, 62.50, and 7.14% in milking cows, dry cows, male young stock, female young stock, male sucklers, female sucklers and bullocks, respectively. Recovery was noticed on seventh day from the onset of out break. No mortality was recorded.
Rotavirus vaccination and herd immunity: an evidence-based review
Seybolt LM, Bégué RE
Pediatric Health, Medicine and Therapeutics , 2012, DOI: http://dx.doi.org/10.2147/PHMT.S25705
Abstract: tavirus vaccination and herd immunity: an evidence-based review Review (1419) Total Article Views Authors: Seybolt LM, Bégué RE Published Date June 2012 Volume 2012:3 Pages 25 - 37 DOI: http://dx.doi.org/10.2147/PHMT.S25705 Received: 11 March 2012 Accepted: 18 April 2012 Published: 28 June 2012 Lorna M Seybolt, Rodolfo E Bégué Department of Pediatrics, Division of Infectious Diseases, Louisiana State University Health Sciences Center, New Orleans, LA, USA Abstract: Until recently, rotavirus was the most common cause of diarrhea in infants and young children with over 100 million cases and 400,000 deaths every year worldwide. Yet, its epidemiology is changing rapidly with the introduction of two rotavirus vaccines in the mid 2000s. Both vaccines were shown to be highly efficacious in prelicensure studies to reduce severe rotavirus disease; the efficacy being more pronounced in high- and middle-income countries than in low-income countries. Herd immunity – the indirect protection of unimmunized individuals as a result of others being immunized – was not expected to be a benefit of rotavirus vaccination programs since the vaccines were thought to reduce severe disease but not to decrease virus transmission significantly. Postlicensure studies, however, have suggested that this assumption may need reassessment. Studies in a variety of settings have shown evidence of greater than expected declines in rotavirus disease. While these studies were not designed specifically to detect herd immunity – and few failed to detect this phenomenon – the consistency of the evidence is compelling. These studies are reviewed and described here. While further work is needed, clarifying the presence of herd immunity is not just an academic exercise but an important issue for rotavirus control, especially in lower income countries where the incidence of the disease is highest and the direct protection of the vaccines is lower.
Rotavirus vaccination and herd immunity: an evidence-based review  [cached]
Seybolt LM,Bégué RE
Pediatric Health, Medicine and Therapeutics , 2012,
Abstract: Lorna M Seybolt, Rodolfo E BéguéDepartment of Pediatrics, Division of Infectious Diseases, Louisiana State University Health Sciences Center, New Orleans, LA, USAAbstract: Until recently, rotavirus was the most common cause of diarrhea in infants and young children with over 100 million cases and 400,000 deaths every year worldwide. Yet, its epidemiology is changing rapidly with the introduction of two rotavirus vaccines in the mid 2000s. Both vaccines were shown to be highly efficacious in prelicensure studies to reduce severe rotavirus disease; the efficacy being more pronounced in high- and middle-income countries than in low-income countries. Herd immunity – the indirect protection of unimmunized individuals as a result of others being immunized – was not expected to be a benefit of rotavirus vaccination programs since the vaccines were thought to reduce severe disease but not to decrease virus transmission significantly. Postlicensure studies, however, have suggested that this assumption may need reassessment. Studies in a variety of settings have shown evidence of greater than expected declines in rotavirus disease. While these studies were not designed specifically to detect herd immunity – and few failed to detect this phenomenon – the consistency of the evidence is compelling. These studies are reviewed and described here. While further work is needed, clarifying the presence of herd immunity is not just an academic exercise but an important issue for rotavirus control, especially in lower income countries where the incidence of the disease is highest and the direct protection of the vaccines is lower.Keywords: rotavirus, vaccine, herd immunity, efficacy
Leptospirosis Seroconversion During an Abortion Outbreak in a Mexican Hairless Swine Herd
M. A. Cisneros-Puebla,D. Mota-Rojas,L. P. Moles-Cervantes,R.Ram?rez-Necoechea,M. Alonso-Spilsbury
Journal of Animal and Veterinary Advances , 2012,
Abstract: A herd of Mexican Hairless Swine, maintained in an agro-silvi-culture pasture in the village of Chapa de Mota, Mexico, underwent a serological study after one of the sows aborted a litter showing fever. Blood samples were drawn from thirty-four animals in reproductive stage, which then underwent a treatment, based on a streptomycin dose of 25 mg/kg live weight during five days. Twenty-eight samples were taken 15 days after the herd either farrowed or aborted. Seroconversion was found in five animals with a serovar of hardjo H 89 origin. One of the animals aborted after seventy-eight days of gestation; in all the cases there was a negative increase of between 1:200 to 1:800 titres, while the serovar bratislava presented titres in six animals. In two cases the seroconversion went from a negative to a 1:200, while one of the pigs miscarried on the 77th day of pregnancy, and two other animals went from a titre 1:100 to 1:200. Another sow lost a litter on day 84, and in the last two animals the titre was maintained at 1:100, though one of the pigs aborted on the 86th day. This paper constitutes the first report of an outbreak of abortions in the Mexican Hairless Swine caused by Leptospira interrogans serovars bratislava and hardjo.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.