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D E Stallknecht - One of the best experts on this subject based on the ideXlab platform.
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The effect of age on avian influenza Viral Shedding in mallards (Anas platyrhynchos).
Avian diseases, 2020Co-Authors: T P Costa, J D Brown, E W Howerth, D E StallknechtAbstract:Avian influenza virus (AIV) prevalence in wild aquatic bird populations varies with season, geographic location, host species, and age. It is not clear how age at infection affects the extent of Viral Shedding. To better understand the influence of age at infection on Viral Shedding of wild bird-origin low pathogenicity avian influenza (LPAI) viruses, mallards (Anas platyrhynchos) of increasing age (2 wk, 1 mo, 2 mo, 3 mo, and 4 mo) were experimentally inoculated via choanal cleft with a 10(6) median embryo infectious dose (EID50) of either A/Mallard/MN/355779/00 (H5N2) or A/Mallard/MN/199106/99 (H3N8). Exposed birds in all five age groups were infected by both AIV isolates and excreted virus via the oropharynx and cloaca. The 1-month and older groups consistently shed virus from 1 to 4 d post inoculation (dpi), whereas, Viral Shedding was delayed by 1 d in the 2-wk-old group. Past 4 dpi, Viral Shedding in all groups varied between individual birds, but virus was isolated from some birds in each group up to 21 dpi when the trial was terminated. The 1-mo-old group had the most productive Shedding with a higher number of cloacal swabs that tested positive for virus over the study period and lower cycle threshold values on real-time reverse-transcription PCR. The Viral Shedding pattern observed in this study suggests that, although mallards from different age groups can become infected and shed LPAI viruses, age at time of infection might have an effect on the extent of Viral Shedding and thereby impact transmission of LPAI viruses within the wild bird reservoir system. This information may help us better understand the natural history of these viruses, interpret field and experimental data, and plan future experimental trials.
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Effect of different routes of inoculation on infectivity and Viral Shedding of LPAI viruses in mallards.
Avian Diseases, 2012Co-Authors: Monique França, J D Brown, E W Howerth, Rebecca L. Poulson, Roy D. Berghaus, Deborah L. Carter, D E StallknechtAbstract:SUMMARY. We studied the effect of different routes of inoculation on the infectivity and duration of Viral Shedding in mallards (Anas platyrhynchos) infected with wild bird-origin low pathogenic avian influenza viruses (LPAIVs). One-month-old mallards were inoculated with 106 median embryo infectious doses of either A/mallard/MN/199106/99 (H3N8) or A/mallard/MN/355779/00 (H5N2) via 1 of 5 different routes: intranasal (IN), intratracheal (IT), intraocular (IO), intracloacal (IC), or intra-ingluvial (II). Birds in all routes of inoculation groups became infected with LPAIV as detected by virus isolation, real time reverse transcription polymerase chain reaction, and serology. Mallards in different route of inoculation groups had similar Viral Shedding through oropharynx and cloaca from 1 day postinoculation (dpi). The peak of oropharyngeal (OP) Viral Shedding was reached between 2 and 3 dpi in all routes of inoculation groups infected with either virus. The peak of cloacal (CL) Viral excretion was reached b...
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reassortant influenza a viruses in wild duck populations effects on Viral Shedding and persistence in water
Proceedings of The Royal Society B: Biological Sciences, 2012Co-Authors: Camille Lebarbenchon, Srinand Sreevatsan, Thierry Lefevre, My Yang, Muthannan Andavar Ramakrishnan, Justin C Brown, D E StallknechtAbstract:Wild ducks of the genus Anas represent the natural hosts for a large genetic diversity of influenza Aviruses. In these hosts, co-infections with different virus genotypes are frequent and result in high rates of genetic reassortment. Recentgenomic datahaveprovided information regarding the patternand frequencyof these reassortant viruses in duck populations; however, potential consequences on Viral Shedding and maintenance in the environment have not been investigated. On the basis of full-genome sequencing, we identified five virus genotypes, in awild duck population in northwestern Minnesota (USA), thatnaturally arose from genetic reassortments. We investigated the effects of influenza A virus genotype on the Viral Shedding pattern in Mallards (Anas platyrhynchos) and the duration of infectivity in water, under different temperature regimens. Overall, we found that variation in the Viral genome composition of these isolates had limited effects on duration, extent and pattern of Viral Shedding, as well as on the reduction of infectivity in water over time. These results support that, in wild ducks, functionally equivalent gene segments could be maintained in virus populations with no fitness costs when genetic reassortments occur.
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variation in Viral Shedding patterns between different wild bird species infected experimentally with low pathogenicity avian influenza viruses that originated from wild birds
Avian Pathology, 2011Co-Authors: T P Costa, J D Brown, E W Howerth, D E StallknechtAbstract:The prevalence of infection with avian influenza (AI) virus varies significantly between taxonomic Orders and even between species within the same Order. The current understanding of AI infection and virus Shedding parameters in wild birds is limited and largely based on trials conducted in mallards (Anas platyrhynchos). The objective of the present study was to provide experimental data to examine species-related differences in susceptibility and Viral Shedding associated with wild bird-origin low-pathogenicity avian influenza (LPAI) viruses in multiple duck species and gulls. Thus mallards, redheads (Aythya americana), wood ducks (Aix sponsa), and laughing gulls (Leucophaeus atricilla) were inoculated experimentally with three wild mallard-origin LPAI viruses representing multiple subtypes. Variation in susceptibility and patterns of Viral Shedding associated with LPAI virus infection was evident between the duck and gull species. Consistent with the literature, mallards excreted virus predominantly via...
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the effect of age on avian influenza Viral Shedding in mallards anas platyrhynchos
Avian Diseases, 2010Co-Authors: T P Costa, J D Brown, E W Howerth, D E StallknechtAbstract:Abstract Avian influenza virus (AIV) prevalence in wild aquatic bird populations varies with season, geographic location, host species, and age. It is not clear how age at infection affects the extent of Viral Shedding. To better understand the influence of age at infection on Viral Shedding of wild bird–origin low pathogenicity avian influenza (LPAI) viruses, mallards (Anas platyrhynchos) of increasing age (2 wk, 1 mo, 2 mo, 3 mo, and 4 mo) were experimentally inoculated via choanal cleft with a 106 median embryo infectious dose (EID50) of either A/Mallard/MN/355779/00 (H5N2) or A/Mallard/MN/199106/99 (H3N8). Exposed birds in all five age groups were infected by both AIV isolates and excreted virus via the oropharynx and cloaca. The 1-month and older groups consistently shed virus from 1 to 4 d post inoculation (dpi), whereas, Viral Shedding was delayed by 1 d in the 2-wk-old group. Past 4 dpi, Viral Shedding in all groups varied between individual birds, but virus was isolated from some birds in each gr...
Benjamin J Cowling - One of the best experts on this subject based on the ideXlab platform.
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Association between influenza A Viral Shedding and infectivity in households
2020Co-Authors: Alex R. Cook, J. S. M. Peiris, Gabriel M. Leung, J Fang, Benjamin J CowlingAbstract:Household transmission studies can provide a wealth of information about influenza attack rates, the effectiveness of pharmaceutical and non-pharmaceutical interventions, and Viral loads over time following naturally-acquired infection. Few previous studies have collected detailed data on Viral Shedding, or been able to relate Shedding to infectiousness. We used data from a household transmission study on Viral Shedding in index cases and subsequent infection of household contacts to infer how infectiousness relates to Viral Shedding.
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Viral Shedding and transmission potential of asymptomatic and paucisymptomatic influenza virus infections in the community
Clinical Infectious Diseases, 2016Co-Authors: Dennis K. M. Ip, Vicky J. Fang, Kwok-hung Chan, J. S. M. Peiris, Timothy M Uyeki, G M Leung, Nancy H L Leung, Benjamin J CowlingAbstract:Background Influenza virus infections are associated with a wide spectrum of disease. However, few studies have investigated in detail the epidemiological and virological characteristics of asymptomatic and mild illness with influenza virus infections. Methods In a community-based study in Hong Kong from 2008 to 2014, we followed up initially healthy individuals who were household contacts of symptomatic persons with laboratory-confirmed influenza, to identify secondary infections. Information from daily symptom diaries was used to classify infections as symptomatic (≥2 signs/symptoms, including fever ≥37.8°C, headache, myalgia, cough, sore throat, runny nose and sputum), paucisymptomatic (1 symptom only), or asymptomatic (none of these symptoms). We compared the patterns of influenza Viral Shedding between these groups. Results We identified 235 virologically confirmed secondary cases of influenza virus infection in the household setting, including 31 (13%) paucisymptomatic and 25 (11%) asymptomatic cases. The duration of Viral RNA Shedding was shorter and declined more rapidly in paucisymptomatic and asymptomatic than in symptomatic cases. The mean levels of influenza Viral RNA Shedding in asymptomatic and paucisymptomatic cases were approximately 1-2 log10 copies lower than in symptomatic cases. Conclusions The presence of influenza Viral Shedding in patients with influenza who have very few or no symptoms reflects their potential for transmitting the virus to close contacts. These findings suggest that further research is needed to investigate the contribution of persons with asymptomatic or clinically mild influenza virus infections to influenza virus transmission in household, institutional, and community settings.
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The Dynamic Relationship between Clinical Symptomatology and Viral Shedding in Naturally Acquired Seasonal and Pandemic Influenza Virus Infections
Clinical Infectious Diseases, 2015Co-Authors: Dennis K. M. Ip, Vicky J. Fang, Malik Peiris, Kwok-hung Chan, Gabriel M. Leung, Benjamin J CowlingAbstract:Background. Although the pattern of Viral Shedding over time has been documented in volunteer challenge studies, understanding of the relationship between clinical symptomatology and Viral Shedding in naturally acquired influenza infections in humans remains limited. Methods. In a community-based study in Hong Kong from 2008 to 2014, we followed up initially healthy individuals and identified 224 secondary cases of natural influenza virus infection in the household setting. We examined the dynamic relationship between patterns of clinical symptomatology and Viral Shedding as quantified using reverse transcription polymerase chain reaction and Viral culture in 127 cases with a clinical picture of acute respiratory infection. Results. Viral Shedding in influenza A virus infections peaked on the first 1-2 days of clinical illness, and decreased gradually to undetectable levels by day 6-7, matching closely with the dynamics of clinical illness. Viral Shedding in influenza B virus infections rose up to 2 days prior to symptom onset and persisted for 6-7 days after onset with a bimodal pattern. Conclusions. Our results suggest that while clinical illness profiles may serve as a proxy for clinical infectiousness in influenza Avirus infections, patients may potentially be infectious even before symptom onset or after clinical improvement in influenza B virus infections.
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Viral Shedding, clinical history and transmission of influenza
Hong Kong medical journal = Xianggang yi xue za zhi, 2013Co-Authors: Benjamin J Cowling, Kwok H. Chan, J. S. M. Peiris, Steven Riley, Gabriel M. LeungAbstract:: 1. During influenza infections, most Viral Shedding occurs within a few days of illness onset. 2. Children may be more infectious than adults because they shed more virus. 3. The degree of Viral Shedding (infectiousness) correlates with symptoms and tympanic temperature.
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heterogeneity in Viral Shedding among individuals with medically attended influenza a virus infection
The Journal of Infectious Diseases, 2013Co-Authors: Dennis K. M. Ip, Vicky J. Fang, Kwok-hung Chan, J. S. M. Peiris, Hiroshi Nishiura, G M Leung, Benjamin J CowlingAbstract:Compared with the average transmissibility of human influenza A virus, much less attention has been paid to the potential variability in its transmissibility. We considered Viral Shedding as a proxy for infectiousness and explored the heterogeneity of infectiousness among patients with medically attended seasonal influenza A virus infection. The analysis revealed that Viral Shedding is more heterogeneous in children than in adults. The top 20% most infectious children and adults were estimated to be responsible for 89%–96% and 78%–82%, respectively, of the total infectiousness in each age group. Further investigation is required to correlate the substantial variations in Viral Shedding with heterogeneity in actual transmissibility.
Alessandro C Pasqualotto - One of the best experts on this subject based on the ideXlab platform.
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prolonged respiratory Viral Shedding in transplant patients
Transplant Infectious Disease, 2014Co-Authors: C R A De Lima, T B Mirandolli, Lilian Carla Carneiro, Cintia Tusset, C M Romer, Huander Felipe Andreolla, Ludmila Fiorenzano Baethgen, Alessandro C PasqualottoAbstract:: Respiratory Viral infections are frequent causes of morbidity in transplant patients. We screened symptomatic adult transplant recipients for respiratory viruses in a cohort of patients attending a referral medical center in Brazil. The duration of Viral Shedding and the prevalence of Viral codetections were also determined. During a 1-year period (2011-2012), swabs were obtained from 50 patients. An in-house polymerase chain reaction panel designed to detect 10 viruses was used. Viruses were identified in 19 (38%) patients, particularly parainfluenza III (32%) and the respiratory syncytial virus (20%); multiple viruses were identified in 26% of patients. Prolonged Viral Shedding was observed with 60% of individuals excreting viruses for >10 days. The clinical and epidemiologic relevance of prolonged Viral Shedding remains to be determined.
Tomoyuki Tanaka - One of the best experts on this subject based on the ideXlab platform.
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long term Viral Shedding and Viral genome mutation in norovirus infection
Journal of Medical Virology, 2015Co-Authors: Tatsuya Miyoshi, Kiyoko Uchino, Hisayoshi Yoshida, Kazushi Motomura, Naokazu Takeda, Yoshiharu Matsuura, Tomoyuki TanakaAbstract:The duration of Viral Shedding in the patients from two outbreaks and four sporadic cases of norovirus (NoV) infections was investigated. The longest period of Viral Shedding into feces was for 173 days in an inpatient from one case of outbreak. The VP1 sequence from two long-term Viral Shedding cases in the outbreak revealed four synonymous and one non-synonymous mutations in one inpatient at 26 days from the onset of illness, and nine synonymous and two non-synonymous mutations and a deletion, 10 synonymous mutations and a deletion in other inpatient at 29 days and 54 days from the onset of illness, respectively. Ten of the 11 amino acid positions detected in these two inpatients were in the outermost P2 domain of the Viral capsid protein, and mutations at positions 295, 297, and 394 were shared in the inpatients. Mutations in the P2 domain were in epitopes A and D or near epitopes A, C, and E, suggesting that the long-term carrier state of norovirus infection contributes to the generation of escape mutants by host immunoselection. J. Med. Virol. 87:1872–1880, 2015. © 2015 Wiley Periodicals, Inc.
C R A De Lima - One of the best experts on this subject based on the ideXlab platform.
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prolonged respiratory Viral Shedding in transplant patients
Transplant Infectious Disease, 2014Co-Authors: C R A De Lima, T B Mirandolli, Lilian Carla Carneiro, Cintia Tusset, C M Romer, Huander Felipe Andreolla, Ludmila Fiorenzano Baethgen, Alessandro C PasqualottoAbstract:: Respiratory Viral infections are frequent causes of morbidity in transplant patients. We screened symptomatic adult transplant recipients for respiratory viruses in a cohort of patients attending a referral medical center in Brazil. The duration of Viral Shedding and the prevalence of Viral codetections were also determined. During a 1-year period (2011-2012), swabs were obtained from 50 patients. An in-house polymerase chain reaction panel designed to detect 10 viruses was used. Viruses were identified in 19 (38%) patients, particularly parainfluenza III (32%) and the respiratory syncytial virus (20%); multiple viruses were identified in 26% of patients. Prolonged Viral Shedding was observed with 60% of individuals excreting viruses for >10 days. The clinical and epidemiologic relevance of prolonged Viral Shedding remains to be determined.