Pdm09 Outbreak Research Articles

Risk Factors of an Influenza A(H1N1)pdm09 Outbreak in a Nursing Institute, Noagaon, Bangladesh, 2015

An H1N1 outbreak in the Noagaon Nursing Institute in Bangladesh allowed examination of risk factors for influenza transmission and a return-to-work policy. We conducted a retrospective cohort study of 119 nursing students residing in the nursing institute’s dormitory. The attack rate of influenza was 51% (61/119) and 28% (5/18) of suspected influenza cases tested positive for influenza A(H1N1)pdm09. Eighty percent of the students returned to their training in the hospital and the classroom three days after the first onset of symptoms. Living in overcrowded dormitories (risk ratios (RR) 1.7, 95% confidence interval (CI) 1.2-2.4), contacting with students with influenza-like illness (RR 2.7, 95% CI 1.6-4.6) placed students at greater risk for receiving and for transmitting influenza. To prevent transmission, we recommended isolating students with influenza during the viral shedding period and annual influenza vaccination.

Changing socio-economic and ethnic disparities in influenza/A/H1N1 infection early in the 2009 UK epidemic: a descriptive analysis

BackgroundHigher incidence of and risk of hospitalisation and death from Influenza A(H1N1)pdm09 during the 2009 pandemic was reported in ethnic minority groups in many high-income settings including in the United Kingdom (UK). Many of these studies rely on geographical and temporal aggregation of cases and can be difficult to interpret due to the spatial and temporal factors in outbreak spread. Further, it can be challenging to distinguish between disparities in health outcomes caused by variation in transmission risk or disease severity.MethodsWe used anonymised laboratory confirmed and suspected case data, classified by ethnicity and deprivation status, to evaluate how disparities in risk between socio-economic and ethnic groups vary over the early stages of the 2009 Influenza A(H1N1)pdm09 epidemic in Birmingham and London, two key cities in the emergence of the UK epidemic. We evaluated the relative risk of infection in key ethnic minority groups and by national and city level deprivation rank.ResultsWe calculated higher incidence in more deprived areas and in people of South Asian ethnicity in both Birmingham and London, although the magnitude of these disparities reduced with time. The clearest disparities existed in school-aged children in Birmingham, where the most deprived fifth of the population was 2.8 times more likely to be infected than the most affluent fifth of the population.ConclusionsOur analysis shows that although disparities in reported cases were present in the early phase of the Influenza A(H1N1)pdm09 outbreak in both Birmingham and London, they vary substantially depending on the period over which they are measured. Further, the development of disparities suggest that clustering of social groups play a key part as the outbreak appears to move from one ethnic and socio-demographic group to another. Finally, high incidence and large disparities between children indicate that they may hold an important role in driving inequalities.

Clinical impact of nosocomial infection with pandemic influenza A (H1N1) 2009 in a respiratory ward in Guangzhou.

BackgroundNosocomial outbreaks of pandemic influenza A (H1N1) 2009 virus [A(H1N1)pdm09] easily develop due to its high transmissibility. This study aimed to investigate the clinical impacts of a nosocomial outbreak of A(H1N1)pdm09 between 21 January and 17 February 2016.MethodsPatients who developed influenza-like illness (ILI) more than 48 hours after hospitalization in the index ward were enrolled as suspected patients, defined as group A and quarantined. Patients in other wards were defined as group B. A phylogenetic tree was constructed to determine the origins of the hemagglutinin and neuraminidase genes.ResultsAfter the implementation of an infection control measure bundle, the outbreak was limited to eight patients with ILIs in group A. Nasal swabs from seven patients were positive for A(H1N1)pdm09. All the patients recovered after treatment. Prolonged viral shedding was observed in a patient with bronchiectasis and Penicillium marneffei infection. Compared to the expected duration of hospitalization in patients without fever, those with fever had a median 7-day delay in discharge and a mean excess cost of 3,358 RMB. The four influenza strains identified were genetically identical to the A/California/115/2015 strain. Six of the 54 patients in group B who underwent bronchoscopy developed transient fever. These patients were hospitalized in various wards of the hospital and recovered after a short-term course of empirical antibiotics.ConclusionsAfter the implementation of infection control measures, the nosocomial A(H1N1)pdm09 outbreak was rapidly contained; infected patients had a delay in discharge and excess costs, but no deaths occurred.

Influenza A (H1N1)pdm09 outbreak of unknown source in a Ghanaian senior high school

BackgroundInfluenza is an acute viral respiratory tract infection caused by influenza virus and transmitted from person to person. Though usually seasonal in temperate climates, influenza occurs throughout the year in the tropics with outbreaks occurring at irregular intervals. On February 6, 2018, a number of students from a Senior High School (SHS) in Accra reported to a district hospital with cough, fever and other respiratory symptoms. An influenza-like illness (ILI) outbreak was suspected. We investigated to determine the magnitude and source of the outbreak and implement control and preventive measures.MethodsWe interviewed health workers, staff and students of the school as well as case-patients and reviewed health records to collect data on demographic characteristics, signs and symptoms, date of illness onset and outcome. We defined ILI case as “any person in the SHS with fever (measured axillary temperature of ≥ 37.5 °C or history of fever) and cough with or without sore throat or runny nose from January 21 to February 26, 2018”. We conducted active case search to identify more cases and took oropharyngeal samples for laboratory testing. We performed descriptive and inferential analysis by calculating attack rate ratios (ARR) and their exact 95% confidence intervals (CI).ResultsOf the 3160 students, 104 case-patients were recorded from January 25, 2018 to February 13, 2018 (overall attack rate of 3.3%). Mean age of case-patients was 16.1 (±2.3) years with males constituting 71.2% (74/104). Sex specific attack rates were 5.6% (74/1331) and 1.6% (30/1829) for males and females respectively. Compared to females, males were 3.4 times as likely to be ill [ARR =3.4, 95%CI = (2.23–5.15)]. Nine oropharyngeal samples from 17 suspected case-patients tested positive for influenza A (H1N1)pdm09.ConclusionOutbreak of influenza A (H1N1)pdm09 occurred in a SHS in Accra from January to February, 2018. Even though source of the outbreak could not be determined, prompt case management and health education on hand and personal hygiene as non-pharmacological factors probably contributed to the outbreak control. The outbreak ended with a scheduled mid-term break. This underscores the need for more evidence on the effect of school closure in influenza outbreak control.

Pulmonary surfactant lipids inhibit infections with the pandemic H1N1 influenza virus in several animal models

The influenza A (H1N1)pdm09 outbreak in 2009 exemplified the problems accompanying the emergence of novel influenza A virus (IAV) strains and their unanticipated virulence in populations with no pre-existing immunity. Neuraminidase inhibitors (NAIs) are currently the drugs of choice for intervention against IAV outbreaks, but there are concerns that NAI-resistant viruses can transmit to high-risk populations. These issues highlight the need for new approaches that address the annual influenza burden. In this study, we examined whether palmitoyl-oleoyl-phosphatidylglycerol (POPG) and phosphatidylinositol (PI) effectively antagonize (H1N1)pdm09 infection. POPG and PI markedly suppressed cytopathic effects and attenuated viral gene expression in (H1N1)pdm09-infected Madin-Darby canine kidney cells. POPG and PI bound to (H1N1)pdm09 with high affinity and disrupted viral spread from infected to noninfected cells in tissue culture and also reduced (H1N1)pdm09 propagation by a factor of 102 after viral infection was established in vitro In a mouse infection model of (H1N1)pdm09, POPG and PI significantly reduced lung inflammation and viral burden. Of note, when mice were challenged with a typically lethal dose of 1000 plaque-forming units of (H1N1)pdm09, survival after 10 days was 100% (14 of 14 mice) with the POPG treatment compared with 0% (0 of 14 mice) without this treatment. POPG also significantly reduced inflammatory infiltrates and the viral burden induced by (H1N1)pdm09 infection in a ferret model. These findings indicate that anionic phospholipids potently and efficiently disrupt influenza infections in animal models.

Influenza A(H1N1)pdm09 outbreak detected in inter-seasonal months during the surveillance of influenza-like illness in Pune, India, 2012-2015.

An outbreak of influenza A(H1N1)pdm09 was detected during the ongoing community-based surveillance of influenza-like illness (ILI). Among reported 119 influenza A(H1N1)pdm09 cases (59 cases in the year 2012 and 60 cases in 2015) in summer months, common clinical features were fever (100%), cough (90·7%), sore throat (85·7%), nasal discharge (48·7%), headache (55·5%), fatigue (18·5%), breathlessness (3·4%), and ear discharge (1·7%). Rise in ILI cases were negatively correlated with the seasonal factors such as relative humidity (Karl Pearson's correlation coefficient, i.e. r = -0·71 in the year 2012 and r = -0·44 in the year 2015), while rise in ILI cases were positively correlated with the temperature difference (r = 0·44 in the year 2012 and r = 0·77 in the year 2015). The effective reproduction number R, was estimated to be 1·30 in 2012 and 1·64 in 2015. The study highlights the rise in unusual influenza activity in summer month with high attack rate of ILI among children aged ⩽9 years. Children in this age group may need special attention for influenza vaccination. Influenza A(H1N1)pdm09 outbreak was confirmed in inter-seasonal months during the surveillance of ILI in Pune, India, 2012-2015.

Demographic and laboratory variables and their effect on mortality in influenza A (H1N1)pdm09 outbreak in 2015 in Rajasthan, India

Abstract Introduction Influenza A (H1N1)pdm09 outbreaks cause considerable morbidity and mortality. There is an unmet need to ascertain the prognostic factors. Material and method In 425 confirmed cases of influenza A (H1N1)pdm09 hospitalized during December 2014 to March 2015, demographic data, clinical presentation, comorbidities and laboratory values at the presentation were studied to determine factors associated with mortality. Result Out of 425 cases, 309 survived and 116 expired (27.20%). Of 112 patients (26.35%) who were hospitalized within 3 days of symptom onset, 18 died (16.03%), but of 313 (73.65%) who presented after 3 days, 98 (31.30%) died (p Presence of at least one major organ dysfunction had higher mortality than those who did not (60.55% versus 2.85%, p Conclusion Factors associated with higher mortality were delay in hospitalization and initiation of oseltamivir, male sex, younger age, higher clinical category of disease, presence of leucocytosis or any major organ dysfunction. Higher serum levels of urea, creatinine, AST, ALT, CPK and LDH were strongly associated with mortality.

A study of an influenza A (H1N1)pdm09 outbreak in pregnant women in Rajasthan, India.

To describe the clinical and epidemiological factors of influenza A (H1N1)pdm09-infected patients who were pregnant or in the puerperal period during a recent influenza outbreak in Rajasthan, India. A retrospective, observational study was performed using hospital records of individuals with confirmed influenza A (H1N1)pdm09 infection admitted to a large tertiary care center in Rajasthan, India, between January 1 and March 15, 2015. The study cohort included 44 patients who were pregnant or in the puerperal period. The mean age was significantly lower in the study cohort than in other female patients treated for influenza A (H1N1)pdm09 infection at the hospital during the study period (25.45±3.45years vs 40.46±13.99 years; P<0.001). Mortality was significantly higher in the study cohort than in the comparison female patients (36% vs 17%; P=0.003). Factors found to be associated with mortality were delayed initiation of oseltamivir, poor oxygen saturation at admission, and more than 50% lung involvement under radiographic examination. None of the patients in the study cohort had received a vaccination against seasonal influenza. Influenza A (H1N1)pdm09 infection during pregnancy causes more severe illness. Early recognition and timely administration of antiviral therapy can improve outcomes. The role of influenza vaccination in this high-risk population cannot be overemphasized.

Prevalence and seasonal distribution of respiratory viruses in patients with acute respiratory tract infections, 2002-2014

The aim of this study was to investigate the prevalence and seasonal distribution of respiratory viruses in pediatric and adult outpatients and inpatients who were admitted to hospital with the symptoms of upper and lower respiratory tract infections, during a 12-year period. A total of 5102 clinical samples (4372 nasopharyngeal swabs, 316 bronchoalveolar lavages, 219 transtracheal aspirates, 163 nasopharyngeal aspirates, 20 sputum, 10 nasal swabs) examined in our laboratory between January 1st 2002 and July 17th 2014, were evaluated retrospectively. Of the specimens, 1107 (21.7%) were obtained from outpatients and 3995 (78.3%) from hospitalized patients. Of the patients, 2851 (55.9%) were male and 2251 (44.1%) were female, while 1233 (24.2%) were adults and 3869 (75.8%) were children (age range: 1 day - 93 years; median: 3 years). Respiratory samples were investigated for the presence of respiratory syncytial virus (RSV), influenza virus type A and B (INF-A, INF-B), adenovirus (AdV), parainfluenza viruses (PIV types 1-4), human rhinoviruses (HRV), human coronaviruses (HCoV), human metapneumovirus (HMPV) and human bocavirus (HBoV). All specimens were tested by both direct immunofluorescence antibody (DFA) and shell vial cell culture (SVCC) methods. In DFA assay the samples were initially screened by fluorescent-labeled polyclonal antibodies, and the positive ones were typed by using monoclonal antibodies (Light Diagnostics, Merck Millipore, USA). In SVCC, HEp-2, MDCK, A-549 and Vero cell lines were used for the isolation of viruses. In addition to these methods, real-time multiplex PCR methods (RealAccurate®, Respiratory RT PCR, PathoFinder, Netherlands and Seeplex® RV15 ACE Detection, Seegene, South Korea) were used for the detection of respiratory viruses in samples (n= 2104) obtained from 2007 to 2014. Respiratory viruses were detected in a total of 1705 (33.4%) patients, of them 967 (19%) were male and 738 (14.4%) were female. Three hundred and eighteen (18.6%) of the 1705 patients were infected with multiple respiratory viruses. The most frequently observed co-infections were RSV+INF-A (40/318; 12.6%), and RSV+PIV (33/318; 10.4%). The rate of positivity for the respiratory viruses in pediatric and adult groups were 35.4% (1369/3869) and 27.3% (336/1233), respectively (p< 0.000). The most frequently detected virus in pediatric group was RSV (336/1369; 24.5%), followed by influenza viruses (314/1369; 22.9%), PIV (197/1369; 14.4%), HRV (118/1369; 8.6%), AdV (75/1369; 5.5%) and the others (49/1369; 3.6%). On the other hand the most frequently detected virus in adult group was influenza viruses (181/336; 53.8%) followed by AdV (37/336; 11%), RSV (24/336; 7.1%), PIV (24/336; 7.1%), HRV (23/336; 6.8%) and the others (9/336; 2.7%). The rate of multiple virus infections in pediatric and adult groups were 7.2% (280/3869) and 3% (38/1233), respectively. Most of the coinfections (280/318; 88%) were detected in children. Respiratory viruses were detected positive in 40.2% (445/1107) of outpatients, and in 31.5% (1260/3995) of inpatients (p< 0.000). The most frequent viruses detected in pediatric outpatients and inpatients were HRV and RSV, respectively, while influenza viruses were the first in line among both adult outpatients and inpatients. During the study period, a PIV-3 outbreak (n= 96) have emerged between December 2004-April 2005, and an influenza A (H1N1)pdm09 outbreak (n= 207) between November 2009-January 2010. When the seasonal distribution was considered, the isolation rates of 1705 respiratory viruses in winter, spring, summer and autumn were 44.4%, 27%, 8.3% and 20.3%, respectively. RSV was most frequently detected from December to March, influenza viruses from November to March, HRV from December to June, and mixed infections from January to February. In conclusion, the data of our study obtained in about 12-year period indicated that the prevalence of respiratory viruses in acute respiratory infections is 33.4%, and they typically active during the months of winter and early spring in our region.

Pandemic 2009 H1N1 influenza in two settings in a small community: the workplace and the university campus.

Data are rare on influenza outbreaks spreading through a workplace, but such transmission dynamics would be useful for comparison with the spread of the infection in other settings. We collected and compared infection data from two settings, a workplace and a university campus, during the 2009 pandemic influenza A(H1N1)pdm09 outbreak in a geographically contained community. Trajectories of infection were markedly alike in both settings. This suggests that transmission behaviour was similar in individuals in the two environments, despite the condition that individuals can leave the workplace setting in order to avoid transmission.

Viral Shedding in University Students Infected by Influenza A(H1N1)pdm09, Nakhon Ratchasima Province, Thailand, June 2011

Oseltamivir is often prescribed to treat influenza patients, yet its effect on viral shedding among Thai young adults infected with influenza A(H1N1)pdm09 virus remained unclear. During May to June 2011, an influenza A(H1N1)pdm09 outbreak was detected in University S, Nakhon Ratchasima Province, Thailand. A prospective observational study was conducted to define duration of viral shedding and immunologic response in infected students undergoing oseltamivir treatment, and identify factors associated with viral shedding. We enrolled all acute respiratory illness (ARI) patients attending the medical center at University S during 3-7 Jun 2011 with laboratory confirmation of influenza A(H1N1)pdm09 infection by real-time reverse transcription polymerase chain reaction (rRT-PCR). Additional throat swabs were collected and tested daily until rRT-PCR results became negative through two consecutive days. Series of serum samples for hemagglutination inhibition (HI) test were also collected from the individuals. Log-rank test was applied in analysis of association between patients’ characteristics and duration of viral shedding. Of 29 sick students enrolled, 45% were males. All were prescribed oseltamivir for five days and none of them were hospitalized. Median duration from onset of symptoms to the last day of viral shedding detected was five days (range 3-9 days). Over 80% of the patients had 4-fold rises of HI titer within 2-3 weeks after onset of symptoms. None of the patients’ characteristics were significantly associated with duration of viral shedding. However, persons with delayed antiviral treatment tended to have longer duration of viral shedding. Early oseltamivir treatment probably reduced risks of severe influenza in young adult patients. However, guidelines on infection control need to emphasize on strict hygiene and prevention measures in treated patients for nine days in order to minimize the risks of influenza transmission.

Influenza risk management: lessons learned from an A(H1N1) pdm09 outbreak investigation in an operational military setting.

BackgroundAt the onset of an influenza pandemic, when the severity of a novel strain is still undetermined and there is a threat of introduction into a new environment, e.g., via the deployment of military troops, sensitive screening criteria and conservative isolation practices are generally recommended.ObjectivesIn response to elevated rates of influenza-like illness among U.S. military base camps in Kuwait, U.S. Naval Medical Research Unit No. 3 partnered with local U.S. Army medical units to conduct an A(H1N1) pdm09 outbreak investigation.Patients/MethodsInitial clinical data and nasal specimens were collected via the existent passive surveillance system and active surveillance was conducted using a modified version of the World Health Organization/U.S. Centers for Disease Control and Prevention influenza-like illness case definition [fever (T > 100.5˚F/38˚C) in addition to cough and/or sore throat in the previous 72 hours] as the screening criteria. Samples were tested via real-time reverse-transcription PCR and sequenced for comparison to global A(H1N1) pdm09 viruses from the same time period.ResultsThe screening criteria used in Kuwait proved insensitive, capturing only 16% of A(H1N1) pdm09-positive individuals. While still not ideal, using cough as the sole screening criteria would have increased sensitivity to 73%.ConclusionsThe results of and lessons learned from this outbreak investigation suggest that pandemic influenza risk management should be a dynamic process (as information becomes available regarding true attack rates and associated mortality, screening and isolation criteria should be re-evaluated and revised as appropriate), and that military operational environments present unique challenges to influenza surveillance.

An observational study of infuenza A(H1N1)pdm09 viral shedding and resistance under standard-duration oseltamivir treatment

An observational study was established in South Africa in 2009, early in the influenza A(H1N1)pdm09 outbreak, to provide information on the virological response of the new virus to oseltamivir and the potential for resistance. Patients (n = 54) aged 1-64 years who were treated with standard five-day courses of oseltamivir, starting within two days of onset of the symptoms, showed rapid reductions in viral load or shedding and clinical signs and symptoms. Oseltamivir was well tolerated, with no serious adverse events. Signs of treatment-emergent phenotypic and genotypic resistance were noted in one patient.

The response of medical virology laboratories to the influenza A(H1N1)pdm09 outbreak in Paris Île-de-France region

The outbreak of influenza A(H1N1)pdm09 was a challenge for the laboratories of Paris Île-de-France region in charge of virological diagnosis. In order to evaluate the quality of their response to this challenge, a retrospective survey based on a self-administered standardized questionnaire was undertaken among the 18 hospital laboratories involved in A(H1N1)pdm09 virus detection over a period of 10 months from April 2009 to January 2010. All concerned laboratories responded to the survey. Due to imposed initial biosafety constraints and indications, virological diagnosis was performed in only two laboratories at the start of the studied period. Step by step, it was further settled in the other laboratories starting from June to November 2009. From the beginning, A(H1N1)pdm09-specific RT-PCR was considered the reference method while the use of rapid influenza detection tests remained temporary and concerned a minority of these laboratories. Among the overall 21,656 specimens received, a positive diagnosis of influenza A(H1N1)pdm09 was obtained in 5,390 cases (25%), the positivity range being significantly higher among women as compared to men (P<0.0001) and subjects below 45 years of age as compared to those over 65 years (P<0.0001). Two peaks in positivity frequency were observed at weeks 24 (30%, 8–12 June 2009) and 44 (50%, 26–30 October 2009) respectively, the latter one occurring 2 weeks earlier than the peak of epidemic at the national level. In contrast, a low positivity rate was detected at weeks 38–40 in relationship with other respiratory virus infections which were clinically misinterpreted as a peak of influenza epidemic. These data demonstrate the ability of medical virology laboratories of Paris Île-de-France region to provide in real time a valuable diagnosis of A(H1N1)pdm09 virus infection and a relevant view of outbreak evolution, suggesting they will be a crucial component in the management of future influenza epidemics.

H1N1 outbreak in a Swiss military boot camp - observations and suggestions

The A(H1N1)pdm09 influenza virus is a highly contagious pathogen which caused the 2009 influenza pandemic. The virus is known to affect mainly younger people and may be a problem in crowded living conditions. The aim of the study was to describe a major A(H1N1)pdm09 outbreak in a Swiss military boot camp and to develop suggestions for similar future situations. Retrospective chart analysis of a A(H1N1)pdm09 outbreak between 14 December and 23 December 2010. Symptoms, signs and lab parameters were documented. 105 of 750 male recruits were affected by the outbreak. All nasopharyngeal swabs of 16 patients with high fever were tested positive. Common clinical symptoms included high fever, myalgia and bronchitis with persistent cough and throat aches. Fever progression typically occurred in two peaks within three days. Median length of stay at the infirmary was 3 days (range: 0.5-9 days). A(H1N1)pdm09 has become a ubiquitous seasonal virus in the region. Complications were uncommon and non life threatening. In the event of new influenza outbreaks, hygienic and containment measures must be quickly and correctly implemented, in order to avoid an epidemic. This should also be considered in non-military settings like school camps or in retirement homes.