Emergence of a novel swine-origin influenza A virus (S-OIV) H1N1 virus in humans

Pandemic (H1N1) 2009 outbreak on pig farm, Argentina

In June-July 2009, an outbreak of pandemic (H1N1) 2009 infection occurred on a pig farm in Argentina. Molecular analysis indicated that the virus was genetically related to the pandemic (H1N1) 2009 influenza virus strain. The outbreak presumably resulted from direct human-to-pig transmission.

Monoclonal antibody kit for identification of the novel 2009 H1N1 influenza A virus

To develop an immunofluorescence assay for identification of the 2009 H1N1 influenza A virus, we generated a number of monoclonal antibodies (MAbs) by using inactivated H1N1 2009 virus (A/California/07/2009) as the immunogen. Two MAbs that target two different epitopes of the 2009 H1N1 hemagglutinin (HA) were selected to make the D(3) Ultra 2009 H1N1 Influenza A ID kit (2009 H1N1 ID kit; Diagnostic Hybrids, Inc., Athens, OH), which is intended for the identification of the 2009 H1N1 virus by indirect immunofluorescence assay (IFA). The kit does not detect any of 14 seasonal H1N1 or H3N2 prototype influenza virus strains and is also not reactive with seven other major respiratory viruses. Clinical respiratory specimens were evaluated using both the 2009 H1N1 ID kit and the CDC human influenza virus real-time reverse transcription-PCR swine flu panel (CDC rRT-PCR) and showed 100% agreement between the two assays. Four of these clinical specimens, however, were positive by the 2009 H1N1 ID kit but were identified as presumptively positive by the CDC rRT-PCR by virtue of showing threshold cycle (C(T)) values only with universal InfA and swInfA primers, not with swH1 primers. Sequence analysis of the HA genes of these four specimens revealed point mutations in both the primer and probe regions. In addition, unlike the CDC rRT-PCR, the 2009 H1N1 ID kit can differentiate the 2009 H1N1 virus from a swine-derived H1 influenza A virus (A/New Jersey/8/76). The 2009 H1N1 ID kit offers clinical laboratories an alternative to RT-PCR for the identification of the 2009 H1N1 influenza A virus.

Recipients of vaccine against the 1976 "swine flu" have enhanced neutralization responses to the 2009 novel H1N1 influenza virus

BACKGROUND. The world is facing a novel H1N1 influenza pandemic. A pandemic scare with a similar influenza virus in 1976 resulted in the vaccination of nearly 45 million persons. We hypothesized that prior receipt of the 1976 "swine flu" vaccine would enhance immune responses to the 2009 novel H1N1 influenza strain. METHODS. A prospective, volunteer sample of employees aged > or = 55 years at a children's cancer hospital in August 2009 was assessed for antibody responses to the 2009 pandemic H1N1 influenza virus and the 2008-2009 seasonal H1N1 influenza virus. RESULTS. Antibody responses by hemagglutination-inhibition assay were high against both the seasonal influenza virus (89.7% had a titer considered seroprotective) and pandemic H1N1 influenza virus (88.8% had a seroprotective titer). These antibodies were effective at neutralizing the seasonal H1N1 influenza virus in 68.1% of participants (titer > or = 40), but only 18.1% had detectable neutralizing titers against the pandemic H1N1 influenza virus. Of 116 participants, 46 (39.7%) received the 1976 "swine flu" vaccine. Receipt of this vaccine significantly enhanced neutralization responses; 8 (17.4%) of 46 vaccine recipients had titers > or = 160, compared with only 3 (4.3%) of 70 who did not receive the vaccine (P = .018 by chi(2) test). CONCLUSIONS. In this cohort, persons aged > or = 55 years had evidence of robust immunity to the 2008-2009 seasonal H1N1 influenza virus. These antibodies were cross-reactive but nonneutralizing against the 2009 pandemic H1N1 influenza strain. Receipt of a vaccine to a related virus significantly enhanced the neutralization capacity of these responses, suggesting homologous vaccination against the 2009 pandemic H1N1 influenza virus would have a similar effect.

Inactivation of influenza A virus H1N1 by disinfection process

BACKGROUND

Because any patient, health care worker, or visitor is capable of transmitting influenza to susceptible persons within hospitals, hospital-acquired influenza has been a clinical concern. Disinfection and cleaning of medical equipment, surgical instruments, and hospital environment are important measures to prevent transmission of influenza virus from hospitals to individuals. This study was conducted to evaluate the efficacy of disinfection processes, which can be easily operated at hospitals, in inactivating influenza A virus H1N1 (H1N1).

METHODS

The effects of 0.1 mol/L NaOH, 70% ethanol, 70% 1-propanol, solvent/detergent (S/D) using 0.3% tri (n-butyl)-phosphate and 1.0% Triton X-100, heat, and ethylene oxide (EO) treatments in inactivating H1N1 were determined. Inactivation of H1N1 was kinetically determined by the treatment of disinfectants to virus solution. Also, a surface test method, which involved drying an amount of virus on a surface and then applying the inactivation methods for 1 minute of contact time, was used to determine the virucidal activity.

RESULTS

H1N1 was completely inactivated to undetectable levels in 1 minute of 70% ethanol, 70% 1-propanol, and solvent/detergent treatments in the surface tests as well as in the suspension tests. H1N1 was completely inactivated in 1 minute of 0.1 mol/L NaOH treatment in the suspension tests and also effectively inactivated in the surface tests with the log reduction factor of 3.7. H1N1 was inactivated to undetectable levels within 5 minutes, 2.5 minutes, and 1 minute of heat treatment at 70, 80, and 90 degrees C, respectively in the suspension tests. Also, H1N1 was completely inactivated by EO treatment in the surface tests.

CONCLUSION

Common disinfectants, heat, and EO tested in this study were effective at inactivating H1N1. These results would be helpful in implementing effective disinfecting measures to prevent hospital-acquired infections.

The 2009 A (H1N1) influenza virus pandemic: A review

In March and early April 2009 a new swine-origin influenza virus (S-OIV), A (H1N1), emerged in Mexico and the USA. The virus quickly spread worldwide through human-to-human transmission. In view of the number of countries and communities which were reporting human cases, the World Health Organization raised the influenza pandemic alert to the highest level (level 6) on June 11, 2009. The propensity of the virus to primarily affect children, young adults and pregnant women, especially those with an underlying lung or cardiac disease condition, and the substantial increase in rate of hospitalizations, prompted the efforts of the pharmaceutical industry, including new manufacturers from China, Thailand, India and South America, to develop pandemic H1N1 influenza vaccines. All currently registered vaccines were tested for safety and immunogenicity in clinical trials on human volunteers. All were found to be safe and to elicit potentially protective antibody responses after the administration of a single dose of vaccine, including split inactivated vaccines with or without adjuvant, whole-virion vaccines and live-attenuated vaccines. The need for an increased surveillance of influenza virus circulation in swine is outlined.

Molecular and phylogenetic analysis of the haemagglutinin gene of pandemic influenza H1N1 2009 viruses associated with severe and fatal infections

The objectives of this research is molecular and phylogenetic analysis of pandemic influenza A(H1N1) 2009 strains that circulated in northern Greece, focusing on severe or fatal infections, identification of sequence variations in relation with the severity of the illness and comparison of circulating viruses with the vaccine strain. A total of 1598 infections were attributed to the novel influenza A(H1N1) virus. Molecular analysis revealed a number of variations at the HA1 sequences of northern Greek circulating strains, some of which were more frequent in viruses that caused severe or fatal infections. Such mutations, the most common being D222G, demand close monitoring to continuously assess associated risks. Phylogenetic analysis confirmed the close match of the majority of circulating strains with A/California/7/09. However it also reveals a trend of 2010 strains to accumulate amino acid variations and form new plylogenetic clades. Constant molecular surveillance is important to monitor the pathogenicity of circulating strains and evaluate the vaccine efficacy.

Recombinant H1N1 virus-like particle vaccine elicits protective immunity in ferrets against the 2009 pandemic H1N1 influenza virus

The pandemic virus of 2009 (2009 H1N1) continues to cause illness worldwide, especially in younger age groups. The widespread H1N1 virus infection further emphasizes the need for vaccine strategies that are effective against emerging pandemic viruses and are not dependent on the limitations of traditional egg-based technology. This report describes a recombinant influenza virus-like particle (VLP) vaccine consisting of hemagglutinin (HA), neuraminidase (NA), and matrix (M1) proteins of influenza A/California/04/2009 (H1N1) virus. Influenza H1N1 VLPs with a diameter of approximately 120nm were released into the culture medium from Sf9 insect cells infected with recombinant baculovirus coexpressing HA, NA, and M1 proteins. Purified recombinant H1N1 VLPs morphologically resembled influenza virions and exhibited biological characteristics of influenza virus, including HA and NA activities. In the ferret challenge model, 2009 influenza H1N1 VLPs elicited high-titer serum hemagglutination inhibition (HI) antibodies specific for the 2009 H1N1 virus and inhibited replication of the influenza virus in the upper and lower respiratory tract tissues following A/Mexico/4482/09 (H1N1) virus challenge. Moreover, a single 15mug dose of H1N1 VLPs resulted in complete virus clearance in the ferret lung. These results provide support for the use of recombinant influenza VLP vaccine as an effective strategy against pandemic H1N1 virus.

H1N1 influenza: initial chest radiographic findings in helping predict patient outcome

PURPOSE

To retrospectively evaluate whether findings on initial chest radiographs of influenza A (H1N1) patients can help predict clinical outcome.

MATERIALS AND METHODS

Institutional review board approval was obtained; informed consent was waived. All adult patients admitted to the emergency department (May to September 2009) with a confirmed diagnosis of H1N1 influenza who underwent frontal chest radiography within 24 hours were included. Radiologic findings were characterized by type and pattern of opacities and zonal distribution. Major adverse outcome measures were mechanical ventilation and death.

RESULTS

Of 179 H1N1 influenza patients, 97 (54%) underwent chest radiography at admission; 39 (40%) of these had abnormal radiologic findings likely related to influenza infection and five (13%) of these 39 had adverse outcomes. Fifty-eight (60%) of 97 patients had normal radiographs; two (3%) of these had adverse outcomes (P = .113). Characteristic imaging findings included the following: ground-glass (69%), consolidation (59%), frequently patchy (41%), and nodular (28%) opacities. Bilateral opacities were common (62%), with involvement of multiple lung zones (72%). Findings in four or more zones and bilateral peripheral distribution occurred with significantly higher frequency in patients with adverse outcomes compared with patients with good outcomes (multizonal opacities: 60% vs 6%, P = .01; bilateral peripheral opacities: 60% vs 15%, P = .049).

CONCLUSION

Extensive involvement of both lungs, evidenced by the presence of multizonal and bilateral peripheral opacities, is associated with adverse prognosis. Initial chest radiography may have significance in helping predict clinical outcome but normal initial radiographs cannot exclude adverse outcome.

A candidate H1N1 pandemic influenza vaccine elicits protective immunity in mice

BACKGROUND

In 2009 a new pandemic disease appeared and spread globally. The recent emergence of the pandemic influenza virus H1N1 first isolated in Mexico and USA raised concerns about vaccine availability. We here report our development of an adenovirus-based influenza H1N1 vaccine tested for immunogenicity and efficacy to confer protection in animal model.

METHODS

We generated two adenovirus(Ad5)-based influenza vaccine candidates encoding the wildtype or a codon-optimized hemagglutinin antigen (HA) from the recently emerged swine influenza isolate A/California/04/2009 (H1N1)pdm. After verification of antigen expression, immunogenicity of the vaccine candidates were tested in a mouse model using dose escalations for subcutaneous immunization. Sera of immunized animals were tested in microneutalization and hemagglutination inhibition assays for the presence of HA-specific antibodies. HA-specific T-cells were measured in IFNgamma Elispot assays. The efficiency of the influenza vaccine candidates were evaluated in a challenge model by measuring viral titer in lung and nasal turbinate 3 days after inoculation of a homologous H1N1 virus.

CONCLUSIONS/SIGNIFICANCE

A single immunization resulted in robust cellular and humoral immune response. Remarkably, the intensity of the immune response was substantially enhanced with codon-optimized antigen, indicating the benefit of manipulating the genetic code of HA antigens in the context of recombinant influenza vaccine design. These results highlight the value of advanced technologies in vaccine development and deployment in response to infections with pandemic potential. Our study emphasizes the potential of an adenoviral-based influenza vaccine platform with the benefits of speed of manufacture and efficacy of a single dose immunization.

Methods for molecular surveillance of influenza

Molecular-based techniques for detecting influenza viruses have become an integral component of human and animal surveillance programs in the last two decades. The recent pandemic of the swine-origin influenza A virus (H1N1) and the continuing circulation of highly pathogenic avian influenza A virus (H5N1) further stress the need for rapid and accurate identification and subtyping of influenza viruses for surveillance, outbreak management, diagnosis and treatment. There has been remarkable progress on the detection and molecular characterization of influenza virus infections in clinical, mammalian, domestic poultry and wild bird samples in recent years. The application of these techniques, including reverse transcriptase-PCR, real-time PCR, microarrays and other nucleic acid sequencing-based amplifications, have greatly enhanced the capability for surveillance and characterization of influenza viruses.

Influenza epidemiology--past, present, and future

In April 2009, Mexican, American, and Canadian authorities announced that a novel influenza virus with pandemic potential had been identified in large segments of the population. Within weeks, it became apparent that the world was dealing with the first influenza pandemic in >40 yrs. Despite the unpredictable nature of influenza severity and spread in the pandemics of the 20th century, understanding the epidemiology of the past pandemics and current influenza pandemic will help prepare physicians, hospitals, and governments to predict and prepare for the subsequent waves and subsequent pandemics. We present a summary of the biology that predisposes influenza to cause sudden pandemics, as well as a summary of the epidemiology of the 20th century pandemics. We also report on the epidemiology, disease severity, and risk factors for severe disease and intensive care admission from the first wave of the current pandemic (April-August 2009). Last, we provide a mathematical model based on transmission dynamics of the H1N1 influenza virus that may provide some guidance in terms of disease incidence and hospital impact.

Tracking the Emergence of Pandemic Influenza A/H1N1/2009 and its Interaction with Seasonal Influenza Viruses in Singapore

Introduction: Since the emergence of the pandemic influenza A/H1N1/2009 virus in April 2009, diagnostic testing in many countries has revealed the rapid displacement and then replacement of circulating seasonal influenza viruses by this novel virus. Materials and Methods: In-house seasonal and pandemic influenza-specific polymerase chain reaction assays were introduced and/or developed at the Molecular Diagnosis Centre (MDC) at the National University Hospital (NUH), Singapore. These assays have been used to test all samples received from in-patients, out-patients, staff and visitors for suspected pandemic influenza A/H1N1/2009 infection. Results: Prior to the arrival of the pandemic A/H1N1/2009 virus in Singapore at the end of May 2009, seasonal influenza A/H3N2 predominated in this population, with very little seasonal influenza A/H1N1 and B viruses detected. Within about 1 month of its arrival in Singapore (mainly during June to July 2009), this pandemic virus rapidly displaced seasonal influenza A/H3N2 to become the predominant strain in the Singaporean population served by MDC/NUH. Conclusions: Real-time molecular techniques have allowed the prompt detection of different influenza subtypes during this current pandemic, which has revealed the displacement/replacement of previously circulating seasonal subtypes with A/H1N1/2009. Although some of this may be explained by immunological cross-reactivity between influenza subtypes, more studies are required. Key words: Diagnostic, H1N1, Polymerase chain reaction

Challenge and polymorphism analysis of the novel A (H1N1) influenza virus to normal animals

The novel influenza A (H1N1) virus that emerged from April 2009 in Mexico has spread rapidly to many countries and initiated a human pandemic. It is important to determine whether the virus has existed in, or will spread to, normal household animals, and whether A (H1N1)-like viruses derived from the animal is able to proliferate in cell lines derived from human. In this current paper, familiar animals, including pigs, chickens, ducks, cats, dogs, rats, mice, and Brandt's voles were challenged with the novel influenza A (H1N1) virus, and genetic variations of the viral genome were analyzed after three passages in the susceptible animals. To further determine the virulence of these animals derived influenza A (H1N1)-like viruses, viral replication dynamic curves were monitored after inoculation in MDCK cells and human A549 cells. Our results indicated that pigs, BALB/c mice, and Brandt's voles, but not chickens, ducks, cats, dogs, and rats, could be infected by the novel influenza A (H1N1) virus. Genome sequence alignment results showed that there was one genetic variation (G408T) in the HA gene of Brandt's vole derived virus and another one (C194A) in the NA gene of BALB/c mice derived virus, and the virulence of these two viruses in MDCK and A549 cells was significantly lower than the virus originally derived from human beings.

New influenza virus (H1N1) related pneumonia with fatal outcome

A H1N1-influenzavírus-fertőzéssel kapcsolatban a legsúlyosabb szövődményként a víruspneumoniát, illetve az ehhez társuló másodlagos fertőzéseket szokás emlegetni. A fatális kimenetelű esetekben a halált progresszív légzési elégtelenség okozza. Egyes, laboratóriumban igazolt H1N1-fertőzött esetekben ugyanakkor nem lehet egyértelműen tüdőgyulladást megállapítani, ilyenkor az amúgy elesett beteg kórlefolyásában a H1N1-fertőzés szerepe is tisztázatlan marad. Ismertetőnkben egy súlyos, veseelégtelenség miatt kezelés alatt álló beteg H1N1-fertőzés asszociált, szervülő pneumoniáját mutatjuk be, mely típusosnak tartható. A vírusfertőzés szövődményeinek igazolása nélkül a járvány epidemológiai és halálozási kimutatásai is torzulhatnak.

Assessment of the removal and inactivation of influenza viruses H5N1 and H1N1 by drinking water treatment

Since 2003, there has been significant concern about the possibility of an outbreak of avian influenza virus subtype H5N1. Moreover, in the last few months, a pandemic of a novel swine-origin influenza A virus, namely A(H1N1), has already caused hundreds of thousands of human cases of illness and thousands of deaths. As those viruses could possibly contaminate water resources through wild birds excreta or through sewage, the aim of our work was to find out whether the treatment processes in use in the drinking water industry are suitable for eradicating them. The effectiveness of physical treatments (coagulation-flocculation-settling, membrane ultrafiltration and ultraviolet) was assessed on H5N1, and that of disinfectants (monochloramine, chlorine dioxide, chlorine, and ozone) was established for both the H5N1 and H1N1 viruses. Natural water samples were spiked with human H5N1/H1N1 viruses. For the coagulation-settling experiments, raw surface water was treated in jar-test pilots with 3 different coagulating agents (aluminum sulfate, ferric chloride, aluminum polychorosulfate). Membrane performance was quantified using a hollow-fiber ultrafiltration system. Ultraviolet irradiation experiments were conducted with a collimated beam that made it possible to assess the effectiveness of various UV doses (25-60 mJ/cm2). In the case of ozone, 0.5 mg/L and 1 mg/L residual concentrations were tested with a contact time of 10 min. Finally, for chlorine, chlorine dioxide and monochloramine treatments, several residual oxidant target levels were tested (from 0.3 to 3 mg/L) with contact times of 5-120 min. The infectivity of the H5N1 and H1N1 viruses in water samples was quantified in cell culture using a microtiter endpoint titration. The impact of coagulation-settling on the H5N1 subtype was quite low and variable. In contrast, ultrafiltration achieved more than a 3-log reduction (and more than a 4-log removal in most cases), and UV treatment was readily effective on its inactivation (more than a 5-log inactivation with a UV dose of 25 mJ/cm2). Of the chemical disinfection treatments, ozone, chlorine and chlorine dioxide were all very effective in inactivating H5N1 and H1N1, whereas monochloramine treatment required higher doses and longer contact times to achieve significant reductions. Our findings suggest that the water treatment strategies that are currently used for surface water treatment are entirely suitable for removing and/or inactivating influenza A viruses. Appropriate preventive actions can be defined for single disinfection treatment plants.

Pneumonia and influenza – specific considerations in care homes

This review provides an update on current evidence surrounding epidemiology, treatment and prevention of lower respiratory tract infection, with special reference to pneumonia and influenza, in care home residents. The care home sector is growing and provides a unique ecological niche for infections, housing frail older people with multiple co-morbidities and frequent contact with healthcare services. There are therefore considerations in the epidemiology and management of these conditions that are specific to care homes. Opportunities for prevention, in the form of vaccination strategies and improving oral hygiene, may reduce the burden of these diseases in the future. Work is needed to research these infections specifically in the care home setting, and this article highlights current gaps in our knowledge.

A novel H1N1 virus causes the first pandemic of the 21st century

A novel H1N1 virus of swine origin (H1N1v ) is currently spreading in humans, giving rise to the first pandemic in 40 years. The disease is of moderate severity but has notable differences from seasonal influenza. In contrast to seasonal influenza, those over 60 years are relatively spared, a likely consequence of the presence of H1N1v cross-neutralizing antibody in this age group. Most patients appear to have mild influenza-like illness and many of the complications leading to hospitalization and mortality occur in those with underlying disease conditions or pregnancy. Studies in animal models suggest that the novel H1N1v pandemic virus causes a more severe illness and appears to have a greater predilection for the alveolar epithelium than seasonal influenza viruses. As there are as yet little data on the pathogenesis and immunology of H1N1v infection in humans, we have reviewed relevant data from past pandemics, from seasonal influenza and avian influenza H5N1 to highlight key issues pertaining to pathogenesis and immunology.

Swine-origin H1N1 influenza A virus and dental practice: a critical review

Since the spring of 2009, there have been a considerable number of infected as well as fatal cases by virologically confirmed swine-origin H1N1 influenza A virus (S-OIV). The virus continues to spread globally. The World Health Organization (WHO) has now raised the level of S-OIV influenza pandemic alert to phase 6 ('the pandemic phase') because of the human-to-human transmission of the virus and the community-level outbreaks worldwide. The WHO also issues its concerns about the global surveillance, the diagnostic capacity for the infection and the pandemic preparedness plan in every country. However, no critical review on S-OIV influenza and dental practice published in the literature exists hitherto. Based on information up to November 2009, the aim of this article was to summarise significant data on this novel virus and a clinical practice guideline for dental professionals.

Protection of mice against lethal challenge with 2009 H1N1 influenza A virus by 1918-like and classical swine H1N1 based vaccines

The recent 2009 pandemic H1N1 virus infection in humans has resulted in nearly 5,000 deaths worldwide. Early epidemiological findings indicated a low level of infection in the older population (>65 years) with the pandemic virus, and a greater susceptibility in people younger than 35 years of age, a phenomenon correlated with the presence of cross-reactive immunity in the older population. It is unclear what virus(es) might be responsible for this apparent cross-protection against the 2009 pandemic H1N1 virus. We describe a mouse lethal challenge model for the 2009 pandemic H1N1 strain, used together with a panel of inactivated H1N1 virus vaccines and hemagglutinin (HA) monoclonal antibodies to dissect the possible humoral antigenic determinants of pre-existing immunity against this virus in the human population. By hemagglutinination inhibition (HI) assays and vaccination/challenge studies, we demonstrate that the 2009 pandemic H1N1 virus is antigenically similar to human H1N1 viruses that circulated from 1918-1943 and to classical swine H1N1 viruses. Antibodies elicited against 1918-like or classical swine H1N1 vaccines completely protect C57B/6 mice from lethal challenge with the influenza A/Netherlands/602/2009 virus isolate. In contrast, contemporary H1N1 vaccines afforded only partial protection. Passive immunization with cross-reactive monoclonal antibodies (mAbs) raised against either 1918 or A/California/04/2009 HA proteins offered full protection from death. Analysis of mAb antibody escape mutants, generated by selection of 2009 H1N1 virus with these mAbs, indicate that antigenic site Sa is one of the conserved cross-protective epitopes. Our findings in mice agree with serological data showing high prevalence of 2009 H1N1 cross-reactive antibodies only in the older population, indicating that prior infection with 1918-like viruses or vaccination against the 1976 swine H1N1 virus in the USA are likely to provide protection against the 2009 pandemic H1N1 virus. This data provides a mechanistic basis for the protection seen in the older population, and emphasizes a rationale for including vaccination of the younger, naïve population. Our results also support the notion that pigs can act as an animal reservoir where influenza virus HAs become antigenically frozen for long periods of time, facilitating the generation of human pandemic viruses.

The first influenza pandemic of the 21st century

The 2009 H1N1 influenza virus (formerly known as swine flu) first appeared in Mexico and the United States in March and April 2009 and has swept the globe with unprecedented speed as a result of airline travel. On June 11, 2009, the World Health Organization raised its pandemic level to the highest level, Phase 6, indicating widespread community transmission on at least two continents. The 2009 H1N1 virus contains a unique combination of gene segments from human, swine and avian influenza A viruses. Children and young adults appear to be the most affected, perhaps reflecting protection in the elderly owing to exposure to H1N1 strains before 1957. Most clinical disease is relatively mild but complications leading to hospitalization, with the need for intensive care, can occur, especially in very young children, during pregnancy, in morbid obesity, and in those with underlying medical conditions such as chronic lung and cardiac diseases, diabetes, and immunosuppression. Bacterial co-infection has played a significant role in fatal cases. The case of fatality has been estimated at around 0.4%. Mathematical modeling suggests that the effect of novel influenza virus can be reduced by immunization, but the question remains: can we produce enough H1N1 vaccine to beat the pandemic?

Pandemic influenza A (H1N1) in Saudi Arabia: description of the first one hundred cases

BACKGROUND AND OBJECTIVES

In April 2009, the World Health Organization (WHO) declared pandemic influenza A (H1N1) "public health emergency of international concern". On June 11, 2009, WHO raised the pandemic alert level to phase 6, indicating a global pandemic. By December 2009, more than 208 countries and territories had reported swine flu cases. The descriptive epidemiology of the first reported 100 cases of this virus in Saudi Arabia are summarized in this report.

METHODS

Data were collected from 1 June to 3 July, 2009 using a predesigned questionnaire. Questionnaires were filled by Field Epidemiology Training Program residents. Data for the first 100 complete cases of confirmed pandemic influenza A (H1N1) were compiled and analyzed.

RESULTS

The age of reported cases was in the range of 1 to 56 years. The highest percentage of cases was in the age group of 20 to 30 years followed by the age group of 1 to 10 years. Females represented 55% of the cases; imported cases represented 47%, 58% of whom had come via the King Khaled Airport. The most common nationalities most were from Saudi Arabia and the Philippines. The main symptoms were fever (56%), cough (54%), and sore throat and the number of cases was seen to peak from the 27 to 29 June.

CONCLUSION

Pandemic influenza A (H1N1) is still a threat to Saudi Arabia. Thus, comprehensive and effective measures for surveillance and prevention of the disease are needed to control its spread.

Influenza immunization with trehalose-stabilized virus-like particle vaccine using microneedles

Morbidity and mortality due to seasonal and pandemic influenza could be reduced by simpler vaccination methods that enable improved vaccination coverage. In this study, solid metal microneedles coated with influenza virus-like particle (VLP) vaccine were inserted into skin for intradermal immunization. Microneedles were applied to the skin by hand and designed for simple administration with little or no training. Inclusion of trehalose in the coating formulation significantly increased vaccine stability during coating by maintaining hemagglutination activity. Mice vaccinated with stabilized microneedles developed strong antibody responses comparable to conventional intramuscular vaccination and were fully protected against subsequent viral challenge. Whereas, coating microneedles with a coating solution lacking trehalose led to only partial protection against lethal viral challenge. Therefore, our results show that microneedles coated with trehalose-stabilized VLP vaccine can be a promising tool for improving influenza vaccination.

Infection and death from influenza A H1N1 virus in Mexico: a retrospective analysis

BACKGROUND

In April, 2009, the first cases of influenza A H1N1 were registered in Mexico and associated with an unexpected number of deaths. We report the timing and spread of H1N1 in cases, and explore protective and risk factors for infection, severe disease, and death.

METHODS

We analysed information gathered by the influenza surveillance system from April 28 to July 31, 2009, for patients with influenza-like illness who attended clinics that were part of the Mexican Institute for Social Security network. We calculated odds ratios (ORs) to compare risks of testing positive for H1N1 in those with influenza-like illness at clinic visits, the risk of admission for laboratory-confirmed cases of H1N1, and of death for inpatients according to demographic characteristics, clinical symptoms, seasonal influenza vaccine status, and elapsed time from symptom onset to admission.

FINDINGS

By July 31, 63 479 cases of influenza-like illness were reported; 6945 (11%) cases of H1N1 were confirmed, 6407 (92%) were outpatients, 475 (7%) were admitted and survived, and 63 (<1%) died. Those aged 10-39 years were most affected (3922 [56%]). Mortality rates showed a J-shaped curve, with greatest risk in those aged 70 years and older (10.3%). Risk of infection was lowered in those who had been vaccinated for seasonal influenza (OR 0.65 [95% CI 0.55-0.77]). Delayed admission (1.19 [1.11-1.28] per day) and presence of chronic diseases (6.1 [2.37-15.99]) were associated with increased risk of dying.

INTERPRETATION

Risk communication and hospital preparedness are key factors to reduce mortality from H1N1 infection. Protective effects of seasonal influenza vaccination for the virus need to be investigated.

FUNDING

None.

[Evaluation of the potential organ and tissue donor within the pandemic of influenza H1N1]

The pandemic strain of H1N1 supposes a challenge to the health care system in general and for Intensive Care Units (ICU) in particular. Therefore, it will undoubtedly have repercussions on the organ and tissue donation process. In a possible scenario of bed shortage in the ICU and difficulties in maintaining the surgical activity at a normal pace, a significant effort must be made to assure the maintenance of normal transplant activity, which should not be considered as an elective surgical procedure. Another problem related with the impact of the pandemic on the organ donation process is the possibility that a donor with influenza virus could transmit the disease to recipients. This work aims to clarify this issue, reviewing existing data on the potential transmission of influenza viruses with transplanted organs or tissue, the recommendations published in other countries and those developed in Spain by an ad hoc work group that is made up by representatives from the National Transplant Organization, the Ministry of Health and Social Policy, Regional Offices of Transplant Coordination, and various scientific societies, including SEMICYUC.

An update on swine-origin influenza virus A/H1N1: a review

Influenza viruses cause annual epidemics and occasional pandemics that have claimed the lives of millions. The emergence of new strains will continue to pose challenges to public health and the scientific communities. The recent flu pandemic caused by a swine-origin influenza virus A/H1N1 (S-OIV) presents an opportunity to examine virulence factors, the spread of the infection and to prepare for major influenza outbreaks in the future. The virus contains a novel constellation of gene segments, the nearest known precursors being viruses found in swine and it probably arose through reassortment of two viruses of swine origin. Specific markers for virulence can be evaluated in the viral genome, PB1-F2 is a molecular marker of pathogenicity but is not present in the new S-OIV. While attention was focused on a threat of an avian influenza H5N1 pandemic emerging from Asia, a novel influenza virus of swine origin emerged in North America, and is now spreading worldwide. However, S-OIV demonstrates that even serotypes already encountered in past human pandemics may constitute new pandemic threats. There are concerns that this virus may mutate or reassort with existing influenza viruses giving rise to more transmissible or more pathogenic viruses. The 1918 Spanish flu pandemic virus was relatively mild in its first wave and acquired more virulence when it returned in the winter. Thus preparedness on a global scale against a potential more virulent strain is highly recommended. Most isolates of the new S-OIVs are susceptible to neuraminidase inhibitors, and currently a vaccine against the pandemic strain is being manufactured and will be available this fall. This review summarizes the current information on the new pandemic swine-origin influenza virus A/H1N1.

Evolutionary trends of A(H1N1) influenza virus hemagglutinin since 1918

The Pandemic (H1N1) 2009 is spreading to numerous countries and causing many human deaths. Although the symptoms in humans are mild at present, fears are that further mutations in the virus could lead to a potentially more dangerous outbreak in subsequent months. As the primary immunity-eliciting antigen, hemagglutinin (HA) is the major agent for host-driven antigenic drift in A(H3N2) virus. However, whether and how the evolution of HA is influenced by existing immunity is poorly understood for A(H1N1). Here, by analyzing hundreds of A(H1N1) HA sequences since 1918, we show the first evidence that host selections are indeed present in A(H1N1) HAs. Among a subgroup of human A(H1N1) HAs between 1918∼2008, we found strong diversifying (positive) selection at HA₁ 156 and 190. We also analyzed the evolutionary trends at HA₁ 190 and 225 that are critical determinants for receptor-binding specificity of A(H1N1) HA. Different A(H1N1) viruses appeared to favor one of these two sites in host-driven antigenic drift: epidemic A(H1N1) HAs favor HA₁ 190 while the 1918 pandemic and swine HAs favor HA₁ 225. Thus, our results highlight the urgency to understand the interplay between antigenic drift and receptor binding in HA evolution, and provide molecular signatures for monitoring future antigenically drifted 2009 pandemic and seasonal A(H1N1) influenza viruses.

Seasonal, avian, and novel H1N1 influenza: prevention and treatment modalities

OBJECTIVE

To review the pathophysiology, pandemics/epidemics, transmissibility, clinical presentation, treatment, prevention/immunization, and resistance associated with seasonal, avian, and swine influenza.

DATA SOURCES

Literature was obtained from MEDLINE (1966-October 2009) and International Pharmaceutical Abstracts (1971-October 2009) using the search terms influenza, seasonal influenza, avian influenza, swine influenza, H1N1, novel H1N1, H3N2, and H5N1.

STUDY SELECTION AND DATA EXTRACTION

Available English-language articles were reviewed, along with information obtained from the Centers for Disease Control and Prevention, the Food and Drug Administration, and the World Health Organization.

DATA SYNTHESIS

The influenza virus has caused disease in birds, swine, and humans for many centuries. Pandemics and epidemics have occurred throughout history and reports of new strains continue to emerge. Two major surface antigenic glycoproteins, hemagglutinin and neuraminidase, have various subtypes, resulting in numerous combinations of these proteins. For example, combinations occur when an influenza strain from a bird "mixes" with a strain from a human. This mixing occurs in a host, often in pigs, resulting in a new strain. This new strain can cause pandemics since people have no immunity to the new strain. An H1N1 subtype pandemic occurred in 1918, causing millions of deaths. Simultaneously, veterinary reports of "influenza" in pigs also emerged. It is postulated that humans infected pigs with this H1N1 virus. H1N1 reappeared in humans in 1976, and more recently in 2009. Other pandemics have occurred with H2N2 and H3N2 strains. In 1997, strain H5N1, which usually causes disease in fowl, was able to infect humans.

CONCLUSIONS

Influenza subtypes continue to change, causing disease in animals and humans. Utilization of immunization and antiviral treatment options are available to prevent, treat, and contain the spread of this infection.

Innate immune responses to influenza A H5N1: friend or foe?

Avian influenza A H5N1 remains unusual in its virulence for humans. Although infection of humans remains inefficient, many of those with H5N1 disease have a rapidly progressing viral pneumonia that leads to acute respiratory distress syndrome and death, but its pathogenesis remains an enigma. Comparison of the virology and pathogenesis of human seasonal influenza viruses (H3N2 and H1N1) and H5N1 in patients, animal models and relevant primary human cell cultures is instructive. Although the direct effects of viral replication and differences in the tropism of the virus for cells in the lower respiratory tract clearly contribute to pathogenesis, we focus here on the possible contribution of the host innate immune response in the pathogenesis of this disease.

Mitigation approaches to combat the flu pandemic

Management of flu pandemic is a perpetual challenge for the medical fraternity since time immemorial. Animal to human transmission has been observed thrice in the last century within an average range of 11-39 years of antigenic recycling. The recent outbreak of influenza A (H1N1, also termed as swine flu), first reported in Mexico on April 26, 2009, occurred in the forty first year since last reported flu pandemic (July 1968). Within less than 50 days, it has assumed pandemic proportions (phase VI) affecting over 76 countries with 163 deaths/35,928 cases (as on 15(th) June 2009). It indicated the re-emergence of genetically reassorted virus having strains endemic to humans, swine and avian (H5N1). The World Health Organisation (WHO) member states have already pulled up their socks and geared up to combat such criticalities. Earlier outbreaks of avian flu (H5N1) in different countries led WHO to develop pandemic preparedness strategies with national/regional plans on pandemic preparedness. Numerous factors related to climatic conditions, socio-economic strata, governance and sharing of information/logistics at all levels have been considered critical indicators in monitoring the dynamics of escalation towards a pandemic situation.The National Disaster Management Authority (NDMA), Government of India, with the active cooperation of UN agencies and other stakeholders/experts has formulated a concept paper on role of nonhealth service providers during pandemics in April 2008 and released national guidelines - management of biological disasters in July 2008. These guidelines enumerate that the success of medical management endeavors like pharmaceutical (anti-viral Oseltamivir and Zanamivir therapies), nonpharmaceutical interventions and vaccination development etc., largely depends on level of resistance offered by mutagenic viral strain and rationale use of pharmaco therapeutic interventions. This article describes the mitigation approach to combat flu pandemic with its effective implementation at national, state and local levels.

Guidelines on management of human infection with the novel virus influenza A (H1N1)--a report from the Hospital das Clínicas of the University of São Paulo

The pandemic novel influenza A (H1N1) infection was considered widespread in Brazil on July, 2009. Since then, 9.249 cases were confirmed in Brazil, most of them concentrated in São Paulo. The Hospital das Clínicas of the University of São Paulo is a reference center for H1N1 cases in São Paulo. The purpose of this review is to analyze the evidence concerning diagnosis, prevention, and treatment of novel influenza A (H1N1) infection. In addition, we propose guidelines for the management of this pandemic emphasizing Hospital das Clínicas "bundles" for the control of the pandemic novel influenza A (H1N1).