Medical treatment of viral pneumonia including SARS in immunocompetent adult

Clinical review: update of avian influenza A infections in humans

Influenza A viruses have a wide host range for infection, from wild waterfowl to poultry to humans. Recently, the cross-species transmission of avian influenza A, particularly subtype H5N1, has highlighted the importance of the non-human subtypes and their incidence in the human population has increased over the past decade. During cross-species transmission, human disease can range from the asymptomatic to mild conjunctivitis to fulminant pneumonia and death. With these cases, however, the risk for genetic change and development of a novel virus increases, heightening the need for public health and hospital measures. This review discusses the epidemiology, host range, human disease, outcome, treatment, and prevention of cross-transmission of avian influenza A into humans.

Amantadine and rimantadine for influenza A in children and the elderly

BACKGROUND

Although amantadine (AMT) and rimantadine (RMT) are used to relieve or treat influenza A symptoms in healthy adults, little is known about the effectiveness and safety of these antivirals in preventing and treating influenza A in children and the elderly.

OBJECTIVES

The aim of this review was to systematically consider evidence on the effectiveness and safety of AMT and RMT in preventing and treating influenza A in children and the elderly.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2007, issue 3); MEDLINE (1966 to July 2007) and EMBASE (1980 to July 2007).

SELECTION CRITERIA

Randomised or quasi-randomised trials comparing AMT and/or RMT in children and the elderly with placebo, control, other antivirals or comparing different doses or schedules of AMT and/or RMT or no intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion and assessed methodological quality. Disagreements were resolved by consensus. In all comparisons except for one, the trials in children and in the elderly were analysed separately. Data were analysed and reported using Cochrane Review Manager 4.2. software.

MAIN RESULTS

In children, RMT was effective in the abatement of fever on day three of treatment. AMT showed a prophylactic effect against influenza A infection. AMT and RMT were not related to an increase in the occurrence of adverse effects. RMT also was considered to be well tolerated by the elderly, but showed no prophylactic effect. Different doses were comparable in the prophylaxis of influenza in the elderly, as well as in reporting adverse effects. Zanamivir prevented influenza A more effectively than RMT in the elderly.

AUTHORS' CONCLUSIONS

AMT was effective in the prophylaxis of influenza A in children. As confounding matters might have affected our findings, caution should be taken when considering which patients should to be given this prophylactic. Our conclusions about effectiveness of both antivirals for the treatment of influenza A in children were limited to a proven benefit of RMT in the abatement of fever on day three of treatment. Due to the small number of available studies we could not reach a definitive conclusion on the safety of AMT or the effectiveness of RMT in preventing influenza in children and the elderly.

Severe acute respiratory syndrome coronavirus as an agent of emerging and reemerging infection

Before the emergence of severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) in 2003, only 12 other animal or human coronaviruses were known. The discovery of this virus was soon followed by the discovery of the civet and bat SARS-CoV and the human coronaviruses NL63 and HKU1. Surveillance of coronaviruses in many animal species has increased the number on the list of coronaviruses to at least 36. The explosive nature of the first SARS epidemic, the high mortality, its transient reemergence a year later, and economic disruptions led to a rush on research of the epidemiological, clinical, pathological, immunological, virological, and other basic scientific aspects of the virus and the disease. This research resulted in over 4,000 publications, only some of the most representative works of which could be reviewed in this article. The marked increase in the understanding of the virus and the disease within such a short time has allowed the development of diagnostic tests, animal models, antivirals, vaccines, and epidemiological and infection control measures, which could prove to be useful in randomized control trials if SARS should return. The findings that horseshoe bats are the natural reservoir for SARS-CoV-like virus and that civets are the amplification host highlight the importance of wildlife and biosecurity in farms and wet markets, which can serve as the source and amplification centers for emerging infections.

[Emerging viral infectious diseases and pregnancy]

Diverses infections émergentes sont rapportées depuis la mise en place d'une surveillance épidémiologique accrue. Ces infections peuvent compromettre le bon déroulement d'une grossesse, en mettant en jeu le pronostic vital maternel ou le développement de l'enfant lors d'une transmission verticale. À travers une revue récente de la littérature, nous rapportons les conséquences de ces virus émergents les plus cités (H5N1, Coronavirus du SRAS, Chikungunya, virus du Nil occidental) et discutons la prise en charge périnatale.

Update on Avian Influenza for Critical Care Physicians

Human influenza pandemics over the last 100 years have been caused by H1, H2, and H3 subtypes of influenza A viruses. More recently, avian influenza viruses have been found to directly infect humans from their avian hosts. The recent emergence, host expansion, and spread of a highly pathogenic avian influenza (HPAI) H5N1 subtype in Asia has heightened concerns globally, both in regards to mortality of HPAI H5N1 in humans and the potential of a new pandemic. In response, many agencies and organizations have been working collaboratively to develop early detection systems, preparedness plans, and objectives for further research. As a result, there has been a large influx of published information regarding potential risk, surveillance, prevention and control of highly pathogenic avian influenza, particularly in regards to animal to human and subsequent human to human transmission. This chapter will review the current human infections with avian influenza and its public health and medical implications.

Update on Avian Influenza for Critical Care Physicians

Human influenza pandemics over the last 100 years have been caused by H1, H2, and H3 subtypes of influenza A viruses. More recently, avian influenza viruses have been found to directly infect humans from their avian hosts. The recent emergence, host expansion, and spread of a highly pathogenic avian influenza (HPAI) H5N1 subtype in Asia has heightened concerns globally, both in regards to mortality of HPAI H5N1 in humans and the potential of a new pandemic. In response, many agencies and organizations have been working collaboratively to develop early detection systems, preparedness plans, and objectives for further research. As a result, there has been a large influx of published information regarding potential risk, surveillance, prevention and control of highly pathogenic avian influenza, particularly in regards to animal to human and subsequent human to human transmission. This chapter will review the current human infections with avian influenza and its public health and medical implications.

Treatment of severe acute respiratory syndrome with glucosteroids: the Guangzhou experience

STUDY OBJECTIVE

To investigate the efficacy and safety profiles of corticosteroid therapy in severe acute respiratory syndrome (SARS) patients.

DESIGN

Four hundred one of 1,278 SARS cases treated in Guangzhou China between December 2002 and June 2003 fulfilled the diagnostic criteria issued by the World Health Organization for confirmed identification of SARS. Among them, the diagnosis of critical SARS was defined by criteria of SARS guidelines incorporated with a low oxygenation index (OI) [< 300 mm Hg]. Data of these patients retrieved from a database were retrospectively analyzed by logistic regression and Cox regression for the effect of corticosteroid therapy on death, hospitalization days, and complication presentation.

RESULTS

Among the 401 SARS patients studied, 147 of 249 noncritical patients (59.0%) received corticosteroids (mean daily dose, 105.3 +/- 86.1 mg) [+/- SD], and all survived the disease; 121 of 152 critical patients (79.6%) received corticosteroids at a mean daily dose of 133.5 +/- 102.3 mg, and 25 died. Analysis of these 401 confirmed cases did not show any benefits of corticosteroid on the death rate and hospitalization days. However, when focused on 152 critical SARS cases, factors correlated with these end points indicated by univariate analysis included use of corticosteroid, age, rigor at onset, secondary respiratory infections, pulmonary rales, grading of OI, and use of invasive ventilation. After adjustment for possible confounders, treatment with corticosteroid was shown contributing to lower overall mortality, instant mortality, and shorter hospitalization stay (p < 0.05). Incidence of complications was significantly associated with the need for invasive ventilation but not with use of corticosteroids.

CONCLUSION

This Guangzhou retrospective study revealed that proper use of corticosteroid in confirmed critical SARS resulted in lowered mortality and shorter hospitalization stay, and was not associated with significant secondary lower respiratory infection and other complications.

Enhancement of the infectivity of SARS-CoV in BALB/c mice by IMP dehydrogenase inhibitors, including ribavirin

Because of the conflicting data concerning the SARS-CoV inhibitory efficacy of ribavirin, an inosine monophosphate (IMP) dehydrogenase inhibitor, studies were done to evaluate the efficacy of ribavirin and other IMP dehydrogenase inhibitors (5-ethynyl-1-beta-D-ribofuranosylimidazole-4-carboxamide (EICAR), mizoribine, and mycophenolic acid) in preventing viral replication in the lungs of BALB/c mice, a replication model for severe acute respiratory syndrome (SARS) infections (Subbarao, K., McAuliffe, J., Vogel, L., Fahle, G., Fischer, S., Tatti, K., Packard, M., Shieh, W.J., Zaki, S., Murphy, B., 2004. Prior infection and passive transfer of neutralizing antibody prevent replication of severe acute respiratory syndrome coronavirus (SARS-CoV) in the respiratory tract of mice. J. Virol. 78, 3572-3577). Ribavirin given at 75 mg/kg 4 h prior to virus exposure and then given twice daily for 3 days beginning at day 0 was found to increase virus lung titers and extend the length of time that virus could be detected in the lungs of mice. Other IMP dehydrogenase inhibitors administered near maximum tolerated doses using the same dosing regimen as for ribavirin were found to slightly enhance virus replication in the lungs. In addition, ribavirin treatment seemed also to promote the production of pro-inflammatory cytokines 4 days after cessation of treatment, although after 3 days of treatment ribavirin inhibited pro-inflammatory cytokine production in infected mice, significantly reducing the levels of the cytokines IL-1alpha, interleukin-5 (IL-5), monocyte chemotactic protein-1 (MCP-1), and granulocyte-macrophage colony stimulating factor (GM-CSF). These findings suggest that ribavirin may actually contribute to the pathogenesis of SARS-CoV by prolonging and/or enhancing viral replication in the lungs. By not inhibiting viral replication in the lungs of infected mice, ribavirin treatment may have provided a continual source of stimulation for the inflammatory response thought to contribute to the pathogenesis of the infection. Our data do not support the use of ribavirin or other IMP dehydrogenase inhibitors for treating SARS infections in humans.

Associated inflammatory response in pneumonia: role of adjunctive therapy with glucocorticoids

PURPOSE OF REVIEW

This article reviews the potential use of glucocorticoids as adjunctive therapy in the management of patients with severe bacterial pneumonia or pulmonary infections of other etiologies.

RECENT FINDINGS

The importance of an adequate assessment of the inflammatory process and the appearance of inflammatory markers that correlate with the severity of pneumonia is underlined. A recent randomized clinical trial indicates that adjunctive treatment of severe community-acquired pneumonia with glucocorticoids reduces complications and improves survival. The role of glucocorticoids in other lung infections is also reviewed. The design of new compounds with similar anti-inflammatory properties to classical glucocorticoids but with significantly fewer side effects constitutes a specific challenge for the near future.

SUMMARY

Although adjunctive treatment with glucocorticoids in severe pneumonia is probably indicated, further randomized clinical trials are urgently needed to confirm the preliminary positive results. In this regard, a proper evaluation of the inflammatory response is likely to be essential for the accurate selection of the target population.

An inhibitory effect of A20 on NF-kappaB activation in airway epithelium upon influenza virus infection

Influenza is a major disease in humans. The reemergence of avian influenza A viruses has indicated that hyperinflammatory responses are closely related to the severity of disease. Influenza virus infection induces nuclear transcription factor kappaB (NF-kappaB) activation. NF-kappaB and NF-kappaB-dependent gene products promote lung inflammation and injury. Therefore, it is important to investigate the means to attenuate NF-kappaB activation. A20 is a cytoplasmic zinc finger protein that inhibits NF-kappaB activity, However, little is known about the role of A20 in influenza virus infection. Here, we have examined the role of A20 in influenza virus infection-induced NF-kappaB promoter activation in human bronchial epithelial cells. The results showed that (1) A20 protein and mRNA are inducible and expressed in the lung from mice and human bronchial epithelial cells upon influenza virus infection; (2) NF-kappaB promoter activation was induced in bronchial epithelial cells upon influenza virus infection; and (3) overexpression by transient transfection of A20 attenuated NF-kappaB promoter activation in bronchial epithelial cells. These results indicate that A20 may function as a negative regulator of NF-kappaB-mediated lung inflammation and injury upon influenza virus infection, thereby protecting the host against inflammatory response to influenza virus infection.

Early intervention can improve clinical outcome of acute interstitial pneumonia

Study objectives:

To report on our experience with acute interstitial pneumonia (AIP) in which patients underwent early diagnostic procedures and received mechanical ventilation with a “lung-protective” strategy and early institution of immunosuppressive therapy.

Design:

A retrospective chart review.

Setting:

A tertiary referral hospital.

Participants:

Ten patients with AIP who presented with idiopathic ARDS and showed diffuse alveolar damage on surgical lung biopsy specimens from July 1995 to March 2004.

Measurements and results:

The median age of patients was 65.5 years (age range, 38 to 73 years). Patients presented with a median duration of severe dyspnea of 9.5 days (range, 2 to 34 days) at the hospital visit. All patients required mechanical ventilation beginning at median time of hospital day 1 (range, hospital day 0 to 5), which continued for a median duration of 9.5 days (range, 4 to 98 days). Patients received ventilation in the pressure assist-control mode with a median tidal volume of 6.97 mL/kg (range, 6.05 to 8.86 mL/kg) and median positive end-expiratory pressure of 11 cm H₂O (range, 8 to 16 cm H₂O). An aggressive diagnostic workup for respiratory infection, including BAL at a median time of hospital day 2 (range, hospital day 1 to 5) was performed. High-dose steroid pulse therapy was initiated on median hospital day 3.5 (range, hospital day 1 to 8), while surgical lung biopsy was performed on median hospital day 4 (range, hospital day 2 to 7). Eight patients (80%) survived to hospital discharge.

Conclusion:

Earlier intervention, such as an aggressive diagnostic approach, mechanical ventilation with lung-protective strategy, and the early institution of immunosuppressive may improve clinical outcome in patients with AIP.

Avian influenza

The current epidemic of H5N1 highly pathogenic avian influenza in Southeast Asia raises serious concerns that genetic reassortment will result in the next influenza pandemic. There have been 164 confirmed cases of human infection with avian influenza since 1996. In 2004 alone, there were 45 cases of human H5N1 in Vietnam and Thailand, with a mortality rate over 70%. In addition to the potential public health hazard, the current zoonotic epidemic has caused severe economic losses. Efforts must be concentrated on early detection of bird outbreaks with aggressive culling, quarantines, and disinfection. To prepare for and prevent increased human cases, it is essential to improve detection methods and stockpile effective antivirals. Novel therapeutic modalities, including short, interfering RNAs and new vaccine strategies that use plasmid-based genetic systems offer promise, should a pandemic occur.

Avian influenza virus infections in humans

Seroepidemiologic and virologic studies since 1889 suggested that human influenza pandemics were caused by H1, H2, and H3 subtypes of influenza A viruses. If not for the 1997 avian A/H5N1 outbreak in Hong Kong of China, subtype H2 is the likely candidate for the next pandemic. However, unlike previous poultry outbreaks of highly pathogenic avian influenza due to H5 that were controlled by depopulation with or without vaccination, the presently circulating A/H5N1 genotype Z virus has since been spreading from Southern China to other parts of the world. Migratory birds and, less likely, bird trafficking are believed to be globalizing the avian influenza A/H5N1 epidemic in poultry. More than 200 human cases of avian influenza virus infection due to A/H5, A/H7, and A/H9 subtypes mainly as a result of poultry-to-human transmission have been reported with a > 50% case fatality rate for A/H5N1 infections. A mutant or reassortant virus capable of efficient human-to-human transmission could trigger another influenza pandemic. The recent isolation of this virus in extrapulmonary sites of human diseases suggests that the high fatality of this infection may be more than just the result of a cytokine storm triggered by the pulmonary disease. The emergence of resistance to adamantanes (amantadine and rimantadine) and recently oseltamivir while H5N1 vaccines are still at the developmental stage of phase I clinical trial are causes for grave concern. Moreover, the to-be pandemic strain may have little cross immunogenicity to the presently tested vaccine strain. The relative importance and usefulness of airborne, droplet, or contact precautions in infection control are still uncertain. Laboratory-acquired avian influenza H7N7 has been reported, and the laboratory strains of human influenza H2N2 could also be the cause of another pandemic. The control of this impending disaster requires more research in addition to national and international preparedness at various levels. The epidemiology, virology, clinical features, laboratory diagnosis, management, and hospital infection control measures are reviewed from a clinical perspective.

Expanding the frontiers of existing antiviral drugs: possible effects of HIV-1 protease inhibitors against SARS and avian influenza

When unexpected diseases such as the severe acute respiratory syndrome (SARS) and avian influenza become a serious threat to public health, an immediate response is imperative. This should take into consideration existing licensed antiviral drugs against other viral diseases already known to be safe for use in humans. In this report, evidence is presented that HIV-1 protease inhibitors (PIs) currently used in anti-HIV-1 therapies might exert some effects on SARS and perhaps, on avian influenza. Evidence for the potential benefits of PIs against the SARS coronavirus (SARS-CoV) is provided by empirical clinical studies, in vivo viral inhibition assays and computational simulations of the docking of these compounds to the active site of the main SARS-CoV protease. As suggested by in silico docking of these molecules to a theoretical model of a subunit of type A influenza virus RNA-dependent RNA polymerase, there also exists a remote possibility that these PIs may have an effect on avian influenza viruses. Although this evidence is still far from being definitive, the results so far obtained suggest that PIs should be seriously taken into consideration for further testing as potential therapeutic agents for SARS and avian influenza.

Pneumonia in pregnancy

OBJECTIVE

Historically, pneumonia during pregnancy has been associated with increased morbidity and mortality compared with nonpregnant women. The goal of this article is to review current literature describing pneumonia in pregnancy. This review will identify maternal risk factors, potential complications, and prenatal outcomes associated with pneumonia and describe the contemporary management of the varied causes of pneumonia in pregnancy.

RESULTS

Coexisting maternal disease, including asthma and anemia, increase the risk of contracting pneumonia in pregnancy. Neonatal effects of pneumonia in pregnancy include low birth weight and increased risk of preterm birth, and serious maternal complications include respiratory failure. Community-acquired pneumonia is the most common form of pneumonia in pregnancy, with Streptococcus pneumoniae, Haemophilus influenzae, and Mycoplasma pneumoniae accounting for most identified bacterial organisms. Beta-lactam and macrolide antibiotics are considered safe in pregnancy and are effective for most community-acquired pneumonia in pregnancy. Viral respiratory infections, including varicella, influenza, and severe acute respiratory syndrome, can be associated with maternal pneumonia. Current antiviral and respiratory therapies can reduce maternal morbidity and mortality from viral pneumonia. Influenza vaccination can reduce the prevalence of respiratory hospitalizations among pregnant women during influenza season. Pneumocystis pneumonia continues to carry significant maternal risk to an immunocompromised population. Prevention and treatment of Pneumocystis pneumonia with trimethoprim/sulfamethoxazole is effective in reducing this risk.

CONCLUSIONS

Prompt diagnosis and treatment with contemporary antimicrobial therapy and intensive care unit management of respiratory compromise has reduced the maternal morbidity and mortality due to pneumonia in pregnancy. Prevention with vaccination in at-risk populations may reduce the prevalence and severity of pneumonia in pregnant women.

Comparative host gene transcription by microarray analysis early after infection of the Huh7 cell line by severe acute respiratory syndrome coronavirus and human coronavirus 229E

The pathogenesis of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) at the cellular level is unclear. No human cell line was previously known to be susceptible to both SARS-CoV and other human coronaviruses. Huh7 cells were found to be susceptible to both SARS-CoV, associated with SARS, and human coronavirus 229E (HCoV-229E), usually associated with the common cold. Highly lytic and productive rates of infections within 48 h of inoculation were reproducible with both viruses. The early transcriptional profiles of host cell response to both types of infection at 2 and 4 h postinoculation were determined by using the Affymetrix HG-U133A microarray (about 22,000 genes). Much more perturbation of cellular gene transcription was observed after infection by SARS-CoV than after infection by HCoV-229E. Besides the upregulation of genes associated with apoptosis, which was exactly opposite to the previously reported effect of SARS-CoV in a colonic carcinoma cell line, genes related to inflammation, stress response, and procoagulation were also upregulated. These findings were confirmed by semiquantitative reverse transcription-PCR, reverse transcription-quantitative PCR for mRNA of genes, and immunoassays for some encoded proteins. These transcriptomal changes are compatible with the histological changes of pulmonary vasculitis and microvascular thrombosis in addition to the diffuse alveolar damage involving the pneumocytes.

Avian Influenza

The current epidemic of H5N1 highly pathogenic avian influenza in Southeast Asia raises serious concerns that genetic reassortment will result in the next influenza pandemic. There have been 164 confirmed cases of human infection with avian influenza since 1996. In 2004, there were 45 cases of human H5N1 in Vietnam and Thailand, with a mortality rate more than 70%. In addition to the potential public health hazard, the current zoonotic epidemic has caused severe economic losses. Efforts must be concentrated on early detection of bird outbreaks with aggressive culling, quarantining, and disinfection. To prepare for and prevent an increase in human cases, it is essential to improve detection methods and stockpile effective antivirals. Novel therapeutic modalities, including short-interfering RNAs and new vaccine strategies that use plasmid-based genetic systems, offer promise should a pandemic occur.