Fatal Type 3 Adenoviral Pneumonia in Immunocompetent Adult Identical Twins

Viral Pneumonia: From Influenza to COVID-19

Respiratory viruses are increasingly recognized as a cause of community-acquired pneumonia (CAP). The implementation of new diagnostic technologies has facilitated their identification, especially in vulnerable population such as immunocompromised and elderly patients and those with severe cases of pneumonia. In terms of severity and outcomes, viral pneumonia caused by influenza viruses appears similar to that caused by non-influenza viruses. Although several respiratory viruses may cause CAP, antiviral therapy is available only in cases of CAP caused by influenza virus or respiratory syncytial virus. Currently, evidence-based supportive care is key to managing severe viral pneumonia. We discuss the evidence surrounding epidemiology, diagnosis, management, treatment, and prevention of viral pneumonia.

Severe Infections Due to Respiratory Viruses

Severe viral infections may result in severe illnesses capable of causing acute respiratory failure that could progress rapidly to acute respiratory distress syndrome (ARDS), related to worse outcomes, especially in individuals with a higher risk of infection, including the elderly and those with comorbidities such as asthma, diabetes mellitus and chronic respiratory or cardiovascular disease. In addition, in cases of severe viral pneumonia, co-infection with bacteria such as Streptococcus pneumoniae and Staphylococcus aureus is related to worse outcomes. Respiratory viruses like influenza, rhinovirus, parainfluenza, adenovirus, metapneumovirus, respiratory syncytial virus, and coronavirus have increasingly been detected. This trend has become more prevalent, especially in critically ill patients, due to the availability and implementation of molecular assays in clinical practice. Respiratory viruses have been diagnosed as a frequent cause of severe pneumonia, including cases of community-acquired pneumonia, hospital-acquired pneumonia, and ventilator-associated pneumonia. In this review, we will discuss the epidemiology, diagnosis, clinical characteristics, management, and prognosis of patients with severe infections due to respiratory viruses, with a focus on influenza viruses, non-influenza viruses, and coronaviruses.

Adenovirus: Epidemiology, Global Spread of Novel Types, and Approach to Treatment

Adenoviruses (AdVs) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or meningoencephalitis. AdV infections are more common in young children, due to lack of humoral immunity. Epidemics of AdV infection may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The vast majority of cases are self-limited. However, the clinical spectrum is broad and fatalities may occur. Dissemination is more likely in patients with impaired immunity (e.g., organ transplant recipients, human immunodeficiency virus infection). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 100 genotypes and 52 serotypes of AdV have been identified and classified into seven species designated HAdV-A through -G. Different types display different tissue tropisms that correlate with clinical manifestations of infection. The predominant types circulating at a given time differ among countries or regions, and change over time. Transmission of novel strains between countries or across continents and replacement of dominant viruses by new strains may occur. Treatment of AdV infections is controversial, as prospective, randomized therapeutic trials have not been done. Cidofovir has been the drug of choice for severe AdV infections, but not all patients require treatment. Live oral vaccines are highly efficacious in reducing the risk of respiratory AdV infection and are in routine use in the military in the United States but currently are not available to civilians.

Molecular Characteristics of Human Adenovirus Type 3 Circulating in Parts of China During 2014-2018

Human adenoviruses (HAdVs) are important pathogens causing respiratory infections; 3.5-11% of childhood community-acquired pneumonia is associated with HAdV infection. Human adenovirus type 3 (HAdV-3), leading to severe morbidity and mortality, is one of the most prevalent genotype among adenoviruses responsible for acute respiratory infections (ARIs) in children in China. To identify the genetic variation of HAdV-3 in children with ARIs in China, a molecular epidemiological study was conducted. A total of 54 HAdV-3 isolated strains were obtained from children with ARIs in Beijing, Wenzhou, Shanghai, Shijiazhuang, Hangzhou, Guangzhou, and Changchun from 2014 to 2018. Thirty-two strains of which were selected for whole-genome sequencing, while the hexon, penton base, and fiber genes were sequenced for remaining strains. Bioinformatics analysis was performed on the obtained sequences. The phylogenetic analyses based on whole-genome sequences, major capsid protein genes (hexon, penton base, and fiber), and early genes (E1, E2, E3, and E4) showed that the HAdV-3 strains obtained in this study always clustered together with the reference strains from Chinese mainland, while the HAdV-3 prototype strain formed a cluster independently. Compared with the prototype strain, all strains possessed nine amino acid (AA) substitutions at neutralization antigenic epitopes of hexon. The homology models of the hexon protein of the HAdV-3 prototype and strain BJ20160214 showed that there was no evident structural change at the AA mutation sites. Two AA substitutions were found at the Arg-Gly-Asp (RGD) loop and hypervariable region 1 (HVR1) region of the penton base. A distinct AA insertion (20P) in the highly conserved PPPSY motif of the penton base that had never been reported before was observed. Recombination analysis indicated that partial regions of protein IIIa precursor, penton base, and protein VII precursor genes among all HAdV-3 strains in this study were from HAdV-7. This study showed that the genomes of the HAdV-3 strains in China were highly homologous. Some AA mutations were found at antigenic sites; however, the significance needs further study. Our data demonstrated the molecular characteristics of HAdV-3 circulating in China and was highly beneficial for further epidemiological exploration and the development of vaccines and drugs against HAdV-3.

Update in Viral Infections in the Intensive Care Unit

The advent of highly sensitive molecular diagnostic techniques has improved our ability to detect viral pathogens leading to severe and often fatal infections that require admission to the Intensive Care Unit (ICU). Viral infections in the ICU have pleomorphic clinical presentations including pneumonia, acute respiratory distress syndrome, respiratory failure, central or peripheral nervous system manifestations, and viral-induced shock. Besides de novo infections, certain viruses fall into latency and can be reactivated in both immunosuppressed and immunocompetent critically ill patients. Depending on the viral strain, transmission occurs either directly through contact with infectious materials and large droplets, or indirectly through suspended air particles (airborne transmission of droplet nuclei). Many viruses can efficiently spread within hospital environment leading to in-hospital outbreaks, sometimes with high rates of mortality and morbidity, thus infection control measures are of paramount importance. Despite the advances in detecting viral pathogens, limited progress has been made in antiviral treatments, contributing to unexpectedly high rates of unfavorable outcomes. Herein, we review the most updated data on epidemiology, common clinical features, diagnosis, pathogenesis, treatment and prevention of severe community- and hospital-acquired viral infections in the ICU settings.

Ongoing outbreak of human adenovirus-associated acute respiratory illness in the Republic of Korea military, 2013 to 2018

BACKGROUND/AIMS

Human adenovirus type 55 (HAdV-55), an emerging epidemic strain, has caused several large outbreaks in the Korean military since 2014, and HAdV-associated acute respiratory illness (HAdV-ARI) has been continuously reported thereafter.

METHODS

To evaluate the epidemiologic characteristics of HAdV-ARI in the Korean military, we analyzed respiratory virus polymerase chain reaction (RV-PCR) results, pneumonia surveillance results, and severe HAdV cases from all 14 Korean military hospitals from January 2013 to May 2018 and compared these data with nationwide RV surveillance data for the civilian population.

RESULTS

A total of 14,630 RV-PCRs was performed at military hospitals. HAdV (45.4%) was the most frequently detected RV, followed by human rhinovirus (12.3%) and influenza virus (6.3%). The percentage of the military positive for HAdV was significantly greater than the percentage of civilians positive for HAdV throughout the study period, with a large outbreak occurring during the winter to spring of 2014 to 2015. The outbreak continued until the end of the study, and non-seasonal detections increased over time. The reported number of pneumonia patients also increased during the outbreak. Case fatality rate was 0.075% overall but 15.6% in patients with respiratory failure. The proportion of severe patients did not change significantly during the study period.

CONCLUSION

A large HAdV outbreak is currently ongoing in the Korean military, with a trend away from seasonality, and HAdV-55 is likely the predominant strain. Persistent efforts to control the outbreak, HAdV type-specific surveillance, and vaccine development are required.

Autopsy findings from the first known death from Severe Acute Respiratory Syndrome SARS-CoV-2 in Spain

The new coronavirus SARS-CoV-2, first identified in Wuhan, China in December, 2019, can cause Severe Acute Respiratory Syndrome (SARS) with massive alveolar damage and progressive respiratory failure. We present the relevant autopsy findings of the first patient known to have died from COVID19 pneumonia in Spain, carried out on the 14^th of February, 2020, in our hospital (Hospital Arnau de Vilanova-Lliria, Valencia). Histological examination revealed typical changes of diffuse alveolar damage (DAD) in both the exudative and proliferative phase of acute lung injury. Intra-alveolar multinucleated giant cells, smudge cells and vascular thrombosis were present. The diagnosis was confirmed by reverse real-time PCR assay on a throat swab sample taken during the patient's admission. The positive result was reported fifteen days subsequent to autopsy.

Severe community acquired adenovirus pneumonia in an immunocompetent host successfully treated with IV Cidofovir

Adenovirus is a common cause of acute febrile respiratory infection in children and are generally self-limiting although pneumonia can occur in neonates and adults with compromised immunity. However, severe adenovirus pneumonia in healthy adults has been rarely described. Here, we report a case of severe community-acquired adenovirus pneumonia in a previously healthy patient successfully treated with intravenous Cidofovir.

Successful Use of Cidofovir in an Immunocompetent Child With Severe Adenoviral Sepsis

Adenovirus infection is common in childhood and is generally associated with self-limited disease. Cidofovir, a viral DNA polymerase inhibitor, is used to treat adenovirus infection in select populations but is not often recommended for immunocompetent patients because of limited antiviral activity and nephrotoxicity. Here, we report a case of fulminant adenovirus infection associated with lymphopenia and multiple organ failure requiring extracorporeal membrane oxygenation support in a previously healthy child. After 1 week of supportive therapy, the patient had persistent organ failure and continued to have adenoviremia of >560 000 copies per mL. Weekly doses of cidofovir with concurrent probenecid for renal protection was initiated. Adenovirus blood load declined after the first cidofovir dose, becoming undetectable after 3 doses. The patient was successfully decannulated from extracorporeal membrane oxygenation, extubated, and eventually discharged at his functional baseline without need for ongoing respiratory support. Lymphopenia improved after viremia resolved, and a subsequent immunologic workup revealed no evidence of primary immunodeficiency. The viral isolate was genotyped as adenovirus type 7. This case reveals the successful use of cidofovir for management of severe adenovirus infection in a previously healthy child. To date, there are no universally accepted recommendations for the use of cidofovir in this population. Further study is warranted to determine the potential role of cidofovir in treating severe adenovirus infections in immunocompetent children.

Molecular Epidemiology of Human Adenovirus-Associated Febrile Respiratory Illness in Soldiers, South Korea1

During January 2013–April 2014, we subjected nasopharyngeal specimens collected from patients with acute febrile respiratory illness in a military hospital to PCR testing to detect 12 respiratory viruses and sequence a partial hexon gene for human adenovirus (HAdV) molecular typing. We analyzed the epidemiologic characteristics of HAdV infections and compared clinical characteristics of HAdV types. Among the 305 patients with acute febrile respiratory illness, we detected respiratory viruses in 139 (45.6%) patients; HAdV was the most prevalent virus (69 cases). Of the 40 adenoviruses identified based on type, HAdV-55 (29 cases) was the most prevalent, followed by HAdV-4 (9 cases). HAdV-55 was common in patients with pneumonia (odds ratio 2.17; 95% CI 0.48–9.86) and hospitalized patients (odds ratio 5.21; 95% CI 1.06–25.50). In soldiers with HAdV infection in Korea, HAdV-55 was the most prevalent type and might be associated with severe clinical outcomes.

Adenovirus pneumonia treated with Cidofovir in an immunocompetent high school senior

Most adenovirus infections are self-limiting in immunocompetent individuals. Here, we report a case of adenovirus pneumonia in a 17-year-old immunocompetent male. He was admitted to our emergency room complaining of a febrile sense, cough, and diarrhea for four days. Crackles in the left lung and a high fever (40.7 °C) were revealed. Initial chest X-ray and computed tomography images showed consolidation in the left lung. We immediately started empirical antibiotic treatment, but his clinical symptoms and pneumonic consolidation in radiography had not improved by hospital day three. Because adenovirus was detected in his sputum using RT-PCR, he was administered Cidofovir. After 24 h of Cidofovir treatment, the symptoms and fever subsided, and the consolidation in his X-ray was significantly reduced by hospital day nine. The early administration of Cidofovir could be beneficial for the treatment of adenovirus infection in immunocompetent patients.

Worldwide increased prevalence of human adenovirus type 3 (HAdV-3) respiratory infections is well correlated with heterogeneous hypervariable regions (HVRs) of hexon

Human adenovirus type 3 (HAdV-3) respiratory infections occurs worldwide in both children and adults, leading to severe morbidity and mortality, particularly in the paediatric age group and especially in neonates. During HAdV infection, neutralizing antibodies are formed against the epitopes located in the hyper variable regions (HVRs) of the hexon protein. These neutralizing antibodies provide protection against reinfection by viruses of the same type. Therefore it is reasonable to speculate that variations of HAdV-3 in the HVRs could impair the immunity acquired by previous infection with a different strain with variation in its HVRs. HAdV-3 has recently become the major agent of acute respiratory infection worldwide, being responsible for 15% to 87% of all adenoviral respiratory infections. However, despite the increased prevalence of HAdV-3 as respiratory pathogen, the diversity of hexon proteins in circulating strains remains unexplored. This study was designed to explore the variation in HVRs of hexon among globally distributed strains of HAdV-3 as well as to discover possible relationship among them, thus possibly shedding light on the cause for the increased prevalence of HAdV-3. In this study, for the first time we analysed the hexon proteins of all 248 available strains of HAdV-3 from the NCBI database and compared them with those of the HAdV-3 prototype (GB stain). We found that the HVRs of HAdV-3 strains circulating worldwide were highly heterogeneous and have been mutating continuously since -their original isolation. Based on their immense heterogeneity, the strains can be categorized into 25 hexon variants (3Hv-1 to 3Hv-25), 4 of which (3Hv-1 to 3Hv-4) comprises 80% of the strains. This heterogeneity may explain why HAdV-3 has become the most prevalent HAdVs type worldwide. The heterogeneity of hexon proteins also shows that the development of a vaccine against HAdV-3 might be challenging. The data on hexon variants provided here may be useful for the future epidemiological study of HAdV-3 infection.

Genomic diversity of human adenovirus type 3 isolated in Fukui, Japan over a 24-year period

Recently, human adenovirus type 3 (HAdV-3) has become the most isolated HAdV worldwide. Restriction endonuclease analysis of globally isolated strains of HAdV-3 has uncovered 51 genome types to date. Information on the genome type is important to the epidemiological study of HAdV-3. In this study, analysis of 75 isolates of HAdV- 3 collected over a 24-year period in Fukui revealed: (1) the emergence of three novel genome types (HAdV-3a52, HAdV-3a53 and HAdV-3a54) and two known genome types (HAdV-3a and HAdV-3a54); (2) the spectrum of diseases caused by individual genome types and their major involvement in the paediatric age population; and (3) the co-circulation and replacement of genome types as a usual phenomenon. The rising number of HAdV-3 genome types indicates that the genetic variation of HAdV-3 is more than other HAdVs. Considering the clinical importance of HAdV-3 infection, its genetic diversity underscores the need for its continuous surveillance and genetic characterization.

Simultaneous Streptococcus pneumoniae empyema in fraternal twins

Streptococcus pneumoniae is the most common bacterial cause of community acquired pneumonia. The current trend in Streptococcus pneumoniae infections has been the rise of multi-drug resistance in the last two decades. We present the case of a pair of 16-month old African-American fraternal twins who presented to the emergency room on the same day for symptoms consistent with pneumonia. Upon further examination, the twins showed remarkably similar symptoms, and cultures revealed penicillin-resistant Streptococcus pneumoniae in both twins. The pneumonia affected both twins in the same way, but a tomography scan did not reveal any shared anatomical abnormalities to account for this near-identical progression. In a review of literature and case reports, there are no reported cases of fraternal twins with simultaneous or non-simultaneous pneumococcal pneumonia or effusions. This case suggests that there may be possible anatomical abnormalities in the fraternal twins which were not evident in routine testing that may have led to near-identical illnesses. The pathophysiology of the simultaneous and near identical infections is not clear but may reflect subtle genetic factors in the siblings.

Characteristics of Adenovirus Pneumonia in Korean Military Personnel, 2012-2016

Adenovirus (AdV) can cause severe pneumonia in non-immunocompromised host, but limited data exist on the distinctive characteristics of AdV pneumonia in non-immunocompromised patients. We evaluated distinctive clinico-laboratory and radiological characteristics and outcomes of AdV pneumonia (n = 179), compared with non-AdV pneumonia (n = 188) in Korean military personnel between 2012 and 2016. AdV pneumonia patients had a higher rate of consolidation with ground-glass opacity (101/152) in lobar distribution (89/152) on computed tomography (CT) (P < 0.001). Laboratory findings showed a higher incidence of unusual blood profiles such as leukopenia (55/179, P < 0.001) or thrombocytopenia (100/179, P < 0.001). The patients had more systemic symptoms such as myalgia (82/179, P = 0.001) or diarrhea (23/179, P < 0.001), compared with non-AdV pneumonia patients. Bacterial co-infection was identified in 28.5% of AdV pneumonia. Most of the AdV isolates typed (69/72, 95.8%) were AdV-55. Patients with a pneumonia severity index ≥ class III were more commonly observed in AdV pneumonia patients compared with non-AdV pneumonia patients (11.2% vs. 2.1%, P < 0.001), and time to clinical stabilization from admission was longer in the AdV pneumonia patients compared with the non-AdV pneumonia patients (3.8 vs. 2.6 days, P < 0.001). Mechanical ventilation (n = 6) was only required in AdV pneumonia patients, one of whom died due to AdV-55. Our data showed that AdV pneumonia in non-immunocompromised patients had distinct characteristics and most of the isolates typed in our study were AdV-55. It is suggested that AdV-55 is an important pathogen of pneumonia in Korean military personnel.

Adenovirus: Epidemiology, Global Spread of Novel Serotypes, and Advances in Treatment and Prevention

Adenoviruses (AdVs) are DNA viruses that typically cause mild infections involving the upper or lower respiratory tract, gastrointestinal tract, or conjunctiva. Rare manifestations of AdV infections include hemorrhagic cystitis, hepatitis, hemorrhagic colitis, pancreatitis, nephritis, or meningoencephalitis. AdV infections are more common in young children, due to lack of humoral immunity. Epidemics of AdV infection may occur in healthy children or adults in closed or crowded settings (particularly military recruits). The disease is more severe and dissemination is more likely in patients with impaired immunity (e.g., organ transplant recipients, human immunodeficiency virus infection). Fatality rates for untreated severe AdV pneumonia or disseminated disease may exceed 50%. More than 50 serotypes of AdV have been identified. Different serotypes display different tissue tropisms that correlate with clinical manifestations of infection. The predominant serotypes circulating at a given time differ among countries or regions, and change over time. Transmission of novel strains between countries or across continents and replacement of dominant viruses by new strains may occur. Treatment of AdV infections is controversial, as prospective, randomized therapeutic trials have not been conducted. Cidofovir is the drug of choice for severe AdV infections, but not all patients require treatment. Live oral vaccines are highly efficacious in reducing the risk of respiratory AdV infection and are in routine use in the military in the United States, but currently are not available to civilians.

Clinical characteristics and factors predicting respiratory failure in adenovirus pneumonia

Background and objective

Limited data exist regarding factors predicting respiratory failure (RF) in non‐immunocompromised patients with adenovirus (AdV) pneumonia.

Methods

We described characteristics of AdV pneumonia (n = 91) versus non‐AdV pneumonia (n = 55) and compared clinico‐laboratory and radiological characteristics in patient groups categorized by RF.

Results

All 91 AdV pneumonia patients presented with acute respiratory symptoms and radiological infiltrations and had significantly lower levels of white blood cell counts and platelet counts compared with non‐AdV pneumonia. Of them, 67 patients had mild pneumonia without RF (non‐RF), 14 patients had no RF at admission but progressed to RF during hospitalization (progressed to RF) and 10 patients had RF at admission (initial RF). Initial monocyte percentage and absolute monocyte counts in RF patient groups (progressed to RF and initial RF) were significantly lower than those of non‐RF patients (both P < 0.001), and the differences among progressed to RF and initial RF patients were not significant. Chest computed tomography findings such as dominant pattern or distribution, clinical symptoms, and bacterial or viral co‐infections other than AdV were not discriminable between patients who had RF and those who did not. On univariate analysis, initial monocytopenia, multilobar infiltrations and pleural effusion were associated with RF. However, on multivariable analysis, only initial monocytopenia remained significant (P = 0.004) for predicting RF.

Conclusion

Our data suggest that initial monocytopenia may help to predict RF during the course of AdV pneumonia in non‐immunocompromised patients.

We described the characteristics of adenovirus (AdV) pneumonia in non‐immunocompromised adult patients and evaluated factors predicting the occurrence of respiratory failure (RF). Our data suggest that initial monocytopenia may help to predict RF during an AdV pneumonia in non‐immunocompromised adult patients.

Severe adenovirus community-acquired pneumonia in immunocompetent adults: chest radiographic and CT findings

BACKGROUND

Severe adenovirus pneumonia and its associated imaging features are well-described in immunocompromised patients but are rare and poorly understood in immunocompetent adults. We sought to describe the radiographic and CT findings of severe adenovirus community-acquired pneumonia (CAP) in eight immunocompetent adults.

METHODS

We reviewed systematically chest imaging manifestations of laboratory-confirmed severe adenovirus pneumonia in eight immunocompetent adults from April 2012 to April 2014.

RESULTS

All patients showed abnormal results on initial chest radiograph and CT, with the exception of one normal initial chest radiograph. The abnormalities of the initial chest radiographs were unilateral (n=4) or bilateral (n=3), including consolidation (n=4), dense patchy opacity (n=3), ground glass opacity (GGO) (n=1), and pleural effusion (n=1). The initial CT findings consisted of unilateral (n=5) and bilateral (n=3) abnormalities, including consolidation (n=8), GGO (n=2), pleural effusion (n=3) and small nodules (n=1). Focal consolidation was the predominant finding in six patients whose initial CT scans were examined within one week after illness onset. Follow-up radiologic findings showed rapid development of bilateral consolidation within ten days after illness onset, usually accompanied by adjacent ground-glass opacity and pleural effusion. The parenchymal abnormalities began to absorb around two weeks after illness onset, with no appearances of fibrosis.

CONCLUSIONS

Severe adenovirus CAP in immunocompetent adults mainly appears as focal consolidation followed by rapid progression to bilateral consolidation, usually accompanied by adjacent GGO and pleural effusion, which may resemble bacterial pneumonia. Adenovirus should be considered in severe pneumonia cases with negative cultures and failure to respond to antibiotics.

Outcomes of early administration of cidofovir in non-immunocompromised patients with severe adenovirus pneumonia

The benefits of treatment with antiviral therapy for severe adenovirus (AdV) pneumonia are not well established. We described the clinical characteristics and treatment outcomes of early cidofovir treatment of severe AdV pneumonia in non-immunocompromised patients. We retrospectively reviewed the medical records of all patients diagnosed with severe AdV pneumonia between 2012 and 2014. A total of seven non-immunocompromised patients with severe AdV pneumonia were identified, and all isolates typed (n = 6) were human AdV-B55. All patients had progressive respiratory failure with lobar consolidation with or without patchy ground glass opacity. Three patients required vasopressors and mechanical ventilation. All patients had abnormal laboratory findings including: leukopenia, thrombocytopenia, or elevated liver enzymes. After admission, all patients received antiviral therapy with cidofovir, and the median time from admission to cidofovir administration was 48 h and median the time from onset of symptoms to cidofovir administration was 7.1 days. After cidofovir administration, complete symptomatic improvement occurred after a median of 12 days and radiographic resolution occurred after a median of 21 days. Consequently, all patients completely improved without complications. Our data suggest that early administration of cidofovir in the course of treatment for respiratory failure as a result of AdV pneumonia in non-immunocompromised patients could be a treatment strategy worth considering, especially in cases of HAdV-55 infection.

Disseminated adenovirus infection in cancer patients presenting with focal pulmonary consolidation

We report disseminated adenovirus (ADV) infection in four adult cancer patients presenting with focal pulmonary consolidation. In all cases, ADV was recovered from respiratory specimens and ADV viremia (>1 × 10(5) copies/ml) was determined by a quantitative PCR assay. Despite antiviral therapy, 3 (75%) patients died. ADV should be considered as a possible cause of severe pneumonia in immunosuppressed patients.

Other viral pneumonias: coronavirus, respiratory syncytial virus, adenovirus, hantavirus

Severe viral pneumonia is an increasing problem among adults. The incidence and number of viruses known to cause pneumonia and respiratory failure have also expanded in recent years. This article provides an overview of severe respiratory disease caused by coronavirus, respiratory syncytial virus, adenovirus, and hantavirus. These emerging pathogens are easily overlooked and timely diagnosis requires a high index of suspicion and confirmation by molecular testing. Management of individual cases is mainly supportive and requires institution of appropriate infection control measures. Vaccines and effective therapeutics for these potentially devastating respiratory viruses are urgently required.

Quantitative real-time PCR assay panel for detection and type-specific identification of epidemic respiratory human adenoviruses

Outbreaks of human adenovirus (HAdV) acute respiratory illness (ARI) have been well documented among civilians and unvaccinated military recruits. Among the 7 recognized HAdV species (A to G), species B (particularly serotypes 3, 7, 11, 14, and 21) and E (serotype 4) have more often been associated with epidemic ARI. Rapid detection and type-specific identification of these viruses would enhance outbreak response and help guide prevention and control measures. To this end, we developed type-specific real-time quantitative PCR (qPCR) assays for HAdV types 3, 4, 7, 11, 14, 16, and 21 targeting the HAdV hexon gene. All type-specific qPCR assays reproducibly detected as few as 10 copies/reaction of quantified hexon recombinant plasmids with a linear dynamic range of 8 log units (10(1) to 10(8) copies); in contrast, a generic qPCR assay that detects all HAdV types run concurrently detected between 10 and 100 copies/reaction, depending on the virus type. No nonspecific amplifications were observed with concentrated nucleic acid from 51 HAdV prototype strains or other common respiratory pathogens. All members of a panel of 137 previously typed HAdV field isolates and positive clinical specimens were correctly characterized by the type-specific qPCR assays; two different HAdV types were detected in three of the clinical specimens and confirmed by amplicon sequencing. The qPCR assays permit sensitive, specific, and quantitative detection and identification of seven clinically important respiratory HAdVs and should provide a convenient adjunct to classical typing methods for a rapid response to HAdV outbreaks.

Province-wide adenovirus type 3 outbreak with severe cases in New Brunswick

Adenovirus is a commonly isolated virus in clinical samples. Life-threatening infections, although rare, are described worldwide. An epidemic spread of an adenovirus type 3 strain occurred in the province of New Brunswick during the fall of 2008 to the winter of 2009; it resulted in three severely ill patients, with one fatality. Adenovirus should be considered as a cause of severe community-acquired viral pneumonia, especially when the influenza test is negative.

Adenovirus pneumonia in an immunocompetent adult

Adenovirus pneumonias are reported relatively commonly in pediatric or immunocompromised patients, but the clinical presentation of adenovirus pneumonia in immunocompetent hosts is not well known. We treated an immunocompetent 42-year-old man with mild adenovirus pneumonia following pharyngitis and conjunctivitis. Diagnosis was established on the basis of chest radiologic findings, detection of adenovirus type 7 DNA by PCR assay in material obtained from bronchoalveolar lavage (BAL), and a greater than fourfold rise in adenovirus-specific antibody titers during the course of illness. The patient's self-limiting symptoms improved within 2 weeks, and chest radiologic findings improved within 4 weeks. PCR assay of material obtained by BAL was useful for the rapid diagnosis of adenovirus pneumonia.

Fatal type 7 adenovirus associated with human bocavirus infection in a healthy child

Adenovirus is a common cause of acute upper respiratory tract infection and rarely causes respiratory failure or septic shock in immunocompetent patients. Severe disease is confined to immunocompromised patients. Human bocavirus (HBoV) is known as the fourth most common virus in respiratory samples from healthy subjects. In patients with respiratory complaints, it can be found alone or, more often, in combination with other viruses known to cause respiratory complaints. A well-documented fatal case of HBoV and adenovirus pneumonia with myocarditis in an immunocompetent child is described.

Prolonged mechanical support in children with severe adenoviral infections: a case series and review of the literature

Adenovirus infections occur primarily in infants and children less than 5 years of age, accounting for 2% to 5% of respiratory illnesses in the pediatric population and 4% to 10% of childhood pneumonias. Although the majority of children with adenovirus disease develop mild upper respiratory tract disease, more severe disease may occur with involvement of the lower respiratory tract characterized by pneumonitis and/or small airways disease. The authors present a case series of 3 high-risk children with severe lower respiratory tract adenoviral infections. These cases demonstrate the potential for the development of severe respiratory involvement from adenovirus in infants and children with comorbid conditions and illustrate that there may be a rapid progression of the disease as well as the need, in selected circumstances, for prolonged mechanical support. We review the role of adenovirus in lower respiratory tract infections in infants and children, its potential to result in life-threatening complications in pediatric patients with comorbid conditions, and the potential life-saving role of mechanical ventilation and extracorporeal life support (ECLS) in these children.

Adenovirus infection with serious pulmonary sequelae in Korean children

INTRODUCTION

Varying clinical progress and long-term pulmonary sequelae have been associated with different adenoviral serotypes.

OBJECTIVE

The purpose of this study was to determine the association between serotype and clinical profiles of pediatric adenoviral pneumonia cases that occurred in Korea from 1996-1998.

METHODS

Nasopharyngeal aspirate samples from 44 adenovirus-positive patients presenting with acute severe respiratory disease were sent to reference laboratories for serotyping. Clinical course and chest X-rays were analyzed during the acute phase, and HRCTs were performed during the convalescent phase to identify long-term pulmonary complications.

RESULTS

Ad-7 was associated with the most severe clinical course and resultant long-term pulmonary sequelae, followed by milder clinical course and lower frequency of sequelae in Ad-3 cases, and even milder outcomes in children infected with Ad-5.

CONCLUSIONS

In complicated adenoviral pneumonia, certain serotypes prevail with Ad-7 being the most severe. Continued serotyping with the eventual goal of creating a database for the early diagnosis, treatment and prognostication of adenoviral pneumonia is needed.

Respiratory viral infections in hematopoietic stem cell and solid organ transplant recipients

Respiratory viral infections (RVIs) are common causes of mild illness in immunocompetent children and adults with rare occurrences of significant morbidity or mortality. Complications are more common in the very young, very old, and those with underlying lung diseases. However, RVIs are increasingly recognized as a cause of morbidity and mortality in recipients of hematopoietic stem cell transplants (HSCT) and solid organ transplants (SOTs). Diagnostic techniques for respiratory syncytial virus (RSV), parainfluenza, influenza, and adenovirus have been clinically available for decades, and these infections are known to cause serious disease in transplant recipients. Modern molecular technology has now made it possible to detect other RVIs including human metapneumovirus, coronavirus, and bocavirus, and the role of these viruses in causing serious disease in transplant recipients is still being worked out. This article reviews the current information regarding epidemiology, pathogenesis, clinical presentation, diagnosis, and treatment of these infections, as well as the aspects of clinical significance of RVIs unique to HSCT or SOT.

Severe community-acquired adenovirus pneumonia in an immunocompetent 44-year-old woman: a case report and review of the literature

INTRODUCTION

This case report describes a rare condition: community-acquired adenovirus pneumonia in an immunocompetent adult. The diagnosis was achieved by using a multiplex real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay and highlights the usefulness of these novel molecular diagnostic techniques in patients hospitalized with acute respiratory illness. We also performed a literature search for previously published cases and present a summary of the clinical, laboratory and radiological features of this condition.

CASE PRESENTATION

A 44-year-old immunocompetent Caucasian woman was admitted to our hospital with an acute febrile respiratory illness associated with a rash. Her blood tests were non-specifically abnormal, and tests for bacterial pathogens were negative. Her condition rapidly deteriorated while she was in our hospital and required mechanical ventilation and inotropic support. A multiplex real-time RT-PCR assay performed on respiratory specimens to detect respiratory viruses was negative for influenza but positive for adenovirus DNA. The patient recovered on supportive treatment, and antibiotics were stopped after 5 days.

CONCLUSIONS

Community-acquired adenovirus pneumonia in immunocompetent adult civilians presents as a non-specific acute febrile respiratory illness followed by the abrupt onset of respiratory failure, often requiring mechanical ventilation. Its laboratory and radiological features are typical of viral infections but also are non-specific. Novel multiplex real-time RT-PCR testing for respiratory viruses enabled us to rapidly make the diagnosis in this case. The new technology could be used more widely in patients with acute respiratory illness and has potential utility for rationalization of the use of antibiotics and improving infection control measures.

Pneumonia in military trainees: a comparison study based on adenovirus serotype 14 infection

BACKGROUND

Adenovirus serotype 14 (Ad-14) recently emerged as a respiratory pathogen in the United States, with studies suggesting higher morbidity and mortality. This study was conducted to determine whether Ad-14 is associated with clinical outcomes in otherwise healthy patients with pneumonia.

METHODS

Medical records of military trainees hospitalized with pneumonia during an outbreak of Ad-14 infection were reviewed. Clinical, radiographic, and laboratory parameters were compared on the basis of Ad-14 infection.

RESULTS

Two hundred thirty-four trainees received a diagnosis of pneumonia, and 83(35%) were hospitalized. Sixty-one percent of patients with pneumonia were Ad-14 positive; 43% of patients with Ad-14 pneumonia were hospitalized (83% of female patients and 40% of male patients; P = .04), compared with 40% of patients with Ad-14 negative cases. Ad-14 infection was associated with higher admission temperature (38.3°C [interquartile range, (IQR) 37.7, 39.4] vs 37.3°C [IQR (36.7, 38.5)]; P < .01) and lower white blood cell count (8.3 × 1000 cells/μL [IQR, 5.7, 12.4] vs 13 × 1000 cells/μL [IQR, 7.5, 12.9]; P = .01), neutrophil count (6.7 × 1000 cells/μL [IQR, 2.8, 9.7] vs 9.7 × 1000 cells/μL [IQR, 5.6, 12.1]; P = .02), lymphocyte count (0.9 × 1000 cells/μL [IQR, 0.8, 1.1] vs 1.3 × 1000 cells/μL [IQR, 1, 1.9]; P = .001), and platelet count (210 × 1000 cells/μL [IQR, 145, 285] vs 261 × 1000 cells/μL [IQR, 238, 343]; P < .01). Ad-14 pneumonia was not associated with specific radiographic findings, pneumonia severity score, intensive care unit admission, longer hospitalization, or 30-day mortality.

CONCLUSIONS

During an outbreak of Ad-14 infection, Ad-14 infection was not associated with excess overall morbidity or mortality. Ad-14 infection was associated with specific laboratory and clinical parameters and higher hospitalization rates in female trainees. These data provide new insight to the epidemiology of Ad-14 infection.

Molecular epidemiology and clinical presentation of human adenovirus infections in Kansas City children

BACKGROUND

A significant increase in adenovirus detection among patients at the Children's Mercy Hospital, Kansas City was observed between June 2007 and January 2008.

OBJECTIVE

To molecularly characterize the human adenoviruses and describe their association with clinical illness in children.

STUDY DESIGN

One hundred adenovirus-positive specimens from 79 children were typed by hexon gene sequence typing method. Restriction enzyme analysis (REA) was performed on isolates of HAdV-3, -7 and -14 to identify genomic variants. Medical records were reviewed to understand the clinical illnesses associated with adenovirus serotypes and genome types.

RESULTS

The most prevalent HAdV serotypes were HAdV-3 (37%), HAdV-7 (25%), HAdV-1 (16%), HAdV-2 (8%). HAdV infection was common in children ≤3 years of age (71%) versus children >3 years (29%). Majority of the HAdV-infected children were hospitalized (78%); 22/79 (28%) stayed >3 days and 8/79 (10%) required intensive care unit stay. Hospitalization rates for HAdV-3 (36%) and HAdV-7 (25%) were comparable. REA data indicated that HAdV-3a2 was the predominant HAdV-3 genome type. Two novel genomic variants of HAdV-3 exhibiting unique BglII or BstEII profiles were identified in isolates from patients with bronchiolitis. All HAdV-7 and -14 isolates were identified as corresponding to genome types 7d2 and 14p1, respectively.

CONCLUSIONS

In Kansas City, we noticed an increase in the incidence of HAdV-7 (25%; n=24/98) infections compared to the previous two years (6%; n=6/107). Two new genomic variants of HAdV-3 appear to have emerged in our area and seem to be associated with lower respiratory tract infections in children.

Adenovirus type 3 outbreak in connecticut associated with a novel variant

An adenovirus outbreak occurred in New Haven, Connecticut in 2006-2007. Molecular typing revealed a twofold increase in adenovirus type 3 infections. Restriction enzyme analysis (REA) indicated that the CT outbreak was largely due to a marked increase in the novel Ad3a51 strain. This outbreak represents the first detection of Ad3a51 in the United States. While most infections were mild, children under 3 were at increased risk for severe disease and one patient with underlying disease died.

A community-derived outbreak of adenovirus type 3 in children in Taiwan between 2004 and 2005

An outbreak of respiratory adenovirus infection in children was observed in northern Taiwan between November 2004 and February 2005. Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to determine the serotype(s) of 172 adenovirus isolates in the outbreak period, we found that adenovirus type 3 (Ad3) was the predominant type (87.2%), followed by Ad2 (6.4%), Ad1 (4.1%), Ad7 (1.2%), Ad4 (0.6%), and Ad5 (0.6%). The genotype of Ad3 was analyzed for 15 isolates from the outbreak period by RFLP of the full-length genome. All these isolates belonged to genotype Ad3a2. Compared with the Ad3-infected patients in the baseline period, a significantly higher proportion of Ad3-infected patients in the outbreak period had severe infections (58.0% vs. 40.2%, P = 0.01), which included bronchopneumonia (28.7%), exudative tonsillitis (24.1%), and tonsillitis (16.1%). Moreover, patients with severe infections were significantly younger than those without (4.10 vs. 8.15 years, P < 0.001). In summary, our study demonstrated that Ad3 was the predominant serotype responsible for the respiratory adenovirus outbreak in northern Taiwan during 2004-2005 and was associated with severe infections in the outbreak period.

Severe adenovirus pneumonia in immunocompetent adults: a case report and review of the literature

Adenovirus is a frequent cause of mild self-limiting upper respiratory tract infection, gastroenteritis, and conjunctivitis in infants and young children. Fatal infections (severe pneumonia progressing to respiratory failure, septic shock and/or encephalitis) are rare among immunocompetent adults. We report a case of severe adenovirus pneumonia in a young immunocompetent male who presented with sudden onset respiratory distress that progressed rapidly to respiratory failure and made a successful recovery on supportive measures. Systematic review of the literature identified 14 cases of severe adenovirus pneumonia (defined as respiratory failure requiring ventilatory support at any point during the course of illness) in otherwise healthy immunocompetent adults both in epidemic and community settings. We describe the clinical characteristics, radiological features, and outcome of identified cases.

Outbreak of human adenovirus type 3 infection in a pediatric long-term care facility--Illinois, 2005

BACKGROUND

Human adenovirus type 3 (HAdV-3) causes severe respiratory illness in children, but outbreaks in long-term care facilities have not been frequently reported. We describe an outbreak of HAdV-3 infection in a long-term care facility for children with severe neurologic impairment, where only 3 of 63 residents were ambulatory.

METHODS

A clinical case of HAdV-3 was defined as fever (temperature, > or = 38.0 degrees C) and either a worsening of respiratory symptoms or conjunctivitis in a resident, with illness onset from June through August 2005. We reviewed medical records; conducted surveillance for fever, conjunctivitis, and respiratory symptoms; and collected nasopharyngeal and conjunctival specimens from symptomatic residents. Specimens were cultured in HAdV-permissive cell lines or were analyzed by HAdV-specific polymerase chain reaction assay.

RESULTS

Thirty-five (56%) of 63 residents had illnesses that met the case definition; 17 patients (49%) were admitted to intensive care units, and 2 (6%) died. Patients were hospitalized in the intensive care unit for a total of 233 patient-days. Illness onset dates ranged from 1 June through 24 August 2005. Thirty-two patients (91%) had respiratory infection, and 3 (9%) had conjunctivitis. HAdV was identified by culture or PCR in 20 patients. Nine isolates were characterized as HAdV-3 genome type a2.

CONCLUSIONS

Considering the limited mobility of residents and their reliance on respiratory care, transmission of HAdV-3 infection during this outbreak likely occurred through respiratory care provided by staff. In environments where patients with susceptible underlying conditions reside, HAdV infection should be considered when patients are identified with worsening respiratory disease, and rapid diagnostic tests for HAdV infection should be readily available to help identify and curtail the spread of this pathogen.