Human adenovirus type 7 outbreak in Police Training Center, Malaysia, 2011

Wastewater and clinical surveillance of respiratory viral pathogens on a university campus

Areas of dense population congregation are prone to experience respiratory virus outbreaks. We monitored wastewater and clinic patients for the presence of respiratory viruses on a large, public university campus. Campus sewer systems were monitored in 16 locations for the presence of viruses using next generation sequencing over 22 weeks in 2023. During this period, we detected a surge in human adenovirus (HAdV) levels in wastewater. Hence, we initiated clinical surveillance at an on-campus clinic from patients presenting with acute respiratory infection. From whole genome sequencing of 123 throat and/or nasal swabs collected, we identified an outbreak of HAdV, specifically of HAdV-E4 and HAdV-B7 genotypes overlapping in time. The temporal dynamics and proportions of HAdV genotypes found in wastewater were corroborated in clinical infections. We tracked specific single nucleotide polymorphisms (SNPs) found in clinical virus sequences and showed that they arose in wastewater signals concordant with the time of clinical presentation, linking community transmission of HAdV to the outbreak. This study demonstrates how wastewater-based epidemiology can be integrated with surveillance at ambulatory healthcare settings to monitor areas prone to respiratory virus outbreaks and provide public health guidance.

Human adenovirus outbreak at a university campus monitored by wastewater and clinical surveillance

Areas of dense population congregation are prone to experience respiratory virus outbreaks. We monitored wastewater and clinic patients for the presence of respiratory viruses on a large, public university campus. Campus sewer systems were monitored in 16 locations for the presence of viruses using next generation sequencing over 22 weeks in 2023. During this period, we detected a surge in human adenovirus (HAdV) levels in wastewater. Hence, we initiated clinical surveillance at an on-campus clinic from patients presenting with acute respiratory infection. From whole genome sequencing of 123 throat and/or nasal swabs collected, we identified an outbreak of HAdV, specifically of HAdV-E4 and HAdV-B7 genotypes overlapping in time. The temporal dynamics and proportions of HAdV genotypes found in wastewater were corroborated in clinical infections. We tracked specific single nucleotide polymorphisms (SNPs) found in clinical virus sequences and showed that they arose in wastewater signals concordant with the time of clinical presentation, linking community transmission of HAdV to the outbreak. This study demonstrates how wastewater-based epidemiology can be integrated with surveillance at ambulatory healthcare settings to monitor areas prone to respiratory virus outbreaks and provide public health guidance.

Comparisons of lymphocytes profiles and inflammatory cytokines levels in blood of patients with differed severity of infection by human adenovirus type 7

BACKGROUND

Human adenovirus (HAdV) infection outbreak causes community-acquired pneumonia. Cellular immune dysfunction and hypercytokinemia play important roles in the pathogenesis of adenovirus respiratory infection. Some soluble factors in peripheral blood can assist in judging the virus-induced disease severity. The expression levels of inflammatory cytokines differ among patients with different disease severity. However, whether and how HAdV-7 infection influences the composition of blood immune cells and serum cytokine levels in patients at different disease stages, as well as the diagnosis values of these parameters, have rarely been intensively studied. We aimed to investigate lymphocytes profiles and cytokines levels in blood of patients at different disease stages upon human adenovirus type 7 (HAdV-7) infections, and explored the diagnosis values of the investigated parameters.

METHODS

Patients from two outbreaks of HAdV-7 in military of China were categorized into upper respiratory infection (URI) group, common pneumonia (CP) group and severe pneumonia (SP) group according to disease severity. Peripheral blood samples were subjected to routine laboratory tests, while flow cytometry and ELISA were used to measure the lymphocyte subsets and cytokines in blood, respectively. The receiver operating characteristic (ROC) curves were performed to examine the diagnostic of these blood parameters.

RESULTS

Signs of imbalanced lymphocytes composition and hypercytokinemia were observed in HAdV-7-infected patients. The percentages of CD3⁺ T cells and NK cells were significantly decreased along with the aggravation of the disease, particularly for NK cells and CD4⁺ T cells. The neutrophil to lymphocyte ratio (NLR) increased significantly in patients with more severe disease. In addition, the levels of serum CXCL10, IL-2 and TNF-α were positively correlated with disease severity, while reduced levels of IFN-γ and IL-10 were found in SP patients. Furthermore, analysis of ROC showed that multiple parameters including the percentage of blood CD3⁺ cells and serum CXCL10 level could predict the progression of HAdV-7 infection.

CONCLUSION

Imbalance of immune state with hypercytokinemia occurred during HAdV-7 infection. The percentages of blood immune cells such as CD3⁺ T cells and the levels of serum cytokines such as CXCL10 showed potential diagnosis values in HAdV-7 infection.

A seroepidemiological survey of adenovirus type 7 circulation among healthy adults in China and in Sierra Leone, West Africa

Adenovirus type 7 (HAdV7) is one of the most pathogenic human adenoviruses (HAdVs) and can cause severe illness and even death, particularly in people with weakened immune systems. Many countries worldwide have experienced epidemics of this highly contagious pathogen, including China and Sierra Leone; however, studies describing the seroprevalence of anti-HAdV7 neutralizing antibodies (nAbs) are still lacking. Herein, we established an efficient neutralization assay based on a recombinant luciferase-expressing HAdV7 virus (HAd7-Luc) to monitor historical HAdV7 infections and predict outbreak distributions. Among the 2,350 serum samples collected from eight sites in China and Sierra Leone in this cross-sectional serological survey, the overall proportion of anti-HAdV7-seropositive individuals was nearly 60%, with higher seroprevalence rates in Sierra Leone than in China. Regionally, HAdV7 nAb titers were higher in China than in Sierra Leone and showed a geographic variation across different regions. Regardless of the location, the seropositive rate of HAdV7 nAb was lower than that of HAdV5 nAb, as was the nAb titer. The prevalence rates of antibodies against HAdV7 and HAdV5 were both related to age but not to sex. In addition, serologic cross-reactions were rarely observed among people infected with HAdV7 and HAdV5. These results indicate a humoral immune response acquired through endemic HAdV7 infection and enrich the understanding of not only the epidemiological prevention and control of HAdV7 but also the clinical application of HAdV7-based vaccines or gene therapy tools.

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.

Adenoviral Infections in Singapore: Should New Antiviral Therapies and Vaccines Be Adopted?

Background

A number of serious human adenovirus (HAdV) outbreaks have been recently reported: HAdV-B7 (Israel, Singapore, and USA), HAdV-B7d (USA and China), HAdV-D8, -D54, and -C2 (Japan), HAdV-B14p1 (USA, Europe, and China), and HAdV-B55 (China, Singapore, and France).

Methods

To understand the epidemiology of HAdV infections in Singapore, we studied 533 HAdV-positive clinical samples collected from 396 pediatric and 137 adult patients in Singapore from 2012 to 2018. Genome sequencing and phylogenetic analyses were performed to identify HAdV genotypes, clonal clusters, and recombinant or novel HAdVs.

Results

The most prevalent genotypes identified were HAdV-B3 (35.6%), HAdV-B7 (15.4%), and HAdV-E4 (15.2%). We detected 4 new HAdV-C strains and detected incursions with HAdV-B7 (odds ratio [OR], 14.6; 95% confidence interval [CI], 4.1–52.0) and HAdV-E4 (OR, 13.6; 95% CI, 3.9–46.7) among pediatric patients over time. In addition, immunocompromised patients (adjusted OR [aOR], 11.4; 95% CI, 3.8–34.8) and patients infected with HAdV-C2 (aOR, 8.5; 95% CI, 1.5–48.0), HAdV-B7 (aOR, 3.7; 95% CI, 1.2–10.9), or HAdV-E4 (aOR, 3.2; 95% CI, 1.1–8.9) were at increased risk for severe disease.

Conclusions

Singapore would benefit from more frequent studies of clinical HAdV genotypes to identify patients at risk for severe disease and help guide the use of new antiviral therapies, such as brincidofovir, and potential administration of HAdV 4 and 7 vaccine.

Epidemiological analysis of an outbreak of an adenovirus type 7 infection in a boot camp in China

BACKGROUND

An outbreak of respiratory disease associated with adenovirus type 7 occurred in a boot camp in China and was characterized by many cases, severe symptoms, and intrapulmonary infection in many patients.

METHODS

We implemented a series of comprehensive preventive and control measures. We analyzed the incubation period and generation time by using the maximum likelihood method, assessed the symptom period and hospitalization duration using the Kaplan-Meier method, and estimated the basic reproductive number and dormitory transmission rate by using established methods.

RESULTS

The epidemic lasted for 30 days, and 375 individuals were affected. Overall, 109 patients were hospitalized, and 266 individuals were isolated and treated. The median incubation period was 5.2 days (95% confidence interval [CI]: 5.0 to 5.4 days). The median generation time was 7.3 days (95% CI: 7.1 to 7.6 days). The median symptom period was 6 days (95% CI: 6 to 7 days). The median hospitalization duration was 9 days (95% CI: 9 to 11 days). The basic reproductive number was 5.1 (95% CI: 4.6 to 5.6), and the dormitory transmission rate was 0.15 (95% CI: 0.12 to 0.18).

CONCLUSION

Patients in the early stage of the epidemic were treated as having a regular cold and were not isolated; therefore, the virus continued to be transmitted to other susceptible individuals.

Genetic variability of human adenovirus type 7 circulating in mainland China

Human adenovirus (HAdV-7) is a highly contagious pathogen that causes severe respiratory illnesses. However, the epidemic patterns and genetic variability of HAdV-7 circulating in mainland China have not been well elucidated. In this study, we used Chinese HAdV sentinel surveillance data obtained from 2012-2015 to investigate the clinical features of 122 HAdV-7-positive cases and performed amplification and sequence determination of three capsid genes (penton base, hexon, and fiber) from 69 isolated viruses covering from seven provinces of China. Additionally, we compared with data from representative sequences of 21 strains covering seven more provinces in China and 32 international HAdV-7 strains obtained from GenBank database to determine the phylogenetic, sequence variations, and molecular evolution of HAdV-7. The results indicated that HAdV-7 infection occurred throughout the year, and a high proportion of severe cases (27 cases, 22.1%) exhibited infantile pneumonia. Moreover, phylogenetic analysis showed that all HAdV-7 strains could be divided into two major evolutionary branches, including subtype 1 and subtype 2, and subtype 3 was also formed according to analysis of the penton base gene. Subtypes 1 and 2 co-circulated in China before 2008, and HAdV-7 strains currently circulating in China belonged to subtype 2, which was also the predominant strain circulating worldwide in recent years. Further sequence variation analysis indicated that three genes of HAdV-7 were relatively stable across time and geographic space, particularly for viruses within subtypes, which shared almost the same variation sites. Owing to continuous outbreaks caused by HAdV-7, resulting in increased illness severity and fatality rates in China, the establishment of a national HAdV surveillance system is urgently needed for the development of effective preventive and infection-control interventions for adenovirus respiratory infections in China.

An artificially simulated outbreak of a respiratory infectious disease

Background

Outbreaks of respiratory infectious diseases often occur in crowded places. To understand the pattern of spread of an outbreak of a respiratory infectious disease and provide a theoretical basis for targeted implementation of scientific prevention and control, we attempted to establish a stochastic model to simulate an outbreak of a respiratory infectious disease at a military camp. This model fits the general pattern of disease transmission and further enriches theories on the transmission dynamics of infectious diseases.

Methods

We established an enclosed system of 500 people exposed to adenovirus type 7 (ADV 7) in a military camp. During the infection period, the patients transmitted the virus randomly to susceptible people. The spread of the epidemic under militarized management mode was simulated using a computer model named “the random collision model”, and the effects of factors such as the basic reproductive number (R₀), time of isolation of the patients (TOI), interval between onset and isolation (IOI), and immunization rates (IR) on the developmental trend of the epidemic were quantitatively analysed.

Results

Once the R₀ exceeded 1.5, the median attack rate increased sharply; when R₀ = 3, with a delay in the TOI, the attack rate increased gradually and eventually remained stable. When the IOI exceeded 2.3 days, the median attack rate also increased dramatically. When the IR exceeded 0.5, the median attack rate approached zero. The median generation time was 8.26 days, (95% confidence interval [CI]: 7.84–8.69 days). The partial rank correlation coefficients between the attack rate of the epidemic and R₀, TOI, IOI, and IR were 0.61, 0.17, 0.45, and − 0.27, respectively.

Conclusions

The random collision model not only simulates how an epidemic spreads with superior precision but also allows greater flexibility in setting the activities of the exposure population and different types of infectious diseases, which is conducive to furthering exploration of the epidemiological characteristics of epidemic outbreaks.

Epidemiology, clinical presentation and respiratory sequelae of adenovirus pneumonia in children in Kuala Lumpur, Malaysia

Objectives

To describe the severity, human adenovirus (HAdV) type and respiratory morbidity following adenovirus pneumonia in children.

Methodology

Retrospective review of children under 12 years of age, admitted with HAdV pneumonia, between January 2011 and July 2013, in a single centre in Malaysia. HAdV isolated from nasopharyngeal secretions were typed by sequencing hypervariable regions 1–6 of the hexon gene. Patients were reviewed for respiratory complications.

Results

HAdV was detected in 131 children of whom 92 fulfilled inclusion criteria. Median (range) age was 1.1 (0.1–8.0) years with 80% under 2 years. Twenty percent had severe disease with a case-fatality rate of 5.4%. Duration of admission (p = 0.02) was independently associated with severe illness. Twenty-two percent developed respiratory complications, the commonest being bronchiolitis obliterans (15.2%) and recurrent wheeze (5.4%). The predominant type shifted from HAdV1 and HAdV3 in 2011 to HAdV7 in 2013. The commonest types identified were types 7 (54.4%), 1(17.7%) and 3 (12.6%). Four out of the five patients who died were positive for HAdV7. Infection with type 7 (OR 8.90, 95% CI 1.32, 59.89), family history of asthma (OR 14.80, 95% CI 2.12–103.21) and need for invasive or non-invasive ventilation (OR 151.84, 95% CI 9.93–2.32E) were independent predictors of respiratory complications.

Conclusions

One in five children admitted with HAdV pneumonia had severe disease and 22% developed respiratory complications. Type 7 was commonly isolated in children with severe disease. Family history of asthma need for invasive or non-invasive ventilation and HAdV 7 were independent predictors of respiratory complications.

A Mini Review of the Zoonotic Threat Potential of Influenza Viruses, Coronaviruses, Adenoviruses, and Enteroviruses

During the last two decades, scientists have grown increasingly aware that viruses are emerging from the human–animal interface. In particular, respiratory infections are problematic; in early 2003, World Health Organization issued a worldwide alert for a previously unrecognized illness that was subsequently found to be caused by a novel coronavirus [severe acute respiratory syndrome (SARS) virus]. In addition to SARS, other respiratory pathogens have also emerged recently, contributing to the high burden of respiratory tract infection-related morbidity and mortality. Among the recently emerged respiratory pathogens are influenza viruses, coronaviruses, enteroviruses, and adenoviruses. As the genesis of these emerging viruses is not well understood and their detection normally occurs after they have crossed over and adapted to man, ideally, strategies for such novel virus detection should include intensive surveillance at the human–animal interface, particularly if one believes the paradigm that many novel emerging zoonotic viruses first circulate in animal populations and occasionally infect man before they fully adapt to man; early detection at the human–animal interface will provide earlier warning. Here, we review recent emerging virus treats for these four groups of viruses.

Epidemiologic analysis of respiratory viral infections among Singapore military servicemen in 2016

Background

Respiratory illnesses have been identified as a significant factor leading to lost training time and morbidity among Singapore military recruits. A surveillance programme has been put in place to determine etiological agents responsible for febrile, as well as afebrile respiratory illnesses in a military camp. The goal of the study is to better understand the epidemiology of these diseases and identify potential countermeasures to protect military recruits against them.

Methods

From Jan 2016 - Jan 2017, a total of 2647 respiratory cases were enrolled into the surveillance programme. The cases were further stratified into Febrile Respiratory Illness (FRI, with body temperature > 37.5 °C) or Acute Respiratory Illness (ARI, with body temperature < 37.5 °C). Nasal washes were collected and tested by multiplex PCR to detect 26 different pathogens.

Results

One thousand ninety five cases (41% of total cases) met the criteria of FRI in which 932 cases (85% of FRI cases) were screened positive for at least one virus. The most common etiological agents for FRI mono-infection cases were Adenovirus E and Rhinovirus. Recruits infected with H3N2 influenza, Influenza B and Adenovirus E viruses were most likely presented as FRI cases. Notably, H3N2 influenza resulted in the greatest rise in body temperature. The remaining 1552 cases (59% of total cases) met the criteria of ARI in which 1198 cases (77% of ARI cases) were screened positive for at least one virus. The most common etiological agent for ARI mono-infection was Rhinovirus. The distribution pattern for dual infections was different for ARI and FRI cases. Maximum number of pathogens detected in a sample was five for both groups.

Conclusion

Previous studies on respiratory diseases in military focused largely on FRI cases. With the expanded surveillance to ARI cases, this study allows unbiased evaluation of the impact of respiratory disease pathogens among recruits in a military environment. The results show that several pathogens have a much bigger role in causing respiratory diseases in this cohort.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3040-x) contains supplementary material, which is available to authorized users.

The Repertoire of Adenovirus in Human Disease: The Innocuous to the Deadly

Adenoviridae is a family of double-stranded DNA viruses that are a significant cause of upper respiratory tract infections in children and adults. Less commonly, the adenovirus family can cause a variety of gastrointestinal, ophthalmologic, genitourinary, and neurologic diseases. Most adenovirus infections are self-limited in the immunocompetent host and are treated with supportive measures. Fatal infections can occur in immunocompromised patients and less frequently in the healthy. Adenoviral vectors are being studied for novel biomedical applications including gene therapy and immunization. In this review we will focus on the spectrum of adenoviral infections in humans.

An outbreak of acute respiratory disease caused by a virus associated RNA II gene mutation strain of human adenovirus 7 in China, 2015

Human adenovirus 7 (HAdV-7) strains are a major cause of acute respiratory disease (ARD) among adults and children, associated with fatal pneumonia. An ARD outbreak caused by HAdV-7 that involved 739 college students was reported in this article. To better understand the underlying cause of this large-scale epidemic, virus strains were isolated from infected patients and sequence variations of the whole genome sequence were detected. Evolutionary trees and alignment results indicated that the major capsid protein genes hexon and fibre were strongly conserved among serotype 7 strains in China at that time. Instead, the HAdV-7 strains presented three thymine deletions in the virus associated RNA (VA RNA) II terminal region. We also found that the mutation might lead to increased mRNA expression of an adjacent gene, L1 52/55K, and thus promoted faster growth. These findings suggest that sequence variation of VA RNA II gene was a potential cause of such a severe HAdV-7 infection and this gene should be a new-emerging factor to be monitored for better understanding of HAdV-7 infection.

Fatal Community-acquired Pneumonia in Children Caused by Re-emergent Human Adenovirus 7d Associated with Higher Severity of Illness and Fatality Rate

Human adenoviruses (HAdVs) are highly contagious pathogens causing acute respiratory disease (ARD), such as community-acquired pneumonia. HAdV-7d, a re-emergent genomic variant, has been recently reported in Asia and the United States after a several-decade absence. However, whether HAdV-7d is associated with higher severity than other types is currently unclear. In this study, the clinical and epidemiological investigation showed that fever, cough, and sore throat were the three most common respiratory symptoms of HAdV infections. HAdV-7 caused longer duration of fever, higher morbidity of tachypnea/dyspnea, pleural effusion, diarrhea, hepatosplenomegaly, consciousness alteration, as well as higher rates of pneumonia, mechanical ventilation and higher fatality rate (28.6%) than other types, particularly HAdV-3 and HAdV-2. The genomes of seven HAdV-7d isolates from mild, severe, and fatal cases were sequenced and highly similar with each other. Surprisingly, two isolates (2011, 2012) had 100% identical genomes with an earlier strain from a fatal ARD outbreak in China (2009), which elucidates the virus origin and confirms the unexpected HAdV genomic conservation and stability. Phylogenetic analysis indicated that L1 52/55-kDa DNA packaging protein may be associated with the higher severity of illness and fatality rate of HAdV-7. Clinicians need to be aware of HAdVs in children with ARD.

Genotyping of human adenoviruses circulating in Southwest India

Adenoviruses are found to be associated with a wide range of diseases in children and adults. There is little data available on the circulating serotypes of Human Adenoviruses (HAdVs) in the southwest region of India. In this study, we explore the molecular epidemiology of HAdVs circulating in southwest India. Twenty-three samples (Adenovirus PCR positive), collected between January 2011 and March 2013, have been typed based on the partial hexon gene sequence and phylogenetic analysis. The commonest serotypes were HAdV-3 and HAdV-2. The other serotypes were HAdV-7, HAdV-1, HAdV-8 and HAdV-40. Respiratory illness was the most common clinical manifestation of HAdV-3, HAdV-2 and HAdV-7 serotypes. HAdV-3, HAdV-7 and HAdV-8 were found to cause conjunctivitis, whereas HAdV-1, HAdV-2 and HAdV-3 caused encephalitis. In conclusion, this study documents the circulating HAdV strains and the epidemiology in southwest India. To the best of our knowledge, this is the first study on the molecular epidemiology of HAdVs in India.

Epidemiology and transmission characteristics of human adenovirus type 7 caused acute respiratory disease outbreak in military trainees in East China

BACKGROUND

Human adenovirus type 7 (HAdV7) is globally attracting great concern as its high morbidity and severity in respiratory diseases, especially in Asia.

OBJECTIVE

To investigate the clinical and epidemiologic characteristics of HAdV7 infection outbreak in East China.

METHODS

The clinical samples were collected from the patients of an ARD outbreak in East Chinafor the detection of causative pathogens by multiplex PCR. The molecular type of human adenovirus isolates were identified by sequencing and homologous comparison based on their hexon genes. The spatiotemporal dynamics of global HAdV7 was investigated using the phylogenetic and phylogeographic analyses. Total 67 referenced HAdV7 hexon sequences (>800 bp) from GenBank were selected for constructing the maximum likelihood tree by MEGA 5.1.0, grouped according to the tree topology for the further migration analysis by PAUP* 4.0 and MigraPhyla 1.0 b to understand the transmission patterns of HAdV7 in global epidemics.

RESULTS

The results showed HAdV7 as the causative pathogen in this outbreak, and the outbreak strains had the hexon sequences highly identical with the isolates in Shaanxi (2012). The origin of HAdV7 was inferred as California, meanwhile a total of 21 migration routes were acquired. HAdV7 in this outbreak was statistically proven dispersed from Shaanxi province (2012).

CONCLUSIONS

The analyses of epidemiology and transmission pattern of HAdV7 would not only enrich the molecular biological basic database but also provide theoretical basis for HAdV7 prevention and control strategy.

Molecular Identification and Epidemiological Features of Human Adenoviruses Associated with Acute Respiratory Infections in Hospitalized Children in Southern China, 2012-2013

BACKGROUND

Acute respiratory infections (ARI) are the major worldwide health problem associated with high morbidity and mortality rates. Human adenovirus (HAdV) is one of the most common pathogens associated with viral ARI, and thus calls for specific diagnosis and better understanding of the epidemiology and clinical characteristics.

METHODS

Total 4,130 children with ARI requiring hospitalization from 2012 to 2013 were retrospectively studied. Throat swab specimens were collected from each patient. Fluorescence Quantitative PCR was performed to detect adenovirus as well as other common ARI-related pathogens. The seven HAdV hypervariable regions (HVRs) of the hexon gene from fifty-seven HAdVs-positive samples collected in the seasonal peaks were sequenced. Phylogenetic analysis of HVRs was also conducted to confirm the molecular types and genetic variation. In addition, epidemiological features and co-infection with other human respiratory pathogens were investigated and analyzed.

RESULTS

Of 4,130 hospitalized pediatric patients tested, the positive rates of respiratory syncytial virus (RSV), Mycoplasma pneumoniae (MP), and HAdV were 13.7%, 13.2%, and 12.0%, respectively. The HAdV positive patients accounted for 7.9%, 17.2%, 17.5% and 10.7% in age groups <1, 1-3, 3-6 and 6-14 years, respectively. Eighty-four HAdV positive children were co-infected with other respiratory pathogens (84/495, 17.0%). The most common co-infection pathogens with HAdV were MP (57.1%) and Human Bocavirus (HBoV) (16.7%). The majority of HAdV infected patients were totally recovered (96.9%, 480/495); However, four (0.8%) patients, who were previously healthy and at the age of 2 years or younger died of pneumonia. Seasonal peaks of HAdV infection occurred in the summer season of 2012 and 2013; the predominant HAdV type was HAdV-3 (70%), followed by HAdV-7 (28%). These epidemiological features were different from those in Northern China. The HAdV-55 was identified and reported for the first time in Guangzhou metropolitan area. Phylogenetic analysis indicated that all the HVR sequences of the hexon gene of HAdV-3 and -7 strains have high similarity within their individual types, and these strains were also similar to those circulating in China currently, indicating the conservation of hexon genes of both HAdV-3 and HAdV-7.

CONCLUSIONS

Knowledge of the epidemiological features and molecular types of HAdV, a major pathogen of pediatric ARI, as well as other co-infected respiratory pathogens circulating in Guangzhou, southern China, is vital to predict and prevent future disease outbreaks in children. This study will certainly facilitate HAdV vaccine development and treatment of HAdV infections in children.

Severe Pediatric Adenovirus 7 Disease in Singapore Linked to Recent Outbreaks across Asia

During November 2012–July 2013, a marked increase of adenovirus type 7 (Ad7) infections associated with severe disease was documented among pediatric patients in Singapore. Phylogenetic analysis revealed close genetic links with severe Ad7 outbreaks in China, Taiwan, and other parts of Asia.

Molecular characterization of adenoviruses among finnish military conscripts

Although adenoviruses were identified as important respiratory pathogens many years ago, little information is available concerning the prevalence of different adenovirus serotypes, which are circulating and causing epidemics in Finnish military training centers. Over a period of five years from 2008 to 2012, 3577 respiratory specimens were collected from military conscripts presenting with symptoms compatible with acute respiratory tract infection. Upon initial testing for certain respiratory viruses by real-time PCR, 837 of these specimens were identified as adenovirus-positive. For 672 of these specimens, the serotype of the adenovirus responsible was successfully determined by DNA sequencing. Serotypes 1, 2, 3, and 4 were detected in 1, 3, 181, and 487 samples, respectively. Adenovirus epidemics were observed during each year of this study. Based on these findings, adenovirus vaccination should be considered for military conscripts in the Finnish Defence Forces.

Whole-genome Sequencing for Tracing the Transmission Link between Two ARD Outbreaks Caused by a Novel HAdV Serotype 7 Variant, China

From December 2012 to February 2013, two outbreaks of acute respiratory disease caused by HAdV-7 were reported in China. We investigated possible transmission links between these two seemingly unrelated outbreaks by integration of epidemiological and whole-genome sequencing (WGS) data. WGS analyses showed that the HAdV-7 isolates from the two outbreaks were genetically indistinguishable; however, a 12 bp deletion in the virus-associated RNA gene distinguished the outbreak isolates from other HAdV-7 isolates. Outbreak HAdV-7 isolates demonstrated increased viral replication compared to non-outbreak associated HAdV-7 isolate. Epidemiological data supported that the first outbreak was caused by introduction of the novel HAdV-7 virus by an infected recruit upon arrival at the training base. Nosocomial transmission by close contacts was the most likely source leading to onset of the second HAdV-7 outbreak, establishing the apparent transmission link between the outbreaks. Our findings imply that in-hospital contact investigations should be encouraged to reduce or interrupt further spread of infectious agents when treating outbreak cases, and WGS can provide useful information guiding infection-control interventions.

Respiratory Infections in the U.S. Military: Recent Experience and Control

This comprehensive review outlines the impact of military-relevant respiratory infections, with special attention to recruit training environments, influenza pandemics in 1918 to 1919 and 2009 to 2010, and peacetime operations and conflicts in the past 25 years. Outbreaks and epidemiologic investigations of viral and bacterial infections among high-risk groups are presented, including (i) experience by recruits at training centers, (ii) impact on advanced trainees in special settings, (iii) morbidity sustained by shipboard personnel at sea, and (iv) experience of deployed personnel. Utilizing a pathogen-by-pathogen approach, we examine (i) epidemiology, (ii) impact in terms of morbidity and operational readiness, (iii) clinical presentation and outbreak potential, (iv) diagnostic modalities, (v) treatment approaches, and (vi) vaccine and other control measures. We also outline military-specific initiatives in (i) surveillance, (ii) vaccine development and policy, (iii) novel influenza and coronavirus diagnostic test development and surveillance methods, (iv) influenza virus transmission and severity prediction modeling efforts, and (v) evaluation and implementation of nonvaccine, nonpharmacologic interventions.

Molecular Epidemiology and Phylogenetic Analysis of Human Adenovirus Caused an Outbreak in Taiwan during 2011

An outbreak of adenovirus has been surveyed in Taiwan in 2011. To better understand the evolution and epidemiology of adenovirus in Taiwan, full-length sequence of hexon and fiber coapsid protein was analyzed using series of phylogenetic and dynamic evolution tools. Six different serotypes were identified in this outbreak and the species B was predominant (HAdV-3, 71.50%; HAdV-7, 15.46%). The most frequent diagnosis was acute tonsillitis (54.59%) and bronchitis (47.83%). Phylogenetic analysis revealed that hexon protein gene sequences were highly conserved for HAdV-3 and HAdV-7 circulation in Taiwan. However, comparison of restriction fragment length polymorphism (RFLP) analysis and phylogenetic trees of fiber gene in HAdV-7 clearly indicated that the predominant genotype in Taiwan has shifted from 7b to 7d. Several positive selection sites were observed in hexon protein. The estimated nucleotide substitution rates of hexon protein of HAdV-3 and HAdV-7 were 0.234×10^-3 substitutions/site/year (95% HPD: 0.387~0.095×10^-3) and 1.107×10^-3 (95% HPD: 0. 541~1.604) respectively; those of the fiber protein of HAdV-3 and HAdV-7 were 1.085×10^-3 (95% HPD: 1.767~0.486) and 0.132×10^-3 (95% HPD: 0.283~0.014) respectively. Phylodynamic analysis by Bayesian skyline plot (BSP) suggested that using individual gene to evaluate the effective population size might possibly cause miscalculation. In summary, the virus evolution is ongoing, and continuous surveillance of this virus evolution will contribute to the control of the epidemic.

Dramatic decline of respiratory illness among US military recruits after the renewed use of adenovirus vaccines

BACKGROUND

In late 2011, after a 12-year hiatus, oral vaccines against adenovirus types 4 (Ad4) and 7 (Ad7) were again produced and administered to US military recruits. This study examined the impact of the new adenovirus vaccines on febrile respiratory illness (FRI) and adenovirus rates and investigated if new serotypes emerged. FRI rates and their associated hospitalizations had markedly risen since vaccine production ceased in 1999.

METHODS

From 1996 to 2013, the Naval Health Research Center conducted FRI surveillance at 8 military recruit training centers in the United States. During this period, 58 103 FRI pharyngeal swab specimens were studied, yielding 37 048 adenovirus-positive cases, among which 64% were typed.

RESULTS

During the 2 years after reintroduction of the vaccines, military trainees experienced a 100-fold decline in adenovirus disease burden (from 5.8 to 0.02 cases per 1000 person-weeks, P < .0001), without evidence that vaccine pressure had increased the impact of adenovirus types other than Ad4 and Ad7. Although the percentage of type 14 increased following reintroduction of the vaccination, the actual number of cases decreased. We estimate that the vaccines prevent approximately 1 death, 1100-2700 hospitalizations, and 13 000 febrile adenovirus cases each year among the trainees.

CONCLUSIONS

These data strongly support the continued production and use of Ad4 and Ad7 vaccines in controlling FRI among US military trainees. Continued surveillance for emerging adenovirus subtypes is warranted.

Community outbreak of adenovirus, Taiwan, 2011

Adenovirus type 7 caused a high proportion of severe infections.

In 2011, a large community outbreak of human adenovirus (HAdV) in Taiwan was detected by a nationwide surveillance system. The epidemic lasted from week 11 through week 41 of 2011 (March 14–October 16, 2011). Although HAdV-3 was the predominant strain detected (74%), an abrupt increase in the percentage of infections caused by HAdV-7 occurred, from 0.3% in 2008–2010 to 10% in 2011. Clinical information was collected for 202 inpatients infected with HAdV; 31 (15.2%) had severe infection that required intensive care, and 7 of those patients died. HAdV-7 accounted for 10%, 12%, and 41% of infections among outpatients, inpatients with nonsevere infection, and inpatients with severe infection, respectively (p<0.01). The HAdV-7 strain detected in this outbreak is identical to a strain recently reported in the People’s Republic of China (HAdV7-HZ/SHX/CHN/2009). Absence of circulating HAdV-7 in previous years and introduction of an emerging strain are 2 factors that caused this outbreak.