Ivan Fan-Ngai Hung

Clinical progression and viral load in a community outbreak of coronavirus-associated SARS pneumonia: a prospective study

Summary Background We investigated the temporal progression of the clinical, radiological, and virological changes in a community outbreak of severe acute respiratory syndrome (SARS). Methods We followed up 75 patients for 3 weeks managed with a standard treatment protocol of ribavirin and corticosteroids, and assessed the pattern of clinical disease, viral load, risk factors for poor clinical outcome, and the usefulness of virological diagnostic methods. Findings Fever and pneumonia initially improved but 64 (85%) patients developed recurrent fever after a mean of 8.9 (SD 3.1) days, 55 (73%) had watery diarrhoea after 7.5 (2.3) days, 60 (80%) had radiological worsening after 7.4 (2.2) days, and respiratory symptoms worsened in 34 (45%) after 8.6 (3.0) days. In 34 (45%) patients, improvement of initial pulmonary lesions was associated with appearance of new radiological lesions at other sites. Nine (12%) patients developed spontaneous pneumomediastinum and 15 (20%) developed acute respiratory distress syndrome (ARDS) in week 3. Quantitative reverse-transcriptase (RT) PCR of nasopharyngeal aspirates in 14 patients (four with ARDS) showed peak viral load at day 10, and at day 15 a load lower than at admission. Age and chronic hepatitis B virus infection treated with lamivudine were independent significant risk factors for progression to ARDS (p=0.001). SARS-associated coronavirus in faeces was seen on RT-PCR in 65 (97%) of 67 patients at day 14. The mean time to seroconversion was 20 days. Interpretation The consistent clinical progression, shifting radiological infiltrates, and an inverted V viral-load profile suggest that worsening in week 2 is unrelated to uncontrolled viral replication but may be related to immunopathological damage. Published online May 9, 2003 http://image.thelancet.com/extras/03art4432web.pdf

Delayed Clearance of Viral Load and Marked Cytokine Activation in Severe Cases of Pandemic H1N1 2009 Influenza Virus Infection

Abstract Background. Infections caused by the pandemic H1N1 2009 influenza virus range from mild upper respiratory tract syndromes to fatal diseases. However, studies comparing virological and immunological profile of different clinical severity are lacking. Methods. We conducted a retrospective cohort study of 74 patients with pandemic H1N1 infection, including 23 patients who either developed acute respiratory distress syndrome (ARDS) or died (ARDS-death group), 14 patients with desaturation requiring oxygen supplementation and who survived without ARDS (survived-without-ARDS group), and 37 patients with mild disease without desaturation (mild-disease group). We compared their pattern of clinical disease, viral load, and immunological profile. Results. Patients with severe disease were older, more likely to be obese or having underlying diseases, and had lower respiratory tract symptoms, especially dyspnea at presentation. The ARDS-death group had a slower decline in nasopharyngeal viral loads, had higher plasma levels of proinflammatory cytokines and chemokines, and were more likely to have bacterial coinfections (30.4%), myocarditis (21.7%), or viremia (13.0%) than patients in the survived-without-ARDS or the mild-disease groups. Reactive hemophagocytosis, thrombotic phenomena, lymphoid atrophy, diffuse alveolar damage, and multiorgan dysfunction similar to fatal avian influenza A H5N1 infection were found at postmortem examinations. Conclusions. The slower control of viral load and immunodysregulation in severe cases mandate the search for more effective antiviral and immunomodulatory regimens to stop the excessive cytokine activation resulting in ARDS and death.

HBsAg Seroclearance in Chronic Hepatitis B in Asian Patients: Replicative Level and Risk of Hepatocellular Carcinoma

BACKGROUND & AIMS Our aims were to study the virologic, histologic, and clinical outcome in chronic hepatitis B (CHB) patients with hepatitis B surface antigen (HBsAg) seroclearance. METHODS We determined the age of HBsAg seroclearance that is associated with a lower risk for hepatocellular carcinoma (HCC) in 298 CHB patients (median follow-up, 108 months). The following virologic and histologic features were also determined: liver stiffness (n = 229), liver histology, serum HBV DNA levels over time (n = 265), intrahepatic HBV DNA with covalently closed circular DNA (cccDNA) levels, and messenger RNA (mRNA) expression. RESULTS The median age of HBsAg seroclearance was 49.6 years. Seven (2.4%) patients developed HCC. Cumulative risk for HCC was higher in patients with HBsAg seroclearance at ages >or=50 years compared with those with HBsAg seroclearance at ages <50 (P = .004) years. Of these 2 groups of patients, 29.5% and 7.9%, respectively, had significant fibrosis by liver stiffness measurement (P = .001), and 15.4% of patients had mild histologic fibrosis. Intrahepatic total HBV DNA and cccDNA were detected in 100% and 79.3% of patients, respectively. All patients had undetectable surface and precore/pregenomic RNA transcripts. One (9.1%) patient had X mRNA expression. Serum HBV DNA were detectable in 13.4%, 6.1%, and 3.7% of patients within 1 year and 5-10 and >10 years after HBsAg seroclearance, respectively, and 82.1% patients had persistently normal alanine aminotransferase levels. CONCLUSIONS HBV persisted at low replicative and transcriptional levels after HBsAg seroclearance. HBsAg seroclearance at age <50 years was associated with a lower risk for the development of HCC.

Viral load in patients infected with pandemic H1N1 2009 influenza A virus.

Viral shedding profile of infections caused by the pandemic H1N1 2009 influenza A virus has not been reported. The aim of this study was to determine the viral load in different body sites. Viral loads of pandemic H1N1 virus in respiratory specimens, stool, urine, and serum were determined by quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR). Respiratory specimens from patients with seasonal influenza were used as historical controls. Initial pre‐treatment viral load were compared between these two groups. Serial respiratory specimens from patients with pandemic H1N1 virus infection were obtained for analysis of viral dynamics. Twenty‐two pandemic H1N1 cases and 44 seasonal influenza historical controls were included. The mean initial viral load before oseltamivir therapy was 1.84 × 108 copies/ml for pandemic H1N1 virus compared with 3.28 × 108 copies/ml in seasonal influenza historical controls (P = 0.085). Among patients with pandemic H1N1 virus infection, peak viral load occurred on the day of onset of symptoms, and declined gradually afterwards, with no virus being detectable in respiratory specimens by RT‐PCR 8 days and by culture 5 days after the onset of symptoms respectively, except in one patient. Pandemic H1N1 virus was detected in stool and in urine from 4/9 and 1/14 patients, respectively. Viral culture was also positive from the stool sample with the highest viral load. Younger age was associated with prolonged shedding in the respiratory tract and higher viral load in the stool. Data from this quantitative analysis of viral shedding may have implications for formulating infection control measures. J. Med. Virol. 82:1–7, 2010.

The infection attack rate and severity of 2009 pandemic H1N1 influenza in Hong Kong

BACKGROUND Serial cross-sectional data on antibody levels to the 2009 pandemic H1N1 influenza A virus from a population can be used to estimate the infection attack rates and immunity against future infection in the community. METHODS From April through December 2009, we obtained 12,217 serum specimens from blood donors (aged 16-59 years), 2520 specimens from hospital outpatients (aged 5-59 years), and 917 specimens from subjects involved in a community pediatric cohort study (aged 5-14 years). We estimated infection attack rates by comparing the proportions of specimens with antibody titers ≥ 1:40 by viral microneutralization before and after the first wave of the pandemic. Estimates were validated using paired serum samples from 324 individuals that spanned the first wave. Combining these estimates with epidemiologic surveillance data, we calculated the proportion of infections that led to hospitalization, admission to the intensive care unit (ICU), and death. RESULTS We found that 3.3% and 14% of persons aged 5-59 years had antibody titers ≥ 1:40 before and after the first wave, respectively. The overall attack rate was 10.7%, with age stratification as follows: 43.4% in persons aged 5-14 years, 15.8% in persons aged 15-19 years, 11.8% in persons aged 20-29 years, and 4%-4.6% in persons aged 30-59 years. Case-hospitalization rates were 0.47%-0.87% among persons aged 5-59 years. Case-ICU rates were 7.9 cases per 100,000 infections in persons aged 5-14 years and 75 cases per 100,000 infections in persons aged 50-59 years, respectively. Case-fatality rates were 0.4 cases per 100,000 infections in persons aged 5-14 years and 26.5 cases per 100,000 infections in persons aged 50-59 years, respectively. CONCLUSIONS Almost half of all school-aged children in Hong Kong were infected during the first wave. Compared with school children aged 5-14 years, older adults aged 50-59 years had 9.5 and 66 times higher risks of ICU admission and death if infected, respectively.

Recurrence of Hepatitis B-Related Hepatocellular Carcinoma Is Associated With High Viral Load at the Time of Resection

BACKGROUND/AIMS: To identify the risk factors for recurrence of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) after resection.METHODS:Seventy-two patients who underwent liver resection for HBV-related HCC were recruited. Demographic, biochemical, tumor, and viral factors at the time of resection were evaluated by univariate and multivariate analyses to identify risk factors associated with recurrence after resection.RESULTS:The median follow-up period was 18.9 months and the median age was 53 yr, with male-to-female ratio of 59:13. Age >60 yr, tumor size >5 cm, poorly differentiated tumor, lymphovascular permeation, the presence of microsatellite lesions, α-fetoprotein (AFP) level >1,000 ng/mL and HBV viral load >2,000 IU/mL (4 log10 copies/mL) at the time of tumor resection, HBV genotype C, core promoter mutations, and patients with no antiviral treatment after tumor resection were associated with increased cumulative risk of HCC recurrence. By multivariate analysis, HBV viral load >2,000 IU/mL (4 log10 copies/mL) (P= 0.001, odds ratio [OR] 22.3), AFP >1,000 ng/mL (P= 0.02, OR 7.4), tumor size >5 cm (P= 0.02, OR 5.1), and age >60 yr (P= 0.01, OR 4) at the time of tumor resection remained to be the independent risk factors.CONCLUSIONS:Viral load of >2,000 IU/mL (4 log10 copies/mL) is the most important correctable risk factor for HCC recurrence after resection. Whether antiviral therapy in these patients can decrease tumor recurrence requires further investigations.

Detection of SARS Coronavirus in Patients with Suspected SARS

Cases of severe acute respiratory syndrome (SARS) were investigated for SARS coronavirus (SARS-CoV) through RNA tests, serologic response, and viral culture. Of 537 specimens from patients in whom SARS was clinically diagnosed, 332 (60%) had SARS-CoV RNA in one or more clinical specimens, compared with 1 (0.3%) of 332 samples from controls. Of 417 patients with clinical SARS from whom paired serum samples were available, 92% had an antibody response. Rates of viral RNA positivity increased progressively and peaked at day 11 after onset of illness. Although viral RNA remained detectable in respiratory secretions and stool and urine specimens for >30 days in some patients, virus could not be cultured after week 3 of illness. Nasopharyngeal aspirates, throat swabs, or sputum samples were the most useful clinical specimens in the first 5 days of illness, but later in the illness viral RNA could be detected more readily in stool specimens.

Relative rates of non-pneumonic SARS coronavirus infection and SARS coronavirus pneumonia

Summary Background Although the genome of severe acute respiratory syndrome coronavirus (SARS-CoV) has been sequenced and a possible animal reservoir identified, seroprevalence studies and mass screening for detection of subclinical and non-pneumonic infections are still lacking. Methods We cloned and purified the nucleocapsid protein and spike polypeptide of SARS-CoV and examined their immunogenicity with serum from patients with SARS-CoV pneumonia. An ELISA based on recombinant nucleocapsid protein for IgG detection was tested with serum from 149 healthy blood donors who donated 3 years previously and with serum positive for antibodies against SARS-CoV (by indirect immunofluorescence assay) from 106 patients with SARS-CoV pneumonia. The seroprevalence of SARS-CoV was studied with the ELISA in healthy blood donors who donated during the SARS outbreak in Hong Kong, non-pneumonic hospital inpatients, and symptom-free health-care workers. All positive samples were confirmed by two separate western-blot assays (with recombinant nucleocapsid protein and recombinant spike polypeptide). Findings Western-blot analysis showed that the nucleocapsid protein and spike polypeptide of SARS-CoV are highly immunogenic. The specificity of the IgG antibody test (ELISA with positive samples confirmed by the two western-blot assays) was 100%, and the sensitivity was 94·3%. Three of 400 healthy blood donors who donated during the SARS outbreak and one of 131 non-pneumonic paediatric inpatients were positive for IgG antibodies, confirmed by the two western-blot assays (total, 0·48% of our study population). Interpretation Our findings support the existence of subclinical or non-pneumonic SARS-CoV infections. Such infections are more common than SARS-CoV pneumonia in our locality.

Two Years after Pandemic Influenza A/2009/H1N1: What Have We Learned?

SUMMARY The world had been anticipating another influenza pandemic since the last one in 1968. The pandemic influenza A H1N1 2009 virus (A/2009/H1N1) finally arrived, causing the first pandemic influenza of the new millennium, which has affected over 214 countries and caused over 18,449 deaths. Because of the persistent threat from the A/H5N1 virus since 1997 and the outbreak of the severe acute respiratory syndrome (SARS) coronavirus in 2003, medical and scientific communities have been more prepared in mindset and infrastructure. This preparedness has allowed for rapid and effective research on the epidemiological, clinical, pathological, immunological, virological, and other basic scientific aspects of the disease, with impacts on its control. A PubMed search using the keywords “pandemic influenza virus H1N1 2009” yielded over 2,500 publications, which markedly exceeded the number published on previous pandemics. Only representative works with relevance to clinical microbiology and infectious diseases are reviewed in this article. A significant increase in the understanding of this virus and the disease within such a short amount of time has allowed for the timely development of diagnostic tests, treatments, and preventive measures. These findings could prove useful for future randomized controlled clinical trials and the epidemiological control of future pandemics.

Viral loads in clinical specimens and SARS manifestations.

The number of anatomical sites with detectable viral loads by RT-qPCR appeared to correlate with death risk.