Serological and molecular findings during SARS-CoV-2 infection: the first case study in Finland, January to February 2020

The first case of coronavirus disease (COVID-19) in Finland was confirmed on 29 January 2020. No secondary cases were detected. We describe the clinical picture and laboratory findings 3-23 days since the first symptoms. The SARS-CoV-2/Finland/1/2020 virus strain was isolated, the genome showing a single nucleotide substitution to the reference strain from Wuhan. Neutralising antibody response appeared within 9 days along with specific IgM and IgG response, targeting particularly nucleocapsid and spike proteins.

Middle East respiratory syndrome coronavirus shows poor replication but significant induction of antiviral responses in human monocyte-derived macrophages and dendritic cells

In this study we assessed the ability of Middle East respiratory syndrome coronavirus (MERS-CoV) to replicate and induce innate immunity in human monocyte-derived macrophages and dendritic cells (MDDCs), and compared it with severe acute respiratory syndrome coronavirus (SARS-CoV). Assessments of viral protein and RNA levels in infected cells showed that both viruses were impaired in their ability to replicate in these cells. Some induction of IFN-λ1, CXCL10 and MxA mRNAs in both macrophages and MDDCs was seen in response to MERS-CoV infection, but almost no such induction was observed in response to SARS-CoV infection. ELISA and Western blot assays showed clear production of CXCL10 and MxA in MERS-CoV-infected macrophages and MDDCs. Our data suggest that SARS-CoV and MERS-CoV replicate poorly in human macrophages and MDDCs, but MERS-CoV is nonetheless capable of inducing a readily detectable host innate immune response. Our results highlight a clear difference between the viruses in activating host innate immune responses in macrophages and MDDCs, which may contribute to the pathogenesis of infection.

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.

Influenza C virus infection in military recruits--symptoms and clinical manifestation

Due to the lack of rapid diagnostic tests, clinical features of Influenza C virus infections are poorly characterized. Respiratory infections in military recruits in eastern Finland were monitored between July 2004 and December 2005 in order to study the epidemiology and clinical picture of infections caused by this virus. Blood samples were obtained at entry and at the end of the military service, and during each episode of respiratory infection to measure antibody responses against 10 viral and 2 bacterial pathogens. If possible, sputum samples were collected during the acute phase of respiratory infection episodes. Symptoms of the episodes were recorded for comparison of the clinical picture caused by various infectious agents. Infection with influenza C virus was detected in 38 of 892 young men during their service. The virus usually caused a mild upper respiratory tract infection. Most typical clinical features of influenza C virus infection were cough, rhinitis, and hoarseness. A striking difference to infections caused by influenza A virus was the lack of fever. Influenza C virus is an important cause of a respiratory tract infection in army conscripts. Infections with this virus are usually mild but can be complicated in some cases.

Decline in temperature and humidity increases the occurrence of influenza in cold climate

BACKGROUND

Both temperature and humidity may independently or jointly contribute to the risk of influenza infections. We examined the relations between the level and decrease of temperature, humidity and the risk of influenza A and B virus infections in a subarctic climate.

METHODS

We conducted a case-crossover study among military conscripts (n = 892) seeking medical attention due to respiratory symptoms during their military training period and identified 66 influenza A and B cases by PCR or serology. Meteorological data such as measures of average and decline in ambient temperature and absolute humidity (AH) during the three preceding days of the onset (hazard period) and two reference periods, prior and after the onset were obtained.

RESULTS

The average temperature preceding the influenza onset was -6.8 ± 5.6°C and AH 3.1 ± 1.3 g/m3. A decrease in both temperature and AH during the hazard period increased the occurrence of influenza so that a 1°C decrease in temperature and 0.5 g decrease per m3 in AH increased the estimated risk by 11% [OR 1.11 (1.03 to 1.20)] and 58% [OR 1.58 (1.28 to 1.96)], respectively. The occurrence of influenza infections was positively associated with both the average temperature [OR 1.10 per 1°C (95% confidence interval 1.02 to 1.19)] and AH [OR 1.25 per g/m3 (1.05 to 1.49)] during the hazard period prior to onset.

CONCLUSION

Our results demonstrate that a decrease rather than low temperature and humidity per se during the preceding three days increase the risk of influenza episodes in a cold climate.

The use of the probiotic Lactobacillus rhamnosus GG and viral findings in the nasopharynx of children attending day care

Limited data are available on the effects of probiotics on the nasopharyngeal presence of respiratory viruses in children attending day care. In this substudy of a randomized, double-blinded, placebo-controlled 28-week intervention study, nasopharyngeal swab samples were collected, on visits to a physician due to symptoms of infection, from children receiving control milk (N = 97) and children receiving the same milk supplemented with probiotic Lactobacillus rhamnosus GG (N = 97). The presence of 14 respiratory viruses was assessed by PCR methods, and viral findings were compared with symptom prevalences in the intervention groups. Rhinovirus was identified in 28.6% of 315 swab samples, followed by respiratory syncytial virus (12.4%), parainfluenza virus 1 (12.1%), enterovirus (8.9%), influenza A(H1N1)pdm09 (7.9%), human bocavirus 1 (3.8%), parainfluenza virus 2 (3.2%), adenovirus (2.9%), and influenza A(H3N2) (0.6%). The children in the probiotic group had less days with respiratory symptoms per month than the children in the control group (6.48 [95% CI 6.28-6.68] vs. 7.19 [95% CI 6.98-7.41], P < 0.001). Probiotic intervention did not reduce significantly the occurrence of the examined respiratory viruses, or have an effect on the number of respiratory symptoms observed at the time of a viral finding. Rhinovirus, respiratory syncytial virus, and parainfluenza virus 1 were the most common respiratory viruses in symptomatic children. Children receiving Lactobacillus rhamnosus GG had fewer days with respiratory symptoms than children in the control group, although probiotic intervention was not effective in reducing the amount of viral findings or the respiratory symptoms associated with viral findings.

Surveillance of influenza in Finland during the 2009 pandemic, 10 May 2009 to 8 March 2010

The first infection caused by pandemic influenza A(H1N1)2009 virus was confirmed in Finland on 10 May 2009. The spread of the disease and its impact were monitored using several surveillance systems, such as the national infectious disease register, notifications of clusters of influenza, influenza-like or influenza-related illnesses, as well as virological, hospital, case-based and mortality surveillance. The epidemic started in early October in the north and then spread to the south about two weeks later. Based on the data from laboratory-confirmed cases, the morbidity was highest in children. The daily number of patients hospitalised with influenza A(H1N1)2009 reached a maximum of over 400 in late November. Of the 1,580 hospitalised patients (median age 32 years), 672 (43%) had at least one chronic underlying illness, 35 (2%) were pregnant, 132 (8%) were treated in intensive care units and 74 (5%) required mechanical ventilation. The median age of patients admitted to intensive care units was 48 years and 78 ( 59%) of them had at least one chronic underlying disease, none were pregnant. Altogether 44 deaths related to influenza A(H1N1)2009 were recorded (median age 56 years): 40 belonged to high-risk groups on the basis of underlying chronic diseases. Combining data from different surveillance systems gave timely information about the spread of the pandemic and contributed to identifying risk groups.

Outbreak of 2009 pandemic influenza A(H1N1) in a Finnish garrison - a serological survey

In September 2009, an outbreak of 2009 pandemic influenza A(H1N1) took place in a Finnish garrison. In November 2009, we performed a serological survey among 984 recruits undergoing their military service at the garrison and related the results to self-reported upper respiratory tract infection (URTI) with or without fever. Of 346 volunteers who donated a blood sample, 169 (49%) had pandemic influenza A(H1N1) virus-specific antibodies. Of those, 84 (50%) reported no recent history of URTI, suggesting that a major part of those infected with pandemic influenza A(H1N1) virus may be asymptomatic.

Outbreak of 2009 pandemic influenza A(H1N1) in a Finnish garrison--a serological survey

In September 2009, an outbreak of 2009 pandemic influenza A(H1N1) took place in a Finnish garrison. In November 2009, we performed a serological survey among 984 recruits undergoing their military service at the garrison and related the results to self-reported upper respiratory tract infection (URTI) with or without fever. Of 346 volunteers who donated a blood sample, 169 (49%) had pandemic influenza A(H1N1) virus-specific antibodies. Of those, 84 (50%) reported no recent history of URTI, suggesting that a major part of those infected with pandemic influenza A(H1N1) virus may be asymptomatic.

Genetic diversity of the 2009 pandemic influenza A(H1N1) viruses in Finland

BACKGROUND

In Finland, the first infections caused by the 2009 pandemic influenza A(H1N1) virus were identified on May 10. During the next three months almost all infections were found from patients who had recently traveled abroad. In September 2009 the pandemic virus started to spread in the general population, leading to localized outbreaks and peak epidemic activity was reached during weeks 43-48.

METHODS/RESULTS

The nucleotide sequences of the hemagglutinin (HA) and neuraminidase (NA) genes from viruses collected from 138 patients were determined. The analyzed viruses represented mild and severe infections and different geographic regions and time periods. Based on HA and NA gene sequences, the Finnish pandemic viruses clustered in four groups. Finnish epidemic viruses and A/California/07/2009 vaccine virus strain varied from 2-8 and 0-5 amino acids in HA and NA molecules, respectively, giving a respective maximal evolution speed of 1.4% and 1.1%. Most amino acid changes in HA and NA molecules accumulated on the surface of the molecule and were partly located in antigenic sites. Three severe infections were detected with a mutation at HA residue 222, in two viruses with a change D222G, and in one virus D222Y. Also viruses with change D222E were identified. All Finnish pandemic viruses were sensitive to oseltamivir having the amino acid histidine at residue 275 of the neuraminidase molecule.

CONCLUSIONS

The Finnish pandemic viruses were quite closely related to A/California/07/2009 vaccine virus. Neither in the HA nor in the NA were changes identified that may lead to the selection of a virus with increased epidemic potential or exceptionally high virulence. Continued laboratory-based surveillance of the 2009 pandemic influenza A(H1N1) is important in order to rapidly identify drug resistant viruses and/or virus variants with potential ability to cause severe forms of infection and an ability to circumvent vaccine-induced immunity.

Respiratory viruses in laryngeal croup of young children

OBJECTIVES

To determine the viral cause of laryngeal croup by use of highly sensitive methods, and including recently recognized viruses in the analysis.

STUDY DESIGN

One hundred forty-four consecutive children with hoarse voice and inspiratory stridor attending the emergency department were enrolled. Age- and season-matched children presenting with a wheezing illness served as control subjects (n = 76). Nasopharyngeal swabs were analyzed by polymerase chain reaction for rhinovirus and enterovirus, coronavirus, respiratory syncytial virus (RSV), parainfluenza virus (PIV), influenza A and B virus, human bocavirus, human metapneumovirus, adenovirus, and Mycoplasma pneumoniae.

RESULTS

Virus infection was documented in 80% of patients with croup and 71% of control subjects. Children with croup had significantly more positive test results for PIV 1 and 2 (31% vs 4% and 6% vs 0%, respectively) and significantly fewer positive test results for RSV (15% vs 28%) than wheezing children. Rhinoviruses and enteroviruses were present equally in both groups (21% vs 25%). There was no significant difference in the frequency of influenza A virus or human bocavirus. Few subjects with adenovirus or M. pneumoniae were detected.

CONCLUSION

Acute laryngeal croup is most often associated with PIV, RSV, rhinovirus, and enterovirus. Rhinovirus and enterovirus appeared equally often in croup and in wheezing illness. During late fall, they were found in 39% and 40%, respectively, of the tested samples.

Presence of viral and bacterial pathogens in the nasopharynx of otitis-prone children. A prospective study

OBJECTIVE

The purpose of the present study was to examine and follow up the presence of respiratory viral and bacterial pathogens in the nasopharynx of otitis-prone children during the cold season and compare the findings with the child's respiratory symptoms.

METHODS

We enrolled 121 otitis-prone children, aged 10 months to 4 years for a prospective study. The nasopharyngeal swab (NPS) were studied at the baseline and after 12 and 24 weeks for respiratory viruses and at the baseline and after 24 weeks for bacteria. Presence of picorna(rhino-entero-parecho)-, influenza-, adenoviruses and Mycoplasma pneumoniae was detected by PCR. NPS specimens were cultured for Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis. Clinical data (the rate of respiratory symptom days, otitis media, tympanometry findings, day-care attendance and the number of siblings) were compared with microbiological data.

RESULTS

Rhinovirus was found in 30% of the samples at the baseline, in 8% and in 19% of the samples after 12 and 24 weeks, respectively. Enterovirus was detected in 19% of the samples, in 21% and in 12% of samples after 12 and 24 weeks, respectively. Picornavirus positivity correlated with the respiratory symptoms but not with the number of otitis media or with abnormal tympanometry. Two samples were adeno- and three samples influenzavirus positive. Parechovirus and M. pneumoniae were negative in all samples. Rhinovirus positivity correlated with that of M. catarrhalis and S. pneumonia but not with H. influenzae. Microbiological positivity was not significantly associated with the type of day-care.

CONCLUSIONS

Picornaviruses as well as bacteria were commonly found in the nasopharynx of otitis-prone children during the cold season, even in the absence of clinical symptoms.

Severe acute respiratory syndrome coronavirus fails to activate cytokine-mediated innate immune responses in cultured human monocyte-derived dendritic cells

Activation of host innate immune responses was studied in severe acute respiratory syndrome coronavirus (SCV)-infected human A549 lung epithelial cells, macrophages, and dendritic cells (DCs). In all cell types, SCV-specific subgenomic mRNAs were seen, whereas no expression of SCV proteins was found. No induction of cytokine genes (alpha interferon [IFN-alpha], IFN-beta, interleukin-28A/B [IL-28A/B], IL-29, tumor necrosis factor alpha, CCL5, or CXCL10) or IFN-alpha/beta-induced MxA gene was seen in SCV-infected A549 cells, macrophages, or DCs. SCV also failed to induce DC maturation (CD86 expression) or enhance major histocompatibility complex class II expression. Our data strongly suggest that SCV fails to activate host cell cytokine gene expression in human macrophages and DCs.

Sample type is crucial to the diagnosis of Mycoplasma pneumoniae pneumonia by PCR

Sensitive and specific methods for rapid laboratory diagnosis of Mycoplasma pneumoniae were not available until nucleic acid amplification methods were developed. The choice of sample type and method of sampling are crucial to optimal diagnostic efficacy. Three types of respiratory samples from 32 young military conscripts with pneumonia were collected during an outbreak of M. pneumoniae infection. Sputum, nasopharyngeal aspirate and throat swab specimens were tested by 16S rRNA gene-based PCR with liquid-phase probe hybridization, and the results were compared with serology. The PCR result was positive for 22 (69 %) of the sputa, 16 (50 %) of the aspirates and 12 (37.5 %) of the swabs. Serology with increasing or high titres supported the positive findings in all instances. Sputum, when available, is clearly the best sample type for young adults with pneumonia.