Page 27 - Epidemiological studies on tuberculosis control and respiratory viruses

Distribution of respiratory viruses by illness severity in adults
2011 until and including March 2013, 100 symptomatic and 100 asymptomatic participants were randomly selected from each ethnic group. Participants were defined as ‘symptomatic’ if they reported at least either a runny nose or both fever and cough on the day of sample collection, irrespective of the presence of symptoms in the 2 weeks preceding sample collection. Participants were defined as ‘asymptomatic’ if they had none of the seven symptoms on the day of sample collection or in the 2 weeks preceding that day.
Patients presenting at the hospital
At the AMC, a tertiary referral centre which also provides non-tertiary care for the local area, nasopharyngeal samples are routinely collected and analysed in real time from patients clinically suspected of respiratory tract infections who are presenting at outpatient clinics or are admitted to the hospital. Types of flocked swabs and collection medium as well as the multiplex RT-PCR platform used for these routine diagnostics are identical to those used in the HELIUS population. Demographic variables and RT- PCR test results are registered in electronic registration and laboratory systems.
Anonymized demographic data and diagnostic results of patients aged ≥18 years with a clinical suspicion of respiratory tract infection, and sampled during the influenza seasons of the years 2011, 2012 and 2013, were included in the analysis.
Virological assay
Extraction of nucleic acids from 200 μl of viral transport medium was performed by 6 MagNA Pure extraction using the total nucleic acid extraction kit (Roche Diagnostics,
Penzberg, Germany). The presence of viral pathogens in samples was detected by
multiplex reverse transcriptase RT-PCR as previously described [5]. Respiratory viruses
detected in this assay included: rhinovirus (RV; A, B, and C), human coronavirus (hCoV: HKU1, NL63, 229E and OC43), influenza A virus (InfA), respiratory syncytial virus (RSV; A and B), influenza B virus (InfB), enterovirus (EV), adenovirus (AdV), human metapneumovirus (hMPV), parainfluenza viruses (PIVs 1, 2, 3, 4), human bocavirus (hBoV) and parechovirus (PeV).
The crossing point (Cp) value, reflecting the cycle at which a positive PCR signal is detected, was calculated using LC480 software (Roche Diagnostics, Penzberg, Germany). It was used as an approximation of the amount of viral nucleic acids
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