To the editor:
A new influenza A strain designated as pandemic H1N1/09 was reported by the World Health Organization in June 2009 and was declared as the first pandemic agent of the 21st century. 1 In Turkey, the Ministry of Health informed the public extensively regarding both the disease and existing vaccination options. The Ministry also prepared services at hospitals in case of a possible outbreak.
Because our clinic was appointed to provide care in the case of a possible outbreak, we wished to determine whether the causative agent in pediatric patients admitted to Istanbul University Cerrahpasa Medical Faculty between November 5, 2009, and March 10, 2010, with flu‐like illness was influenza A (H1N1) or other respiratory tract viruses. In our study, influenza A (H1N1) and other respiratory tract viruses (adenovirus, coronavirus 43, coronavirus 229, metapneumovirus, parainfluenza 1‐3, respiratory syncytial virus (RSV) A, RSV B, rhinovirus) were investigated by testing 187 nasal and nasopharyngeal secretions, taken from 182 patients, using Multiplex polymerase chain reaction (M‐PCR) (Seeplex RV 12 ACE Detection; Seegene, Seoul, South Korea). Multiplex PCR was performed using a dual priming oligonucleotide (DPO) system, and the results were analyzed in 2% agarose gel.
The average patient age was 3·22 and the range was 2 months–16 years old. Of a total of 139 samples, 84 samples contained one, 23 samples contained two, and three samples contained three different viruses. The following agents were found from positive samples: influenza A (H1N1) (63/45·3%), parainfluenza 3 (18/13%), rhinovirus (16/11·5%), coronavirus 229 (8/5·8%), RSV A (7/5%), RSV B (7/5%), parainfluenza 1 (6/4·3%), adenovirus (5/3·6%), parainfluenza 2 (5/2·9%), metapneumovirus (4/2·9%), and coronavirus 43 (1/0·7%) (Figure 1). In addition to flu‐like illness symptoms, 31·2% of the virus‐positive patients had findings of bronchiolitis and 6·3% had a previous diagnosis of asthma and presented with an attack of asthma.
Figure 1.
Quantity and frequency of viruses found in nasopharyngeal swab.
Carhan et al. 2 analyzed 1157 samples from nine different provinces in their surveillance studies between November 2007 and May 2008. Of the 1157 samples, 337 samples tested positive. The ratios were influenza A (55·8%), influenza B (26·1%), parainfluenza (8%), adenovirus (7·1%), RSV A (3%), and RSV B (3%). These ratios were obtained 2 years before the pandemic. However, they are similar to the ratios we have found during the pandemic.
In 2009, a Greek study on viruses causing influenza‐like illness, using different methods, tested 58 patients from three centers. Their results showed the following incidences and ratios: 39 cases of rhinovirus (67%), 15 cases of adenovirus (26%), 11 cases of influenza virus (19%), 6 cases of coronavirus (10%), three cases of parainfluenza virus (5%), and one case of bocavirus (2%). 3 In the study, the highest detection ratio was in samples obtained by nasal washing. In Spain, 183 pharyngeal swabs were tested from patients with an influenza‐like disease during the 2007–2008 and 2008–2009 seasons. These swabs were analyzed with multiple rt‐PCR, and the ratios were found as follows: influenza A (49%), influenza B/C (29%), RSV A/B (3%), and adenovirus (6%). 4
Influenza A has often been the most frequently detected agent in influenza‐like illness in children and adults prior to 2009. During the 2009–2010 pandemic period, in our study, it was found that other viruses (54·7%) caused influenza‐like illness in children rather than influenza A (H1N1) (45·3%). According to Casalegno et al. 5 , in the 2009–2010 pandemic season, RSV was more frequently seen only after the new influenza (H1N1) A virus had disappeared, as seen in our patients (Figure 2).
Figure 2.
Temporal distribution of influenza (H1N1) A virus and respiratory syncytial virus (RSV) diagnosis.
The last pandemic season reminds us that during the winter season, in addition to influenza A, other significant respiratory viruses should not be overlooked.
Conflict of interest
None declared.
References
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