Correspondence

International Journal of Infectious Diseases (2008) 12, e129—e130

http://intl.elsevierhealth.com/journals/ijid

CORRESPONDENCE

Detection of influenza C during an outbreak infectious doses for influenza A and influenza B viruses, and between 1 and 10 molecules of cloned amplified products of at an internal school, using a molecular tool; 5 Havana, Cuba, September 2006 influenza C virus, RSV A, RSV B, and adenovirus. Of the 16 samples tested, we obtained four positive for Influenza C virus usually causes a mild upper respiratory influenza C (25%). In individuals positive for influenza C virus, illness,1 but can also cause lower respiratory infections, such the predominant symptoms were arthralgia (75%), fever as bronchiolitis and pneumonia.2 Seroepidemiological studies (75%), cough (50%), acute rhinorrhea (50%), and sore throat have revealed a wide distribution of influenza C virus (50%); Table 1. We did not find evidence of any co-infections, throughout the world.3,4 however we did detect co-circulation with rhinovirus (13%) in At the end of September 2006, the health authorities in two patients. This is the first report from Cuba of an influenza Cuba detected an increase in acute respiratory infections at C outbreak causing respiratory symptoms. one internal school located in Arroyo Naranjo, a peripheral During the influenza season particular attention is paid to municipality of Havana City. influenza A and B virus isolates, as well as serology and In order to detect virus in nasopharyngeal swabs, a multi- molecular studies. However,during the winter,infection with plex nested reverse transcription-polymerase chain reaction influenza C virus may coincide with influenza A (H3N2 and 6,7 (RT-PCR) was employed that is able to detect respiratory H1N1) and influenza B virus activity. syncytial virus (RSV) A, RSV B, adenovirus, influenza A virus, There have been several earlier reports of influenza C influenza B virus, and influenza C virus in clinical samples outbreaks occurring in closed environments such as military 8,9 (previously described by Coiras et al. in 20035). Primers encod- induction camps, hospitals, and children’s homes. People ing the nucleoprotein segment of influenza virus, the fusion infected with influenza C virus may exhibit symptoms with a protein of RSV, and the hexon gene of adenovirus were used. severity similar to that caused by influenza A and B virus To avoid false negative results due to specimen inhibitors infections. It is important to gain better understanding of the or extraction failure, an internal amplification control was epidemiology of this virus with regular surveillance to deter- 10 included in the reaction mixture. The sensitivity achieved in mine its exact role in acute viral respiratory infections. this reaction ranged between 0.1 and 0.01 50% tissue culture Conflict of interest: No conflict of interest to declare.

Table 1 Clinical data for four patients with inﬂuenza C; Cuba, 2006

Patient Age Gender Days from onset Signs and Inﬂuenza C detection Co-infections (years) of symptoms to symptoms by multiplex sampling date nested RT-PCR 1 14 M 1 Fever, cough + None detected 2 15 F 3 Fever, cough, + None detected headache, arthralgia 3 38 M 1 Fever, arthralgia, + None detected sore throat, rhinorrhea 4 16 F 1 Sore throat, + None detected arthralgia, rhinorrhea RT-PCR, reverse transcription-polymerase chain reaction.

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