respiratory specimens from 2 groups of children ( all < 2 years of age ) were collected in 2004 and screened for kiv and wuv . the first group comprised symptomatic children whose respiratory specimens were submitted to the clinical virology laboratory , yale  new haven hospital , new haven , connecticut . these respiratory specimens tested negative for respiratory syncytial virus ( rsv ) , parainfluenza viruses ( types 13 ) , influenza viruses a and b , and adenovirus by direct fluorescence antibody assay . the second group comprised asymptomatic children at the hospital - affiliated pediatric clinic for well - child care . nucleic acids were extracted from each specimen by using qiaamp nucleic acid purification kits ( qiagen , valencia , ca , usa ) . samples were screened by nested pcr for both kiv and wuv ( for wuv , the first primers were those used by gaynor et . any child who had multiple specimens with positive results was included once in the total number of children whose specimens tested positive for a given virus . specimens from symptomatic children who tested positive for kiv or wuv were also screened for human bocavirus ( hbov ) ; human metapneumovirus ( hmpv ) ; human coronaviruses ( hcov ) 229e , nl63 , and hku1 ; and human picornaviruses ( including rhinoviruses [ hrv ] ) by using previously described methods ( 612 ) . to screen for human parainfluenzavirus type 4 and hcov oc43 , rna extraction and reverse transcription were performed as previously described ( 7 ) . the primers used to amplify hpiv4 were 5-gcgagaggatccagctggtggc-3 and 5-gcgccctaatctttcctgttgatgg-3. the primers for hcov - oc43 were 5-gcataagccccgccagaagaggag-3 and 5-gcgctgacgctgtggttttggact-3. we tested 423 direct fluorescent antibody  negative respiratory specimens , from 367 children , for kiv and wuv . of the 367 symptomatic children , there were 8 ( 2.2% ; 95% confidence interval [ ci ] 1.0%4.3% ) whose specimens tested positive for kiv and 26 ( 7.1% ; 95% ci 4.7%10.2% ) whose specimens tested positive for wuv . none ( 0% ; 95% ci 0%4.0% ) of the 96 specimens from asymptomatic children tested positive for kiv . specimens from six ( 6.3% ; 95% ci 2.3%13.1% ) of the 96 asymptomatic children tested positive for wuv . the odds ratio for the proportions of symptomatic and asymptomatic children positive for wuv was 1.14 ( 95% ci 0.462.86 ; p = 1.0 , fisher exact test ) . the odds ratio for the proportions of symptomatic and asymptomatic children positive for kiv is undefined ( none of the specimens from children in the asymptomatic group tested positive ) . the distribution of number of samples screened per month was similar for the asymptomatic and symptomatic groups . the monthly distribution of children positive for kiv or wuv is shown in figure 1 . the age distribution of kiv- and wuv - positive children is shown in figure 2 . monthly distribution of children positive for ki virus ( kiv ) and wu virus ( wuv ) . the wuv - positive children include both asymptomatic and symptomatic children whose specimens tested positive for wuv . one child who tested positive for wuv in february and march is represented in both months . age distribution of children positive for ki virus ( kiv ) and wu virus ( wuv ) . one child whose specimens tested positive at age 6 months and again at age 9 months is represented in both age groups . viral co - infection was detected in 2 ( 25% ) of the 8 kiv - positive specimens ; 1 specimen tested positive for both hbov and hmpv , and the other tested positive for hbov . of the 6 kiv - positive children whose specimens tested negative for other respiratory viruses , all had evidence of respiratory tract disease or fever . viral co - infection was detected in 13 ( 50% ) of the 26 wuv - positive symptomatic children ; 7 ( 26% ) were positive for hmpv , 4 ( 15% ) for hrv , 2 ( 7% ) for hcov - nl63 , and 2 ( 7% ) for hbov . two wuv - positive specimens tested positive for both hmpv and hbov . of the 13 wuv - positive children whose specimens tested negative for the other respiratory viruses , 12 had records available for review . one female child had end - stage pulmonary hypertension , and it was unclear whether her respiratory distress was due to worsening pulmonary hypertension or an infectious process . respiratory distress developed in a male child after suspected aspiration ; his symptoms resolved within 6 hours . three of the wuv - positive children had been hospitalized since birth ; specimens from 1 of these children tested positive for wuv on 2 occasions . the interval between the first and second specimen was 98 days , and during that time 3 other specimens from this child tested negative for wuv . the child was hospitalized throughout this period and received mechanical ventilation for chronic lung disease . this child and 2 others were hospitalized in the same respiratory care unit at the time of wuv detection . another child whose specimens tested positive for wuv had recently been discharged from that respiratory care unit . of 25 wuv - positive children whose records were available for review , 11 ( 44% ) had underlying illnesses . of the 6 asymptomatic children whose specimens tested positive for wuv , 1 had a history of prematurity and the other 5 had no underlying illnesses . we detected kiv and wuv in respiratory samples obtained from children in connecticut in 2004 . the rates of detection for the symptomatic children in our study are similar to those observed in prior studies ( 1,3,4 ) . as in studies by others however , it is possible that subclinical infection with kiv occurs and that we failed to detect any cases because of the low prevalence of kiv in our study population . our study had only 15% power to detect a difference between 2.2% and 0% for kiv , whereas it had adequate power ( 90% ) to detect a difference between 7.1% and 0% for wuv . co - infection with other respiratory viruses was a common finding in both kiv- and wuv - positive children . because specimens from symptomatic children were tested for common viruses by antigen testing rather than pcr , which is presumably more sensitive , the co - infection rate could , in fact , be greater . the high rates of co - infection observed in our study and the studies of others support the notion that kiv and wuv may not cause respiratory tract disease . however , kiv or wuv was the only virus detected for a small number of children with evidence of respiratory tract disease , so it is still possible that these viruses contribute to respiratory tract disease in susceptible children . detection of wuv in 3 patients hospitalized since birth suggests the potential for nosocomial , congenital , or perinatal infection . le et al . recently reported detection of wuv in multiple samples obtained from 2 immunocompromised patients ( 13 ) . , we have established that 2 recently discovered polyomaviruses , kiv and wuv , are circulating in connecticut . because of the high rates of viral co - infection and detection of wuv in both asymptomatic and symptomatic children , these viruses may not be respiratory pathogens .
ki virus was detected in respiratory secretions of 8/367 ( 2.2% ) symptomatic and 0/96 asymptomatic children ( p = 0.215 ) . 
 wu virus was detected in 26/367 ( 7.1% ) symptomatic and 6/96 ( 6.3% ) asymptomatic children ( p = 1.00 ) . 
 these human polyomaviruses may not independently cause respiratory tract disease in young children .