[Virologic and epidemiological characteristics of non-polio infection in Croatia over a ten-year period (2000-2009)].

AIM

The aim of the present study was to show the virologic and epidemiological characteristics of non-polio enterovirus (NPEV) infection over a ten-year period in Croatia.

METHODS

During the 2000-2009 period, the Laboratory for Enteroviruses, Croatian Public Health Institute analyzed 2754 clinical samples collected from 1880 patients with a clinical picture of enteroviral infection. The diagnosis of enteroviral infection was confirmed by virus isolation in cell culture. Viruses were typed using indirect immunofluorescence and/or neutralization assay.

RESULTS

NPEV was proven in 394 (21%) of 1880 patients. Males were more commonly infected than females, at a ratio of 1.8:1, while the number of infected cases was highest among preschoolers and schoolchildren. Patients with isolated NPEV were most frequently diagnosed with aseptic meningitis (234/394; 59.4%). Infections were most commonly caused by echoviruses (218/394; 55.3%), followed by Coxsackie B (126/394; 32.0%) and Coxsackie A (31/394; 7.9%) viruses, rarely by echovirus 22 - parechovirus 1 (16/394; 4.1%) and enterovirus 71 (3/394; 0.8%). In most cases, echoviruses of the following serotypes were proven: 6, 9, 11, 13, 14, 18 and 30 (45/218, 21%; 14/218, 6.4%; 18/218, 8.3%; 15/218, 6.9%; 11/218, 5.0%; 55/218, 25.2% and 42/218, 19.3%), while serotypes 2, 3, 4, 5, 7, 12, 20, 21,25 and 26 were evidenced in a minority of patients or individual cases. Coxsackie B5 was the predominant serotype among Coxsackie B viruses (50/126, 40%), while Coxsackie A9 was most common Coxsackie A virus (26/31, 84%). Coxsackie B5 and B4 viruses were continually detected during the study period and appeared more frequently every four to five years. The most common echovirus isolate was echovirus 18, detected continually between 2000 and the outbreak year of 2006. Echovirus 6 and echovirus 30 were also isolated continually with peaks in 2002 and 2008, or 2002, 2006 and 2008.

CONCLUSION

The results of this study pointed to a specific pattern of the occurrence of certain NPEV serotypes in Croatia. The epidemic pattern (echovirus 18 and Coxsackie 81) was characterized by peaks with an elevated number of isolations in given years. Contrary to this, endemic viruses were isolated in similar counts every year (Coxsackie B3), or manifested milder epidemic peaks every few years (echoviruses 30 and 6, Coxsackie B4 and B5). Data on NPEV infections, given their serotype and specific pattern of occurrence, contribute significantly to prompt diagnostic, clinical and epidemiological response to NPEV infections.