A report in Eurosurveillance Weekly in September 2001 discussed the concurrent increases in the incidence of echovirus 30 in Germany and the United Kingdom in 2001 (1). Outbreaks of echovirus 13 infection had also occurred in both England and Wales, and Germany, in 2000. Other European countries informed the Eurosurveillance team that they had experienced similar outbreaks, and it was decided to conduct a small study through Eurosurveillance of echovirus incidence in European and other countries.

Results

The table shows the number of cases of echoviruses 13 and 30 in 2000 and 2001 reported by various countries.

Echovirus 30

This is one of the commoner echovirus types isolated by laboratories, and outbreaks occur every few years. Echovirus 30 caused outbreaks in France, Iceland, Kosovo, and the Netherlands in 2000, and in England and Wales, Scotland, Germany, and Ireland in 2001. Smaller outbreaks heralded these in 2000 in England and Wales, Scotland, and Germany. In England and Wales, previous echovirus 30 outbreaks occurred in 1996, and in Germany in 1997.

Ireland reported an increase in the incidence of echovirus 30 beginning in 2000, with the number of cases peaking between May and July 2001. Most isolations were associated with a clinical diagnosis of viral meningitis, and the virus was isolated from adults and children. The last time an increase in the number of cases of echovirus 30 infection was noted in Ireland was 1996. Echovirus 6 and echovirus 33 were also prevalent in Ireland in 2000.

In Iceland, an outbreak of aseptic viral meningitis between September 2000 and January 2001 was attributed mainly to echovirus 30. Of 63 isolates of this virus between September and December 2000, 52 were isolated from cerebrospinal fluid (CSF). Echovirus 6 and echovirus 7 were other enteroviruses isolated in Iceland during this period.

In France in 2000, echovirus 30 accounted for 41% of the 1262 enteroviruses identified.

In Belgium, as in many other European countries, echovirus 30 is one of the most common enterovirus types and accounted for 43 of 84 cases of lymphocytic meningitis tested by the laboratory in 2001. Echovirus 6 accounted for 17 cases and echovirus 13 for two cases.

Findings from the Finnish virology laboratories show only two echovirus isolations during the past two years.

In the Netherlands, of 1215 enterovirus isolates in 2000, 120 (10%) were echovirus 30. The peak of all enterovirus activity (including echovirus 30) in the Netherlands was June/July in 2000.

The Rijksinstituut voor Volksgezondheid en Milieu in the Netherlands (RIVM, National Public Health Institute) was alerted by the World Health Organization of several patients with meningitis in Kosovo, all of whom were admitted to hospital for a short period around September/November 2000. Echovirus 30 was considered to be the cause of the epidemic as this enterovirus was found in 80% of the samples of CSF taken from these patients.

The RIVM carries out all the enterovirus work (including polio) for Turkey. The institute reported that the data in the table for Turkey came mainly from cases of acute flaccid paralysis and their contacts. A great diversity of enteroviruses was isolated, but, given the small number of enterovirus isolations, no particular serotype was identified as predominant.

Echovirus 13

This virus is one of the less commonly isolated echovirus types. In England and Wales, in the 10 years from 1990 to 1999, of a total of 4405 echoviruses isolated and typed, 25 (0.02%) were found to be type 13.

Echovirus 13 caused outbreaks in England and Wales, Scotland, Ireland, Germany, France, and the Netherlands in 2000. In Germany in 2001 the number of identifications of this virus more than doubled that in the previous year. Another small outbreak occurred in the Netherlands where this virus accounted for 31 of 473 (7%) enteroviruses isolated in 2001. Compared with 2000, peak enterovirus activity in 2001 was about three months later.

In France, the echovirus 13 outbreak accounted for 32.1% of the 1262 enteroviruses identified. In the Netherlands, the number of isolations of echovirus 13 peaked in October in 2000 and in September and October in 2001.

Outside Europe

There have also been reports of echovirus 13 and echovirus 30 in Australia and the US (2-4). In the US, 76 cases of echovirus 13 infection were reported between January and August 2001. Before this, this enterovirus was rarely detected, accounting for only 65 of the 45 000 enterovirus isolates reported to the Centers for Disease Control and Prevention (CDC) between 1970 and 2000 (2). In Western Australia, a community enterovirus surveillance project undertaken between March and July 2001 identified echovirus 13 in a large proportion of the children. A large seasonal outbreak of aseptic meningitis occurred concurrently with the surveillance project, with about 60 children admitted to hospital who met the case definition of lymphocytic meningitis. Echovirus 30 was the predominant serotype isolated from the CSF or throat swabs (12 of 21 isolates) of cases of aseptic meningitis, although four cases were identified as due to echovirus 13. Neither echovirus 30 nor 13 had been identified from cases of aseptic meningitis in Western Australia in the four years preceding the 2001 season (3). Before this year, echovirus 13 had been rarely isolated in New South Wales (NSW) and the Australian Capital Territory (ACT), but an increase in cases of echovirus type 13 was reported in the first seven months of 2001. This occurred in the context of very high non-polio enteroviral activity in 2001 (4).

Table. Incidence of echoviruses 13 and 30 in 2000-2001

The data reported in this table were provided voluntarily by laboratories in various countries and are not complete or representative.

Conclusion

This data compilation suggests that outbreaks of specific echovirus types are more widespread than previously realised. Outbreaks may occur not only in several countries within one continent, but also in different continents – for example, echovirus 13, a rare echovirus type, seems to have caused outbreaks in the US, Australia, and Europe. In light of this, other countries experiencing recent or current epidemics of this kind are encouraged to contact Franky Lever (flever@phls.org.uk), who will be investigating enterovirus incidence in more detail as part of a master’s thesis.

We are grateful to the following for providing data.

Gráinne Tuite (grainne.tuite@ucd.ie), Virus Reference Laboratory, University College Dublin, Ireland; Véronique Pavec (Veronique.Pavec@scieh.csa.scot.nhs.uk), EPIET fellow, Scottish Centre for Infection and Environmental Health, Glasgow, Scotland; Harrie van der Avoort (Harrie.van.der.Avoort@rivm.nl), on behalf of the Dutch Clinical Virology Group, Netherlands; Hanne Vestergaard (HVS@ssi.dk), Department of Virology, Statens Serum Institut, Copenhagen, Denmark; Gudrun Baldvinsdóttir (geb@landspitali.is), Department of Medical Virology, Landspitali University Hospital, Reykjavik, Iceland; Eckart Schreier (SchreierE@rki.de), Sabine Diedrich, Nationales Referenzzentrum für Poliomyelitis und Enteroviren, Robert Koch-Institut, Berlin, Germany; Marc Van Ranst (Marc.VanRanst@uz.kuleuven.ac.be), Laboratory of Virology, University of Leuven, Belgium; and Denise Antona (d.antona@invs.sante.fr), Unité des Maladies Infectieuses, Institut de Veille Sanitaire, France and Bruno Lina (lina@univ-lyon1.fr), Centre national de référence pour les entérovirus, on behalf of the French Network for Enteroviruses Surveillance, France.