Enterovirus Season and Aseptic Meningitis Clusters: It’s That Time of Year

Indiana Epidemiology Newsletter
September 2007

Wayne Staggs, MS
Invasive Disease Epidemiologist

Sandra Gorsuch, MS
Field Epidemiologist, District 5

Aseptic meningitis is an illness characterized by typical meningeal symptoms including sudden onset of fever, headache, stiff neck, malaise, nausea, confusion, and photophobia. It is usually accompanied by an increased number of lymphocytes in the cerebral spinal fluid (CSF). The illness is usually mild and self-limiting; however, some cases can be severe and life threatening. Viral meningitis is the most common type of aseptic meningitis. Coxsackieviruses and echoviruses, members of the enterovirus family, account for about 90 percent of viral meningitis cases.

Aseptic meningitis can occur sporadically and as outbreaks, with outbreaks normally occurring during the enteroviral season, which runs from July through October. In 2005 and 2006, the highest incidence of aseptic meningitis occurred during the month of September (see Figure 1).

Two small clusters of viral meningitis have occurred in Indiana counties in recent weeks:

  • Five cases have occurred in County A, four of which had onset dates ranging from August 27-31. Ages of these cases range from 9 days to 13 years. Three cases attend schools in the same school district. A fourth case has an epidemiologic link to the school-age cases. Two cases have tested positive for entero-like viruses, and further subtyping of these isolates is being conducted at the Centers for Disease and Control and Prevention (CDC) Laboratory. The fifth case, an infant with onset on September 9, has no identified link to the other four cases.

  • Seven cases have occurred in County B with onsets ranging from September 4-20. Ages of the cases range from 10 to 15 years. Two school districts had three cases each. The seventh case has no identified link to the other cases. None of these cases has been confirmed as enteroviral, but laboratory tests are pending on some individuals.

Populations that appear to be more susceptible to viral meningitis include children and elderly persons who interact or live in group settings. Fall sports teams may be at increased risk, because the season coincides with the enteroviral peak period and the likelihood of athletes sharing water bottles and having close contact with each other.

Transmission of aseptic meningitis is primarily the fecal-oral route, but infection can also be transmitted by respiratory droplets and fomites. Adherence to good hygienic practices, such as frequent and thorough hand washing (especially after diaper changes), disinfection of contaminated surfaces by household cleaners (e.g., diluted bleach solution), and avoidance of shared utensils and drinking containers, are recommended to interrupt transmission. More information on hand-washing and proper hand washing techniques can be found on the Indiana State Department of Health (ISDH) Web site at: http://www.in.gov/isdh/healthinfo/handwashing.htm. A quick fact sheet on aseptic meningitis can be found at http://www.in.gov/isdh/healthinfo/viral%20meningitis.htm.

The ISDH Laboratory is available for enteroviral testing in outbreak situations. Viral culture testing in outbreak situations will assist the ISDH and local health departments in determining whether a case may be a part of a cluster or outbreak. Stool or rectal swabs are the preferred specimens; enteroviruses may also be recovered from throat specimens and CSF fluid. The ISDH Laboratory will accept specimens for testing from any of these sources. If throat or CSF specimens are submitted, the ISDH Laboratory would prefer that stool or rectal swabs also be collected. Specimen collection kits may be obtained by contacting the Containers Section, ISDH Laboratory, at:

Clinical Containers
Indiana State Department of Health (ISDH) Laboratories
550 West 16th Street, Suite B
Indianapolis, IN 46202
(317) 921-5500
Specimens should be submitted to the ISDH Laboratories at:

Indiana State Department of Health Laboratories
550 West 16th Street, Suite B
Indianapolis, IN 46202

For questions regarding aseptic meningitis, please contact Wayne Staggs, ISDH, 317-234-2804; or your local health department.