Content Information
A. Purpose of Surveillance and Reporting
- To identify cases of WNV infection to understand the epidemiology of this emerging disease in our area.
- To identify locally acquired cases of LaCrosse infection in humans to better understand the local epidemiology of LaCrosse virus.
- To help target mosquito control measures.
- To identify cases of other arboviral infections (e.g., California encephalitis, St. Louis encephalitis) in Iowa residents or visitors to determine whether they are imported or locally acquired.
- To provide residents of Iowa and travelers to the state with appropriate preventive health information.
B. Laboratory and Healthcare Provider Reporting Requirements
Iowa Administrative Code 641-1.3(139) stipulates that the laboratory and the healthcare provider must report. The preferred method of reporting is by utilizing the Iowa Disease Surveillance System (IDSS). However, if IDSS is not available, the reporting number for IDPH Center for Acute Disease Epidemiology (CADE) is (800) 362-2736; fax number (515) 281-5698, mailing address:
Iowa HHS, CADE
Lucas State Office Building, 5th Floor
321 E. 12th St.
Des Moines, IA 50319-0075
Postage-paid disease reporting forms are available free of charge from the clearinghouse. Call (319) 398-5133.
If the patient is hospitalized at the time of diagnosis, the hospital’s Infection Preventionist (IP) may need to assist with the investigation.
Laboratory Testing Available
Arboviral Infections (WEE, EEE, SLE, WNV) The University of Iowa State Hygienic Laboratory (SHL) performs antibody detection for arboviral infections (SLE, WEE, EEE) using immunofluorescent assay (IFA) methods and will be performed on specimens submitted for the arboviral panel and are negative for WNV IgM. Single acute sera are tested for the presence of IgM antibodies to arboviruses and, if found, usually indicates recent infection. IgG testing is not routinely performed unless indicated by case. Confirmatory testing, if indicated, is performed at CDC. Accurate information about date of specimen collection, date of onset of symptoms, travel history, vaccination and disease history are helpful for test result interpretation. For information on specimen submission and testing, contact SHL at (319) 335-4500. Additional information, test request forms, and sample collection instructions can be found at the SHL web site at: www.shl.uiowa.edu/
West Nile Virus
The University of Iowa State Hygienic Laboratory (SHL) performs antibody detection for West Nile virus using enzyme immunoassay (EIA) methods. This method will be performed on all specimens submitted for WNV testing. Single acute sera and cerebrospinal fluid (CSF) are tested for the presence of IgM antibodies. WNV antibodies develop soon after onset and peak around 8 day, therefore, sera and CSF collected 5-10 days post onset are ideal specimens for testing. The presence of IgM antibody usually indicates recent infection by this virus; however, it has been shown that IgM antibodies to WNV may persist for many months after onset. IgG testing is not routinely done. Confirmatory testing, if indicated, is performed at CDC. Accurate information about date of specimen collection, date of onset of symptoms, travel history, vaccination and disease history are helpful for test result interpretation. For information on specimen submission and testing contact SHL at (319) 335-4500. Additional information and test request forms and sample collection instructions can be found at the SHL web site at: www.shl.uiowa.edu/
C. Local Public Health Agency Responsibilities
1. Reporting Requirements
IDPH stipulates that local public health agencies (LPHA) must report the occurrence of any case of arboviral encephalitis.
2. Case Investigation
LPHAs may initiate the follow-up on reported cases of arboviral encephalitis. Due to the significant morbidity and mortality associated with symptomatic illness individuals are likely to be hospitalized at the time of diagnoses. The LPHA should work with the infection preventionist (IP) at the hospital to complete the Iowa Disease Surveillance System (IDSS) investigation concerning WNV. Epidemiologists with IDPH/CADE are available 24 hours a day to provide assistance and consultation regarding case investigation. Please contact IDPH/CADE at (800) 362-2736 with any questions.
- Case investigation of arboviral encephalitis in Iowa residents will be directed by the LPHA.
The LPHA may be asked to assist in completing an IDSS arbovial encephalitis case followup by interviewing the case and others who may be able to provide pertinent information. Most of the information required can be obtained from the patient, healthcare provider, or the medical record.
- It is preferred to use IDSS to report cases and submit followup information. If IDSS is unavailable, print and complete the IDSS form and fax or mail (in an envelope marked “Confidential”) to IDPH Center for Acute Disease Epidemiology. The confidential fax number is (515) 281-5698. The mailing address is:
Iowa Department of Public Health, CADE
Lucas State Office Building, 5th Floor
321 E. 12th Street
Des Moines, IA 50319-0075
- Institution of disease control measures is an integral part of case investigation. It is the LPHA responsibility to understand, and if necessary, institute the control guidelines listed below in Controlling Further Spread.