Minnesota Department of Health (MDH) Bug Bytes
October 31, 2002
Vol. 3: No. 13
1. Wash Your Hands
Dr. Julie Gerberding, Director of the CDC, said it best, " Hand hygiene saves lives." Last week, the CDC released the "Guideline for Hand Hygiene in Health-Care Settings" (at http://www.cdc.gov/handhygiene/).
A focus of the new guideline is the recommendation for the use of alcohol-based hand rubs as the primary hand hygiene tool in healthcare settings. Alcohol-based hand rubs are recommended as the routine method to clean hands, except when hands are visibly soiled. The use of alcohol-based hand rubs has been found to increase adherence to hand hygiene practices and may ultimately improve patient safety by reducing rates of healthcare-acquired infections. Alcohol hand rubs are more effective at reducing bacterial counts on the hands than either plain or antimicrobial soaps, can be made more accessible than sinks and other handwashing facilities, take less time to use, and cause less skin irritation and dryness than soap and water handwashing.
Additional recommendations on related issues (e.g., the use of surgical hand antiseptics, hand lotions or creams, and wearing of artificial fingernails) are also included in the guideline.
2. West Nile Virus Season Ends
We have now reached the end of the 2002 mosquito season in Minnesota, and as such the risk of West Nile Virus (WNV) infection has ended until next year. During 2002, in addition to documenting a large WNV epizootic in horses (963 cases) and wild birds (318 tested positive from a convenience sample tested), 41 human WNV cases were reported in Minnesota (a map of cases is at www.health.state.mn.us/divs/idepc/
diseases/westnile/). Twenty-seven (66%) were male and 14 (34%) were female, with a median age of 48 years (ranging from 4 to 85). Of the human cases, 27 (59%) were hospitalized, for a duration of 1 to 40 days. Twenty-four (59%) case-patients had fever, 9 (22%) encephalitis, 7 (17%) aseptic meningitis, and 3 (7%) acute flaccid paralysis (AFP). Fortunately, there were no fatalities. All of the hospitalized patients have now been discharged; however, most of the encephalitis and AFP cases required extensive post-hospitalization rehabilitation. Two patients who were hospitalized mid- to late-August are still in long-term rehabilitation facilities. None of our cases acquired their infection from a blood transfusion or organ transplant.
We received over 1,000 blood and CSF samples from 850 patients for WNV testing, and many more were performed at private commercial laboratories. Interpretation of serology results has raised questions within both the medical and the public health community. To maintain uniformity, all state health departments and the CDC use the antibody-capture ELISA to look for the presence of IgM and IgG in serum or CSF. IgM levels rise within 2-3 days of illness onset and stay elevated for at least 2-3 months in infected persons before starting to decline. Elevated IgM levels have been detected as far out as 18 months after acute infection. IgG levels start to rise within 3-4 weeks of illness onset, and theoretically should remain elevated indefinitely. The purpose of obtaining acute and convalescent titers is to longitudinally "map-out" the IgM/IgG response in order to look for a four-fold or greater rise in titer.
To be considered as having a current/recent infection, the patient must demonstrate the presence of an elevated IgM (alone or plus IgG) in the blood or CSF. Patients with IgG elevations but not IgM should not be considered cases of current/recent infection. Isolated IgG elevations can be evidence of remote infection, but since widespread exposure to WNV was previously not an issue, they are more likely to be a cross-reaction with non-specific antibodies. Yellow fever or Japanese encephalitis vaccination, or previous infection with other flaviviruses such as St. Louis encephalitis virus, may cause a false-positive IgG elevation.
The latest date of illness onset for a human case in Minnesota was September 28. With the arrival of frost and the disappearance of mosquitoes, we do not expect any new WNV cases until next summer, unless the patient has traveled to other endemic areas where mosquitoes are still active.
3. Conference Reminder
There's still time to register for our "8th Annual Emerging Infections in Clinical Practice and Emerging Health
Threats Conference." If not for the great topics such as E. coli O157:H7, antibiotic resistance, pneumococcal disease, and bioterrorism, come for all the free stuff we'll be giving out! Registration is available through University of Minnesota Continuing Medical Education. Call 612 626-7600 or 1-800-776-8636 or access the conference brochure and registrations materials at http://www.med.umn.edu/cme/brochures2002/
Bug Bytes is a combined effort of the Infectious Disease Epidemiology, Prevention and Control Division and the Public Health Laboratory Division of MDH. We provide Bug Bytes as a way to say THANK YOU to the infection control professionals, laboratorians, local public health professionals, and health care providers who assist us.
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