MMWR

Morbidity and Mortality Weekly Report

False-Positive Results with a Commercially Available West Nile Virus Immunoglobulin M Serologic Assay Kit – United States, 2008

Press Contact: CDC Division of Media Relations
Phone: (404) 639-3286

This investigation determined that use of one commercially available WNV IgM ELISA kit lot at four laboratories in the United States produced a substantial number of false-positive test results and impacted the number of WNV disease cases reported to ArboNET for 2008. Commercially available ELISA tests help provide a presumptive diagnosis of WNV neuroinvasive disease; any positive result should be confirmed by additional testing at a state health department or CDC. A multistate investigation into an increased number of false-positive West Nile virus (WNV) results obtained with a commercially-available WNV IgM ELISA identified one test kit lot as the source of the problem. The lot was subsequently recalled. Starting July 2008, the affected lot was used by four laboratories resulting in positive tests from 518 patients in 42 states. Retesting of available samples established a 72 percent false-positive rate. The majority of false-positive samples were from individuals without symptoms of neuroinvasive disease. The kit was labeled for use on serum to aid in a presumptive diagnosis of WNV neuroinvasive disease. The indicated use of commercially-available kits should be considered when requesting testing and interpreting results; positive results should be confirmed at a state health department or CDC.

Assessment of Body Mass Index Screening of Elementary School Children – Florida, 2007-2008

Florida Department of Health
Communications Office
(850) 245-4111

Body mass index (BMI) screening activities need improvement in policy and guideline development, training procedures, appropriate selection and use of equipment, and use of electronic data systems before Florida establishes a more extensive statewide surveillance system. The prevalence of childhood obesity has increased substantially in the United States and is associated with chronic diseases. State level surveillance is needed to monitor trends, investigate risk factors, and inform communities regarding childhood obesity. Florida Department of Health considered establishing a more extensive statewide BMI surveillance system using existing school-based BMI screening activities. Among 66 counties that provided complete surveys, 58 (88 percent) screened ≥75 percent of children in the first, third, and sixth grades, and 51 (77 percent) had written protocols or guidelines for measuring weight, height, or BMI. Nineteen counties (29 percent) were training ≥90 percent of screeners, and 21 (32 percent) consistently used appropriate equipment for measuring height and weight. Thirty-one counties (47 percent) used appropriate electronic systems to calculate BMI percentile-for-age.

Primary and Secondary Syphilis – Jefferson County, Alabama, 2002-2007

Press Contact: National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention
Phone: (404) 639-8895

A CDC investigation into increases of primary and secondary (P&S) syphilis cases in Jefferson County, Ala. between 2002 and 2007 shows sharp increases in annual new infections among heterosexuals – a population previously with declining rates of infection. Increased U.S. syphilis rates since the early 2000s have been associated primarily with transmission among men who have sex with men (MSM). CDC’s investigation found that between 2002 and 2004, MSM accounted for almost half (46.3 percent) of all new syphilis cases in Jefferson County, which includes Birmingham. However, between 2005 and 2007, heterosexuals accounted for a majority (87.7 percent) of all new infections in Jefferson County, while MSM accounted for only 12.3 percent. Overall cases increased from 9 in 2002 to 238 in 2006, then slightly down to167 in 2007. During this period, the proportion of cases among women increased from 26.9 percent to 43.3 percent. Nationally, P&S syphilis cases among women throughout the Southern United States have increased by 69 percent from 2003 to 2007 after more than 10 years of decline. The authors advise public health officials to remain alert for potentially similar re-emergence of syphilis among women and heterosexual men in other areas of the United States.

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES