Updates
Updates by Carol A. Kemper, MD, FACP
Fears of West Nile Virus Displace Olympic Dressage
Source: Media site, March 23, 2000; [email protected].
Concerns regarding the risk of West Nile Virus (WNV) infection along the East Coast have prompted officials to relocate the U.S. Olympic dressage trials from New Jersey to Florida. The trials were originally scheduled for mid-May at the U.S. equestrian team headquarters. The possible persistence of WNV identified in dormant mosquitoes that survived the winter in underground structures in New York City cinched the decision. (See, Kemper CA. Infect Dis Alert 2000;19:104.) In addition, horses that have been training in New Jersey may be restricted from traveling to Europe for the semi-finals, which would eliminate them from Olympic competition in Sydney in September.
Meningococcus W-135 in Mecca
Source: ProMED-mail post, March 26-April 28, 2000; www.promedmail.org.
Numerous countries, including the United States, England, France, the Netherlands, and Oman, are reporting an increase in cases of meningococcal infection in pilgrims returning from the Haj or in their close relatives. Many of the cases have been due to the relatively rare W-135 strain of Neisseria meningitidis. A total of 225 cases with 57 deaths have been reported by Saudi Arabia since the Haj in March, with at least 54 cases confirmed due to serogroup A, 50 due to serogroup W-135, and one due to serogroup B. Three cases of serogroup W-135 infection have been reported in New Yorkers, one of whom was a returning pilgrim and the other a close relative. Additional cases of W-135 infection have been reported in other countries.
Recurrent outbreaks of meningococcal infection occur each year during the Haj. This year, ~1.3 million pilgrams traveled to Mecca, all of whom are now required by the Saudi Arabian government to provide verification of vaccination against meningococcal strains A and C. Although there is evidence that some travelers may have entered the country with falsified vaccination certificates, the current vaccine requirement does not protect against W-135. Only one of two vaccines presently available in Europe provides some protection from W-135 disease. In addition, the vaccine widely used in the United States (ACYW135) may not be as immunogenic against W-135 strains as it is against A and C polysaccharides. While it may provide protection against disease, it does not prevent colonization and transmission of the organism to close contacts.
International health authorities ruefully commented that they had solved the problem of certification, but not of effective vaccination.
Hepatitis A & B Vaccines—What’s New?
Source: Hepatitis Control Report Winter 1999-2000;4:7; AAP News, November 1999; www.immunize.org/news.d/ aap.
You may recall that based on concerns regarding the presence of thimerosal, which contains small amounts of mercury in certain vaccines, the American Academy of Pediatrics (AAP) and the United States Public Health Service recommended in July 1999 that vaccination of infants and children with hepatitis B vaccine be delayed until children were at least 1 year of age or until a mercury-free vaccine was made available. Thimerosal has been used for many years as a preservative in vaccines (including many recombinant vaccines such as hepatitis B, diphtheria, pertussis, acellular pertussis, tetanus, and Hib), where it functions as an antimicrobial, especially in multidose containers. Concerns were raised last year that the administration of multiple sequential thimerosal-containing vaccines, especially to low-birth-weight infants, may pose a risk, although clinical evidence of mercury toxicity in vaccine recipients was lacking. The FDA gave a directive to vaccine manufacturers to replace existing vaccines with reduced mercury or mercury-free vaccines.
The FDA subsequently approved a new thimerosal-free hepatitis B vaccine (Recombivax HB Pediatric, Merck & Co., Inc.) in September. However, some physicians and hospitals may not be aware of the availability of the new vaccine and have not begun to use it—resulting in inadequate vaccination of infants. Hepatitis B vaccine can be safely reinstituted using the new vaccine for all infants. Children should be optimally vaccinated at birth or no later than 2 months of age.
The FDA has also recently approved an alternate two-dose schedule for hepatitis B vaccine in children ages 11-15. In order to improve compliance with the vaccine and limit trips to the doctor, adolescents can now receive two doses of the adult Recombivax HB (10 mcg) at 0 and 4-6 months of age in lieu of a three-dose adolescent formulation (5 mcg).
In addition, hepatitis A vaccine has been included, for the first time, in the list of recommended vaccines for children beginning at age 24 months living in certain states and counties (MMWR Morb Mortal Wkly Rep 1999;48:1-37). Children at risk reside in counties where the rate of hepatitis A is 20 cases or more per 100,000 population.
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