Cases of vaccine-preventable invasive meningococcal disease may be higher than reported along US-Mexico border

Chacon-Cruz E. Emerg Infect Dis. 2011;doi:10.3201/eid1703.101254.

Rates of invasive meningococcal disease along the US-Mexico border may be substantially higher than previously reported, according to researchers.

From Oct. 1, 2005, to May 31, 2008, researchers observed patients aged 17 years and younger admitted to Tijuana General Hospital (catchment population of approximately 200,000 children) and San Diego County hospitals (723,000 children). Patients in each group who were suspected to have sepsis, meningitis or purpura fulminans had blood or cerebrospinal fluid specimens, or both, tested. Data on all pediatric cases of reported invasive meningococcal disease reported to the San Diego County Health and Human Services Agency were retrospectively analyzed for the same period.

Twenty-nine pediatric cases of invasive meningococcal disease were diagnosed during the study period; 16 cases in Tijuana (approximately 3.08 cases per year, per 100,000 pediatric patients) and 13 cases in San Diego (0.69 cases per year, per 100,000 pediatric patients). Patients aged 5 years and younger accounted for most cases, with nine in Tijuana and 10 in San Diego (P=.24). Eleven of the 29 cases occurred in patients aged 1 to 4 years; eight were infants. The infants accounted for two cases in Tijuana and six cases in San Diego (P<.05).

Most of the San Diego cases were caused by serogroup B. Boys were more likely to be infected in both groups (55.2%), and 65.5% of cases were diagnosed from November to February. Serogroup C was found in 41.4% of all 29 cases; serogroup B in 34.5%; 10.3% in serogroup Y. Serogroup C was more common in Tijuana (62.5%); serogroup B was more common in San Diego (61.5%; P=.005).

Of the 29 cases, five patients died, three from Tijuana and two in San Diego. Four patients were younger than 5 years, and one patient was 15 years. The organisms in four of the deaths were not in a serogroup; one fatality was caused by serogroup C.

“This study suggests that rates of [invasive meningococcal disease] at [Tijuana General Hospital], and presumably Tijuana and elsewhere in Mexico, may be substantially higher than reported,” researchers wrote. “Widespread meningococcal vaccination has not yet been introduced in Tijuana or elsewhere in Mexico, although the monovalent meningococcal C conjugate vaccine has been licensed in Mexico. This study suggests that a substantial number of [invasive meningococcal disease] cases might have been prevented with quadrivalent conjugated meningococcal vaccine (75%) or monovalent serogroup C vaccine (63%).”

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