Prospective cohort study with active surveillance for fever in four dengue endemic countries in Latin America.

To prepare for a Phase III dengue vaccine efficacy trial, 20 investigational sites were selected for this observational study to identify dengue infections in a closed cohort (N = 3,000 children 9-16 years of age). Of 255 acute febrile episodes experienced by 235 children, 50 (21.3%) were considered serologically probable dengue, and 18 (7.7%) were considered virologically confirmed (i.e., dengue NS1 antigen positive) dengue cases. Considering the disease-free and at-risk period from study start to onset of symptoms, the overall incidence density of acute febrile episodes was 17.7 per 100 person-years of follow-up, ranging from 15.3 in Colombia to 22.0 in Puerto Rico. This study showed that all sites were capable of capturing and following up acute febrile episodes within a specific timeframe among the established cohort and to detect dengue cases.

Concomitant use of the oral pentavalent human-bovine reassortant rotavirus vaccine and oral poliovirus vaccine.

OBJECTIVES: The live oral pentavalent rotavirus vaccine (PRV) is well tolerated and highly efficacious against rotavirus gastroenteritis. This open-label, multicenter study evaluated the immunogenicity and safety of coadministering oral poliovirus vaccine (OPV) with PRV. METHODS: From 2005 to 2006, healthy 6- to 12-week-old Latin American infants were randomized to PRV and OPV concomitantly or PRV 2-4 weeks before OPV. Three doses of each vaccine were administered 8-10 weeks apart. Subjects did not receive OPV at birth. Routine licensed pediatric vaccines were allowed. Antibody responses to PRV and OPV were evaluated 42 days after the last dose of each vaccine. Adverse events were recorded for 14 days after each study visit. RESULTS: In the concomitant-use group (n = 372), more than 98% of subjects achieved serum-neutralizing antibody titer > or = 1:8 against poliovirus types 1, 2, and 3. The poliovirus seroprotection rate in the concomitant-use group was statistically noninferior to the staggered-use group (n = 363). The immunoglobulin A (IgA) antirotavirus geometric mean titer was 46% lower in the concomitant-use group than in the staggered-use group. However, concomitant use elicited a > or = 3-fold increase (from predose 1 to postdose 3) in serum antirotavirus IgA in 93% of subjects and achieved the definition of noninferiority. Both regimens were similarly well tolerated. CONCLUSIONS: PRV did not interfere with immune responses to OPV. Although coadministration with OPV reduced serum antirotavirus IgA geometric mean titer, seroresponse rates were high and consistent with those observed in previous studies showing high vaccine efficacy. These results support including PRV in vaccination schedules involving OPV.

High-virulence clone of group B streptococci unable to grow at high temperatures is present in serotypes other than type III.

Highly virulent clonotypes of serotype III seem to cause much of the perinatal morbidity and mortality attributed to Streptococcus agalactiae (group B streptococci, GBS), One of these clonal types, designated the "high-virulence clone" (HVC), was identified by its inability to grow at 40 degrees C in a chemically defined medium. In the present study, this inability to grow at high temperatures was used as a marker to identify HVC in a sample of 286 Mexican GBS isolates. Forty-three isolates (15%) were identified as belonging to this clone: 15 were invasive isolates, 33 were serotype III (77%), and 10 were of serotypes other than type III (23%). These results demonstrate that HVC is more prevalent in Mexico than previously reported and that this clone is not restricted to serotype III isolates.

Serotypes of 286 group B streptococci isolated from asymptomatic carriers and invasive disease cases in Mexico.

BACKGROUND: Group B Streptococcus (GBS) remains as a leading cause of neonatal sepsis and meningitis in developed countries, where type III is the most common serotype. Although GBS is considered an uncommon cause of perinatal pathology in Mexico, a vaginal colonization rate of 14% in pregnant women and a neonatal infection rate of 1/1500 live births have been reported. The aim of this study was to determine the serotype distribution in a collection of 286 GBS strains isolated in Mexico from asymptomatic carriers and in adult and neonatal invasive disease cases. METHODS: The collection included GBS strains isolated between January 1988 and April 1998 at the Instituto Nacional de Perinatologia and Hospital de Pediatria in Mexico City. GBS and serotype were confirmed by latex agglutination. RESULTS: Most strains were isolated from asymptomatic carriers (66%). 30% were invasive isolates, and 10% of them were from neonates. 48.6% were type I, 32.9% type III, 14% type II, and 4% were non-typeable. CONCLUSION: Serotype I is predominant in Mexico but participation of serotype III is increasing, and a decrease of non-typeable isolates was detected.