Herminio Hernandez

Efficacy of bone marrow, blood, stool and duodenal contents cultures for bacteriologic confirmation of typhoid fever in children

The relative efficacy of cultures made from duodenal contents (obtained by string capsules), bone marrow, blood and rectal swab was compared in 118 pediatric patients, 2 to 13 years old with suspected typhoid fever. Only 47% of children 2 to 6 years old tolerated the string device, as compared with 89% in children 7 to 13 years old (P < 0.05). The four culture techniques were performed and at least one was positive for Salmonella typhi in 43 patients. Bone marrow cultures were positive in 84% of the confirmed cases, a sensitivity significantly greater than for duodenal contents (42%), blood (44%) and stool (65%) cultures. Higher recovery rates for blood cultures were found during the first week of illness than later (70 vs. 22%). Bone marrow cultures remain the most effective method for the recovery of S. typhi. Stool cultures appear to be more effective in children than in adults. Duodenal contents cultures offer little advantage in young (2 to 6 years old) children.

Viscerotropic disease following yellow fever vaccination in Peru.

Five suspected cases of yellow fever vaccine-associated viscerotropic disease (YEL-AVD) clustered in space and time following a vaccination campaign in Ica, Peru in 2007. All five people received the same lot of 17DD live attenuated yellow fever vaccine before their illness; four of the five died of confirmed YEL-AVD. The surviving case was classified as probable YEL-AVD. Intensive investigation yielded no abnormalities of the implicated vaccine lot and no common risk factors. This is the first described space-time cluster of yellow fever viscerotropic disease involving more than two cases. Mass yellow fever vaccination should be avoided in areas that present extremely low risk of yellow fever.

Comparison of high titer Edmonston-Zagreb, Biken-CAM and Schwarz measles vaccines in Peruvian infants.

In an effort to identify the optimal dose and strain of measles vaccination for early immunization, Peruvian infants were randomly assigned to receive one of three measles vaccines in varying doses at 5 to 6 or 8 to 9 months of age. Edmonston-Zagreb vaccines were significantly (P < 0.001) more immunogenic than equivalent or higher titers of Schwarz or Biken-CAM vaccines as determined by neutralization antibody response 3 months after vaccination. Eighty-two percent of infants who received high titer Edmonston-Zagreb vaccine at 5 to 6 months of age developed protective concentrations of measles antibody, a response rate similar to that observed after standard titer Schwarz (81%) or high titer Biken-CAM vaccine (81%) at 8 to 9 months of age. No significant differences in the rates of fever, rash or other adverse events were noted by vaccine group 10 to 14 days after vaccination. Although the high titer vaccines are more immunogenic in young infants than standard vaccines, long term safety must be assured before these vaccines can be put into widespread use.

Immune response to measles vaccine in Peruvian children

OBJECTIVE To evaluate the immune response in Peruvian children following measles vaccination. METHODS Fifty-five Peruvian children received Schwarz measles vaccine (about 10(3) plaque forming units) at about 9 months of age. Blood samples were taken before vaccination, then twice after vaccination: one sample at between 1 and 4 weeks after vaccination and the final sample 3 months post vaccination for evaluation of immune cell phenotype and lymphoproliferative responses to measles and non-measles antigens. Measles-specific antibodies were measured by plaque reduction neutralization. FINDINGS The humoral response developed rapidly after vaccination; only 4 of the 55 children (7%) had plaque reduction neutralization titres <200 mlU/ml 3 months after vaccination. However, only 8 out of 35 children tested (23%) had lymphoproliferative responses to measles antigens 3-4 weeks after vaccination. Children with poor lymphoproliferative responses to measles antigens had readily detectable lymphoproliferative responses to other antigens. Flow cytometric analysis of peripheral blood mononuclear cells revealed diffuse immune system activation at the time of vaccination in most children. The capacity to mount a lymphoproliferative response to measles antigens was associated with expression of CD45RO on CD4+ T-cells. CONCLUSION The 55 Peruvian children had excellent antibody responses after measles vaccination, but only 23% (8 out of 35) generated detectable lymphoproliferative responses to measles antigens (compared with 55-67% in children in the industrialized world). This difference may contribute to the less than uniform success of measles vaccination programmes in the developing world.

Use of rapid needs assessment as a tool to identify vaccination delays in Guatemala and Peru

OBJECTIVE To explore the use of rapid needs assessment (RNA) surveys to determine the prevalence and factors contributing to delays in vaccination of children in two low middle-income countries (LMIC). METHODS Data from two RNA surveys performed as part of program improvement evaluations in Guatemala and Peru were used for this analysis. The primary endpoint was the timeliness of immunization with delay defined as administration of vaccines beyond 28 days from recommended age for DTwP-HepB-Hib (Penta) and measles-mumps-rubella (MMR) vaccines, as well as past age-restrictions for rotavirus vaccine. Independent risk factors analyzed included childs gender, birth year, number of children in household, maternal age, maternal education, and food insecurity. RESULTS Vaccine information was available from 811 children from 838 households surveyed. High rate of immunization delays was observed, with 75.6% of children in Guatemala and 57.8% of children in Peru being delayed for the third dose of Penta primary series. Factors associated with delayed vaccination in Guatemala included advanced maternal age and increased number of children in household. In Peru, significant associations were birth year before 2009, lower maternal education level, and increased number of children in household. CONCLUSIONS RNA is a fast and effective method to identify timely vaccine coverage and derive a hypothesis of factors possibly associated with vaccination delay.