Randomized, double-blind, phase III, pivotal field trial of the comparative immunogenicity, safety, and tolerability of two yellow fever 17D vaccines (Arilvax and YF-VAX) in healthy infants and children in Peru.

We conducted a randomized, double-blind, phase III yellow fever (YF) vaccine trial among 1,107 healthy children in Sullana in northern Peru. The safety and efficacy (by measurement of geometric mean neutralizing antibody titer responses) were determined for two YF vaccines, ARILVAX (n = 738) and YF-VAX(R) (n = 369). Serocon-version rates were higher (94.9%) in ARILVAX than in YF-VAX (90.6%) recipients. The two-sided 95% confidence interval (YF-VAX-ARILVAX) was (-12.8% to -2.5%), indicating that the higher seroconversion rate for Arilvax was significant. Post-vaccination (30-day) mean log(10) neutralization indices were found to be similar for both products: 1.32 for ARILVAX and 1.26 for YF-VAX (P = 0.1404, by analysis of variance). A similar number of subjects in each group reported at least one adverse event (AE); 441 (59.8%) for ARILVAX versus 211 (59.9%) for YF-VAX. Most (591; 96.7%) of these were of a mild nature and resolved without treatment. There were no treatment-related serious AEs. This is the first randomized, double-blind comparison of two YF vaccines in a pediatric population; both vaccines were shown to be highly immunogenic and well-tolerated.

Spatial and temporal characteristics of the 2009 A/H1N1 influenza pandemic in Peru.

BACKGROUND: Highly refined surveillance data on the 2009 A/H1N1 influenza pandemic are crucial to quantify the spatial and temporal characteristics of the pandemic. There is little information about the spatial-temporal dynamics of pandemic influenza in South America. Here we provide a quantitative description of the age-specific morbidity pandemic patterns across administrative areas of Peru. METHODS: We used daily cases of influenza-like-illness, tests for A/H1N1 influenza virus infections, and laboratory-confirmed A/H1N1 influenza cases reported to the epidemiological surveillance system of Peru's Ministry of Health from May 1 to December 31, 2009. We analyzed the geographic spread of the pandemic waves and their association with the winter school vacation period, demographic factors, and absolute humidity. We also estimated the reproduction number and quantified the association between the winter school vacation period and the age distribution of cases. RESULTS: The national pandemic curve revealed a bimodal winter pandemic wave, with the first peak limited to school age children in the Lima metropolitan area, and the second peak more geographically widespread. The reproduction number was estimated at 1.6-2.2 for the Lima metropolitan area and 1.3-1.5 in the rest of Peru. We found a significant association between the timing of the school vacation period and changes in the age distribution of cases, while earlier pandemic onset was correlated with large population size. By contrast there was no association between pandemic dynamics and absolute humidity. CONCLUSIONS: Our results indicate substantial spatial variation in pandemic patterns across Peru, with two pandemic waves of varying timing and impact by age and region. Moreover, the Peru data suggest a hierarchical transmission pattern of pandemic influenza A/H1N1 driven by large population centers. The higher reproduction number of the first pandemic wave could be explained by high contact rates among school-age children, the age group most affected during this early wave.

Influenza and other respiratory viruses in three Central American countries.

BACKGROUND: Despite the disease burden imposed by respiratory diseases on children in Central America, there is a paucity of data describing the etiologic agents of the disease. AIMS: To analyze viral etiologic agents associated with influenza-like illness (ILI) in participants reporting to one outpatient health center, one pediatric hospital, and three general hospitals in El Salvador, Honduras, and Nicaragua Material & METHODS: Between August 2006 and April 2009, pharyngeal swabs were collected from outpatients and inpatients. Patient specimens were inoculated onto cultured cell monolayers, and viral antigens were detected by indirect and direct immunofluorescence staining. RESULTS: A total of 1,756 patients were enrolled, of whom 1,195 (68.3%) were under the age of 5; and 183 (10.4%) required hospitalization. One or more viral agents were identified in 434 (24.7%) cases, of which 17 (3.9%) were dual infections. The most common viruses isolated were influenza A virus (130; 7.4% of cases), respiratory syncytial virus (122; 6.9%), adenoviruses (63; 3.6%), parainfluenza viruses (57; 3.2%), influenza B virus (47; 2.7% of cases), and herpes simplex virus 1 (22; 1.3%). In addition, human metapneumovirus and enteroviruses (coxsackie and echovirus) were isolated from patient specimens. DISCUSSION: When compared to the rest of the population, viruses were isolated from a significantly higher percentage of patients age 5 or younger. The prevalence of influenza A virus or influenza B virus infections was similar between the younger and older age groups. RSV was the most commonly detected pathogen in infants age 5 and younger and was significantly associated with pneumonia (p < 0.0001) and hospitalization (p < 0.0001). CONCLUSION: Genetic analysis of influenza isolates identified A (H3N2), A (H1N1), and B viruses. It also showed that the mutation H274Y conferring resistance to oseltamivir was first detected in Honduran influenza A/H1N1 strains at the beginning of 2008. These data demonstrate that a diverse range of respiratory pathogens are associated with ILI in Honduras, El Salvador, and Nicaragua. RSV infection in particular appears to be associated with severe disease in infants in the region.

Epidemiology of influenza-like illness in the Amazon Basin of Peru, 2008-2009.

BACKGROUND: Data addressing the incidence and epidemiology of influenza and influenza-like illness (ILI) in tropical regions of the world is scarce, particularly for the neotropics of South America. METHODS: We conducted active, population-based surveillance for ILI across 45 city blocks within the Amazon Basin city of Iquitos, Peru. Demographic data and household characteristics were collected for all participants, and participating households were visited three times weekly to inquire about ILI (fever plus cough or sore throat) among household residents. Nasal and oropharyngeal swabs were collected from participants with ILI and tested for influenza virus infection. RESULTS: Between May 1, 2008 and July 8, 2009, we monitored 10,341 participants for ILI for a total of 11,569.5 person-years. We detected 459 ILI episodes, with 252 (54.9%) of the participants providing specimens. Age-adjusted incidence of ILI was estimated to be 46.7 episodes/1000 person-years. Influenza A and B viruses were detected in 25 (9.9%) and 62 (24.6%) specimens of ILI patients, respectively, for an estimated age-adjusted incidence rate of 16.5 symptomatic influenza virus infections/1000 person-years. Risk factors for ILI included age, household crowding, and use of wood as cooking fuel. For influenza virus infection specifically, age and use of wood as a cooking fuel were also identified as risk factors, but no effect of household crowding was observed. CONCLUSIONS: Our results represent the initial population-based description of the epidemiology of ILI in the Amazon region of Peru, which will be useful for developing region-specific strategies for reducing the burden of respiratory disease.

Association of herpes simplex virus type 2 infection and syphilis with human immunodeficiency virus infection among men who have sex with men in Peru.

BACKGROUND: We evaluated associations between human immunodeficiency virus (HIV) infection, herpes simplex virus type 2 (HSV-2) infection, and syphilis among men who have sex with men (MSM) in Peru. METHODS: A surveillance survey of 3280 MSM was conducted; sexual behavior was assessed with a structured computer-assisted self-interview, and serum antibody testing was performed for HIV, HSV-2, and Treponema pallidum. RESULTS: HIV, HSV-2, and syphilis seroprevalences of 13.9%, 46.3%, and 13.4% were detected, respectively. HSV-2 seroprevalence was twice as high in HIV-infected subjects (80.5%) than it was in HIV-uninfected subjects (40.8%) (P < .01), and HSV-2 seropositivity (adjusted odds ratio [AOR], 5.66) was found to be strongly associated with HIV infection. In addition, homosexual self-definition (AOR, 3.12), exchange of sex for money (AOR, 1.61), unprotected sex (no condom) (AOR, 2.81), history of sex work (AOR, 1.89), oral receptive sex (AOR, 1.43), and cocaine use before/during sex (AOR, 2.53) within the preceding 6 months, as well as such sexually transmitted infections (STIs) and STI syndromes as proctitis (AOR, 2.80), genital ulcer disease (GUD) (AOR, 2.06), prior syphilis (AOR, 2.64), genital warts (AOR, 1.70), and self-reported STIs within the preceding 6 months (AOR, 1.61), were also found to be significant predictors of HIV infection. CONCLUSIONS: We found a strong association between HSV-2 seropositivity and HIV infection. Intervention measures against GUD due to HSV-2 infection and syphilis, such as routine testing, early detection, HSV-2 suppressive treatment, and condom distribution, need to be enhanced as part of STI prevention strategies at a national level to effectively reduce HIV infection among MSM in Peru.