Establishing a regional network of academic centers to support decision making for new vaccine introduction in Latin America and the Caribbean: the ProVac experience.

BACKGROUND: The Pan American Health Organization's ProVac Initiative, designed to strengthen national decision making regarding the introduction of new vaccines, was initiated in 2004. Central to realizing ProVac's vision of regional capacity building, the ProVac Network of Centers of Excellence (CoEs) was established in 2010 to provide research support to the ProVac Initiative, leveraging existing capacity at Latin American and Caribbean (LAC) universities. We describe the process of establishing the ProVac Network of CoEs and its initial outcomes and challenges. METHODS: A survey was sent to academic, not-for-profit institutions in LAC that had recently published work in the areas of clinical decision sciences and health economic analysis. Centers invited to join the Network were selected by an international committee on the basis of the survey results. Selection criteria included academic productivity in immunization-related work, team size and expertise, successful collaboration with governmental agencies and international organizations, and experience in training and education. The Network currently includes five academic institutions across LAC. RESULTS: Through open dialog and negotiation, specific projects were assigned to centers according to their areas of expertise. Collaboration among centers was highly encouraged. Faculty from ProVac's technical partners were assigned as focal points for each project. The resulting work led to the development and piloting of tools, methodological guides, and training materials that support countries in assessing existing evidence and generating new evidence on vaccine introduction. The evidence generated is shared with country-level decision makers and the scientific community. CONCLUSIONS: As the ProVac Initiative expands to other regions of the world with support from immunization and public health partners, the establishment of other regional and global networks of CoEs will be critical. The experience of LAC in creating the current network could benefit the formation of similar structures that support evidence-based decisions regarding new public health interventions.

Temporal trends in diarrhea-related hospitalizations and deaths in children under age 5 before and after the introduction of the rotavirus vaccine in four Latin American countries.

INTRODUCTION: Rotavirus infection mainly affects children under 5 years of age and causes 453,000 deaths annually throughout the world. Several countries in Latin America have introduced the rotavirus vaccine and the majority have epidemiological data to measure impact following vaccine introduction. OBJECTIVE: To assess the impact of rotavirus immunization on the number of all-cause diarrhea-related deaths and hospitalizations in children under 1 and 5 years of age in Bolivia, El Salvador, Honduras and Venezuela. METHODS: Interrupted time-series analyzed with the integral method and the projection method to evaluate the pre and post-vaccine introduction trend in diarrheal disease compared to Argentina as the control country. The analysis period was from 2002 to 2010, including 2 to 4 post-vaccine years depending on the country. Information sources included records from PAHO, the Ministry of Health, public hospitals, social security, the private health system, the Expanded Programme on Immunization and UNPop 2008. RESULTS: Over the period studied, reductions were observed in trends of diarrhea-related deaths and hospitalizations in children under five. In diarrhea-related deaths, under the integral method, the range of reduction was between 15.7% (13.5-17.9) and 56.8% (56.0-57.5) while with the projection method was between 19.9% (4.9-34.8) and 63.7%(56.1-71.4). In diarrhea-related hospitalizations, under the integral method was 5.6% (4.1-6.7) and 17.9% (16.7-19.1)) while with the projection method was between 5.1%(1.7-8.7) and 11.1% (5.8-16.3) CONCLUSIONS: A decrease was observed in the number of diarrhea related deaths and hospitalizations in all countries under study following introduction of the rotavirus vaccine as opposed to the control country. The impact on reduction of deaths was greater than hospitalization.

Survey of drug resistance of Mycobacterium tuberculosis in 3 Mexican states, 1997.

BACKGROUND: Drug resistance threatens global tuberculosis (TB) control efforts. Population-based estimates of drug resistance are needed to develop strategies for controlling drug-resistant TB in Mexico. OBJECTIVE: To obtain population-based data on Mycobacterium tuberculosis drug resistance in Mexico. METHODS: To obtain drug resistance data, we conducted a population-based study of TB cases in the states of Baja California, Sinaloa, and Oaxaca, Mexico. We performed cultures and drug susceptibility testing on M tuberculosis isolates from patients with newly diagnosed, smear-positive TB from April 1 to October 31, 1997. RESULTS: Mycobacterium tuberculosis was isolated from 460 (75%) of the 614 patients. Levels of resistance in new and retreatment TB cases to 1 or more of the 3 current first-line drugs used in Mexico (isoniazid, rifampin, and pyrazinamide) were 12.9% and 50.5%, respectively; the corresponding levels of multi-drug-resistant TB were 2.4% and 22.4%. Retreatment cases were significantly more likely than new cases to have isolates resistant to 1 or more of the 3 first-line drugs (relative risk [RR], 3.9; 95% confidence interval [CI], 2.8-5.5), to have isoniazid resistance (RR, 3.6; 95% CI, 2.5-5.2), and to have multi-drug-resistant TB (RR, 9.4; 95% CI, 4.3-20.2). CONCLUSIONS: This population-based study of M tuberculosis demonstrates moderately high levels of drug resistance. Important issues to consider in the national strategy to prevent M tuberculosis resistance in Mexico include consideration of the most appropriate initial therapy in patients with TB, the treatment of patients with multiple drug resistance, and surveillance or periodic surveys of resistance among new TB patients to monitor drug resistance trends.

[The epidemiological surveillance of dengue in Mexico]. / Vigilancia epidemiológica del dengue en México.

The clinical behavior of dengue fever in Mexico has changed, now with the occurrence of hemorrhagic cases. In response to the emergence of such cases, a specific epidemiologic surveillance system has been designed and implemented. This system includes the means to monitor the factors involved in the evolution of the disease. The identification and analysis of these factors is necessary to implement prevention and control measures. This paper presents the main components and procedures of the epidemiologic surveillance system for common and hemorrhagic dengue fever in Mexico, emphasizing the usefulness of the risk approach to predict the pattern of this disease. The model includes the collaboration of a multidisciplinary group. The Epidemiologic Surveillance State Committee, coordinated by the National Health System, participates in the collection and analysis of epidemiologic data, particularly data related to the population, the individual, the vector, the viruses and the environment.

[Accidents and injuries in 4 general hospitals of the Distrito Federal]. / Accidentes y lesiones en cuatro hospitales generales del Distrito Federal.

We report the injuries for "E" code in 10191 subjects attending four general hospitals of Mexico City. Seventy-nine per cent of them were males and 29.1 per cent were females. THe highest utilization rate of the care unit was during weekends. Only 14 per cent of the study population were admitted to the hospital. People classified as drunk were more likely to have more severe injuries and to be admitted to the hospital and female drinkers had the highest risk of hospitalization (RR = 3.03; IC = 1.85-5.04). Only in 49 per cent of the cases was the external cause of injury coded The main causes were gunshots and stabbing with knife or cutting weapon. In this study we found a greater proportion of fractures in women than in men, pointing toward the possible presence of osteoporosis in the female population.

Five cases of primary amebic meningoencephalitis in Mexicali, Mexico: study of the isolates.

Five Naegleria strains isolated from patients with primary amebic meningoencephalitis and one strain isolated from the water of an artificial canal were investigated. All strains were pathogenic for mice when instilled intranasally and showed cytopathic effects in Vero cell cultures. Their growth characteristics (isolation and subculture at 45 degrees C), serological results, and isoenzyme patterns permitted us to identify the six strains as Naegleria fowleri. This is the first time that Naegleria fowleri has been isolated from patients with primary amebic meningoencephalitis in Mexico.

[Epidemiologic investigation of measles in Mexico. A methodological proposal]. / La investigación epidemiológica del sarampión en México. Propuesta metodológica.

The epidemiological study of measles needs a critical perspective in addition to a descriptive study of variables in time, place and person. The goal of this critical and methodological study of measles is to evaluate the coverage and efficacy of the vaccine in the affected population. These indicators will provide an indirect evaluation of the preventable services. This document presents a general view of the epidemiological design of cohorts and case-control studies and their immediately application to the study of measles. It describe the mathematical procedures for calculating the coverage and efficacy of the measles vaccine in community and hospital outbreaks.

[Postneonatal mortality caused by diarrhea: a case-control study]. / Mortalidad postneonatal por diarreas: un estudio de casos y controles.

A matched case-control study was undertaken in Naucalpan de Juárez, Estado de México. The goal of this study was to identify the risk factors for diarrheal disease in children between seven days and one year of age. We identified 63 case and 188 controls. The most important risk factors were: mother's age greater than 36 years with an odds ratis (OR) 3.7, lack of breastfeeding (OR 11.3), breast and bottle feeding (OR 5.4), lack of intradomiciliary sewage (OR 8.3), repeated episoded of disease (OR 8.6) and father's consumption alcoholic beverages (OR 3.6). The main possible paths by which these factors influence mortality are discussed. Specific interventions for some of the factors are proposed.

[Epidemiologic study of a whooping cough outbreak in Rincón Grande, Veracruz]. / Estudio epidemiológico de un brote de tosferina en Rincón Grande, Veracruz.

An outbreak of whooping cough occurred in February 1988 in the town of Rincon Grande, borough of Santa Ana Atzacan, Veracruz. The objectives of this study were: to corroborate the presence of infection by Bordetella pertussis, to survey the immunizational status against this organism in this population, to identify the etiologic agent involved and the main epidemiologic characteristics of the outbreak. A descriptive study of the cases with the known population as well as a study of the cases and controls to identify the risk factors associated with illness were performed. Among the 461 inhabitants of the town of Rincon Grande, Veracruz, 85 cases were detected giving an attack rate of 18.4 per 100 inhabitants. The outbreak lasted 13 weeks with the highest incidence occurring from the 7th to the 13th of January 1988. The 7 to 11 month old group was the age group most affected having a rate of attack of 85%. The rate of secondary attacks was greater at the intrafamiliar level than at the scholastic level. The main symptoms included: the paroxysmal cough, fever, stridor, epistaxis and conjunctival hemorrhage. Among the complications found were: pneumonia, hemotympanus and dehydration; 84% of the affected children showed leukocytosis and lymphocytosis. The determination of serum B. pertussis antibody levels, demonstrated high levels in 60% of the paired samples. In 14% of the patients there was serologic evidence of an association with an adenovirus infection. The study of the cases and the controls revealed that living with 10 or more persons in the same room, and that having an intrafamiliar contact represented a greater risk for acquiring the disease (odds ratio = 21, P less than 0.05). The immunization survey revealed low coverage (6%) in this locale.

[Estimate of the cost/benefit ratio of measles vaccination]. / Estimación de la razón beneficio/costo de la vacunación contra el sarampión.

Among primary health care programs, one of those that has the highest benefit/cost ratio is measles immunization. An estimate of cases, complicated cases and deaths that could have occurred if such immunization program would not have been run, and costs of medical care (hospitalization, physician's visits, medical treatment and rehabilitation), were calculated. Since population at risk has a steady-state given by those who enter -births- and releave it -when they are 15 years old-, if the program did not exist more than 2 million cases and at least 60,000 deaths from measles would have occurred annually. This hypothetical situation is compared with the actual situation of measles in Mexico during the 80's; 1) no more than 100,000 cases could have been estimated to occur in the very extreme case of notifying only one out of 10 cases. 2) The proportions of vaccinated and immune children under five reach 70 percent; this situation has produced 3) a fade out of epidemicity and has increased the critical size of community population for epidemics and doubled the interepidemic interval with the corollary of 4) increasing the average age of infection. The average cost of vaccinating a child was estimated near 1.25 dollars (US). Estimated costs of disease are related to individual losses. Taking into account these factors, benefit/cost ratio of measles immunization in Mexico is, at least, 100:1. Measles transmission patterns in Mexico are discussed since they lead to increase the benefit/cost ratio as compared to countries where the age of infection was put up before the immunization era. To expand investments on measles immunization is recommended.