Correction: Association between breastfeeding, host genetic factors, and calicivirus gastroenteritis in a Nicaraguan birth cohort.

[This corrects the article DOI: 10.1371/journal.pone.0267689.].

Epidemiology of pediatric astrovirus gastroenteritis in a Nicaraguan birth cohort.

Background: Astrovirus is a leading cause of acute gastroenteritis in children worldwide. However, few prospective studies have analyzed astrovirus in community-dwelling pediatric populations in low-and-middle-income countries. Methods: We assessed the incidence, risk factors, clinical characteristics, genotypes, viral coinfections and seasonality of astrovirus gastroenteritis in 443 healthy Nicaraguan children born in 2017-2018, followed for 36 months. Children were recruited from maternity hospitals and birth records in an economically-diverse neighborhood of León, the second-largest city in Nicaragua. Astrovirus-positive episodes and genotypes were identified from diarrheal specimens with reverse transcription quantitative polymerase chain reaction and Sanger sequencing. Results: Of 1708 total specimens tested, eighty children (18%) experienced at least 1 astrovirus episode, and 9 experienced repeat episodes, mostly during the rainy season (May-October). The incidence of astrovirus episodes was 7.8/100 child-years (95% CI: 6.2, 9.8). Genotype-specific incidence of astrovirus also exhibited seasonality. Median age of astrovirus episode onset was 16 months (IQR 9, 23). Initial astrovirus episodes were not associated with protection against future episodes during the age span studied. Astrovirus cases were exclusively breastfed for a shorter period than uninfected children, and the human milk oligosaccharide lacto-N-fucopentaose-I was more concentrated in mothers of these children. Home toilets appeared to protect against future astrovirus episodes (HR=0.19, 95% CI 0.04-0.91). Human astrovirus-5 episodes, comprising 15% of all typed episodes, were associated with longer diarrhea and more symptomatic rotavirus co-infections. Conclusion: Astrovirus was a common cause of gastroenteritis in this cohort, and future studies should clarify the role of astrovirus genotype in clinical infection severity.

Timing and genotype distribution of symptomatic and asymptomatic sapovirus infections and re-infections in a Nicaraguan birth cohort.

OBJECTIVES: To characterize the timing and genotype distribution of symptomatic and asymptomatic sapovirus infections and re-infections in a Nicaraguan birth cohort. METHODS: Infants (N = 444) were enrolled at 10-14 days of life and observed weekly until 2 years of age. Stool samples were collected for each acute gastroenteritis (AGE) episode, and routine stool samples were collected monthly. Stool samples were tested for sapovirus using RT-qPCR, and positive samples were genotyped. RESULTS: A total of 348 children completed 2 years of AGE weekly surveillance; 93 (26.7%) of them experienced sapovirus AGE. Most infections occurred after 5 months of age and mainly during the second year of life (62.4%, 58/93) and early in the rainy season. Sapovirus screening in all stools from a subset of 67 children who consistently provided samples showed sapovirus infections in 91 of 330 (27.6%) AGE episodes and in 39 of 1350 (2.9%) routine stools. In this subset, the median age at the first sapovirus AGE was 11.2 months (95% CI, 9.3-15.9 months); 38 of 67 (57%) children experienced re-infections, 19 symptomatic and 19 asymptomatic. On average, sapovirus re-infections were reported 7.2 months after symptomatic and 5.3 months after asymptomatic infections. Genogroup GI (64%, 69/108) was the most common detected. Sapovirus GI.1 was more frequently detected in AGE stool samples than in routine stool samples (47.2%, 43/91 vs. 25.6%, 10/39; p 0.005), and re-infection with the same genotype was uncommon. DISCUSSION: The first sapovirus infections occurred at approximately 11 months of age, whereas the median time to symptomatic re-infection was 7.2 months. Re-infections with the same sapovirus genotype were rare during 2 years of life suggesting genotype-specific protection after natural infection.

Association between breastfeeding, host genetic factors, and calicivirus gastroenteritis in a Nicaraguan birth cohort.

BACKGROUND: Norovirus and sapovirus are important causes of childhood acute gastroenteritis (AGE). Breastfeeding prevents AGE generally; however, it is unknown if breastfeeding prevents AGE caused specifically by norovirus and sapovirus. METHODS: We investigated the association between breastfeeding and norovirus or sapovirus AGE episodes in a birth cohort. Weekly data on breastfeeding and AGE episodes were captured during the first year of life. Stools were collected from children with AGE and tested by RT-qPCR for norovirus and sapovirus. Time-dependent Cox models estimated associations between weekly breastfeeding and time to first norovirus or sapovirus AGE. FINDINGS: From June 2017 to July 2018, 444 newborns were enrolled in the study. In the first year of life, 69 and 34 children experienced a norovirus and a sapovirus episode, respectively. Exclusive breastfeeding lasted a median of 2 weeks, and any breastfeeding lasted a median of 43 weeks. Breastfeeding in the last week did not prevent norovirus (HR: 1.09, 95% CI: 0.62, 1.92) or sapovirus (HR: 1.00, 95% CI: 0.82, 1.21) AGE in a given week, adjusting for household sanitation, consumption of high-risk foods, and mother's and child's histo-blood group phenotypes. Maternal secretor-positive phenotype was protective against norovirus AGE, whereas child's secretor-positive phenotype was a risk factor for norovirus AGE. INTERPRETATION: Exclusive breastfeeding in this population was short-lived, and no conclusions could be drawn about its potential to prevent norovirus or sapovirus AGE. Non-exclusive breastfeeding did not prevent norovirus or sapovirus AGE in the first year of life. However, maternal secretor-positive phenotype was associated with a reduced hazard of norovirus AGE.

Norovirus Infection in Young Nicaraguan Children Induces Durable and Genotype-Specific Antibody Immunity.

There are significant challenges to the development of a pediatric norovirus vaccine, mainly due to the antigenic diversity among strains infecting young children. Characterizing human norovirus serotypes and understanding norovirus immunity in naïve children would provide key information for designing rational vaccine platforms. In this study, 26 Nicaraguan children experiencing their first norovirus acute gastroenteritis (AGE) episode during the first 18 months of life were investigated. We used a surrogate neutralization assay that measured antibodies blocking the binding of 13 different norovirus virus-like particles (VLPs) to histo-blood group antigens (HBGAs) in pre- and post-infection sera. To assess for asymptomatic norovirus infections, stools from asymptomatic children were collected monthly, screened for norovirus by RT-qPCR and genotyped by sequencing. Seroconversion of an HBGA-blocking antibody matched the infecting genotype in 25 (96%) of the 26 children. A subset of 13 (50%) and 4 (15%) of the 26 children experienced monotypic GII and GI seroconversion, respectively, strongly suggesting a type-specific response in naïve children, and 9 (35%) showed multitypic seroconversion. The most frequent pairing in multitypic seroconversion (8/12) were GII.4 Sydney and GII.12 noroviruses, both co-circulating at the time. Blocking antibody titers to these two genotypes did not correlate with each other, suggesting multiple exposure rather than cross-reactivity between genotypes. In addition, GII titers remained consistent for at least 19 months post-infection, demonstrating durable immunity. In conclusion, the first natural norovirus gastroenteritis episodes in these young children were dominated by a limited number of genotypes and induced responses of antibodies blocking binding of norovirus VLPs in a genotype-specific manner, suggesting that an effective pediatric norovirus vaccine likely needs to be multivalent and include globally dominant genotypes. The duration of protection from natural infections provides optimism for pediatric norovirus vaccines administered early in life.

Preexisting Heterotypic Ligand-blocking Antibody Does Not Protect Against Genogroup II Norovirus Episodes in Young Children.

A birth cohort design was used to understand whether heterotypic ligand-blocking norovirus antibodies provide cross-protection within the GII genogroup. We found that almost one-half of children who experienced a norovirus GII episode had preexisting antibodies heterotypic to the infecting genotype; therefore, these antibodies did not provide cross-protection.

First Episodes of Norovirus and Sapovirus Gastroenteritis Protect Against Subsequent Episodes in a Nicaraguan Birth Cohort.

BACKGROUND: Norovirus and sapovirus cause a large burden of acute gastroenteritis (AGE) in young children. We assessed protection conferred by norovirus and sapovirus AGE episodes against future episodes. METHODS: Between June 2017 and July 2018, we recruited 444 newborns in León, Nicaragua. Weekly household surveys identified AGE episodes over 36 months, and AGE stools were tested by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) for norovirus genogroup (G)I/GII and sapovirus. We used recurrent-event Cox models and negative control methods to estimate protection conferred by first episodes, controlling for observed and unobserved risk factors, respectively. RESULTS: Sapovirus episodes conferred a 69% reduced hazard of subsequent episodes using the negative control method. Norovirus GI (hazard ratio [HR] = 0.67; 95% confidence interval [CI] = 0.31, 1.3) and GII (HR = 0.20; 95% CI = 0.04, 0.44) episodes also appeared highly protective. Protection against norovirus GII was enhanced following two episodes. CONCLUSIONS: Evidence of natural immunity in early childhood provides optimism for the future success of pediatric norovirus and sapovirus vaccines.

Secretor Status Strongly Influences the Incidence of Symptomatic Norovirus Infection in a Genotype-Dependent Manner in a Nicaraguan Birth Cohort.

BACKGROUND: The role of histo-blood group on the burden and severity of norovirus gastroenteritis in young infants has not been well documented. METHODS: Norovirus gastroenteritis was assessed in 443 Nicaraguan children followed from birth until 3 years of age. Stool samples were tested for norovirus by reverse-transcription quantitative polymerase chain reaction (RT-qPCR), and histo-blood group antigens (HBGAs) were determined by phenotyping of saliva and blood. Hazard ratios and predictors of norovirus acute gastroenteritis (AGE) outcome stratified by HBGA were estimated using Cox proportional hazards models. RESULTS: Of 1353 AGE episodes experienced by children, 229 (17%) tested positive for norovirus with an overall incidence of 21.9/100 child-years. Secretor children were infected as early as 2 months of age and had a higher incidence of norovirus GII compared to nonsecretor children (15.4 vs 4.1/100 child-years, P = .006). Furthermore, all GII.4 AGE episodes occurred in secretor children. Children infected with GI (adjusted odds ratio [aOR], 0.09 [95% confidence interval {CI}, .02-.33]) or non-GII.4 viruses (aOR, 0.2 [95% CI, .07-.6]) were less likely to have severe AGE compared to GII.4-infected children. CONCLUSIONS: Secretor status in children strongly influences the incidence of symptomatic norovirus infection in a genogroup or genotype-dependent manner and provides evidence that clinical severity in children depends on norovirus genotypes.

Seroepidemiology of SARS-CoV-2 infections in an urban Nicaraguan population.

In a Nicaraguan population-based cohort, SARS-CoV-2 seroprevalence was 34%, with higher prevalence in children compared to adults. Having a seropositive household member was associated with a two-fold probability of individual seropositivity, suggesting a role for household transmission. Co-morbidities and preventive behaviors were not associated with SARS-CoV-2 seroprevalence.

Clinical Characteristics, Risk Factors, and Population Attributable Fraction for Campylobacteriosis in a Nicaraguan Birth Cohort.

Campylobacteriosis is an important contributor to the global burden of acute gastroenteritis (AGE). In Nicaragua, the burden, risk factors, and species diversity for infant campylobacteriosis are unknown. Between June 2017 and December 2018, we enrolled 444 infants from León, Nicaragua, in a population-based birth cohort, conducting weekly household AGE surveillance. First, we described clinical characteristics of symptomatic Campylobacter infections, and then compared clinical characteristics between Campylobacter jejuni/coli and non-jejuni/coli infections. Next, we conducted a nested case-control analysis to examine campylobacteriosis risk factors. Finally, we estimated the population attributable fraction of campylobacteriosis among infants experiencing AGE. Of 296 AGE episodes in the first year of life, Campylobacter was detected in 59 (20%), 39 were C. jejuni/coli, and 20 were non-jejuni/coli species, including the first report of Campylobacter vulpis infection in humans. Acute gastroenteritis symptoms associated with C. jejuni/coli lasted longer than those attributed to other Campylobacter species. In a conditional logistic regression model, chickens in the home (odds ratio [OR]: 3.8, 95% CI: 1.4-9.8), a prior AGE episode (OR: 3.3; 95% CI: 1.4-7.8), and poverty (OR: 0.4; 95% CI: 0.2-0.9) were independently associated with campylobacteriosis. Comparing 90 infants experiencing AGE with 90 healthy controls, 22.4% (95% CI: 11.2-32.1) of AGE episodes in the first year of life could be attributed to Campylobacter infection. Campylobacter infections contribute substantially to infant AGE in León, Nicaragua, with non-jejuni/coli species frequently detected. Reducing contact with poultry in the home and interventions to prevent all-cause AGE may reduce campylobacteriosis in this setting.

Risk Factors and Clinical Profile of Sapovirus-associated Acute Gastroenteritis in Early Childhood: A Nicaraguan Birth Cohort Study.

BACKGROUND: Sapovirus is increasingly recognized as an important cause of acute gastroenteritis (AGE) in children. We identified risk factors and characterized the clinical profile of sapovirus AGE in a birth cohort in León, Nicaragua. METHODS: We conducted a case-control study nested within a birth cohort (n = 444). Fieldworkers conducted weekly household AGE surveillance. AGE stools were tested for sapovirus by reverse transcriptase quantitative polymerase chain reaction. For each first sapovirus episode, we selected 2 healthy age-matched controls and estimated independent risk factors of sapovirus AGE using conditional logistic regression. We compared clinical characteristics of sapovirus AGE episodes with episodes associated with other etiologies and identified co-infections with other enteric pathogens. RESULTS: From June 2017 to July 2019, we identified 63 first sapovirus AGE episodes and selected 126 controls. Having contact with an individual with AGE symptoms and vaginal delivery were independent risk factors for sapovirus AGE. All cases experienced diarrhea, lasting a median 6 days; 23% experienced vomiting. Compared with children with AGE due to another etiology, sapovirus AGE was similar in severity, with less reported fever. Most cases experienced co-infections and were more likely than controls to be infected with diarrheagenic Escherichia coli or astrovirus. CONCLUSIONS: Sapovirus was a commonly identified AGE etiology in this Central American setting, and symptoms were similar to AGE associated with other etiologies. The association between vaginal delivery and sapovirus is a novel finding. Gut microbiome composition might mediate this relationship, or vaginal delivery might be a proxy for other risk factors. Further investigation into more specific biological mechanisms is warranted.

Seroepidemiology of SARS-CoV-2 infections in an urban population-based cohort in León, Nicaragua.

In a Nicaraguan population-based cohort, SARS-CoV-2 seroprevalence reached 28% in the first 6 months of the country's epidemic and reached 35% 6 months later. Immune waning was uncommon. Individuals with a seropositive household member were over three times as likely to be seropositive themselves, suggesting the importance of household transmission.

G6PD deficiency, primaquine treatment, and risk of haemolysis in malaria-infected patients.

BACKGROUND: The incidence of malaria in the Americas has decreased markedly in recent years. Honduras and the other countries of Mesoamerica and the island of Hispaniola have set the goal of eliminating native malaria by the year 2020. To achieve this goal, Honduras has recently approved national regulations to expand the possibilities of a shortened double dose primaquine (PQ) treatment for vivax malaria. Considering this new shortened anti-malarial treatment, the high frequency of G6PDd genotypes in Honduras, and the lack of routinely assessment of the G6PD deficiency status, this study aimed at investigating the potential association between the intake of PQ and haemolysis in malaria-infected G6PDd subjects. METHODS: This was a prospective cohort and open-label study. Participants with malaria were recruited. Plasmodium vivax infection was treated with 0.25 mg/kg of PQ daily for 14 days. Safety and signs of haemolysis were evaluated by clinical criteria and laboratory values before and during the 3rd and 7th day of PQ treatment. G6PD status was assessed by a rapid test (CareStart™) and two molecular approaches. RESULTS: Overall 55 participants were enrolled. The frequency of G6PD deficient genotypes was 7/55 (12.7%), where 5/7 (71.4%) were hemizygous A- males and 2/7 (28.6%) heterozygous A- females. Haemoglobin concentrations were compared between G6PD wild type (B) and G6PDd A- subjects, showing a significant difference between the means of both groups in the 3rd and 7th days. Furthermore, a statistically significant difference was evident in the change in haemoglobin concentration between the 3rd day and the 1st day for both genotypes, but there was no statistical difference for the change in haemoglobin concentration between the 7th day and the 1st day. Besides these changes in the haemoglobin concentrations, none of the patients showed signs or symptoms associated with severe haemolysis, and none needed to be admitted to a hospital for further medical attention. CONCLUSIONS: The findings support that the intake of PQ during 14 days of treatment against vivax malaria is safe in patients with a class III variant of G6PDd. In view of the new national regulations in the shortened treatment of vivax malaria for 7 days, it is advisable to be alert of potential cases of severe haemolysis that could occur among G6PD deficient hemizygous males with a class II mutation such as the Santamaria variant, previously reported in the country.

La competencia investigativa del Licenciado en Imagenología: reto contemporáneo en el sector de la salud / Researching competence of the Bachelor in Imaging: contemporary challenge in the health branch

Fundamento: la competencia investigativa es trascendental para los profesionales de la salud en función de la resolución de problemas y las exigencias contemporáneas del sector. Objetivo: caracterizar el estado actual de la competencia investigativa del Licenciado en Imagenología en su contexto profesional en el municipio Holguín. Métodos: se realizó un estudio descriptivo en la Facultad de Tecnología de la Salud de Holguín, y las instituciones de salud donde laboran los egresados de esta carrera, en el período mayo de 2013 a junio de 2014. Se utilizaron métodos teóricos para la fundamentación de la investigación: histórico-lógico, análisis-síntesis, hermenéutico-dialéctico; y empíricos: se aplicaron cuestionarios a 9 jefes del servicio de Imagenología, 43 egresados de la carrera y 10 profesores propios y adjuntos, y se realizó una revisión documental para la obtención de información. Resultados: se constataron carencias en la competencia investigativa del Licenciado en Imagenología en el contexto estudiado, dadas principalmente por la carencia de investigaciones, de conocimientos en metodología de la investigación científica e insuficientes actividades de superación profesional. La proyección posgraduada resulta escasa, lo que limita la proyección investigativa en la tutoría de trabajos científicos a los estudiantes para la resolución de problemas del entorno. Conclusiones: se logró caracterizar el estado actual de la competencia investigativa de los Licenciados en Imagenología del municipio Holguín, y se determinaron resultados poco satisfactorios.

Background: the research competence is vital for health professionals based on problem solving and contemporary demands of the branch. Objective: to characterize the current state of the research competence of the Bachelor of Imaging in their professional context in Holguín municipality. Methods: a descriptive study was carried out at Holguín Health Technology School and health institutions where the graduates of this career work, in the period from May 2013 to June 2014. Theoretical methods were used for the background of this research work: historical and logical analysis-synthesis, hermeneutical-dialectical; and empirical ones: questionnaires to the head of 9 Imaging services, 43 graduates and 10 career professors were applied, and a literature review to gather information. Results: deficiencies were found in the research competence of the Bachelor of Imaging in the context studied, given mainly by the lack of research knowledge in scientific methodology and insufficient professional development in researching activities. The postgraduate projection is scarce, limiting the researching projection for the tutoring of the students' scientific environmental problem solving work. Conclusions: the current state of the research competence of the Holguin municipality Bachelor of Imaging was characterized and unsatisfactory results were determined.

La competencia investigativa del Licenciado en Imagenología: reto contemporáneo en el sector de la salud / Researching competence of the Bachelor in Imaging: contemporary challenge in the health branch

Fundamento: la competencia investigativa es trascendental para los profesionales de la salud en función de la resolución de problemas y las exigencias contemporáneas del sector. Objetivo: caracterizar el estado actual de la competencia investigativa del Licenciado en Imagenología en su contexto profesional en el municipio Holguín. Métodos: se realizó un estudio descriptivo en la Facultad de Tecnología de la Salud de Holguín, y las instituciones de salud donde laboran los egresados de esta carrera, en el período mayo de 2013 a junio de 2014. Se utilizaron métodos teóricos para la fundamentación de la investigación: histórico-lógico, análisis-síntesis, hermenéutico-dialéctico; y empíricos: se aplicaron cuestionarios a 9 jefes del servicio de Imagenología, 43 egresados de la carrera y 10 profesores propios y adjuntos, y se realizó una revisión documental para la obtención de información. Resultados: se constataron carencias en la competencia investigativa del Licenciado en Imagenología en el contexto estudiado, dadas principalmente por la carencia de investigaciones, de conocimientos en metodología de la investigación científica e insuficientes actividades de superación profesional. La proyección posgraduada resulta escasa, lo que limita la proyección investigativa en la tutoría de trabajos científicos a los estudiantes para la resolución de problemas del entorno. Conclusiones: se logró caracterizar el estado actual de la competencia investigativa de los Licenciados en Imagenología del municipio Holguín, y se determinaron resultados poco satisfactorios(AU)

Estrategia metodológica para mejorar la ortografía en estudiantes de tecnología de la salud / Methodological strategy to improve spelling in health technology students

Introducción: el dominio de la Lengua materna y el desarrollo de una de sus habilidades, escribir sin errores ortográficos, se ha convertido en uno de los objetivos supremos de la educación médica cubana. Objetivo: elaborar una estrategia metodológica para el tratamiento ortográfico del vocabulario básico de las asignaturas de tercer año en Nutrición y Dietética. Métodos: se realizó un estudio diagnóstico en la Facultad de Tecnología de la Salud de Holguín (curso 2010-2011) en 33 estudiantes de tercer año de Nutrición y Dietética, de ambos sexos, comprendidos entre los 21 y 30 años de edad, y en 5 profesores de las diferentes asignaturas de la carrera, acerca del dominio de la ortografía del vocabulario básico empleado en ellas. Resultados: se detectaron varias insuficiencias: solo 2 estudiantes se ubicaron en la categoría de MB, 6 en la de B, 15 en la de R y 10 en la categoría de M. En cuanto a los profesores, 3 consideraron el estado actual del desarrollo del componente ortográfico como M y 2 lo evaluaron de R. Se propuso como solución al problema detectado una estrategia metodológica. Conclusiones: existen deficiencias en el dominio del componente ortográfico del vocabulario básico de las asignaturas; luego de aplicada la estrategia demostró que contribuye a su mejoramiento, lo que corroboró la hipótesis de esta investigación.

Introduction: the command of the mother tongue and the improvement of one of its skills, writing without spelling mistakes, has become one of the supreme goals of Cuban medical education. Objective: to develop a methodological strategy for promoting the correct spelling of the basic vocabulary of third-year Nutrition and Dietetics subjects. Methods: a diagnostic study was conducted at the Health Technology Faculty of Holguin (academic year 2010-2011) with 33 third-year Nutrition and Dietetics students, of both sexes, aged 21 to 30 years, and 5 teachers of different subjects in the course, on the command of the spelling of the basic vocabulary used in them. Results: several shortcomings were identified: only 2 students were ranked in the Very Good category, 6 were in the Good category, 15 were Fair and 10 were in the Poor category. With regard to teachers, 3 of them believed that the current status of spelling was Poor and 2 of them considered it as Fair. As a solution to the identified problem, a methodological strategy was proposed. Conclusions: there are deficiencies in the spelling of the basic vocabulary of the subjects. After implementing the strategy, it was found that it contributes to improve spelling, which corroborated the hypothesis of this research.

Estrategia metodológica para mejorar la ortografía en estudiantes de tecnología de la salud / Methodological strategy to improve spelling in health technology students

Introducción: el dominio de la Lengua materna y el desarrollo de una de sus habilidades, escribir sin errores ortográficos, se ha convertido en uno de los objetivos supremos de la educación médica cubana. Objetivo: elaborar una estrategia metodológica para el tratamiento ortográfico del vocabulario básico de las asignaturas de tercer año en Nutrición y Dietética.Métodos: se realizó un estudio diagnóstico en la Facultad de Tecnología de la Salud de Holguín (curso 2010-2011) en 33 estudiantes de tercer año de Nutrición y Dietética, de ambos sexos, comprendidos entre los 21 y 30 años de edad, y en 5 profesores de las diferentes asignaturas de la carrera, acerca del dominio de la ortografía del vocabulario básico empleado en ellas.Resultados: se detectaron varias insuficiencias: solo 2 estudiantes se ubicaron en la categoría de MB, 6 en la de B, 15 en la de R y 10 en la categoría de M. En cuanto a los profesores, 3 consideraron el estado actual del desarrollo del componente ortográfico como M y 2 lo evaluaron de R. Se propuso como solución al problema detectado una estrategia metodológica.Conclusiones: existen deficiencias en el dominio del componente ortográfico del vocabulario básico de las asignaturas; luego de aplicada la estrategia demostró que contribuye a su mejoramiento, lo que corroboró la hipótesis de esta investigación(AU)