Patrón Estacional de la Influenza en México: Regiones tropicales vs. templadas

La influenza es una enfermedad respiratoria aguda que afecta a personas de todas las edades. Generalmente se caracteriza por la aparición espontánea de síntomas agudos, incluyendo fiebre, mialgias y síntomas respiratorios. En personas sanas, la enfermedad resuelve sin consecuencias. La influenza causa altas tasas de morbilidad y mortalidad a nivel mundial; sólo en México, anualmente se reportan más de 10,000 casos de enfermedad tipo influenza

Serologic Evidence of Human and Swine Influenza in Mayan Persons

Antibodies against influenza viruses were detected in 115 serum samples from indigenous Mayan persons from Kochol, Yucatán. Seropositivity rates were 26.9% to A/Bayern/7/95, 40.8% to A/Sydney/5/97, 1.7% to A/Swine/Wisconsin/238/97, and 79.1% to A/Swine/Minnesota/593/99. This report is the first in Mexico of the prevalence of antibodies to swine influenza virus in humans

Estudio de la hiperplasia epitelial multifocal en tres comunidades rurales del Estado de Yucatán, México

Introducción. La hiperplasia epitelial multifocal (HEM) es una patología de la mucosa oral descrita principalmente en diversos grupos étnicos de Latino América. Se ha reportado el ADN del papiloma humano tipo 13 y 32 en las lesiones. Objetivo. Describir la epidemiología y cuadro clínico de la HEM en comunidades rurales en Yucatán, México. Material y Métodos. Se realizó un estudio prospectivo, descriptivo y transversal, 525 niños de 3-13 años fueron examinados para identificar lesiones compatibles con HEM. Adicionalmente se les tomó una muestra de la mucosa oral para identificación viral, la cual se llevó a cabo por amplificación genómica del VPH 13. Datos clínicos y epidemiológicos fueron recabados de las madres. Resultados. La prevalencia fue de 11.8% (62/525, 53% niñas y 47% varones), alcanzando hasta 15.5% solo en la comunidad de Kochol; el grupo etario más afectado fueron los de 13 años. El tiempo de evolución promedio fue de 17 meses, el 50% de los niños con HEM tenían familiares afectados. El 73% tenían lesiones múltiples, predominando las de superficie lisa, el 82% de los niños tenían lesiones en el labio inferior, seguido de la lengua 35%. Todas las muestras resultaron positivas a VPH 13 exceptuando dos que resultaron inadecuadas para PCR. Conclusiones. La prevalencia de HEM encontrada está entre las mas altas reportadas en la literatura. Se confirmó el papel etiológico del genotipo 13 en esta patología y su carácter familiar

Dengue Immunopathogenesis: A Crosstalk between Host and Viral Factors Leading to Disease: Part I - Dengue Virus Tropism, Host Innate Immune Responses, and Subversion of Antiviral Responses

Dengue is the most prevalent emerging mosquito-borne viral disease, affecting more than 40% of the human population worldwide. Many symptomatic dengue virus (DENV) infections result in a relatively benign disease course known as dengue fever (DF). However, a small proportion of patients develop severe clinical manifestations, englobed in two main categories known as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Secondary infection with any of the four dengue virus serotypes (DENV1, -2, -3, and -4) is a risk factor to develop severe forms of dengue disease. DSS is primarily characterized by sudden and abrupt endothelial dysfunction, resulting in vascular leak and organ impairment, which may progress to hypovolemic shock and death. Severe DENV disease (DHF/DSS) is thought to follow a complex relationship between distinct immunopathogenic processes involving host and viral factors, such as the serotype cross-reactive antibody-dependent enhancement (ADE), the activation of T cells and complement pathways, the phenomenon of the cytokine storm, and the newly described viral toxin activity of the nonstructural protein 1 (NS1), which together play critical roles in inducing vascular leak and virus pathogenesis. In this chapter that is divided in two parts, we will outline the recent advances in our understanding of DENV pathogenesis, highlighting key viral-host interactions and discussing how these interactions may contribute to DENV immunopathology and the development of vascular leak, a hallmark of severe dengue. Part I will address the general features of the DENV complex, including the virus structure and genome, epidemiology, and clinical outcomes, followed by an updated review of the literature describing the host innate immune strategies as well as the viral mechanisms acting against and in favor of the DENV replication cycle and infection

Dengue Immunopathogenesis: A Crosstalk between Host and Viral Factors Leading to Disease: PART II - DENV Infection, Adaptive Immune Responses, and NS1 Pathogenesis

Severe disease is associated with serial infection with DENV of different serotypes. Thus, primary DENV infections normally cause asymptomatic infections, and secondary heterotypic infections with a new DENV serotype potentially increase the risks of developing severe disease. Despite many proposed hypotheses trying to explain it, the exact immunological mechanism leading to severe dengue disease is unknown. In turn, severe manifestations are believed to be a consequence of the combinations of many immunopathogenic mechanisms involving viral and host factors leading to increased pathogenesis and disease. Of these mechanisms, the adaptive immune response has been proposed to play a critical role in the development of severe dengue manifestations. This includes the effect of non-neutralizing but enhancing antibodies produced during primary infections, which results in enhanced-DENV infection of Fc-γ-receptor-expressing cells (e.g. monocytes and macrophages) during DENV heterotypic exposure in a phenomenon called antibody-dependent enhancement (ADE); the increased activation of memory T cells during secondary infections, which has low affinity for the current infecting serotype and high affinity for a past infection with a different serotype known as the original antigenic sin; the unbalanced production of pro-inflammatory cytokines that have a direct effect on vascular endothelial cells resulting in plasma leak in a phenomenon known as cytokine storm; and the excessive activation of the complement system that causes exacerbated inflammatory responses, increasing disease severity. In addition to the adaptive immune responses, a secreted viral factor known as the nonstructural protein 1 (NS1) has been recently proposed as the missing corner piece of the DENV pathogenesis influencing disease. This Part II of the chapter will discuss the interplay between the distinct host adaptive immune responses and viral factors that together contribute to the development of DENV pathogenesis and severe disease

Detection of Herpes Simplex Virus Infection in Patients With Ongoing Miscarriage Using Serological Tests and Real-Time Polymerase Chain Reaction

Background: Herpes simplex virus (HSV) is one of the most frequent viruses affecting females’ sexual and reproductive health. Objectives: The current study aimed to determine the HSV serostatus and viral shedding in patients with ongoing miscarriage. Methods: Two hundred and eight females were included in the study; IgM antibodies against HSV1/2 were detected in serum samples; the real-time polymerase chain reaction (PCR) quantification of viral DNA was performed on cervicovaginal samples. Positive females were tested for IgG anti-HSV-2. Results: The results indicated 12.5% IgM-positive and 2.9% real-time PCR positive samples. None of the patients was positive for the both analyses, simultaneously. Among IgM-positives cases, 16.6% were also IgG-positive; whilst in PCR-positives samples, 20% were also IgG-positive. The presence of viral DNA without detectable IgM or IgG antibodies could indicate a recent infection or a reactivation with low copy numbers. Conclusions: IgM alone is not a marker for viral shedding in genital tract. Molecular testing in conjunction of IgG test should be evaluated as an option to determine HSV status, and applied for research on HSV genital infections records. Keywords: Herpes, Diagnosis, Viral Sheddin

Estimating absolute indoor density of Aedes aegypti using removal sampling

Exhaustive removal sampling represents a promising method for quantification of absolute indoor Aedes aegypti density, leading to improved entomological estimates of mosquito distribution. The study describes the use of sequential removal sampling to estimate absolute numbers of indoor resting Aedes in the city of Merida, Mexico. The study was performed in 200 houses based on recent occurrence of Aedes-borne viral illness in residents. The lack of a numerical association between relative and absolute density of adult Ae. aegypti represent a significant gap in vector surveillance. Merida is highly endemic for dengue and other Aedes-borne viruses.Bureau for Global HealthU.S Agency for International Development (USAID)US Centers for Disease Control and Prevention (CDC)Canadian Institutes of Health Research (CIHR

Temporal distribution and genetic variants in influenza A(H1N1)pdm09 virus circulating in Mexico, seasons 2012 and 2013

The 2012 and 2013 annual influenza epidemics in Mexico were characterized by presenting different seasonal patterns. In 2012 the A(H1N1)pdm09 virus caused a high incidence of influenza infections after a two-year period of low circulation; whereas the 2013 epidemic presented circulation of the A(H1N1)pdm09 virus throughout the year. We have characterized the molecular composition of the Hemagglutinin (HA) and Neuraminidase (NA) genes of the A(H1N1)pdm09 virus from both epidemic seasons, emphasizing the genetic characteristics of viruses isolated from Yucatan in Southern Mexico. The molecular analysis of viruses from the 2012 revealed that all viruses from Mexico were predominantly grouped in clade 7. Strikingly, the molecular characterization of viruses from 2013 revealed that viruses circulating in Yucatan were genetically different to viruses from other regions of Mexico. In fact, we identified the occurrence of two genetic variants containing relevant mutations at both the HA and NA surface antigens. There was a difference on the temporal circulation of each genetic variant, viruses containing the mutations HA-A141T / NA-N341S were detected in May, June and July; whereas viruses containing the mutations HA-S162I / NAL206S circulated in August and September. We discuss the significance of these novel genetic changes