Dengue immunopathogenesis : a cross talk between host and viral factors leading to disease : part I - Dengue virus tropism, host innate immune responses, and subversion of antiviral responses

Two part articleThis detailed paper addresses the general features of the dengue virus (DENV) infections complex, including the virus structure and genome, epidemiology, and clinical outcomes. This is 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.Canadian Institutes of Health ResearchFondo Mixto CONACYT-Gobierno del Estado de Yucatá

Spatio-temporal coherence of dengue, chikungunya and Zika outbreaks in Merida, Mexico

Longitudinal Dengue (DENV) data generated patterns indicative of the resulting introduction and transmission patterns of chikungunya (CHIKV) and Zika virus (ZIKV), leading to important insights for the surveillance and targeted control of emerging Aedes-borne viruses. About 42% of the 40,028 DENV cases reported during 2008–2015 clustered in 27% of Merida (Mexico), and these clustering areas were where the first CHIKV and ZIKV cases were reported in 2015 and 2016. Findings from this article open a window to the consideration of spatially-targeted approaches for delivery of vector control interventions and surveillance.National Science FoundationOffice of Infectious Disease, Bureau for Global Health, U.S. Agency for International DevelopmentUS Centers for Disease Control and Preventio

ACE I/D (Rs1799752), MTHFR C677T (Rs1801133), and CCR5 D32 (Rs333) Genes and their Association with Hypertension and Diabetic Nephropathy in Urban Areas of Costa Rica, Nicaragua, and Mexico

Aim: Type 2 diabetes mellitus (T2DM) is a procoagulant state because it is associated with increased risk of atherosclerosis. The purpose of this study was to investigate the prevalence in thrombotic markers that lead to hypercoagulability and its association with hypertension and diabetic nephropathy (DN)

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

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

Dengue immunopathogenesis : a crosstalk between host and viral factors leading to disease : part II—DENV infection, adaptive immune responses, and NS1 pathogenesis

Two part articleThis chapter details the interplay between distinct host adaptive immune responses and viral factors that together contribute to the development of the dengue virus (DENV) pathogenesis and severe disease. As Part II, it addresses: the multifactorial immunopathogenic process of DENV infection from the perspective of the pre-existing serotype cross-reactive antibodies; the hyperactivation of DENV infected immune cells (monocytes, mast cells) leading to increased cytokine production; the role of T cell responses; the activation of complement pathways; and the new pathogenic roles of the secreted NS1 of DENV that may act together to occasionally cause severe dengue manifestations.Canadian Institutes of Health ResearchFondo Mixto CONACYT-Gobierno del Estado de Yucata

Rapid Detection of Trypanosoma cruzi in Human Serum by Use of an Immunochromatographic Dipstick Test ▿

We evaluated a commercially available immunochromatographic dipstick test to detect Trypanosoma cruzi infection in 366 human serum samples with known serological results from Argentina, Ecuador, Mexico, and Venezuela. One hundred forty-nine of 366 (40.7%) and 171/366 (46.7%) samples tested positive by dipstick and serology, respectively. Dipstick sensitivity was calculated to be 84.8% (range between countries, 77.5 to 95%), and specificity was 97.9% (95.9 to 100%)

Epidemiology of dengue and other arboviruses in a cohort of school children and their families in Yucatan, Mexico: Baseline and first year follow-up.

Dengue is the most prevalent mosquito-borne viral disease of humans and is caused by the four serotypes of dengue virus. To estimate the incidence of dengue and other arboviruses, we analyzed the baseline and first year follow-up of a prospective school-based cohort study and their families in three cities in the state of Yucatan, Mexico. Through enhanced surveillance activities, acute febrile illnesses in the participants were detected and yearly blood samples were collected to evaluate dengue infection incidence. A Cox model was fitted to identify hazard ratios of arboviral infections in the first year of follow-up of the cohort. The incidence of dengue symptomatic infections observed during the first year of follow-up (2015-2016) was 3.5 cases per 1,000 person-years (95% CI: 1.9, 5.9). The incidence of dengue infections was 33.9 infections per 1,000 person-years (95% CI: 31.7, 48.0). The majority of dengue infections and seroconversions were observed in the younger age groups (≤ 14 years old). Other arboviruses were circulating in the state of Yucatan during the study period. The incidence of symptomatic chikungunya infections was 8.6 per 1,000 person-years (95% CI: 5.8, 12.3) and the incidence of symptomatic Zika infections was 2.3 per 1,000 person-years (95% CI: 0.9, 4.5). Our model shows that having a dengue infection during the first year of follow-up was significantly associated with being female, living in Ticul or Progreso, and being dengue naïve at baseline. Age was not significantly associated with the outcome, it was confounded by prior immunity to dengue that increases with age. This is the first report of a cohort in Latin America that provides incidence estimates of the three arboviruses co-circulating in all age groups. This study provides important information for understanding the epidemiology of dengue and other arboviruses and better informing public health policies

Natural arbovirus infection rate and detectability of indoor female Aedes aegypti from Mérida, Yucatán, Mexico.

Arbovirus infection in Aedes aegypti has historically been quantified from a sample of the adult population by pooling collected mosquitoes to increase detectability. However, there is a significant knowledge gap about the magnitude of natural arbovirus infection within areas of active transmission, as well as the sensitivity of detection of such an approach. We used indoor Ae. aegypti sequential sampling with Prokopack aspirators to collect all mosquitoes inside 200 houses with suspected active ABV transmission from the city of Mérida, Mexico, and tested all collected specimens by RT-PCR to quantify: a) the absolute arbovirus infection rate in individually tested Ae. aegypti females; b) the sensitivity of using Prokopack aspirators in detecting ABV-infected mosquitoes; and c) the sensitivity of entomological inoculation rate (EIR) and vectorial capacity (VC), two measures ABV transmission potential, to different estimates of indoor Ae. aegypti abundance. The total number of Ae. aegypti (total catch, the sum of all Ae. aegypti across all collection intervals) as well as the number on the first 10-min of collection (sample, equivalent to a routine adult aspiration session) were calculated. We individually tested by RT-PCR 2,161 Aedes aegypti females and found that 7.7% of them were positive to any ABV. Most infections were CHIKV (77.7%), followed by DENV (11.4%) and ZIKV (9.0%). The distribution of infected Aedes aegypti was overdispersed; 33% houses contributed 81% of the infected mosquitoes. A significant association between ABV infection and Ae. aegypti total catch indoors was found (binomial GLMM, Odds Ratio > 1). A 10-min indoor Prokopack collection led to a low sensitivity of detecting ABV infection (16.3% for detecting infected mosquitoes and 23.4% for detecting infected houses). When averaged across all infested houses, mean EIR ranged between 0.04 and 0.06 infective bites per person per day, and mean VC was 0.6 infectious vectors generated from a population feeding on a single infected host per house/day. Both measures were significantly and positively associated with Ae. aegypti total catch indoors. Our findings provide evidence that the accurate estimation and quantification of arbovirus infection rate and transmission risk is a function of the sampling effort, the local abundance of Aedes aegypti and the intensity of arbovirus circulation