The impact of Zika emergence in remote communities in northwestern Ecuador.

The Zika virus (ZIKV) epidemic in Latin America (2015-2016) has primarily been studied in urban centers, with less understanding of its impact on smaller rural communities. To address this gap, we analyzed ZIKV sero-epidemiology in six rural Ecuadorian communities (2018-2019) with varying access to a commercial hub. Seroprevalence ranged from 19% to 54% measured by NS1 blockade of binding ELISA. We observed a decline in ZIKV seroprevalence between 2018 and 2019 that was greater among younger populations, suggesting that the attack rates in the 2015-16 epidemic were significantly higher than our 2018 observations. These data indicate that the 2015-16 epidemic included significant transmission in rural and more remote settings. Our observations of high seroprevalence in our area of study highlights the importance of surveillance and research in rural areas lacking robust health systems to manage future Zika outbreaks and vaccine initiatives.

Multiple burdens of malnutrition and relative remoteness in rural Ecuadorian communities.

OBJECTIVE: Social and economic changes associated with new roads can bring about rapid nutritional transitions. To study this process, we: (1) describe trends in adult overweight and obesity (OW/OB) among rural Afro-Ecuadorians over time and across a gradient of community remoteness from the nearest commercial centre; (2) examine the relationship between male and female adult OW/OB and factors associated with market integration such as changing livelihoods and (3) examine the co-occurrence of adult OW/OB and under-five stunting and anaemia. DESIGN: Adult anthropometry was collected through serial case-control studies repeated over a decade across twenty-eight communities. At the same time, anthropometry and Hb were measured for all children under 5 years of age in every community. SETTING: Northern coastal Ecuador. PARTICIPANTS: Adults (n 1665) and children under 5 years of age (n 2618). RESULTS: From 2003 and 2013, OW/OB increased from 25·1 % to 44·8 % among men and 59·9 % to 70·2 % among women. The inverse relationship between remoteness and OW/OB in men was attenuated when adjusting for urban employment, suggesting that livelihoods mediated the remoteness-OW/OB relationship. No such relationship was observed among women. Communities with a higher prevalence of male OW/OB also had a greater prevalence of stunting, but not anaemia, in children under 5 years of age. CONCLUSIONS: The association between male OW/OB and child stunting at the community level, but not the household level, suggests that changing food environments, rather than household- or individual-level factors, drove these trends. A closer examination of changing socio-economic structures and food environments in communities undergoing rapid development could help mitigate future public health burdens.

Fatal acute Chagas disease by Trypanosoma cruzi DTU TcI, Ecuador.

BACKGROUND: Chagas disease is caused by the haemoflagellate protozoan Trypanosoma cruzi. Currently, T. cruzi recognizes seven discrete typing units (DTUs): TcI to TcVI and Tcbat. The genetic diversity of T. cruzi is suspected to influence the clinical outcome. Acute clinical manifestations, which include myocarditis and meningoencephalitis, are sometimes fatal; occur most frequently in children and in immunocompromised individuals. Acute disease is often overlooked, leading to a poor prognosis. CASE PRESENTATION: A 38-year-old man from a subtropical area of the Andes mountains of Ecuador was hospitalized after 3 weeks of evolution with high fever, chills, an enlarged liver, spleen, and lymph nodes, as well as facial edema. ECG changes were also observed. T. cruzi was identified in blood smears, culture and amplification of DNA by PCR. Tests for anti-T. cruzi IgG and IgM and HIV were negative. Molecular typing by restriction fragment length polymorphism (PCR-RFLP) determined the parasite to DTU TcI. In the absence of a timely anti-T. cruzi medication, the patient died. CONCLUSIONS: This is a case of severe pathogenicity and the virulence of a DTU TcI strain in an adult patient. The severe acute Chagas disease was probably overlooked due to limited awareness and its low incidence. Our findings suggest that T. cruzi DTU TcI strains circulating in Ecuador are capable of causing fatal acute disease. Early diagnosis and prompt treatment is of paramount importance to avoid fatalities in acute infections.

Metagenomic Signatures of Gut Infections Caused by Different Escherichia coli Pathotypes.

Escherichia coli is a leading contributor to infectious diarrhea and child mortality worldwide, but it remains unknown how alterations in the gut microbiome vary for distinct E. coli pathotype infections and whether these signatures can be used for diagnostic purposes. Further, the majority of enteric diarrheal infections are not diagnosed with respect to their etiological agent(s) due to technical challenges. To address these issues, we devised a novel approach that combined traditional, isolate-based and molecular-biology techniques with metagenomics analysis of stool samples and epidemiological data. Application of this pipeline to children enrolled in a case-control study of diarrhea in Ecuador showed that, in about half of the cases where an E. coli pathotype was detected by culture and PCR, E. coli was likely not the causative agent based on the metagenome-derived low relative abundance, the level of clonality, and/or the virulence gene content. Our results also showed that diffuse adherent E. coli (DAEC), a pathotype that is generally underrepresented in previous studies of diarrhea and thus, thought not to be highly virulent, caused several small-scale diarrheal outbreaks across a rural to urban gradient in Ecuador. DAEC infections were uniquely accompanied by coelution of large amounts of human DNA and conferred significant shifts in the gut microbiome composition relative to controls or infections caused by other E. coli pathotypes. Our study shows that diarrheal infections can be efficiently diagnosed for their etiological agent and categorized based on their effects on the gut microbiome using metagenomic tools, which opens new possibilities for diagnostics and treatment.IMPORTANCEE. coli infectious diarrhea is an important contributor to child mortality worldwide. However, diagnosing and thus treating E. coli infections remain challenging due to technical and other reasons associated with the limitations of the traditional culture-based techniques and the requirement to apply Koch's postulates. In this study, we integrated traditional microbiology techniques with metagenomics and epidemiological data in order to identify cases of diarrhea where E. coli was most likely the causative disease agent and evaluate specific signatures in the disease-state gut microbiome that distinguish between diffuse adherent, enterotoxigenic, and enteropathogenic E. coli pathotypes. Therefore, our methodology and results should be highly relevant for diagnosing and treating diarrheal infections and have important applications in public health.

Locals get travellers' diarrhoea too: risk factors for diarrhoeal illness and pathogenic Escherichia coli infection across an urban-rural gradient in Ecuador.

OBJECTIVES: Diarrhoea is a common and well-studied cause of illness afflicting international travellers. However, traveller's diarrhoea can also result from travel between high and low disease transmission regions within a country, which is the focus of this study. METHODS: We recruited participants for a case-control study of diarrhoea at four sites along an urban-rural gradient in Northern Ecuador: Quito, Esmeraldas, Borbón and rural communities outside of Borbón. At each of these sites, approximately 100 subjects with diarrhoea (cases) were recruited from Ministry of Health clinics and were age-matched with subjects visiting the same clinics for other complaints (controls). RESULTS: Travellers to urban destinations had higher risk of diarrhoea and diarrhoeagenic Escherichia coli (DEC) infections. Travel to Quito was associated with diarrhoea (aOR = 2.01, 95% CI = 1.10-3.68) and travel to Guayaquil (another urban centre in Ecuador) was associated with Diffuse Adherent E. coli infection (OR = 2.09, 95% CI = 1.01-4.33). Compared to those not travelling, urban origins were also associated with greater risk of diarrhoea in Esmeraldas (aOR = 2.28, 95% CI = 1.20-4.41), and with higher risk of diarrhoeagenic E. coli infections in Quito (aOR = 2.61, 95% CI = 1.16-5.86), with >50% of travel from Quito and Esmeraldas specified to another urban destination. CONCLUSIONS: This study suggests that individuals travelling from lower-transmission regions (rural areas) to higher transmission regions (urban centres) within a single country are at a greater risk of acquiring a diarrhoea-related illness. Investments to improve water, sanitation and hygiene conditions in urban areas could have impacts on outlying rural areas within a given country.

The Role of Mobile Genetic Elements in the Spread of Antimicrobial-Resistant Escherichia coli From Chickens to Humans in Small-Scale Production Poultry Operations in Rural Ecuador.

Small-scale production poultry operations are increasingly common worldwide. To investigate how these operations influence antimicrobial resistance and mobile genetic elements (MGEs), Escherichia coli isolates were sampled from small-scale production birds (raised in confined spaces with antibiotics in feed), household birds (no movement constraints; fed on scraps), and humans associated with these birds in rural Ecuador (2010-2012). Isolates were screened for genes associated with MGEs as well as phenotypic resistance to 12 antibiotics. Isolates from small-scale production birds had significantly elevated odds of resistance to 7 antibiotics and presence of MGE genes compared with household birds (adjusted odds ratio (OR) range = 2.2-87.9). Isolates from humans associated with small-scale production birds had elevated odds of carrying an integron (adjusted OR = 2.0; 95% confidence interval (CI): 1.06, 3.83) compared with humans associated with household birds, as well as resistance to sulfisoxazole (adjusted OR = 1.9; 95% CI: 1.01, 3.60) and trimethoprim/sulfamethoxazole (adjusted OR = 2.1; 95% CI: 1.13, 3.95). Stratifying by the presence of MGEs revealed antibiotic groups that are explained by biological links to MGEs; in particular, resistance to sulfisoxazole, trimethoprim/sulfamethoxazole, or tetracycline was highest among birds and humans when MGE exposures were present. Small-scale production poultry operations might select for isolates carrying MGEs, contributing to elevated levels of resistance in this setting.

Determinants of Short-term Movement in a Developing Region and Implications for Disease Transmission.

BACKGROUND: Human mobility is important for infectious disease spread. However, little is known about how travel varies by demographic groups and how this heterogeneity influences infectious disease risk. METHODS: We analyzed 10 years of survey data from 15 communities in a remote but rapidly changing region in rural Ecuador where road development in the past 15-20 years has dramatically changed travel. We identify determinants of travel and incorporate them into an infection transmission model. RESULTS: Individuals living in communities more remote at baseline had lower travel rates compared with less remote villages (adjusted odds ratio [OR] = 0.51; 95% confidence interval [CI] = 0.38, 0.67). Our model predicts that less remote villages are, therefore, at increased disease risk. Though road building and travel increased for all communities, this risk differential remained over 10 years of observation. Our transmission model also suggests that travelers and nontravelers have different roles in disease transmission. Adults travel more than children (adjusted OR = 1.73; 95% CI = 1.30, 2.31) and therefore disseminate infection from population centers to rural communities. Children are more likely than adults to be infected locally (attributable fraction = 0.24 and 0.09, respectively) and were indirectly affected by adult travel patterns. CONCLUSIONS: These results reinforce the importance of large population centers for regional transmission and show that children and adults may play different roles in disease spread. Changing transportation infrastructure and subsequent economic and social transitions are occurring worldwide, potentially causing increased regional risk of disease.

Trends of child undernutrition in rural Ecuadorian communities with differential access to roads, 2004-2013.

Road access can influence protective and risk factors associated with nutrition by affecting various social and biological processes. In northern coastal Ecuador, the construction of new roads created a remoteness gradient among villages, providing a unique opportunity to examine the impact of roads on child nutritional outcomes 10 years after the road was built. Anthropometric and haemoglobin measurements were collected from 2,350 children <5 years in Esmeraldas, Ecuador, from 2004 to 2013 across 28 villages with differing road access. Logistic generalized estimating equation models assessed the longitudinal association between village remoteness and prevalence of stunting, wasting, underweight, overweight, obesity, and anaemia. We examined the influence of socio-economic characteristics on the pathway between remoteness and nutrition by comparing model results with and without household-level socio-economic covariates. Remoteness was associated with stunting (OR = 0.43, 95% CI [0.30, 0.63]) and anaemia (OR = 0.56, 95% CI [0.44, 0.70]). Over time, the prevalence of stunting was generally decreasing but remained higher in villages closer to the road compared to those farther away. Obesity increased (0.5% to 3%) over time; wasting was high (6%) but stable during the study period. Wealth and education partially explained the better nutritional outcomes in remote vs. road villages more than a decade after some communities gained road access. Establishing the extent to which these patterns persist requires additional years of observation.

Enzyme-linked immunosorbent assay for diagnosis of Amphimerus spp. liver fluke infection in Humans.

BACKGROUND: Amphimerus spp. is a liver fluke that infects humans and domestic animals. It is highly prevalent in some Ecuadorian communities. Currently, diagnosis is based on the microscopic observation of eggs in faeces, but this has variable sensitivity. More sensitive methods are needed for diagnostic testing. OBJECTIVE: The main objective of this work was to develop an enzyme-linked immunosorbent assay (ELISA) using crude antigens from Amphimerus spp. adult worms to detect anti-Amphimerus IgG in human sera. METHODS: Crude somatic antigens were obtained from adult Amphimerus spp. worms. Human sera from 119 patients were tested: 48 from individuals with a confirmed Amphimerus spp. infection, 78 from non-infected Ecuadorians living in the endemic region, 60 from persons living in non-endemic areas (20 Ecuadorians, 20 Europeans, and 20 Africans), and 33 who had other parasitic and non-parasitic infections. PRINCIPAL FINDINGS: Results were analysed using the receiver-operator characteristic (ROC) curve analysis with an area under curve (AUC) value of 0.967. The accuracy of the ELISA was high. The sensitivity was 85.0% [95% confidence interval (CI): 80.3-89.7%] and the specificity was 71.0% (95% CI: 65.2-76.8%). Some cross reactivity was detected against Paragonimus mexicanus, Fasciola hepatica, Schistosomiasis, Taenia solium, Strongyloides stercoralis, Mansonella spp., and Vampirolepis nana. MAIN CONCLUSIONS: We have developed the first ELISA technique that detects anti-Amphimerus IgG in human sera with good sensitivity, repeatability and reproducibility. However, more specific antigens are needed to further enhance performance of this assay. Regardless, this ELISA test could be useful for early diagnosis and prompt treatment of human Amphimerus spp. infections.

[Social factors associated with use of prenatal care in Ecuador]. / Factores sociales asociados con la utilización de los servicios de atención prenatal en Ecuador.

OBJECTIVES: Prenatal care is a pillar of public health, enabling access to interventions including prevention of mother-to-child transmission of HIV and congenital syphilis. This paper describes social factors related to use of prenatal care in Ecuador. METHODS: In 2011 and 2012, participant clinical history and interview information was analyzed from a national probability sample of 5 998 women presenting for delivery or miscarriage services in 15 healthcare facilities in Ecuador, to estimate prevalence of HIV, syphilis, and Chagas disease, and prenatal care coverage. RESULTS: The study found that 94.1% of women had attended at least one prenatal visit, but that attendance at no less than four visits was 73.1%. Furthermore, lower educational level, greater number of pregnancies, occupation in the agriculture or livestock sector, and membership in ethnic indigenous, Afro-Ecuadorian, or other minority groups were factors associated with lack of use (no prenatal visits) or insufficient use of prenatal care (fewer than four visits or first visit at >20 weeks gestation) in Ecuador. CONCLUSIONS: These results point to persistence of marked inequalities in access to and use of prenatal health services attributable to socioeconomic factors and to the need to strengthen strategies to address them, to reach the goal of universal prenatal care coverage.

Effects of selection pressure and genetic association on the relationship between antibiotic resistance and virulence in Escherichia coli.

Antibiotic selection pressure and genetic associations may lead to the cooccurrence of resistance and virulence in individual pathogens. However, there is a lack of rigorous epidemiological evidence that demonstrates the cooccurrence of resistance and virulence at the population level. Using samples from a population-based case-control study in 25 villages in rural Ecuador, we characterized resistance to 12 antibiotics among pathogenic (n = 86) and commensal (n = 761) Escherichia coli isolates, classified by the presence or absence of known diarrheagenic virulence factor genes. The prevalences of resistance to single and multiple antibiotics were significantly higher for pathogenic isolates than for commensal isolates. Using a generalized estimating equation, antibiotic resistance was independently associated with virulence factor carriage, case status, and antibiotic use (for these respective factors: odds ratio [OR] = 3.0, with a 95% confidence interval [CI] of 1.7 to 5.1; OR = 2.0, with a 95% CI of 1.3 to 3.0; and OR = 1.5, with a 95% CI of 0.9 to 2.5). Virulence factor carriage was more strongly related to antibiotic resistance than antibiotic use for all antibiotics examined, with the exception of fluoroquinolones, gentamicin, and cefotaxime. This study provides epidemiological evidence that antibiotic resistance and virulence factor carriage are linked in E. coli populations in a community setting. Further, these data suggest that while the cooccurrence of resistance and virulence in E. coli is partially due to antibiotic selection pressure, it is also genetically determined. These findings should be considered in developing strategies for treating infections and controlling for antibiotic resistance.

Heavy rainfall events and diarrhea incidence: the role of social and environmental factors.

The impact of heavy rainfall events on waterborne diarrheal diseases is uncertain. We conducted weekly, active surveillance for diarrhea in 19 villages in Ecuador from February 2004 to April 2007 in order to evaluate whether biophysical and social factors modify vulnerability to heavy rainfall events. A heavy rainfall event was defined as 24-hour rainfall exceeding the 90th percentile value (56 mm) in a given 7-day period within the study period. Mixed-effects Poisson regression was used to test the hypothesis that rainfall in the prior 8 weeks, water and sanitation conditions, and social cohesion modified the relationship between heavy rainfall events and diarrhea incidence. Heavy rainfall events were associated with increased diarrhea incidence following dry periods (incidence rate ratio = 1.39, 95% confidence interval: 1.03, 1.87) and decreased diarrhea incidence following wet periods (incidence rate ratio = 0.74, 95% confidence interval: 0.59, 0.92). Drinking water treatment reduced the deleterious impacts of heavy rainfall events following dry periods. Sanitation, hygiene, and social cohesion did not modify the relationship between heavy rainfall events and diarrhea. Heavy rainfall events appear to affect diarrhea incidence through contamination of drinking water, and they present the greatest health risks following periods of low rainfall. Interventions designed to increase drinking water treatment may reduce climate vulnerability.

HIV and syphilis infection in pregnant women in Ecuador: prevalence and characteristics of antenatal care.

OBJECTIVES: This study aimed to obtain nationally representative estimates of HIV and syphilis prevalence and coverage of preventive antenatal services in pregnant women in Ecuador, in order to develop a national strategy for the elimination of mother-to-child transmission of HIV and syphilis. METHODS: A national probability sample of 5988 women presenting for delivery or miscarriage services was selected from 15 healthcare facilities during 2011-2012, using a two-stage cluster sample technique. Biological specimens were collected and an interview and review of medical records were performed. Agreement between these last two sources was measured. Estimates were adjusted for the sampling design. RESULTS: Estimated national HIV prevalence (0.60%) was higher than confirmed syphilis infection prevalence (0.25%). In the coastal region, HIV prevalence (1.13%) exceeded the threshold that defines a generalised epidemic and syphilis prevalence reached 0.37%. An estimated 5.9% of women did not use antenatal care services while 73.0% completed at least four consultations. HIV testing coverage (89.9%) was higher than for syphilis (71.6%). Agreement between medical records and interviews was mostly moderate (0.40-0.75). Important variables were frequently not recorded, such as timing of syphilis testing, which was not recorded in 49.6%. CONCLUSIONS: The concentration of HIV and syphilis infections in the coastal region of Ecuador highlights the need for intensified prevention and a response tailored to local epidemic conditions. Major challenges for the elimination initiative include achieving universal, early access to antenatal care, improving coverage of HIV and syphilis testing, and improving the quality of medical records to support progress monitoring.

Correlates of maternal depression, anxiety and functioning across an urban-rural gradient in northern Ecuador.

Maternal depression remains under characterised in many low- and middle-income countries, especially in rural settings. We aimed to describe maternal depression and anxiety symptoms in rural and urban communities in northern Ecuador and to identify socioeconomic and demographic factors associated with these symptoms. Data from 508 mothers participating in a longitudinal cohort study were included. Depression and anxiety symptoms were assessed using the Hopkins Symptom Checklist (HSCL-25), and maternal psychological functioning was assessed using a checklist of daily activities. Tobit regression models were used to examine associations with sociodemographic variables and urbanicity. The median HSCL-25 score was 1.2 (IQR: 0.4) and 14% of women scored above the threshold for clinically relevant symptoms. Rural women reported similar food insecurity, less education, younger age of first pregnancy, and lower socio-economic status compared to their urban counterparts. After adjusting for these factors, rural women reported lower HSCL-25 scores compared to women lin urban areas (ß = -0.48, 95%CI:0.65, -0.31). Rural residence was also associated with lower depression and anxiety HSCL-25 sub-scale scores, and similar levels of maternal functioning, compared to urban residence. Our results suggest that both household and community-level factors are risk factors for maternal depression and anxiety in this context.

Molecular identification of Giardia duodenalis in Ecuador by polymerase chain reaction-restriction fragment length polymorphism.

The aim of this study was to determine the genetic diversity of Giardia duodenalis present in a human population living in a northern Ecuadorian rain forest. All Giardia positive samples (based on an ELISA assay) were analysed using a semi-nested polymerase chain reaction-restriction fragment length polymorphism assay that targets the glutamate dehydrogenase (gdh) gene; those amplified were subsequently genotyped using NlaIV and RsaI enzymes. The gdh gene was successfully amplified in 74 of 154 ELISA positive samples; 69 of the 74 samples were subsequently genotyped. Of these 69 samples, 42 (61%) were classified as assemblage B (26 as BIII and 16 as BIV), 22 (32%) as assemblage A (3 as AI and 19 as AII) and five (7%) as mixed AII and BIII types. In this study site we observe similar diversity in genotypes to other regions in Latin America, though in contrast to some previous studies, we found similar levels of diarrheal symptoms in those individuals infected with assemblage B compared with those infected with assemblage A.

A Qualitative Study of Food Choice in Urban Coastal Esmeraldas, Ecuador.

Background: Constraints on food choice increase risk of malnutrition worldwide. Residents of secondary cities within low- and middle-income countries are a population of particular concern because they often face high rates of food insecurity and multiple nutritional burdens. Within this context, effective and equitable interventions to support healthy diets must be based on an understanding of the lived experience of individuals and their interactions with the food environment. Objectives: The primary objectives of this study were to describe considerations that drive household decision making around food choice in the city of Esmeraldas, Ecuador; to identify trade-offs between these considerations; and to understand how an evolving urban environment influences these trade-offs. Methods: Semistructured interviews were conducted with 20 mothers of young children to explore drivers in food choice throughout the purchase, preparation, and consumption chain. Interviews were transcribed and coded to identify key themes. Results: Personal preference, economic access (costs), convenience, and perceptions of food safety were key influencers of decision making related to food. In addition, concerns about personal safety in the urban environment limited physical access to food. This, combined with the need to travel long distances to obtain desirable foods, increased men's participation in food purchasing. Women's increasing engagement in the workforce also increased men's participation in food preparation. Conclusions: Policies to promote healthy food behavior in this context should focus on increasing access to health foods, such as affordable fresh produce, in convenient and physically safe locations. CurrDev Nutr 2023;x:xx.

Distribution of Escherichia coli Pathotypes along an Urban-Rural Gradient in Ecuador.

Diarrheal diseases are a leading cause of mortality and morbidity in low- and middle-income countries. Diarrhea is associated with a wide array of etiological agents including bacterial, viral, and parasitic enteropathogens. Previous studies have captured between- but not within-country heterogeneities in enteropathogen prevalence and severity. We conducted a case-control study of diarrhea to understand how rates and outcomes of infection with diarrheagenic pathotypes of Escherichia coli vary across an urban-rural gradient in four sites in Ecuador. We found variability by site in enteropathogen prevalence and infection outcomes. Any pathogenic E. coli infection, coinfections, diffuse adherent E. coli (DAEC), enteroinvasive E. coli (EIEC), and rotavirus were significantly associated with acute diarrhea. DAEC was the most common pathotype overall and was more frequently associated with disease in urban areas. Enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC) were more common in rural areas. ETEC was only associated with diarrhea in one site. Phylogenetic analysis revealed that associations with disease were not driven by any single clonal complex. Higher levels of antibiotic resistance were detected in rural areas. Enteropathogen prevalence, virulence, and antibiotic resistance patterns vary substantially by site within Ecuador. The variations in E. coli pathotype prevalence and virulence in this study have important implications for control strategies by context and demonstrate the importance of capturing within-country differences in enteropathogen disease dynamics.

Plesiomonas shigelloides infection, Ecuador, 2004-2008.

Diarrheal risk associated with Plesiomonas shigelloides infection was assessed in rural communities in northwestern Ecuador during 2004-2008. We found little evidence that single infection with P. shigelloides is associated with diarrhea but stronger evidence that co-infection with rotavirus causes diarrhea.

Synergistic effects between rotavirus and coinfecting pathogens on diarrheal disease: evidence from a community-based study in northwestern Ecuador.

In developing countries where diarrheal disease is a leading cause of morbidity and mortality in children under 5 years of age, enteric coinfection is common. There is little understanding, however, of the biologic interaction between coinfecting pathogens. The authors investigated the potential for synergistic interaction between coinfecting pathogens on diarrhea pathogenesis using an epidemiologic framework. They conducted community-based, case-control studies in 22 communities in northwestern Ecuador between 2003 and 2008. Risk ratios of diarrhea associated with single infections and coinfections were estimated. Interaction between coinfecting pathogens was assessed through departure from risk ratio additivity and multiplicativity after adjustment for age. On the additive scale, the authors found departure from the null value of 0 for rotavirus-Giardia coinfections (interaction contrast ratio = 8.0, 95% confidence interval: 3.1, 18.9) and for rotavirus-Escherichia coli coinfections (interaction contrast ratio = 9.9, 95% confidence interval: 2.6, 28.4). On the multiplicative scale, they found departure from the value of 1 for rotavirus-Giardia coinfections (multiplicative interaction = 3.6, 95% confidence interval: 1.3, 8.7). This research provides epidemiologic evidence for synergism between rotavirus and other enteric pathogens. During coinfection, the pathogenic potential of each organism appears to be enhanced. The potential for pathogenesis to be more severe in the presence of a rotavirus coinfection amplifies the need for rotavirus vaccination.

Social connectedness and disease transmission: social organization, cohesion, village context, and infection risk in rural Ecuador.

Social networks are typically seen as conduits for the spread of disease and disease risk factors. However, social relationships also reduce the incidence of chronic disease and potentially infectious diseases. Seldom are these opposing effects considered simultaneously. We have shown how and why diarrheal disease spreads more slowly to and in rural Ecuadorian villages that are more remote from the area's population center. Reduced contact with outside individuals partially accounts for remote villages' relatively lower prevalence of diarrheal disease. But equally or more important is the greater density of social ties between individuals in remote communities, which facilitates the spread of individual and collective practices that reduce the transmission of diarrheal disease.