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.

In-roads to the spread of antibiotic resistance: regional patterns of microbial transmission in northern coastal Ecuador

The evolution of antibiotic resistance (AR) increases treatment cost and probability of failure, threatening human health worldwide. The relative importance of individual antibiotic use, environmental transmission and rates of introduction of resistant bacteria in explaining community AR patterns is poorly understood. Evaluating their relative importance requires studying a region where they vary. The construction of a new road in a previously roadless area of northern coastal Ecuador provides a valuable natural experiment to study how changes in the social and natural environment affect the epidemiology of resistant Escherichia coli. We conducted seven bi-annual 15 day surveys of AR between 2003 and 2008 in 21 villages. Resistance to both ampicillin and sulphamethoxazole was the most frequently observed profile, based on antibiogram tests of seven antibiotics from 2210 samples. The prevalence of enteric bacteria with this resistance pair in the less remote communities was 80 per cent higher than in more remote communities (OR = 1.8 [1.3, 2.3]). This pattern could not be explained with data on individual antibiotic use. We used a transmission model to help explain this observed discrepancy. The model analysis suggests that both transmission and the rate of introduction of resistant bacteria into communities may contribute to the observed regional scale AR patterns, and that village-level antibiotic use rate determines which of these two factors predominate. While usually conceived as a main effect on individual risk, antibiotic use rate is revealed in this analysis as an effect modifier with regard to community-level risk of resistance.

Rapid changes in rotaviral genotypes in Ecuador

Previous studies suggest that the emerging G9P[8] genotype was the most prevalent rotavirus genotype in Ecuador during 2005. This present study provides a temporal analysis of the distribution of rotavirus genotypes in two locations within Ecuador by adding additional years (2006 - early 2008) to the originally reported 2005 data. Data were collected in a rural (northern coastal Ecuador) and urban (Quito) area. In the rural area, a community sample of cases (those presenting diarrhea) and controls (those not presenting diarrhea) were collected between August 2003 and March 2008 resulting in a total of 3,300 stool samples (876 cases and 2,424 controls). Of these samples, 260 were positive for rotavirus by an immunochromatographic test (196 cases and 64 controls). In Quito, 59 fecal samples were collected from children presenting diarrhea and diagnosed with rotavirus. An RT-PCR analysis of samples collected between 2005 and 2007 suggested that G9 was replaced by G1 and G2 in the rural and urban settings. During this period G9 decreased from 79% to 9% while G2 increased from 0% to 43% in the rural communities, and G9 decreased from 79% to 37% while G2 increased from 3% to 57% in the urban area of Quito. This rapid replacement of G9 by G1 and G2 reinforces the necessity of surveillance to inform vaccination programs.

Symptomatic and subclinical infection with rotavirus P[8]G9, rural Ecuador

Prevalence of this genotype is increasing.

During the past decade, rotavirus genotype G9 has spread throughout the world, adding to and sometimes supplanting the common genotypes G1–G4. We report evidence of this spread in a population sample within rural Ecuador. A total of 1,656 stool samples were collected from both patients with diarrhea and asymptomatic residents in 22 remote communities in northwestern Ecuador from August 2003 through February 2006. Rotavirus was detected in 23.4% of case-patients and 3.2% of controls. From these 136 rotavirus-positive samples, a subset of 47 were genotyped; 72% were of genotype G9, and 62% were genotype P[8]G9. As a comparison, 29 rotavirus-positive stool samples were collected from a hospital in Quito during March 2006 and genotyped; 86% were of genotype P[8]G9. Few countries have reported P[8]G9 rotavirus detection rates as high as those of the current study. This growing prevalence may require changes to current vaccination programs to include coverage for this genotype.

High prevalence of enteroinvasive Escherichia coli isolated in a remote region of northern coastal Ecuador

Enteroinvasive Escherichia coli (EIEC) causes dysentery; however, it is less widely reported than other etiological agents in studies of diarrhea worldwide. Between August 2003 and July 2005, stool samples were collected in case-control studies in 22 rural communities in northwestern Ecuador. Infection was assessed by PCR specific for LT and STa genes of enterotoxigenic E. coli (ETEC), the bfp gene of enteropathogenic E. coli (EPEC), and the ipaH gene of both enteroinvasive E. coli and Shigellae. The pathogenic E. coli most frequently identified were EIEC (3.2 cases/100 persons) and Shigellae (1.5 cases/100 persons), followed by ETEC (1.3 cases/100 persons), and EPEC (0.9 case/100 persons). EIEC exhibited similar risk-factor relationships with other pathotypes analyzed but different age-specific infection rates. EIEC was the predominant diarrheagenic bacteria isolated in our community-based study, a unique observation compared with other regions of the world.

Environmental change and infectious disease: how new roads affect the transmission of diarrheal pathogens in rural Ecuador

Environmental change plays a large role in the emergence of infectious disease. The construction of a new road in a previously roadless area of northern coastal Ecuador provides a valuable natural experiment to examine how changes in the social and natural environment, mediated by road construction, affect the epidemiology of diarrheal diseases. Twenty-one villages were randomly selected to capture the full distribution of village population size and distance from a main road (remoteness), and these were compared with the major population center of the region, Borbón, that lies on the road. Estimates of enteric pathogen infection rates were obtained from case-control studies at the village level. Higher rates of infection were found in nonremote vs. remote villages [pathogenic Escherichia coli: odds ratio (OR) = 8.4, confidence interval (CI) 1.6, 43.5; rotavirus: OR = 4.0, CI 1.3, 12.1; and Giardia: OR = 1.9, CI 1.3, 2.7]. Higher rates of all-cause diarrhea were found in Borbón compared with the 21 villages (RR = 2.0, CI 1.5, 2.8), as well as when comparing nonremote and remote villages (OR = 2.7, CI 1.5, 4.8). Social network data collected in parallel offered a causal link between remoteness and disease. The significant and consistent trends across viral, bacterial, and protozoan pathogens suggest the importance of considering a broad range of pathogens with differing epidemiological patterns when assessing the environmental impact of new roads. This study provides insight into the initial health impacts that roads have on communities and into the social and environmental processes that create these impacts.